5.1 Intestinal nemathodes edited class.ppt
- 1. HELMINTHS
- 2. 3.1. Introduction to Helminths Helminths derived from the Greek word “helminths” or “helminthose” meaning worm Medical helminthology: study of these parasitic worms and their medical consequence 2
- 3. 3.2.General features of helminths Higher, multicellular forms with specialized organs Adult worms vary in size (6mm->10m) Their life cycles may be simple or complex Laboratory diagnosis mainly depends on Detection and identification egg , larva or embryo and rarely adults 3
- 5. General features of Nemathelminths Round in cross-section Unsegmented Digestive system complete Possess mouth, oesophagus and anus Have separate sexes Can be oviparous/ovoviviporous/viviparous Egg (ova) -Larva(L1-L4)-Adult 5
- 6. 4.2. Classification of Nemathelminths INTESTINE NEMATODE Small intestine Ascaris lumbricoides Hook worm Strongyloides stercoralis Large intestine Trichuris trichuria Enterobius vermicularis BLOOD &TISSUE NEMATODE Adults or larval stage in tissue Filaria – Wuchereria bancrofti Brugia malayi Onchocerca volvulus Loa loa Trichinella spiralis, Draconculus medinensis 6
- 7. INTESTINAL NEMATODES General features Live in gastro-intestinal tract In humans, often spread by poor hygiene related to feces Most species are geo-helminths (soil transmited) Female worms are oviparous 7
- 8. Intestinal Nematodes It includes Ascaris lumbricoides Trichuris trichiura Enterobius vermicularis Hook worm Strongyloides stercoralis Small intestine Ascaris lumbricoides Hook worm Strongyloides stercoralis Large intestine Trichuris trichuria Enterobius vermicularis 8
- 9. Classification of Intestinal nematodes A. Intestinal nematodes with tissue stage (heart lung migration) Ascaris lumbricoides Hookworms Strongyloides stercoralis Before becoming adults in their human host, the larvae of A. lumbricoides, S. stercoralis , and hookworms have heart lung migration B. Intestinal nematodes without tissue stage(no heart to lung migration) Enterobius vermicularis Trichuris trichuira. 9
- 10. Ascaris lumbricoides Also known as largest intestinal round worm the first human helminth recorded in chinse medical literature(about 300-200 B.C.) Epidemiology The most common human helminthic infection. Worldwide distribution. Highest prevalence in tropical and subtropical regions, and areas with inadequate sanitation. 10
- 11. Cont…. 11
- 12. Cont… 12
- 13. Transmission and Life Cycle Transmission A. lumbricoides Infective stage:- egg containing 2nd stage larva A person acquire infection by 1- Ingestion of food or water contaminated with infective eggs 13
- 14. Cont… 2-eating soil(geophge) frequently seen in children 3-putting contaminated finger or toys with infective egg in to mouth 4- rarely by inhalation of eggs carried in air 14
- 15. Life cycle 15
- 16. Cont… Pathogenesis and clinical feature 1. “Verminous” pneumonia, lung tissue damage due to migratory larvae. 2. Bowel obstruction - too many adult worms. 3. Parasite secretes trypsin inhibitor, prevents host from digesting proteins. 4. Aberrant migration of “irritated” adult worms to: a. Common duct b. Liver c. Pharynx d. Peritoneum 16
- 17. Cont… With heavier worm loads a tangled mass of worms can obstruct the bowel, or an individual worm can block a duct 17
- 18. Laboratory Diagnosis A. Finding and identification of eggs in the stool. Direct wet mount concentration technique may be used In light infection, Formolo-ether concentration technique & Sodium chloride floatation technique 18
- 19. Cont… B. Adult worms occasionally passed in the stool or through the mouth or nose C. Larvae can be identified in sputum or gastric aspirate during the pulmonary 19
- 20. Cont… Treatment Mebendazole Prevention and control washing hands before eating & trimming finger Avoid eating uncooked foods such as vegetables 1. Preventing soil become faecally polluted by o sanitary disposal of faeces in latrines o avoiding the use of night soil as a fertilizer 2.Treatment and health education • Mass de-worming programmes repeated at 3-6 month intervals, have been advocated in areas of high prevalence 20
- 21. Trichuris trichiura Common name : whipworm, due to the whip-like form of the body. Epidemiology Cosmopolitan with poor sanitation The third most common round worm of humans worldwide Infections more frequent in areas with tropical weather and poor sanitation practices, and among children 21
- 22. Cont… Morphology Adults: whip-like shape anterior 3/5th of the worm resembles a whip & the posterior 2/5th are thick Male : Size 30-45 mm , coiled tail Female: 35-50mm, straight thick tail Habitat Adult: large intestine ( cecum, appendix, rectum) Eggs : In the faeces, not infective when passed 22
- 23. Cont…… -Longer than the male. - posterior end is thick and linear. . -Shorter than the female. posterior end curved and -has a single spicule enveloped with sheath. . Adult female Adult female Adult male Adult male 23
- 24. Cont… Transmission and life Cycle Transmission Ingestion of embryonated egg in contaminated water , food or from contaminated hand 24
- 25. life Cycle 25
- 27. Cont…. Trichuris trichiura adults in gut Trichuris trichiura: a macroscopic view of a tangled mass of adults 27
- 28. 28
- 29. Laboratory diagnosis 1.Finding of characteristics egg in faeces 2. Sigmoidoscopy may enable visualisation of worms 29
- 30. Cont… Treatment Mebendazole Treat the iron deficiency anaemia Prevention and Control : the same as described for A. lumbricodes 30
- 31. The next topic will be on Enterobius vermicularls 31
- 32. Enterobius vermicularls . Common name: “Pin Worm” or “threadworm” or “ seat worm” Epidemiology Occurs world-wide estimated that 500 million people are infected Worldwide Children (5-14 years ) are more commonly infected than adults Enterobiasis is most common where people live under crowded conditions such as orphanages, kindergartens, and large families 32
- 33. Cont… In Ethiopia : 5 % school children in rural communities had E. Vermicularis eggs under their finger nails and that only 0.5% of them were found to shed eggs in the stool Recent studies done using routine stool examination method, a prevalence rate up to 1% were reported 33
- 34. Cont… Habitat Adult: Caecum & appendix Eggs: deposited on perianal skin & occasionally in faeces Morphology Adults: Color: yellow white Male: Size 2-5mm long and have the posterior ends strongly curved and have a single spicule Female: 8-13mm long and have the posterior end extended into a long, slender point. 34
- 35. Transmission and Life cycle Transmission Ingestion of infective eggs (embryonated eggs) Person –to- person transmission Eggs remains viable 20 days Autoinfection Retro infection Inhalation 35
- 36. Life cycle 36
- 37. 37
- 38. Life cycle Ingestion embryonated eggs, usually carried on fingernails, clothing, bedding or house-dust. Eggs hatch , larvae migrate to caecal region where they mature into adults Copulation takes place in the caecum Gravid females migrate nocturnally outside the anus and oviposite on the perianal area 1 pin worm lay over 10,000 -15,000 eggs eggs /day 38
- 39. Cont… With in 4-6 hours being laid the egg contain infective larvae Perianal itching from the eggs Induces scratching, and hence the eggs are transmitted to the mouth on the fingers Retroinfection, or the migration of newly hatched larvae from the anal skin back into the rectum interval from ingestion of infective eggs to oviposition by the adult females is about one month The life span of the adults is about two months 39
- 40. Clinical features Enterobiasis is usually asymptomatic , the adults may cause slight irritation of the intestinal mucosa Nocturnal anal pruritis. The cause of this is unknown, but may be related to the intensity of the infestation, and/or an allergic reaction to parasite Sleeplessness, because of the irritation Vulvovaginitis, and even urethritis may occur in girls when migrating worms lay their eggs in these sites Abdominal pain or appendicitis resulting from the worms are considered to be very rare 40
- 41. Adult Pinworms on the perianal skin 41
- 42. Laboratory Diagnosis 1.Finding eggs from perianal skin using adhesive tape or swab method Done by pressing transparent adhesive tape ("Scotch test", cellulose-tape slide test) on the perianal skin and then examining the tape placed on a slide. Collect sample in the morning, before defecation and washing advisable. 42
- 43. Cont… The “Scotch Tape Test” place a piece of Scotch Tape on the anal area. The tape is placed on a slide and examined under a microscope for the flat sided eggs. 43
- 44. Cont… 2. Finding eggs in the faeces Eggs can also be found stool, but less frequently Less than 10% found in stools, i.e. not a useful examination; 3. Finding of female worms from perianal skin or faeces Adult worms are also diagnostic, when found in the perianal area, or during ano-rectal or vaginal examinations 44
- 45. Treatment Pyrental Pamoate or Mebendazole Prevention and Control 1. Treating all members of a family in which infection has occurred 2. Wearing tight-fitting cotton pants to infected children 3. Washing of the anal skin each morning 4.Washing of clothing worn at night 5. washing hands after using toilet and before eating , avoidance of putting fingers in the mouth & trimming finger 45
- 46. The next topic will be on hook worm ( reading assignment)
- 47. Are hematophagous nematodes Two major species (medical importance) -Ancylomstoma duodenale -Necator americanus Less important : A. ceylanicum, A. braziliense ,A. caninum Hook Worms
- 48. Epidimology widely distributed throughout the tropics and subtropics estimated 576 to 740 million people are infected world-wide cause daily blood loss of 7 million liters Most commonly infected are children, agricultural workers and miners
- 49. Cont… Ancylostoma is found in Europe around the Mediterranean, on the West coast of South America and in parts of China and India Necator is found over much of the western hemisphere, Africa and South East Asia
- 50. In Ethiopia : Necator americanus are more common than Ancylostoma duodenale highest infection rates: Ilubabor, Kefa ,Welega A.duodonale is associated with areas of poor soil coverage and high rate of drainage N.americanus is found in red soil areas on flat plain Cont…
- 51. -The adult parasites are small cylindrical worms, 0.5 - 1.5cm long (Ancylostoma duodenale being slightly larger than Necator americanus ). Adult: A. duodenale N. americanus Morphology 51
- 52. Comparison of Hookworms adults N. americanes A. duodenale Size(length) about 10 mm slight larger Shape “ S ” “ C ” Buccal capsule a pair of two pair of cutting plates curved teeth 52
- 53. Cont… The head of both worm slightly bend ‘’hook’’ like Ancylostoma duodenale the mouth carries Curved teeth Necator americanus the presence of two cutting plates
- 54. larvae Rhabiditiform Larvae Filariform Larvae 1.Size 250-500m 600- 700 m 2.Bucal cavity long short 3.Oesophages 1/3 body length 1/4 body length 4.Tail end Pointed end Sharply pointed 54
- 55. Cont… Egg: Size : 65-40m Shape: oval Shell: very thin and appears as black line Colour: the cells inside are pale gray Content: contains an ovum which appears segmented usually 4-8 blastomeres Morphologically it is not possible to differentiate between A. duodenale and N. americanus eggs. 55
- 56. Habitat Adult: Jejunum and less often in the duodenum of man Eggs: In the faeces; not infective to man Rhabditiform and filariform larvae: free in soil and water Cont…
- 57. =Soil polluted with human excreta is commonly responsible for exposure to infection with human hookworms =Individuals become infected, usually by walking bare footed across contaminated soil Transmission and life cycle 57
- 58. Cont… 58
- 59. Life Cycle 1. Final host: man 2. Inf. Stage: Larva 3 or filariform larva 3. Inf. Route: by skin 4. Blood-lung migration: skin, right heart, lungs 5. Site of inhabitation: small intestine 6. Food: blood and tissue fluid 7. Life span: Ad 15years, Na 3-7years
- 60. Adult worms live in the small intestine and female lay 5-10000 eggs a day over 5 years Eggs are passed with the feces Larvae develop outside the body and molt twice The filariform or L3 larvae move to the surface in search for a host If they come into contact with the host they penetrate the skin, enter blood vessels and leave the circulatory system into the alveoli The larvae move up the trachea into the esophagus, are swallowed and finally reach the intestine, where they molt twice more before they reach maturity Life Cycle
- 61. Pathogenesis and clinical manifestation (1) Cutaneous or invasive phase: by hookworm larvae Dermatitis(ground itch): irritation and itching The larva of a hookworm is visible in the center of this photograph 61
- 62. (2) Pulmonary phase: by hookworm larvae Local haemorrhaging, pneumonitis Symptoms in respiratory system cause a cough and a sore throat. Cont… 62
- 63. (3) Intestinal phase: By adult worm A)the intestinal mucosa are damaged B)Anemia: Protein and iron in-take is insufficient Blood loss Hypochromic microcytic anemia Cont… 63
- 64. Blood loss a)Ingestion of the blood by the worm b)Seepage of the blood around the site of attachment of the worm c)Oozing of the blood from the burrowed site previously attached by the worm Cont… 64
- 65. This is a photograph of the hookworm's appearance against the lining of the intestine (intestinal mucosa). 65
- 66. Laboratory Diagnosis 1.Finding eggs in faeces Microscopic identification of eggs in the stool is the most common method A.duodenale and N.americanus eggs morphologically indistinguishable
- 67. Cont… 2. Serological tests (IgG and IgE) 3.PCR Epidemiological studies and monitoring of success of control programs
- 68. Treatment Pyrantel pamoate, Mebendazole or Thiabendazole if anemic : high protein diet supplemented with ferrous sulphate, folic acid and vitamin B12 Prevention and control 1. sanitary disposal of night soil 2. individual protection 3. health education 4. cultivate hygienic habits 5. treat the patients and carriers. Cont.....