MICROBIOLOGY NOTES FOR SEPT 2017 CLASS REVISED.ppt
- 2. CONTENT • The students will be able to acquire knowledge, skills, and attitude to be able to promote health, prevent illness, diagnose and manage patients/clients suffering from microbial infections, parasites, and immunosuppression. 2
- 3. Specific objectives 1. The student will be able to explain historical development of microbes and its relevance in nursing. 2. The student will be able to identify various classes of microorganisms and parasites 3. The student will be able to explain immunological process 3
- 4. Content 1. Introduction to microbiology 2. Historical background of microbiology 3. relevance of microbiology to nursing 4. Micro-organisms: • Sources of microbes • Properties of microbes • Infection process • Mode of transmission of infections 4
- 5. Micro-orgnisms • Structure • Morphology <shape> • Classification of micro-organisms Bacteria Viruses Fungi <yeast> Rickettsia and clamydiae Protozoa Helminthes 5
- 6. Immunology • Body defence mechanisms • Humoral immunity • Antibodies • Complement systems • Cell mediated immunity • Hypersensitivity 6
- 7. Immunology • Anaphylaxis • Delayed hypersensitivity • Immunological tolerance • Auto-immune diseases 7
- 8. Teaching and learning methods • Group discussion • Lecture • Assignments • Self directed learning • Demonstrations • Video show 8
- 9. Resources • Flip charts • Flip chart stand • Procedure manuals • Models • Text books • Computers • Manuals • DVD player • DVD 9
- 10. Microbiology • Microbiology is derived from a greed word Micro= small, tiny, minute Bio= life Ology= study Micro-biology is the study of micro-organisms which very small and cannot be seen by naked eye. 10
- 11. Definition of terms • Pathogens/the infectious or causative agent: Microbes that are capable of causing disease are called pathogenic. • Infectious disease process: The interaction between the pathogen microorganism, the environment and the host 11
- 12. Definition of terms • An infection: when pathogen invades the body and the conditions are favorable for it to multiply and cause injurious effects or disease. • The resulting condition is called an infection 12
- 13. Definition of terms Infectivity: Multiplication of an infectious agent within the body. Pathogenicity: The ability of an infectious agent to cause disease. Virulence: The quantitative ability of an agent to cause disease. Virulence involves invasiveness and toxigenicity. 13
- 14. Definition of terms Toxigenicity: The ability of a microorganism to produce a toxin that contributes to the development of disease Invasion: The process which bacteria, parasites, fungi and viruses enter the host cells or tissues and spread in the body. 14
- 15. Definition of terms Many factors determine the virulence of bacteria, or their ability to cause infection and disease. Toxins: Endotoxin, Exotoxins Enzymes Antiphagocytic factors Adherence factors 15
- 16. Definition of terms Toxins produced by bacteria are generally classified into two groups: Endotoxins:derived from bacterial cell walls and are often eliberated when the bacteria lyse (death). Endotoxemia: is the the presence of endotoxins in the blood. 16
- 17. Definition of terms • Exotoxins: are biological poisons secreted by microorganisms • Can cause damage to the host by destroying cells or disrupting normal cellular metabolism 17
- 18. Definition of terms • Vaccine: an antigenic substance prepared from the causative agent of a disease or a synthetic substitute, used to provide immunity against one or several diseases • Incubation period – the time between exposure to a pathogenic organism and when first symptoms apparent Opportunistic- a pathogen becomes a pathogenic when host is compromised 18
- 19. Branches of micro-biology It is divided into branches according to the types of micro-organisms 1.Parasitology; the study of parasites 2.Mycology ; study of fungi/yeast 3.Bacteriology; bacteria 4.Virology; viruses 5.Protozoology; protozoa 19
- 20. Historical development of micro- biology • In ancient times, men associated illnesses with sorts of will and hypothetical factors. • E.g. Gods wrath, ancestral spirits, demons, witchcrafts, bad weather e.t.c 20
- 21. Evolution of micro-biology • Antony Leeuwenhoek (1632-1723); discovered bacteria using primitive microscope. • He help described many microorganisms 21
- 22. Evolution of micro-biology • Robert hook (1822-1895) • He developed compound microscope in 1672 and confirmed Leeuwenhoek observation. 22
- 23. Evolution of micro-biology • Louis Pasteur (1822-1895) • Was a French chemist who contributed much to medical knowledge. • He disapproved that life arose from decomposing non-living material but proved that it arose from pre-existing life (biogenesis) 23
- 24. Evolution of micro-biology Louis Pasteur • He demonstrated that boiling of substances (fluids) rendered them sterile. • He added that such sterilized fluids can be contaminated by particles form air. 24
- 25. Evolution of micro-biology Louis Pasteur i. He discovered that fermentation involved in the production of beer and wine is the results yeast. ii.He showed that it is possible to weaken (attenuate) pathogenic micro-organisms or microbes and use then for immunization. 25
- 26. Evolution of micro-biology Louis Pasteur • He introduced 4 vaccines (for; small pox, cholera, anthrax, and rabies) • He also discovered many pathogenic micro- organisms and invented means of culturing them in the lab. 26
- 27. Evolution of micro-biology 6. Joseph Lister (1827-1912) • He was a surgeon. • As a surgeon, he observed that wound suppuration mortality rate following surgery was alarming. • He concluded that if micro-organisms caused fermentation, they wound also cause suppuration of wounds. 27
- 28. Evolution of micro-biology Joseph Lister • He introduced aseptic technique and recommended: i. Washing of wounds with disinfectants ii. Spraying operating theatre environment with disinfectants iii.Application of protective dressing on the wounds to prevent entry of micro-organisms iv. There was marked reduction of death among operated patients. 28
- 29. Evolution of micro-biology 6. Robert Koch 1843-1910 • He was a German physician who had a lot of interest in the study of bacteria. • In 1870, he cultured Bacillus anthraxis • He showed that anthrax is caused by a bacteria found in animals 29
- 30. Evolution of micro-biology • OTHERS • Hansen (1874) described leprosy bacillus • Neisser (1879) ,, gonococcus • Ogoston (1881) discovered staphylococcus • Loeffler (1884) isolated diphtheria bacillus • Nicolaire (1884) observed tetanus bacillus in the soil • Fraenuel (1886) described pneumococcus 30-Apr-23 30 MAKUMI
- 31. Evolution of micro-biology cted • Schaudin & Hoffman discovered spirocheate of syphilis. • Roux & Yersin (1888) described mechanism of pathogenesis when they discovered diphtheria toxin • Loeffler & Frosch (1898) observed that foot & mouth disease of cattle was caused by a microbe ie filter passing virus 30-Apr-23 31 MAKUMI
- 32. Evolution of micro-biology cted • Walter Reed (1902) observed yellow fever was caused by a filtrate virus which was transmitted thru’ mosquito bites • Towert (1951) & Herelle (1917) discovered Red Lytic phenomenon in bacterial culture which the agent responsible was termed as bacteriophage (viruses that attack bacteria) 30-Apr-23 32 MAKUMI
- 33. Evolution of micro-biology cted • Landsteiner & Popper (1909) showed poliomyelitis was caused by filterable virus • Fleming (1925) made an accidental discovery that the fungus Penicillin produces a substance which destroys staphylococci • Ruska (1934) introduced electron microscope & hence detailed study morphology of virus 30-Apr-23 33 MAKUMI
- 34. SOURCES AND SPREAD OF INFECTION Sources of infection Environmental sources Person- to-person Medical or surgical procedures Self-infection Inanimate objects Water, food, soil, etc. Animals (bites and scratches; zoonoses) Arthropod vectors Airborne infection Direct contact (touching, kissing, etc.) Maternal transmission (intrauterine, transplacental) Sexual transmission Instrumentation, operations Transfusion (blood and blood products) Transplants (tissues, organs) Endogenous sources (normal flora) Shared needles Needlestick injuries Infected person or healthy carriers
- 35. RELEVANCE OF MICROBIOLOGY TO NURSING • Nurse becomes familiar with the source of potentially dangerous microorganisms e.g. animal transmit anthrax, insects like mosquito transmit malaria, drinking contaminated water causes diarrhea. • Nurse is able to describe the effect of pathogenic and non pathogenic microorganisms in the human body. 35
- 36. Relevance of microbiology to nursing • Nurse is able to apply the knowledge in management of disease conditions • She gets to understand the various roots of entry and port of exit • With this knowledge he/she is able to arrest spread of infection b4 they occur. • He/she is able to participate in epidemiological research that enhances future discoveries and management of disease condition. 36
- 37. Classification of micro-organisms Bacteria Viruses Fungi <yeast> Rickettsia and clamydiae Protozoa Helminthes 37
- 38. Classification of microorganisms • Micro-organisms can either be pathogenic or non pathogenic • Can be further classified into 2 1.Unicellular- single cell, prokaryotes. fungi, bacteria, 2.Multicellular (eukaryotes) 38
- 39. Differences between Prokaryotes and eukaryotes Prokaryotes: bacteria eukaryotes • Less complex • Circular chromosomes • Lack nuclear membrane • Lack membrane bound organelles (mitochondrial, lysosomes • Divides through binary fission More complex True nuclears with nuclear membrane Membrane bound organelles Contain multiple chromosomes and mitotic apparatus E.gs of eukaryotic cells: plant; animal; protozoa, human; fungi; algae Divides by mitosis 39
- 40. Typical eukaryotic cell diagram
- 41. Typical prokaryotic cell diagram
- 42. Nomenclature • According to binomial Linear system that classifies and names animals and plants according to their natural relationship using both genus (generic) and the species name. • The 1st name is generic and 1st letter written in capital. • 2rd name is the species and is written in small letters e.g. Salmonella typhi, Mycobacterium tubercle, Candida albicans, Escherichia coli. 42
- 43. Reason for classifying micro-organisms 1. For purpose of grouping (how they are alike and how they are different. 2. For identification and determination of pathogens 3. To make treatment possible
- 44. BACTERIA SPORES • Resistant dormant state of the bacteria when under conditions of limited supply of nutrition vegetative forms • Eg. Bacillus, clostridium, rickettsial agent • Not destroyed by ordinary methods of boiling but autoclaving under very high temperatures of 121o C for 20 min • This is due to impermeability of the spores, cortex & coat, low H20 content, low metabolic & enzymatic activities 30-Apr-23 44
- 46. FUNCTIONS OF SPORES • Facilitate survival of certain organisms under unfavourable conditions –Resistant to heating, drying, freezing & toxic chemicals 30-Apr-23 46
- 47. GERMINATION OF SPORES • Germination is the process of converting a spore into a vegetative cell. • In a bacteria, it takes less than 2 hours and has 3 stages 1. Activation Growth is spontaneous or may be through activators like heat, low PH etc 30-Apr-23 47
- 48. GERMINATION OF SPORES 2. Germination proper This requires water & a trigerring germination agent like manganese or alanine 3. Outgrowth Occurs following germination in a nutrient medium after which gradual resumption of life of bacteria begins 30-Apr-23 48
- 49. NUTRITIONAL REQUIREMENTS OF BACTERIA • For optimal growth, the bacteria require the following:- 1. GAS- 4 types a) Obligate Anaerobes- only grow in absence of O2 EG Clostridium b) Falcultative Anaerobes- can grow in presence or absence of O2 30-Apr-23 49
- 50. NUTRITIONAL REQUIREMENTS OF BACTERIA C). Obligatory Aerobes- cannot grow in absence of O2 eg Pseudomonas d). Microphilic organisms- grow under conditions with low O2 tension eg clostridium tetani e). Some will require CO2 for their growth eg Nisseria gonorrheae & Brucella Arbotus 30-Apr-23 50
- 51. NUTRITIONAL REQUIREMENTS OF BACTERIA 2). Temperature 3 types of bacteria a). Psychrophilic – grow in temperature range of 5- 300C but average of 10- 200C b). Mesophilic- grow in 20- 400C bu a range of 10- 400C c). Thermophilic- require temp of 25- 800C but grow well at 50- 600C 30-Apr-23 51
- 52. NUTRITIONAL REQUIREMENTS OF BACTERIA 3). PH – most bacteria require a PH of 7.2- 7.6 for optimal growth 4). Moisture – water is required for growth 5. Ionic strength and osmotic pressure. 6. Light. Optimum condition for growth is darkness 30-Apr-23 52
- 53. BACTERIAL GROWTH CURVE 1. LAG PHASE; There is increase in size of bacteria without multiplication for some time –Has short duration with the following:- • Increase in size of cell • Increase in metabolic rate • Adaptation to new environment 30-Apr-23 53
- 54. BACTERIAL GROWTH CURVE 2. LOG PHASE-(Logarithmic phase or Exponential phase) –The cells start to divide –Numbers increase –High metabolic rate –Bacteria are more sensitive to antibiotics 30-Apr-23 54
- 55. 3. STATIONARY PHASE –Rate of multiplication & death are almost equal –This is due to depletion 0f nutrients –Accumulation of toxic materials –Sporulation may occur. – Sporulation is the process of producing spores. 30-Apr-23 55
- 56. 4. DECLINE PHASE • Cells die hence decrease of bacteria • This is due to:- –Nutritional –Accumulation of toxic materials –Autolysis of enzymes 30-Apr-23 56
- 57. 5. SURVIVAL PHASE – Many organisms have died – A few survive for months or years 30-Apr-23 57
- 59. Bacterial Growth Curve NB • CFU- Colony Forming Unit. Used to estimate t he number of viable bacteria. 59
- 60. BACTERIA Structure and characteristics: 1.Are unicellular/some are Multicellular 2.Their cytoplasm contain both DNA and RNA 3.They produce by binary fission 4.Have no defined nucleus 5.Shape: can be divided into various classes depending on their shapes, size, and characteristics.
- 61. Bacteria They survive in two forms; 1.Free living- capable of growing on lab media in absence of human or other animal 2.Obligate intracellular- survive only within hum an or other animal cells NB: ASSIGNMENT- DRAW A DIAGRAM OF BACTERIA AND DESCRIBE VAROUS ORGANELLES 61
- 62. Bacteria cell
- 63. Microscopic structure of bacteria cell Capsule: Is the outermost, slimy coating over the bacterial surface. • It provides protection against phagocytosis by host cells • It confers increased virulence of bacteria possessing them. • It helps in reliable means of diagnosis in bacterial infections 63
- 64. Microscopic structure of bacteria cell Cell wall • It contributes to the ultimate shape of the organism • Helps in bacterial identification • Gives rigidity to the organism 64
- 65. Microscopic structure of bacteria cell Flagella • Are long helical filaments extending from the cell surface • Aids in bacterial motility • Flagella are built of protein components (flagellum) which are strong antigenic. These antigens are important targets of protective antibody responses. 65
- 66. Microscopic structure of bacteria cell Pilli A very thin hair like external appendages of a cell protruding from the Capsule. Aid in bacterial attachment. Motility and DNA exchange. 66
- 67. Microscopic structure of bacteria cell NUCLEA It contains the genetic material of the cell. It stores hereditary materials in the form of DNA strands. Also stores ribonucleic acid RNA in the Nucleas. It is responsible for protein synthesis, cell division and growth. 67
- 68. BACTERIA • Only pathogenic bacteria cause disease in man or animals • Comensals- live on the host but do not cause harm to the host under normal circumstances • Bacteria of medical importance can be divided/grouped depending on structure, shape, size, staining properties, and ability to form spores. 68
- 69. Shape and size • Bacteria are found in 3 shapes: a. Cocci (spherical)- Cocci have characteristics arrangements: i. Diplococci- occur in pairs ii. Streptococci- occur in chains iii.Staphylococci- occur in clusters b.Rod shaped- are mainly bacilli which may have square round ends, club shaped c. Spiral shape-appear like relaxed coil e.g. treponema, spirochaetes 69
- 70. Diagrammatic shapes of bacteria
- 71. Shapes of bacteria Bacterial cell shapes • A=bacillus or pl. bacilli • B= round, coccus, cocci pl., in chains “Streptococcus) • C. Staphylococcus – clusters • D= diplococcus • E=Spirillum, spirilla pl. • Spirochete is a corkscrew shape • F= vibrio, more comma shaped
- 72. Shapes of Cocci • Diplococci- double • Staphylococci- cluster • Streptococci – chain • Tetrad – in fours • Sarcina – in groups of eight 30-Apr-23 72
- 73. Characteristics of bacteria Spore forming bacteria • Some bacteria especially rods / bacilli form a thin keratin like coat that allows bacteria to survive for years in the soil. • Spores are formed when nutrients are in short supply. • But when nutrients are formed, spores germinate to form bacteria which can cause disease. Spore forming bacteria are highly heat resistant. • Non spore forming bacteria have no spores. 73
- 74. Characteristics of bacteria Staining properties • Through staining (exposure to dyes) bacteria can be divided into two, i.e. i. Gram positive bacteria: takes a blue dye i.e. it stains blue ii.Gram negative bacteria stains red. 74
- 75. Characteristis of bacteria • Obligatory anaerobes cannot grow in presence of O2 E.g. clostridium tetani. • Obligatory aerobes can only grow in the presence of O2. 75
- 76. COCCI • Diploccocci • Eg. Pneumococus • Gram negative • Normally in human throat. • Require media with blood, serum or ascitic fluid to grow. • Sensitive to Sulphonamides. 76
- 77. Diseases caused by Pneumococcus • Lobar pneumonia • Broncho pneumonia • Pneumococcal meningitis • Suppurative lesions like emphyma, pericarditis, otitis media, sinusitis, conjuctivitis & peritonitis 30-Apr-23 77
- 78. COCCI GRAM POSITIVE COCCI 1.Streptococcus • Mostly exist as normal commensal cell in humans e.g. the skin, mouth, nasophalynx. • When they become pathogenic they cause pyogenic (pus forming) diseases ranging from boils to septicaemia 78
- 79. COCCI Pathogenic streptococcus include: i. Beta Haemolytic streptococcus- it causes sore throat, pharyngitis, .e.t.c ii.Streptococcal pneumonia- causes pneumonia, tooth abscess, meningitis iii.Streptococcal faecalis (enterococcus faecalis), streptococcal viridans- causes endocarditis, urinary tract infections. 79
- 80. COCCI 2. Staphylococcus • They are normal flora of in the skin, mouth, and nasophalynx. • They causes boils, toxic shock, pneumonia, pemphigus neonatorium, food poisoning, and surgical wound infections. e.g. staphylococcus aureus, staphylococcus epidermidis, e.t.c. NB: Streptococcus and staphylococcus are very common causes of hospital acquired infection (nosocomial infections) 80
- 81. COCCI GRAM NEGATIVE COCCI 1.Nesseria • Genus Nesseria contains two important human pathogens. • They contain endotoxin: causes- fever, chock, and other pathological changes. 81
- 82. COCCI The 2 common infection caused by bacteria are: i. Nesseria meningitidis • Causes meningococcal meningitis • Is transmitted via airborne droplets • Easily causes outbreak of meningococcal disease in colleges and schools and students live in dormitories • It causes pyogenic type of infection 82
- 83. COCCI ii. Nesseria gonorrhoeae • Causes gonorrhea and ophthalmia neonatorum in newborns • Transmitted sexually, newborns are infected during child birth. 83
- 84. BACILLI Bacilli • These can be: Gram positive, spore forming Gram positive, non spore forming Gram negative Acid fast 84
- 85. BACILLI 1. Gram positive spore forming bacilli (rods) i. Bacillus anthracis • A spore forming bacillus • Anaerobic • Found in herbivals and is also a Zoonotic disease <animals and their products: wool, carcasses, meat, hides • Causes anthrax disease via eating of infected meat or contact with their products 85
- 86. BACILLI 2. Clostridium species • Are spore forming gram positive. Examples includes: i. Clostridium tetani • Found in soil • Produces toxins <tetanospasmin> a neurotoxin • Causes tetanus: a disease characterized by painful muscular spasms that can lead to respiratory failure • Newborn babies can get infected via umbilical stump. 86
- 87. CHARATERISTICS OF TETANUS 4/30/2023 MAKUMI 87
- 88. BACILLI ii. Clostridium perfringen <welchii> • Found in the soil and normal flora of the colon and vagina • Produces enterotoxin: causes- food poisoning, myonecrosis, gas gangrene, cellulitis. • And necrotizing fascitiis (The infection leads to death of body tissues. Areas mostly affected are the limbs and perineum. 88
- 89. BACILLI Clostridium perfringen <welchii> • Clostridial food-borne disease. • Heat resistance spores survive cooking and germinates. Causes diarrhoea. • It can also cause septic abortion 89
- 90. BACILLI iii. Clostridium botulinum • Anaerobic, spore forming • Wide spread in soil, contaminated vegetables and meat especially canned food. • Toxin contamination occurs in inadequately cooked food. • Causes botulism <toxin>: • food poisoning 90
- 91. BACILLI GRAM POSITIVE NON-SPORE FORMING BACILLI. There are 2 types of medical importance i. Corynbacterium diphtheriae • Corynebacteria : aerobic, rod-shaped bacteria • Causes diphtheria disease; an upper respiratory tract infection. • Diphtheria toxin produced by C. diphtheriae, can cause myocarditis, polyneuritis, and other systemic toxic effects 91
- 93. BACILLI ii. Listeria monocytogenes • Gram +ve rod, individually or in short chains non-spore forming. • Causes infection Listeriosis. • Most virulent foodborne pathogens. • It is a fulcatative anerobic. 93
- 94. BACILLI Listeria Monocytogenes cont • There4 storage of contaminated food in refrigerators enhances growth of the bacteria. • Causes: G/E, menengitis, sepsis in newborns, pg women, and iss pts. • It is found in animals, plants and in soil from where it is transmitted into humans primarily by ingestion or raw vegetables. 94
- 95. BACILLI ACID FAST BACILLI • This group of rod‐shaped bacteria possesses large amounts of mycolic acid in the cell wall: makes the bacteria very difficult to stain, the bacteria resist decolorization with a dilute acid‐alcohol solution. Therefore, they are said to be acid‐fast. 95
- 96. BACILLI ACID FAST BACILLI i. Mycobacterium tuberculosis <tubercle bacilli> • Commonest of AFM and causes TB in man • Transmitted through droplets • It is obligate aerobe 96
- 97. BACILLI ii. Mycobacterium leprae • Transmitted via direct skin contact • It causes leprosy 97
- 98. BACILLI iii. Mycobacterium bovis • Mainly found in cows and humans • Causes milliary tuberculosis • In human it is spread by droplet infection • Also spread via contaminated/ infected cattle products 98
- 99. Gram negative non-spore forming rod • Usually affect the GIT (Gastrointestinal Tract.) 1.Enterobacteria: a large family of gram negative rods in the colon of human and other animals • many of which are normal flora. • They are the major facultative aerobes in he large intestines 99
- 100. i. Escherichia coli: • Normal flora in the colon. • It colonizes the vagina and the urethra • Also causes diarrhoea acquired via fecal-oral route and neonatal sepsis acquired during child birth. • Women are predisposed to UTI (Urinary Tract Infections) coz of proximity of anus to urethra and vagina. 100
- 101. BACILLI ii. Salmonella typhi • Live the human colon • It is a motile, facultative anaerobe • Causes typhoid fever • The disease is transmitted via oral-fecal route 101
- 102. BACILLI iii. Salmonella enteritis <enterica> • It invades mucosa of small and large intestines • It causes salmonellosis • It also causes entero-colitis and sepsis 102
- 103. BACILLI iv. Shigella species • Causes enterocolitis called bacillary dysentery <bloody diarrhoea> • Species that commonly cause diarrhoea are: Shigella dysenteriae Shigella sonnei • Are transmitted via oral fecal route. 103
- 104. v. Vibrio cholerae • Coma shaped • Causes cholera • Habitat is the human colon • Transmitted via fecal oral route 104
- 105. iv. Helicobacter pylori • Spiral shaped. • Gram negative • Habitat is human stomach • Causes gastritis, stomach and duodenal ulcers • A risk factor for gastric Cancer. 105
- 106. vii. Klebsiella • Habitat is human upper respiratory tract and GIT • Causes pneumonia through inspiration of the organism, urinary tract infection via inoculation with fecal matter 106
- 107. Gram negative rods affecting respiratory tract i. Haemophilus influenzae (coco bacilli) • Causes sinusitis, otitis media, and pneumonia • Transmitted via droplet ii.Bordetella Pertussis (coco bacilli) • Inhibits human respiratory tract • Causes whopping cough or pertussis • Transmitted via droplet. 107
- 108. Spirochaetes • These organisms differ from the ‘true’ bacteria in being slender flexuous spiral filaments. • Which, unlike the spirilla, are motile without possession of flagella. • Gram-negative Prokaryotes. • Vary in size, shape, waveform and refractility,
- 109. Spirochaetes cntd. • Spirochaetes, such as Treponema pallidum, the causative agent of syphilis, • Have a flexible cell wall enabling them to move readily through tissues • Other examples are Borellia; lyme disease- spread by Tick-Affects brain –Relapsing Fever. Leptospira ; Leptospirosis-blood disease found in animals. Spread by Tick- causes renal failure
- 110. Mycoplasmas • Are prokaryotes that differ from ‘true’ bacteria in their smaller size and their lack of a rigid cel l wall • which leads to extreme pleomorphism (they a ppear in various shapes) and sensitivity to ext ernal osmotic pressure.
- 111. Mycoplasmas contd. • are the smallest and simplest organisms capab le of autonomous growth • have no rigid cell shape • reproduce slowly, are relatively fragile, and are resistant to antibiotics that deter cell wall synt hesis. • Causes Mycoplasmas Pneumonia and Mycopl asmas Genitalium.
- 112. Chlamydiae • Are rod-shaped, spherical or pleomorphic Gram-negative organisms. • Are obligate intracellular bacteria • Are agents of common sexually transmitted diseases: urethritis, cervicitis, lymphogranuloma venereum • It also causes: trachomatis (conjunctivitis, trachoma), and pneumonia 112
- 113. Rickettsiae • Are rod-shaped, spherical or pleomorphic Gram- negative organisms. • Are obligate intracellular • Agents of typhus fever, spotted fevers, & Orienta fever. • Transmitted by arthropods such as ticks, lice, fleas, mites • R. Prowazeki is transmitted by human body louse leading to epidemic typhus fever disease 113
- 114. 114 Rigid thick walled cells Flexible, thin walled cells Wall –less cells Free living(Extracellular bacteria) Non free living(Obl.I.P) Gram positive Acid fast Gram negative Cocci Spore forming rods Non spore forming rods Aerobic Anaerobic Non filamentous filamentous Rods cocci Facultative Aerobic Anaerobic Resp. organisms Zoonotic org. Enteric & related org
- 115. Classification of medically important bacteria 1. Rigid, thick-walled cells 2. Flexible, thin-walled cells 3. Wall-less cells 115
- 116. Classification of medically important bacteria Rigid, thick-walled cells A. Free living (extracellular bacteria) B. Non-free-living (obligate intracellular parasites) 116
- 117. Classification of medically important bacteria Free living (extracellular bacteria) i. Gram-positive bacteria ii. Gram negative bacteria iii. Acid fast bacteria 117
- 118. Classification of medically important bacteria I. Gram positive: a. Cocci: -genus- streptococcus. It causes pneumonia, pharyngitis, cellulitis -genus-staphylococcus. It causes abscess of skin and other organs b. Spore Forming Rods: -aerobic e.g. bacillus, it causes anthrax -anaerobic e.g. clostridium, it causes tetanus, gas gangrene, botulism 118
- 119. c. Non Spore Forming Rods; Non filamentous e.g. -Corynbacterium causes diphtheria -Listeria causes meningitis 119
- 120. Filamentous e.g. -Actinomyces, causes actinomycosis Infection involving the deeper tissue of the skin and mucous membrane of head and neck. Lesion tumour like masses. -Nocardia, causes nocardiosis Illness like TB coughing blood, chills, light sweat etc. weight loss. 120
- 121. 2. Gram Negative Bacteria a.Cocci: genus; Nesseria. It causes; gonorrhea, meningitis, b.Rods -facultative -aerobic -anaerobic 121
- 122. i. FACULTATIVE: • Respiratory organisms; -Haemophilus which cause meningitis -Borditella: causes Whooping cough -Legionella: causes pneumonia • Zoonotic organisms -Brucella: causes Brucellosis -Pasteurella: causes Cellulitis -Yersinia: causes Plague 122
- 123. • Enteric and related organisms -Escherichia: it causes UTI, Diarrhea -Enterobacter: it causes UTI -Klebsiella: Pneumonia, UTI -Salmonella: Enterocolitis, Typhoid fever -Shigella: Enterocolitis -Proteus: UTI -Campylobacter: Enterocolitis -Helicobacter: Gastritis, Peptic ulcer -Vibrio: Cholera 123
- 124. ii. AEROBIC - Pseudomonas: Pneumonia, UTI iii. Anaerobic - Bacteroides: Peritonitis 3. Acid fast bacteria - Once stained cannot loose the stain even when washed with acid alcohol. -Mycobacterium: TB, leprosy 124
- 125. NON FREE LIVING (obligate intracellular parasites) -Rickettsia: Typhus fever -Chlamydia: Urethritis, Trachoma 125
- 126. Flexible, thin-walled cells bacteria (Spirochetes) -Borrelia: Lyme disease -Spread by tick. -Affect brain. -Relapse fever. Neck stiffness, chronic fatigue. -Treponema: Syphilis 126
- 127. • Leptospirosis -Spread through animal urine. -Affects people who handle infected animals & infected tissues. -Symptoms: headache, muscle pains, fever to severe bleeding from the lungs, skin & mucous membrane, Jaundice and kidney failure. Wall-less cells bacteria -Mycoplasma: Pneumonia 127
- 128. MYCOLOGY 128
- 129. Mycology • Fungi are eukaryotic organisms. There are two types of fungi: Yeast and molds. • Yeast grow as single cells while molds grow as long filaments. • Most are obligate anaerobes. 129
- 130. Mycology • Candida albicans is part of normal human flora. • Intact skin is an effective host defense mechanism. • Against certain fungi (Candida, dermatopytes) . • Normal flora of skin and mucous membrane suppress fungi. • Antibiotics can inhibit normal flora and overgrowth of fungi e.g. Can. albicans can occur. 130
- 131. Mycology GENUS HABITAT PORTAL OF ENTRY DISEASE Histoplasma Soil (associated with bird’s faeces) Inhalation into lungs hisostoplasmis Cryptococcus Soil (ass with pigeon droppings inhalation Cryptococcal meningitis Aspergillus Soil and vegetation Inhalation into lungs Aspergillosis Candida Human body N. Flora of skin, GIT, & vagina Candidiasis 131
- 132. • Aspergillosis -It usually affects the respiratory system persistent fever, cough, shock, deliriums leading to liver failure, kidney failure then death. 132
- 133. Cutaneous, subcutaneous, and Opportunistic Mycosis Medical mycosis can be divided into 4 1.Cutaneous 2.Subcutaneous 3.Systemic 4.Opportunistic 133
- 134. Cutaneous, subcutaneous, and Opportunistic Mycosis Type Anatomical location -Representative diseases Serious ness of disease genus/ causative org. Cutaneous Dead layer of skin Epidermis, hair, nails -Tinea versicolor -Dermatopytosis (ringworm) 1+ 2+ -Malassezia Epidermophy ton Subcutaneous Subcutis Sporotrichosis Mycetoma 2+ 2+ Sporothrix Several genera Systemic Internal organs -Histoplasmosis -Blastomycosis 4+ 4+ Histoplasma Blastomyces Opportunistic Internal organs -Cryptococcosis -Candidiasis -Aspergillosis -Mucormycosis 4+ 4+ 4+ 4+ Cryptococcus Candida Aspergillus Mucor,
- 135. • Mucormycosis -Attacks blood vessel walls. -Attacks nerves etc. -Fungal infection and very fatal. -Attacks patients with diabetes. 135
- 136. • Tinea vesicolor -Skin diseases. -Acid bleaches from the yeast causes spots or patches on skin. • Dermatopytosis Ringworms. • Sporotrichosis mycetoma -Caused by penetrated trauma to the skin form tumour like mass ( madula foot). 136
- 137. • Histoplasmosis -Technically silent manifestations and no ill effect. Acute phase is flu like. Chronic phase resembles TB. Its fatal unless treated. • Blastomycosis -Present as a primary lung infection in 70% of the cases are suggestive of pneumonia – later affect skin causing lesions in 60% of cases. 137
- 138. Cutaneous Mycosis Dermatopytosis (Tinea, rings worms) • Are chronic infections often in warm humid areas of the body • Lesions have inflamed circular border containing papules & vesicles. i. Tinea capitis - scalp ii. Tinea cruris – groin, & P.area iii.Tinea unguium - hands iv.Tinea barbae – beard area v. Tinea pedis – athletes feet vi.Tinea corporis – other body parts eg Trunk. 138
- 139. Fungi and Yeast • These are eukaryotes that lack chlorophyl • Reproduce by budding or by forming spores • Have rigid cell wall • Are either simple oval cells or long tubular septate hyphae (with true lateral branching) • They need organic compounds as nutrients 30-Apr-23 139
- 140. Fungi and Yeast • They break down complex carbohydrates & proteins of dead bodies of other organisms (scavangers) • Useful in fermentation, baking bread, making antibiotics • 30-Apr-23 140
- 141. CLASSIFICATION • Morphologically, Fungi is divided into four 1.Moulds • Filamentous & mycelial fungi- long filaments or hyphae which branch & interlace • Reproduce by forming spores 2. Yeasts • Spherical in shape & unicellular • Reproduce by budding • Example- cryptococcal neoforms 30-Apr-23 141
- 142. 3. Yeast like Fungi – Grow partly as fungi & partly as long filamentous cells forming pseudo- mycelin – Form creamish colonies on the substances – Example- Candida Albicans 4. Dimorphic Fungi – Grow like mycelin but in low temp of 22oC – Pathogens are- Histoplasma Capsulatum, Blastomyces etc 30-Apr-23 142
- 143. VIRUSES 143
- 144. Viruses Objectives: students should be able to: 1.State general properties of viruses 2.Correctly classify viruses 3.Describe viral replication process 4.Give examples of DNA & RNA viruses plus the associated diseases 144
- 145. VIRUS 30-Apr-23 145
- 146. 146
- 150. Morphology of Virus • Vary according to:- • Size – smaller than other micro organisms • Shape- bullet eg rabies – brick eg smallpox or chickenpox –Bacteriophage has head & tail –Spherical eg influenza & polio 30-Apr-23 150
- 151. • Structure- – some have RNA & others have DNA – Core of nucleic acid is coated by a protein CAPSID – Capsid is composed of capsomeres – A viron may be enveloped or non enveloped 30-Apr-23 151
- 152. Reaction to physical & chemical agents • Heat & cold- mostly destroyed by heating at 60oc for 30 minutes except Hepatitis virus & Adeno viruses. Some are preserved in very low temp -20 to -70oc • PH- stable at 5- 9 • Ether- some are destroyed by ether like Arbo, Myxo & Herpes • Radiation- UV light, X- Rays inactivate viruses 30-Apr-23 152
- 153. Reaction to physical & chemical agents • Salt- magnesium chloride & sulphate stabilize some viruses inorder to resist heat at 50oC • Disinfectants- lysol & Dettol are not effective against viruses but higher concentration of chlorine & iodine may kill them • Antiviral agents- specific drugs will destroy or kill specific viruses. 30-Apr-23 153
- 154. Properties of viruses • Consist either RNA or DNA but never both • Obligate intracellular parasites • Fail to grow on artificial media • Smallest infectious agents • Nucleic acid is enclosed in a protein shell • Entire infectious unit is also called a Virion • Not inactivated by antibiotics • Divide by replication 154
- 155. Classification of human viruses Human viruses can be classified: 1.Depending on area/body system affected i.e. i. Respiratory viruses ii.Enteric viruses 2. RNA or DNA (Kind of nucleic acid) 3. Single strand or double strand 4. Enveloped or no enveloped 155
- 156. DNA viruses • Adenoviruses • Poxviruses • Papovaviruses • Parvoviruses • Herpes simplex viruses • Varicella-zoster virus • Cytomegalovirus (CMV) • Epstein-barr (EB) virus. • Smallpox Virus. 156
- 157. RNA VIRUSES 1. Immune deficiency virus 2. Arboviruses 3. Rubella virus 4. Picornaviridae 5. Orthomyxoviridae 6. Paramyxoviridae 7. Rhabdoviridae 8. Rotavirus 157
- 158. RNA VIRUSES • Influenza Virus. • Human Parainflueza Virus. • Rabies Virus. • Polio Virus. • Coxsakie Virus. • Rhino Virus (Common Cold). • Hepatitis A,B,C,D Viruses. • Yellow Fever Virus. 158
- 159. Replication of viruses • Viruses are obligatory intracellular parasites • Lacks machinery of self propagation • They make use of the metabolic machinery of the host cell to synthesize their nucleic acids or proteins 159
- 160. VIRAL MULTIPLICATION 1. Adsorption- Attaches on the receptor site of the host cell (key & lock) 2. Penetration- The virus particles are engulfed by the host cell thru’ Viropexia (phangocytosis) 3. Uncoating- the virus loses its outer layer & capsid, then release of Nuclea Acid into the Cell. 4. Biosynthesis- synthesis of the viral nucleic acid &capsid protein stopping the normal host cell function 30-Apr-23 160
- 161. VIRAL MULTIPLICATION 5. Varion Assembly- i.e of various Viral component into Virion. 6. Release – from the destroyed host cell to other healthy cells NB: Antiviral drugs will interfere with the stages of development 30-Apr-23 161
- 162. DNA viruses Adenovises Characteristics • Are double stranded DNA genome • Inactivated by chlorine • No effective chemotherapy NB: adenovirus infection occur throughout the world, by age of 5yrs all children have been infected. 162
- 163. DNA viruses Adenovirus infections of human • Acute resp. disease • Sore throat • Epidemic keratoconjuctivities • Pneumonia • Acute hemorrhagic cystitis • Meningoenchophalitis • Swimming pool conjunctivitis • Febrile cold 163
- 164. DNA viruses Poxvirus • The family poxvirus belongs to the causative agent of small pox (has been eradicated from the earth) Characteristics • Large, brick shaped • Double stranded DNA • Contains 20 antigens 164
- 165. DNA viruses Other diseases associated with Poxviridae • Buffalo pox- mainly affect domestic buffaloes but can affect cows and human. Contagious zoonitic disease. Human become febrile, with vesicular lesions on hands and forearm’ • Cowpox. Infect human while milking the cow. S/S- Pustular eruption. 165
- 166. DNA viruses • Other diseases associated with poxviridae • Monkey pox- infection thro contact with pastulas or respiratory droplets. S/S- Flu like symptoms, pus filled blisters, diarrhoea, body rash, cough, sorethroat and lymphadenopathy • Tanapox. Infection is contagious or thro athropods. S/S – fever , pustula, nodular rash, 166
- 167. DNA viruses • Other diseases associated with poxviridae. Molluscum contagiosum – Skin disease marked by soft rounded cutaneous tumors caused by the virus. 167
- 168. DNA viruses Papovaviruses Characteristics • Non enveloped DNA • No effective chemotherapy The family papovavirus consist of 3 genera. • HPV has 80 serotypes: cause warts at different sites of human body 168
- 169. DNA viruses Parvovirus • Infection in the 1st trimester leads to missed & spontaneous abortions • Infection during 2rd trimester is associated with hydrops fetalis. • Aiso infects mamals eg Dogs, cats and birds. • No specific antiviral Rx 169
- 170. DNA viruses Herpesviruses • Family herpesviridae consist of more than 80 viruses. • Is double stranded linear DNA • There is great diversity in pathology & biology of herpes viruses • Common feature of herpes viruses: property of establishing latent infection lasting throughout life of the victim • 7 different herpes viruses whose natural host is man 170
- 171. DNA viruses Herpes simplex virus • Exist in 2 types: type 1 virus (HSV-1): affects regions of body above the waist • Type 2 virus (HSV-2): affects genital & anal regions Diseases caused by herpes simplex virus • Stomatitis (sore mouth), herpes labialis (h. lips), keratitis ( inflam of cornea), proctitis (inflam of the mucous membrane of the rectum), acute necrotic cervicitis, neonatal herpes, meningitis, encephalitis, genital lesions. 171
- 172. Genital Warts 172
- 173. Herpes labialis
- 176. DNA viruses Varicella zoster virus • Agent of 2 diseases: Varicella & herpes zoster • Varicella follows primary exogenous contact with causative virus • Zoster reflects endogenous activation of Varicella zooster virus infection that has survived in latent form following an attack of Varicella 176
- 177. DNA viruses Varicella zoster virus • Varicella is a contagious generalized exanthematous disease of seasonal epidemic • Commonly known as chickenpox • Common in children • Herpes zoster (shingles), common in elderly people. • Characterized by unilateral painful, vesicular eruption localized to dermatome innervated by specific dorsal root of extra medullary cranial ganglion 177
- 178. Zoster Shingles
- 179. DNA viruses Cytomegalovirus (CMV)- causes Cytomegalic inclusion disease. • Most common virus that affect man • Are found in salivary glands or renal tubules of many asymptomatic children’ • Most or the infections remain asymptomatic but in rare cases, when disease manifest, the outcome is usually fatal. 179
- 180. • Cytomegalovirus (CMV)- causes Cytomegalic inclusion disease. • Various manifestation include, fever, malaise, Pneumonia, lymphadenopathy, hepatomegaly and those that cause permanent damage to the brain. • Vertical transmission is possible causing still birth, low birth weight, growth retardation and malformations. 180
- 181. DNA viruses Epstein-Barr (EB) virus • Was discovered by Epstein & Barr • Features are same as for other members of family herpesviridae • Cause glandular fever (infectious mono-nucle osis): s & s- fever, lymphadenopathy, sore throat, malaise, fatigue • In ISS pts it may trigger Burkitt’s lymphoma 181
- 182. Burkitt's lymphoma
- 183. DNA viruses Human herpes virus 6 • Causes childhood illness Roseola Infantum. A benign illness ch aractered by high fever rash mostly occuring to babies ages 6 mnths -2yrs. • Causes severe infection such as fulminate hepatitis and Pneu monia in ISS Patient. Human Herpes virus 7. • A virus without a disease. Human Herpes Virus 8. Causes Karposis Sarcoma 183
- 184. RNA viruses Human immunodeficiency virus • HIV is a retrovirus that cause AIDS • In all organisms, DNA, is the store house of genetic information where its then transmitted into RNA • Sequence is reversed in HIV, genetic information is passed on from RNA to DNA with help of reverses transcriptase enzyme 184
- 185. RNA viruses • HIV has 3 antigens; 1.The core antigen 2.The envelope antigen 3.The RT (reverse transcriptase) enzyme HIV has 2 sub-types designated as HIV-1 and HIV-2 • Once infected with HIV, the virus gets integrated into the host chromosomes and the infection persist making the person at risk for developed virus associated disease throughout his life. 185
- 186. RNA viruses HIV: • Presence: various body fluids e.g. blood, semen, tears, saliva, vaginal fluids, breast milk, and urine, childbirth • Transmission: sexually (hetero and homosexual), blood transfusion, IV drug, breast milk, accidental needle stick injury • Incubation period: 1-10 years 186
- 187. RNA viruses Arboviruses • Are viruses which multiply in blood sucking arthropods and are transmitted to vertebrates by bite. • There are more than 500 Arboviruses • Most do not produce clinical disease in human • About 50 types produce serious ailment 187
- 188. RNA viruses Arboviruses Classification of Arboviruses based on clinical syndrome • Causing fever, rash, arthralgia: dengue, sandfly fever, West Nile • Causing haemorrhagic fever: yellow fever, dengue • Causing haemorrhagic fever with hepatitis and nephritis: yellow fever. 188
- 189. RNA viruses Arboviruses . Classification of Arboviruses based on clinical syndrome. • Causing encephalitis: tick-borne encephalitis, west Nile encephalitis • No specific Tx, usually asymptomatic • Vaccines are available 189
- 190. RNA viruses cont’d • West nile – spread by mosquito –s/s fever, headache, muscle aches, later encephalitis – stiff neck, convulsions. • Hemorrhagic fever –s/s fever, diarrhoea epistaxis, hemoptysis. Transmitted by anthropods. • Dengue – Presents like malaria through mosquito bite, bone pain. Patients immunized against the disease – 5 years duration – Also known as break bone fever. • Yellow fever – mosquito –s/s fever, jaundice and necrosis of liver. 190
- 191. RNA viruses Rubella virus • It causes German measles • The disease is important because it causes severe congenital malformations Clinical manifestation: rash, lymphadenopathy, fever. 191
- 192. RNA viruses Rubella Congenital rubella: microcephaly, retinopathy (damage to the retina), cataract, deafness, pulmonary stenosis, Patent duct arteriosus ( Ductus arteriosus fail to close at birth), ventricular septa defect. PREVENTION: through vaccination prior to attainment of reproductive age 192
- 193. RNA viruses Picornaviridae • One of the largest and most important family of human pathogens • These viruses are also the smallest (pico- small) • Members of this family: polio virus, coxsackie viruses, hepatitis A virus 193
- 194. RNA viruses Picornaviridae Characteristics: single stranded, nonenveloped, No effective Rx. Poliovirus: causes paralytic polio, aseptic meningitis Coxsackievirus: causes conjunctivitis, myocarditis, aseptic meningitis Enterovirus: conjunctivitis, gastroenteritis, viral encephalitis. Rhino virus: transmitted via droplet, causes resp. infections 194
- 195. poliomylitis 195
- 196. RNA viruses Orthomyxoviridae • Is a family of influenza viruses • Grouped into 3 genera: influenza A, B, & C. • General signs and symptoms- Fever chills, sore throat, headache, cough, muscle pain, GIT disturbance. 196
- 197. RNA viruses • Orthomyxoviridae. • A infect man, animals and birds. • B and C- Infects only men. • Influenza A- Is responsible for most flu cases a nd its highly virulent. • B and C- Less common and cause mild illness. 197
- 198. RNA viruses Paramyxoviridae • Comprises of 3 genera which have viruses pathogenic to man 198 Genus Virus Disease Paramyxovirus Parainfluenza virus URTI esp in children Mumps virus Mumps Morbilivirus Measles virus Measles Pneumovirus Respiratory syncytial virus Bronchiolitis , pneumonia in infancy
- 199. Recommended Case Definition Clinical case definition : Suspect measles in a pers on with macula-papular r ash, fever plus one of th e following; cough, cond uctivities and coryza Laboratory criteria for diagnosis: Serum/blood specimen f 4/30/2023 MAKUMI 199
- 200. RNA viruses Rhabdoviridae • Rabies virus belongs to this class • Rabies causes hydrophobia in man • One of the most terrifying of all communicable diseases and is invariably fatal Characteristics rabies virus: singe stranded RNA genome, enveloped, bullet shaped, resistant to drying, cold. 200
- 201. RNA viruses Rabies virus • Primarily a disease of animals who transmit it to man through their bite • The virus has high affinity for CNS and travels to that destination irrespective of site of inoculation. • It has no cure once the disease has set in. • The long incubation period of disease permits post exposure immunoprophylaxis. 201
- 202. RNA viruses Rotaviridae, genus: Rota virus • Rotavirus is spherical in shape (rota) • Single most important agent of infantile gastroenteritis occasionally accompanied by vomiting and fever. • Manifest after incubation of 2-3 days and last 4-7days • May cause dehydration and convulsions in children • In developing world, ↑ 123m cases or rotavirus associated diarrhoea occur annually & results in ~1m deaths 202
- 203. Viral hepatitis • Viral hepatitis refers specifically to a primary infection of the liver by one of the 4 etiologically associated but different hepatotropic viruses 203
- 204. 204 HEPATITIS PRIMARY LIVER INFECTION LIVER INVOLVED AS A PART OF GENERAL INFECTION BLOOD-BORNE ENTERICALLY TRANSMITTED HBV HDV HCV HAV HEV •Yellow fever •Cytomegalovirus •Rubella virus •Mumps virus •EB virus •Herpes simplex virus
- 205. Hepatitis A virus • Belongs to family of Picornaviridae • Transmission is by fecal oral route • It survives for long periods in water and wet environments. • Occasionally HAV infection can be transmitted by blood or blood products. S/Symptoms – develop between 2-6 wks after infection. 205
- 206. Hepatitis A virus • Flu like symptoms. • Diarrhoea especially for children. • dark urine and pale stool. • Abdominal pain. • Loss of appetite. • Jaundice. • Symptoms usually not severe, at times goes a way on their own, overtime. 206
- 207. Hepatitis A virus Prevention: • maintaince of hygiene, food handlers with HAV must be kept away from work for 2weeks • patients should be nursed with appropriate precautions • safe disposal of faeces during the infective period. • Vaccination for high risk group. 207
- 208. Hepatitis B virus • Belongs to a new family called Hepadnaviridae • The virus is stable at -20 degrees Celsius for more than 20 years • Incubation period is 4-6 months • Clinical manifestation is similar to those of HAV • It may give rise to persistent infection, prolonged carrier state, and progression to chronic liver disease • It is also associated with hepatocellular carcinoma 208
- 209. Hepatitis B virus Prevention Screening of blood donors and blood products can reduce risk of transmission. Following group of people are recommended to undergo active immunizations with hepatitis B vaccine: • health care workers handling blood & blood products • Medical and paramedics working in dialysis units or haemophilia centres 209
- 210. Hepatitis B virus • Individuals receiving prolonged inpatient treatment • Pts requiring repeated blood transfusions • Immuno deficient individuals • Cancer patients • Prostitutes • Spouses and sexual contacts of patients with acute hepatitis B-carriers of HBV. 210
- 211. Hepatitis D virus • HDV belongs to a genus- Deltavirus • It is a defective virus and can only survive in the presence of HBV • The agent is transmitted along with HBV either at the time of first infection (co-infection) or during any subsequent exposure • It may have little of no effect on the associated HBV infection • Sometimes it causes fulminant hepatitis and death 211
- 212. Hepatitis C virus • HCV is a flavirus • Transmitted in a fashion similar to HBV • Most prevalent in injectable drug users • HCV causes chronic hepatitis and eventually liver cirrhosis • Sometimes HCV infection leads to hepatocellular carcinoma • Screening of blood donors and blood products can reduce risk of transmission. • Hepatitis B&C have a high mortality rate than A. 212
- 213. Hepatitis E virus • HEV is a calcivirus. • Transmission is by fecal oral route. • Clinically and epidemiologically HEV infection resembles those due to HAV but are severe in pregnant women and more likely to cause fulminant disease. • At present no vaccine is available against this agent. • Control measures: maintenance of clean water supply. • Other preventive measures are the same as those for HAV 213
- 214. Examples of viruses + diseases Herpesviruses All herpesviruses have a core of double-stranded DNA Common and important herpesviruses of humans include herpes simplex virus types 1 and 2, varicella-zoster virus, Epstein-Barr (EB) virus, and cytomegalovirus 214
- 215. Examples of viruses + diseases Varicella zooster viruses Varicella: commonest childhood axenthemata. Portal of entry is resp tract. 215
- 216. Examples of viruses + diseases Zooster virus <shingles> • Activation <2⁰ ↓immunity to ineffective levels>. • produces painful vesicles in areas of skin. • Common in pts 60yrs>, ca pts, iss pts,…. 216
- 217. Examples of viruses + diseases Human Herpesvirus 1 (Herpes Labialis) & Human Herpesvirus 2 (Herpes Genitalis). Infection is sometimes seen as severe keratitis, meningoencephalitis, and a disseminated illness of the newborn. 217
- 218. Examples of viruses + diseases • Herpesviruses have been linked with malignant diseases in humans : herpes simplex virus type 2 with cervical and vulvar carcinoma 218
- 219. Examples of viruses + diseases Cytomegalovirus Cytomegalic inclusion disease is a generalized infection of infants caused by intrauterine or early postnatal infection with the cytomegaloviruses. The disease causes severe congenital anomalies. Most fatalities occur in children under 2 years of age Severe cytomegalovirus infections are frequently found in adults receiving immunosuppressive therapy 219
- 220. Examples of viruses + diseases Epstein-Barr (EB) virus (Epstein-Barr) virus associated with Burkitt's lymphoma and nasopharyngeal carcinoma • The virus is transmitted by intimate contact. 220
- 221. Examples of viruses + diseases Polio virus • Droplet infection, no intermediate host • Causes poliomyelitis • Prevention <prophylaxis>: inactivated polio vaccine 221
- 222. Examples of viruses + diseases Rhino-virus • Major cause of common cold <accounts for ~ ½ of all colds. • Transmission: via inhalation of infected drops, hand contact= primary mode of transmission. 222
- 223. Examples of viruses + diseases Rabies virus • Host is all warm blooded animals. • Pathogenesis: rabies is a natural infection of dogs, foxes, skunks, cats, wolves, and bats • Virus is excreted in saliva of infected animals. • Man gets via bites by infected animals. 223
- 224. Examples of viruses + diseases Paramyxoviruses < parainfluenza, mumps, and measles viruses>. Are indistinguishable in the e. microscope. Parainfluenza virus: types 1-4, • Highly transmissible & are acquired by droplets, • They causes URTI & in children may cause pneumonia. • In kids (6/12-5yrs) may get larnyngotracheo- bronchitis (croup) 224
- 225. Examples of viruses + diseases Mumps virus • Respiratory tract is the portal of entry via resp and oral secretions • Causes mumps a predominantly childhood disease • Major manistation is painful, swelling of parotid gland (unilateral or bilateral • May cause: encephalitis, orchitis, oophoritis, pancreatitis, arthritis, myocarditis, renal dysfunction. 225
- 226. Examples of viruses + diseases Measles virus • Commonest cause of highly contagious childhood disease- measles • Spread is via resp secretions, multiplies locally and spread to regional lymphoid tissue then into blood <viraemia>. • It causes URTI, fever, rhinitis, cough, conjunctivitis, koplik’s spots <rash>. 226
- 227. Examples of viruses + diseases • It also causes sinusitis, otitis media, bronchitis, croup, bronchopneumonia, encephalitis etc • Prevention: measles vaccine 227
- 228. Examples of viruses + diseases Yellow fever virus • Causes yellow fever disease • Transmitted by mosquitoes from monkeys and man to man. • Liver is the major target organ • Prevention is via eradication of Aedes aegypti mosq, vaccination with 17D vaccine-provides protection for 10yrs. 228
- 229. Examples of viruses + diseases HIV virus • Retrovirus • Causes AIDS • ssRNA • Transmission: sexual, vertical, parenteral. 229
- 230. Examples of viruses + diseases Hepatitis viruses • Causes viral hepatitis <liver infection> • Strains: HAV, HBV (ds-DNA), HCV, HDV, HEV, and HGV. 230
- 231. Examples of viruses + diseases Hepatitis viruses • Causes viral hepatitis <liver infection> • Strains: HAV, HBV (dsDNA), HCV, HDV, HEV, and HGV. 231
- 233. PARASITES • They are organisms that survive at the expense of another organism. 30-Apr-23 233
- 234. Definitions of terms • Medical Parasitology: deals with parasites which infect man and diseases produced by them • Parasite: organism which is dependent on another organism for survival. Obtains nourishment and shelter from the organism on which it thrives 234
- 235. Definitions of terms • Host: organism which harbors the parasite and is usually larger than the parasite • Ectoparasite: Thrives on the outer surface of the host • Endoparasite: lives within the body of the host • Commensal: a parasite which does not damage the host while deriving its advantages. 235
- 236. Parasites • Obligate parasite: a parasite which is completely dependent upon the host • Pathogen: a parasite capable of producing disease. PROTOZOA • Protozoa: the simplest organism of the animal kingdom, consisting of unicellular eukaryotic organism. Most are free living but others lead a parasitic existence. 236
- 237. Parasites • Sarcodina ( amoebas); a group of protozoa ch aracterized by the ability to produce pseudopo dia (false feet) during most of the life cycle. • Mastigophora ( flagellates): the smallest of th e protozoa with flagella. • Cilliata ( Cilliates): the largest of the Protozoa. They have cilia and eat other protozoa and bac teria 237
- 238. Parasites 1. Those living inside the host are endoparasite. –These are like tapeworm, plasmodium (malarial parasite) 2. Those living on the host are ectoparasite eg. Lice 3. Obligate parasites must spend some part of their life cycle in or on a host eg plasmodium 30-Apr-23 238
- 239. Parasites 4. Facultative parasites may be free living but can obtain their nutrition from a host too. 5. Accidental parasites are the parasites that will attack unnatural host 6. Aberrant parasite are the parasites that come to a site during migration where they cannot develop or live 30-Apr-23 239
- 240. Parasites • Parasites include:- • PROTOZOA • HELMINTHS • PROTOZOA are like:- –Amoeba- Entamoeba Histolytica –Flagellates – Leishmania, Trypanosoma, Girdia, Trichomona Vaginalis –Sporozoa- Plasmodium, Toxoplasma –Ciliates- Balantidium 30-Apr-23 240
- 241. Parasites Helminths • Trematodes- schistosoma (leaf like un- segmented) • Cestodes- Taenia (tape like segmented) • Nematodes – hookworm, roundworm, Threadworm (Elongated cylindrical un- segmented) 30-Apr-23 241
- 242. 242
- 243. Parasites Host- an organism that harbours a parasite • TYPES OF HOSTS • Definitive- Harbours an adult parasite & the parasite utilizes sexual reproduction within it. (Anopheles mosquito is the definitive host for malaria) 30-Apr-23 243
- 244. Parasites • Intermediate- Harbours larval stages of parasite. E.g human for Malaria. • Paratenic- harbours parasites exhibiting no development but the parasite remains viable. E.g Human are Paratenic Host to dog tape worm. The larva do not develop further. 244
- 245. Parasites Association btw a parasite & a host • Symbiosis (Mutalism)- both are dependent on each other ie one cannot live without the other & none is harmful to the other • Commensalism- parasite is benefiting without causing harm to the host • Parasitism- the parasite benefits while the host does not get any benefit 30-Apr-23 245
- 246. How parasites cause disease to man 1. Mechanical injury- – Pressure on the tissues as the parasite grow larger e.g hydatid cyst – Blocking the blood vessels (strongyloides) or lymphatic vessels (elephantiasis) causing oedema – Intestinal obstruction, perforation & necrosis (Ascaris Lumbricoides) – Destruction of of human Red blood cells (plasmodium) 30-Apr-23 246
- 247. How parasites cause disease to man 2. Release of toxic substances – Plasmodium falciparum produces toxic substances that cause rigors & other malarial symptoms. – Entamoeba Histolytica- cause lesions due to the histolytica enzymes produced i.e they dissolve tissues 30-Apr-23 247
- 248. How parasites cause disease to man 3. Deprivation of nutrients, fluids & metabolites –The parasite competes for nutrients with the host eg • Diphylobothrium Latum (fish tapeworm competes for vit. B12 causing megaloblastic Anaemia) • Ancylostoma Duodenale & other blood sucking arthropods lead to severe iron deficiency Anaemia 30-Apr-23 248
- 249. How parasites cause disease to man 4. Introduction of pathogenic micro organisms –Lesions produced by parasites may later have bacterial infection. – Eg. High incidence of schistosoma haematobium in human blood could cause one to be a carrier of salmonella typhi 30-Apr-23 249
- 250. Protozoa Sporozoa: plasmodium Objectives 1.State plasmodium species 2.Life cycle of malaria parasite (sexual & asexual 3.Effects of plasmodium in the body 250
- 251. Plasmodium: The Agent of Malaria • Dominant protozoan disease • Obligate intracellular sporozoan • 4 species: P. malariae, P. vivax, P. falciparum and P. ovale • Female Anopheles mosquito is the primary vector; blood transfusions, mother to fetus • 300-500 million new cases each year • 2 million deaths each year 251
- 252. 2 distinct phases of malarial parasite development: • asexual phase – human host – Infected female mosquito injects asexual sporozoite which localizes in liver; it then undergoes schizogony generating 2,000-40,000 merozoites which enter circulation in 5-16 days depending on species. – Merozoites attach to and enter red blood cells, convert to trophozoites and multiply; red cell bursts releasing merozoites that differentiate into gametes. 252
- 253. • Sexual phase – mosquito host – Mosquito draws infected RBCs; gametes fertilize forming diploid cell which forms sporozoites in stomach. – Sporozoites lodge in salivary glands; available to infect human host 253
- 254. Plasmodium • Symptoms include episodes of chills-fever-sweating, anemia, and organ enlargement. • Symptoms occur at 48-72 hour intervals as RBCs rupture; interval depends on species. • P. falciparum most malignant type; highest death rate in children • Diagnosis by presence of trophozoite in RBCs, symptoms • Increasing drug resistance 254
- 255. Helminthes Objectives 1.Classify helminthes of medical importance 2.Brief life-cycle & characteristics 3.Effects/diseases associated with each 255
- 256. Helminthes • Pathology arises from worms feeding on and migrating through tissues, accumulation of worms and worm products. • Diagnosis based on blood cell count (eosinophilia), serological tests; eggs, larvae, or adult worms in feces; sputum, urine, blood, or tissue biopsies. • Antihelminthic drugs suppress a helminthic metabolic process that differs from the human process, inhibit the worm’s movement, prevent it from holding position, and act locally in the intestine. 256
- 257. Nematode (Roundworm) Infestations • Most abundant animal groups; 50 species that affect humans • Enlongated, cylindrical worms with protective cuticles, circular muscles, a complete digestive tract, and separate sexes • Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, hookworms, Strongyloides stercoralis, Trichinella spiralis, filarial worms 257
- 258. Ascaris lumbricoides • A large intestinal roundworm • Most cases in the U.S. occur in the southeastern states • Indigenous to humans • Ascaris spends its larval and adult stages in humans; release embryonic eggs in feces, and are spread to other humans; food, drink, or contaminated objects • Ingested eggs hatch into larvae and burrow through the intestine into circulation and travel to the lungs and pharynx and are swallowed. • Adult worms complete cycle in intestines and reproduce – 200,000 eggs/day. 258
- 259. Ascaris lumbricoides • Worms retain motility, do not attach. • Severe inflammatory reactions mark the migratory route. • Allergic reactions can occur. • Heavy worm loads can retard physical and mental development. 259
- 260. Trichuris trichiura and Whipworm Infection • Whipworm • Humans sole host • Trichuriasis has its highest incidence in the tropics. • Eggs hatch in intestines, larvae attach, penetrate the outer wall and develop into adults. • Females lay 3,000-5,000 eggs daily. • Worms can pierce capillaries, cause localized hemorrhage, and allow bacteria to leave intestine. • Heavy infestations can cause dysentery, rectal prolapse – can be fatal in children. 260
- 261. Enterobius vermicularis and Pinworm Infection • Pinworm or seatworm • Enterobiasis most common worm disease of children in temperate zones • Eggs are picked up from surroundings and swallowed. • After hatching in the small intestine, they develop into adults. • Anal itching occurs when mature females emerge from intestine to release eggs. • Self-inoculation is common. • Tape test 261
- 262. Hookworms • Characteristic curved ends and hooked mouths • Necator americanus and Ancylostoma duodenale • Humans shed eggs in feces, which hatch into filariform larvae and burrow into the skin of the lower legs. • Larvae travel from blood to lungs, proceed up bronchi and throat and are swallowed. • Worms mature and reproduce in small intestine and complete, the cycle. • May cause pneumonia, nausea, vomiting, cramps and bloody diarrhea • Blood loss is significant – anemia. 262
- 263. Strongyloides stercoralis and Strongyloidiasis • Threadworm • Tiny roundworms completes life cycle in humans or moist soil. • Larvae penetrate skin and migrate to lungs, are swallowed and complete development in the intestine. • Can reinfect the same host without leaving the body • Heavy worm loads can cause pneumonitis and eosinophilia, bloody diarrhea, liver enlargement, bowel obstruction and malabsorption. 263
- 264. Tissue Nematodes • Complete their life cycle in human blood, lymphatics, or skin • Filarial worms; elongate, filamentous bodies, spread by biting arthropods • Cause chronic, deforming disease • Wuchereria bancrofti – elephantiasis • Onchocerca volvulus – river blindness • Loa loa – eye worm 264
- 265. Wucherereia bancrofti and Bancroftian Filariasis • Tropical infection spread by mosquitoes • Vector deposits larvae which move into lymphatics and develop into adults. • Filariasis in early stage causes chills, headache and skin lesions. If untreated leads to Elephantiasis. 265
- 266. Wucherereia bancrofti and Bancroftian Filariasis • Chronic infection causes blockage of lymphatic circulation and elephantiasis, massive swelling in the extremities. 266
- 267. Onchocerca volvulus and River Blindness • Transmitted by biting black flies • Larvae develop into adults in subcutaneous tissues. • Adult females migrate via the blood to the eyes, provoking inflammatory reactions. • Coinfection with Wolbachia bacteria causes river blindness. • Treatment: tetracycline and ivermectin 267
- 268. Loa loa: The African Eye Worm (LOASIS) • Spread by bite of small flies • Temperature-sensitive worm migrates around/under the skin and may enter the eye. • Treatment – pull worm from a small hole in conjunctiva or diethylcarbamazine 268
- 269. Trematodes or Flukes • Flatworms with ovoid leaflike bodies • Have digestive, excretory, neuromuscular, and reproductive systems • Lack circulatory and respiratory systems • Animals such as snails or fish are usually the intermediate hosts and humans are the definitive hosts. 269
- 270. Blood Flukes: Schistosomes • Schistosomiasis (Bilhaziasis)- prominent parasitic disease • Schistosoma mansoni, S. japonicum, S. haematobium • Adult flukes live in humans who release eggs into water; early larva (miracidium) develops in freshwater snail into a 2nd larva (cercaria). 270
- 271. Blood Flukes: Schistosomes • This larva penetrates human skin and moves i nto the liver to mature. • Adults migrate to intestine or bladder and she d eggs, giving rise to chronic organ enlargeme nt. • Early symptoms- fever, cough, diarrhoea or sw ollen glands. 271
- 272. Blood Flukes: Schistosomes • S. Manson and S. Japanicum produce intestina l symptoms. • S. Haematibium produces hematuria and oth er urinary symptoms, eg Cystitis. 272
- 273. Cestode (Tapeworm) Infestations • Flatworms • Long, very thin, ribbonlike bodies composed of sacs (proglottids) and a scolex that grips the intestine • Each proglottid is an independent unit adapted to absorbing food and making and releasing eggs. • Taenia saginata • Taenia solium 273
- 274. 274
- 275. Taenia saginata • Beef tapeworm • Very large, up to 2,000 proglottids • Humans are the definitive host. • Animals are infected by grazing on land contaminated with human feces. • Infection occurs from eating raw beef in which the larval form has encysted. • In humans, larva attaches to the small intestine and becomes an adult. • Causes few symptoms; vague abdominal pain and nausea; proglottids in stool 275
- 276. Taenia solium • Pork tapeworm • Infects humans through ingesting cysts or eggs • Eggs hatch in intestine, releasing tapeworm larva that migrate to all tissues and encyst. • Most damaging if they lodge in heart muscle, eye, or brain • May cause seizures, psychiatric disturbances 276
- 277. The Arthropod Vectors of Infectious Disease • Arthropods – exoskeleton and jointed legs; includes arachnids(spiders, mites, ticks etc) and crustaceans(aquatic arthropods like lobsters crubs etc); must feed on blood and tissue fluid of host during life cycle; ectoparasites • Those of medical importance transmit infectious microbes in the process of feeding – biological vectors 277
- 278. INSECTS • Mosquitoes – require an aquatic habitat; females take blood meal transmitting disease: malaria, filariasis, zoonoses • Fleas – highly motile, flattened bodies; feed on warm-blooded animals; carry zoonotic diseases: plague, murine typhus • Lice – small, soft; attach to head and body hair feeding inconspicuously on blood and tissue fluid; release feces that contaminate wound; epidemic typhus, relapsing fever • Flies – tsetse fly, sand fly 278
- 279. Arachnids • Ticks – cling on vegetation and attach to host on contact; larvae, nymph and adults get blood meal by piercing skin of host – hard ticks – Dermacentor (Ixodidae family) – small compact, rigid bodies; transmit rickettsial, borrelial, and viral diseases – soft or argasid ticks – Ornithodoros- flexible outer bodies; transmit relapsing fever 279
- 280. 280 Intestinal and urogenital protozoa Organism mode of transmission Disease Entamoeba histolytica Ingestion of cyst Amoebic dysentery, liver abscess Giardia lamblia Ingestion of cyst in food Giardiasis Cryptosporidium Ingestion of cyst in food Cryptosporidiosis (sympt= diarrhoea, severe in ISS Trichomonas vaginalis Sexual Trichomoniasis Medically important protozoa
- 281. 281 Blood and tissue protozoa Organisms Mode of transmission diseases Plasmodium: vivax, ovale, malariae, falciparum Anopheles mosquito Malaria Leishmania donovani Sandfly (phlebotomus) Kala-azar (visceral leishmaniasis Leishmania tropica, L.mexican, & L.braziliensis Sandfly (vector) Cutaneous leishmaniasis Trypanasoma gambiense & T. rhodesiense Tsetse fly (glossina) Sleeping sickness (drawsiness, lethergy and encephalitis) Trypanasoma cruzi Reduviid bug Chagas’ disease Toxoplasma gondii Cyst in raw meat, cat feces Toxoplasmosis Pneumocystis jiroveci Inhalation Pneumonia esp in ISS
- 282. Blood & Tissue Protozoa Chagas’ disease • Can also be transmitted by person to person through needle prick injury, organ donation or vertical transmission. • Caused by trypanasomia cruzi – swelling on the skin. • Lymphnode enlargement, cardiomyopathy, megacolon (mostly in young children). 282
- 283. Toxoplasma gondii • Cysts in raw meat causes toxoplasmosis • Enlarged lymphnodes, fever, muscle pain. • Encephalomyelitis calcification of brain (microcephaly, hydrocephaly at birth).. 283
- 284. T. Gambiense(Sleeping sickness) Found in central & west africa • Encephalitis. • Splenomegally, pyrexia, drawsiness, anorexia – coma then death. 284
- 285. T. Rhodesian Sleeping sickness. Found in East & Central africa. • Like gambiense but shorter duration and more acute. • S/S Pyrexia, anaemia & cardiac failure. Walbachia bacteria • A bacteria that infect a wide variety of vertebrates including insects, spiders, crustaceans and nematodes. 285
- 286. 286 Organism Intermediat e host Stage that infects human Disease Taenia solium Pigs -Larvae in <cooked pork -Eggs in food or water cont’ with human faeces -Adult form= Taeniasis (intestines) -larvae= cysticercosis (brain & eyes) Taenia saginata Cattle Larvae in < cooked beef -Taeniasis (adult tape in intestine Diphyllobothrium latum Fish Larvae in <cooked fish -diphyllobothriasis Echinococcus granulosus (dog tape worm) Sheep Eggs in food or water contaminated with dog faeces - Hydatid cyst disease (in liver and lungs) Cestodes (Tape worms) NB: has no insect vector
- 287. Diphyllobothriasis. • Infection with half cooked fish • S/S: Diarrhoea, abdominal discomfort, vomiting, weight loss. • Causes microcytic anemia – resembles pernicious anaemia • Causes leukocytosis (incre W/B cells) and oesinophilia ( incre oesinophils). Due to parasitic infection. 287
- 288. 288 Schistosoma: they cause schistosomiasis Trematode Intermediate host mode of transmission Main sites affected Schistosoma mansoni Snail Penetrate skin Veins of colon Schistosoma haematobium Snail Penetrate skin Veins of urinary bladder Schistosoma japonicum Snail Penetrate skin Veins of intestine, liver Clonorchis sinensis Snail &fish Ingested with raw fish Colon Trematodes (flukes)
- 289. Clonorchis sinensis. • Caused by ingestion of half cooked fish. • Affects biliary tree, and causes liver cirrhosis. 289
- 290. 290 Intestinal nematodes Genus & species Common name /disease Mode of transmission Enterobius vermicularis Pinworm infection Ingested eggs, dvp into adult in gut , lay eggs on anal skin=reinfection Ascaris lumbricoides Ascariasis Eggs=ingested, from larvae in gut, larvae migrate via bld to lungs, then via trachea, swallowed. Bcome adults, lay eggs, pass in stool , embryonate in soil Strongyloides stercoralis Strongyloidiasis Larvae pen’ skin, into bld, to lungs, trachea, swallowed, bcome adults, enter mucosa-fem lay eggs, hatch in colon into non infectious larv, passed in stool Trichuris trichiura Whipworm infection Human ingest eggs, dvp in gut into adult, eggs passed in stool, embryonate in soil Nematodes (Nemathelminthes): are round worms
- 291. 291 Genus & species Common name /disease Mode of transmission Ancylostoma duodenale & A. americanus Hookworm Larvae pen’ skin, inter bld, migrate to lungs, trachea, swallowed, adults in small int, attach to walls, eggs passed in stool, form non inf’ larvae, then inf’ filariform larvae Trichinella spiralis Trichinosis s/s,nausea, Diarrhea ,vomiting,s weating. Larvae ingested in <cooked pork, mature into adult in small int, female release larvae- enter bld, migrate to skeletal muscle or brain (they encyst) causing myocarditis, encephalitis,death, Nematodes
- 292. Immunology Objectives 1. Definition of terms 2. Review of relevant A & P 3. Describe the levels of body defence mechanisms against infections • 1st line, 2rd line, 3rd line 4. Describe the cells of immune system 5. Describe Humoral and cell mediated immune system. 6. Describe the hypersentivity reactions, autoimmunity 292