Arbo viruses
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This document provides information on arboviruses (arthropod-borne viruses) that are transmitted to humans via insect bites. It discusses the structure, transmission cycles, clinical presentation, diagnosis, and examples of important alphaviruses and bunyaviruses that cause diseases in humans. Key points include that arboviruses have RNA genomes and lipid envelopes, are transmitted between arthropods and vertebrate hosts in cycles, and can cause febrile illnesses, hemorrhagic fevers, or encephalitis in humans. Important alphaviruses that cause encephalitis are eastern equine encephalitis virus, western equine encephalitis virus, and Venezuelan equine encephalitis
![Anti-adult measures
Residual spray-DDT(Dichlorodiphenyltrichloroethane) (1-2
gm/m²)
Space spray- Pyrethrem (1 oz/1000c.ft)
Genetic control
THERMO FOGGING -Aerosol spray of ultra low volume
[ULV] of MALATHION or SUMITHION 250 ml/hectare is
effective in interrupting transmission and stopping epidemics.
ULV treatments 10 days apart has shown to reduce mosquito
densities more than 98%.](https://image.slidesharecdn.com/arboviruses-191004131813/85/Arbo-viruses-59-320.jpg)
Arbo viruses
- 1. ARBOVIRAL INFECTION PART -1 Dr. Dinesh Kr Jain, MD., Assistantprofessor, Department of Microbiology, SMS Medical college, Jaipur
- 2. ARBOVIRUS • The term ARBO is an abbreviation of "ARthropod BOrne". • "Arbovirus" is the name given to viruses that are transmitted to vertebrate ( human and mammals), by blood-feeding insects - arthropods. • Vertebrate infection occurs when the infected insect bites an animal or person and takes a blood meal.
- 3. • They can multiply in the tissues of the arthropod without evidence of disease or damage. The vector may acquire a lifelong infection through the ingestion of blood from a viremic vertebrate. • All arboviruses have an RNA genome, and most have a lipid-containing envelope and consequently are inactivated by ether or sodium deoxycholate.
- 5. TRANSMISSION CYCLES Man-Arthropod-Man Cycle e.g. dengue, urban yellow fever
- 6. Animal-Arthropod-Man Cycle • e.g. Japanese encephalitis, EEE, WEE, jungle yellow fever • The reservoir is in an animal. • Man becomes infected incidentally.
- 7. ANIMAL RESERVOIRS • In many cases, the actual reservoir is not known. The following animals are implicated as reservoirs. • Birds - Japanese encephalitis, St Louis encephalitis, Eastern equine encephalitis (EEE), Western equine encephalitis (WEE) • Pigs - Japanese encephalitis • Monkeys - Yellow Fever • Rodents - Venezuelan equine encephalitis(VEE), Russian Spring-Summer encephalitis
- 8. ARTHROPOD VECTORS Mosquitoes Japanese encephalitis, dengue, yellow fever, St. Louis encephalitis, EEE, WEE, VEE etc. Ticks Crimean-Congo haemorrhagic fever, various tick-borne encephalitis etc. Sandflies Sicilian sandfly fever,
- 9. EXAMPLES OF ARTHROPOD VECTORS Aedes Aegyti TicksPhlebotmine Sandfly Culex Mosquito Anopheles
- 10. CLINICAL PRESENTATION • Diseases produced by arboviruses may be divided into three clinical syndromes: • Fevers of an undifferentiated type with or without a maculopapular rash and usually benign. • Hemorrhagic fevers, also frequently severe and fatal. • Encephalitis (inflammation of the brain), often with a high case- fatality rate. • some arboviruses may be associated with more than one syndrome (eg, dengue).
- 11. DIAGNOSIS • Serology - usually used to make a diagnosis of arbovirus infections. • Culture - a number of cell lines may be used, including mosquito cell lines. However, it is rarely carried out since many of the pathogens are group 3 or 4 pathogens. • Direct detection tests - e.g detection of antigen and nucleic acids.
- 13. • Spherical, 70 nm in diameter, nucleocapsid has 42 capsomeres. • Genome: positive-sense, single- stranded RNA, 11–12 kb in size. • Enveloped with three or four major structural polypeptides, two glycosylated. • Replication: cytoplasm. • Assembly: budding through host cell membranes. • All viruses serologically related. STRUCTURE
- 14. MULTIPLICATION
- 15. FIGURE Alphavirus transmission. Virus abbreviations: Chik, chickungunya; RR, Ross River; MAY, Mayaro; ONN, O'nyong-nyong; SIN, Sindbis; EEE, eastern equine encephalitis; VEE, Venezuelan equine encephalitis. Inapparent infection( alphavirus) Febrile illness,rash,arthralgia(CHIK, RR, MAY, ONN, SIN) Febrile illness, encephalitis (EEE,WEE,VEE) TRANSMISSION CYCLE
- 16. PATHOGENESIS
- 17. ALPHAVIRUS • All alpha viruses are antigenically related. Because of common antigenic determinants, the viruses show cross-reactions in immunodiagnostic techniques. • Hemagglutination-inhibition (HI), Enzyme-linked immunosorbent assay (ELISA) Immunofluorescence tests define 8 antigenic complexes or serogroups of alphaviruses,
- 18. MEDICALLY IMPORTANT ALPHAVIRUSES ( ENCEPHALITIS) Virus Antigenic Clinical Syndrome Vector Host Distribution Eastern equine encephalitis Encephalitis (EEE) Mosquito (Aedes, Culex ) Birds America Western equine encephalitis Encephalitis (WEE) Mosquito (Culex tarsalis, Aedes) Birds America Venezuelan equine encephalitis Febrile illness, encephalitis (VEE) Mosquito (Aedes, Culex) Rodents, horses America
- 19. Virus Antigenic Clinical Syndrome Vector Host Distribution Chikungunya (CHIK) Febrile illness, rash, arthralgia Mosquito (Aedes) Primates , humans Africa, India, Southeast Asia O’nyong-nyong (ONN) Febrile illness, rash, arthralgia Mosquito (Anopheles) Primates Africa Sindbis (SIN) Febrile illness, rash, arthralgia Mosquito (Culex) Birds Nothern Europe, Africa, Asia, Australia MEDICALLY IMPORTANT ALPHAVIRUSES ( FEBRILE ILLNESS)
- 20. EASTERN AND WESTERN EQUINE ENCEPHALITIS • Geographically restricted (America) • Most people have no symptoms. • Causes the most severe encephalitis. • Sudden onset of fever, muscle aches, headache. • Central Nervous system symptoms develop 4-10 days after being bitten by mosquito. • 30 to 50% of patients with encephalitis die of the disease. • Experimental inactivated vaccines against Eastern, Western, and Venezuelan equine encephalitis viruses are available on an investigational basis to protect laboratory workers.
- 21. VENEZUELAN EQUINE ENCEPHALITIS • In America, there have been 21 reported outbreaks of Venezuelan Equine Encephalitis. • This virus was isolated in 1938. • Vaccine contains TC-83 strain - only used on humans. • TC-83 strain is generated by passing the virus 83 times through the heart cells of a guinea pig. • The human vaccine can result in side effects and does not fully immunize the patient. • C-84 is a derivative of TC-83,is used to immunize horses.
- 22. CHIKUNGUNYA • Chikungunya was first described in Tanzania, Africa in 1952. • Chikungunya is not considered to be fatal. However, in 2005-2006, 200 deaths have been associated with Chikungunya on Réunion island. • first reported in India in 1963. • In 2006 there was a big outbreak in India • Andhra Pradesh - Nearly 2 lac people were affected. • North Karnataka ,Malegaon (Maharastra),Orissa
- 23. • The mosquito picks up the virus from an infected person during the viraemic period – within five days from the day of starting of symptoms. • An infected mosquito will remain infected all its life span and can transmit the virus each time it bites. • An infected person cannot spread the infection directly to other persons.
- 24. Sl. No. Affected States/UTs 2010 2011 2012 2013* 2014 2015(Prov.) 2016* 1 Andhra Pradesh 116 99 2827 4827 1359 817 934 2 Arunachal Pd. 0 0 0 0 0 35 239 3 Assam 0 0 0 742 0 0 38 4 Bihar 0 91 34 0 0 3 566 5 Goa 1429 664 571 1049 1205 561 308 6 Gujarat 1709 1042 1317 2890 574 406 2920 7 Haryana 26 215 9 1 3 1 5336 Himachal Pradesh - - - - - - 1 8 J&K - - - - - - 1 9 Jharkhand 0 816 86 61 11 21 47 10 Karnataka 8740 1941 2382 5295 6962 20763 13506 11 Kerala 1708 183 66 273 272 175 124 12 Madhya Pd. 113 280 20 139 161 67 2215 13 Meghalaya 16 168 0 0 0 78 248 14 Maharashtra 7431 5113 1544 1578 1572 391 7354 15 Orissa 544 236 129 35 10 81 51 16 Punjab 1 0 1 0 2 180 4314 17 Rajasthan 1326 608 172 76 50 7 1686 18 Tamil Nadu 4319 4194 5018 859 543 329 72 19 Telangana 0 0 0 0 1687 2067 611 20 Tripura 0 0 0 0 34 180 283 21 Uttar Pradesh 5 3 13 0 4 0 2299 22 Uttarakhand 0 18 0 0 0 0 35 23 West Bengal 20503 4482 1381 646 1032 1013 1071 24 A& N Island 59 96 256 202 161 68 14 25 Chandigarh 0 1 0 1 0 1 1315 26 D&N Haveli 0 0 100 2 0 0 0 27 Delhi* 120 110 6 18 8 64 12221 28 Lakshadwee p 0 0 0 0 0 0 0 29 Puduchery 11 42 45 146 399 245 327 Total 48176 20402 15977 18840 16049 27553 58136 * Provisional till 31th Dec. 2016 | NR=Not Received CLINICALLY SUPECTED CHIKUNGUNYA FEVER CASES SINCE 2010
- 26. • Symptoms are • Incubation period 3-12 days – Fever up to 39°C, (102.2 °F) – Petechial or maculopapular rash usually involving the limbs and trunk. – Arthralgia or arthritis affecting multiple joints which can be debilitating. – Headache, conjunctival injection and slight photophobia. • Clinically, the infection resembles dengue fever.
- 27. • Symptoms are generally self-limiting and last for 1–10 days. • Arthralgia may persist for months or years. • In some patients, minor hemorrhagic signs such as epistaxis or gingival bleeding have also been described. • Neurological complications such as meningoencephalitis have been reported in a small proportion of patients. • Mother to child transmission of chikungunya virus was recorded during French Reunion islands outbreak.
- 28. O’NYONG-NYONG FEVER • First isolated by researchers at the Uganda Virus Research Institute , Uganda, during a large outbreak of a disease in 1959 that resembled dengue fever. • Closely related to the chikungunya. • Common symptoms are polyarthritis, rash and fever. • The disease is self-limiting. • No fatalities due to infection are known.
- 29. SINDBIS FEVER (SINV ) • Sindbis fever is most common in South and East Africa, Egypt, Israel, Philippines and parts of Australia. • Sindbis fever symptoms include arthralgia, rash and malaise. • Most patients recover within 14 days. In 50% of the patients, joint symptoms last for 12 months to 2.5 years. • Incubation period 1-7 days. • No specific treatment.
- 30. ALPHAVIRUS: DIAGNOSIS • Clinical manifestations. • History of known exposure. • Detection of IgM by ELISA. • Antigen detection and polymerase chain reaction (PCR) assays are available for direct detection of viral RNA or proteins. • Isolate virus- usually able to grow in common cell lines, such as Vero, BHK, HeLa, and MRC-5. Intracerebral inoculation of suckling mice or hamsters also used.
- 32. • Spherical, 80–120 nm in diameter. • Genome: triple segmented, negative-sense, single stranded RNA, 11–19 kb in total size. • Virion contains a transcriptase. Four major polypeptides. • Enveloped
- 33. • Bunyaviruses replicate in the cytoplasm. • Their RNA genome is transcribed to mRNA. • The host RNA sequence in some representative viruses primes viral mRNA synthesis. • It mature by budding into vesicles at or near the Golgi apparatus. • Reassortment of RNA segments can occurs between closely related members. MULTIPLICATION
- 34. FIGURE. Pathogenesis of bunyavirus infections. Humans are dead-end hosts of most bunyaviruses; however, the blood of Crimean-Congo hemorrhagic fever patients may be highly infectious. PATHOGENESIS
- 35. Genus and Group Virus Disease Vector Distribution Orthobunyavirus Bunyamwera Bunyamwera Fever Mosquito (Aedes aegypti) Africa Bwamba Bwamba Fever , Rash Mosquito (Anopheles gambiae and A . funestus) Africa California California encephalitis Encepha- litis Mosquito (Aedes triseriatus ) North America HUMAN DISEASES CAUSED BY VIRUSES OF THE FAMILY BUNYAVIRIDAE
- 36. HUMAN DISEASES CAUSED BY VIRUSES OF THE FAMILY BUNYAVIRIDAE Genus and Group Virus Disease Vector Distribution Phlebovirus Phlebovirus Naples Fever Sand fly (Phlebotominae) Europe, Asia, Africa Phlebovirus Rift Valley Fever Fever, encephalitis, hemorrhagic fever, blindness Mosquito (Culex tritaeniorhynchus and Aedes vexans) Africa Phlebovirus Sicilian Fever Sand fly (Phlebotomus papatasi ) Europe, Africa, Asia
- 37. HUMAN DISEASES CAUSED BY VIRUSES OF THE FAMILY BUNYAVIRIDAE Genus and Group Virus Disease Vector Distribution Nairovirus Crimean- Congo Crimean-Congo hemorrhagic fever Hemorrhagic fever Tick (Hyalomma) Africa, Asia Nairobi Nairobi sheep disease Fever Tick (Rhipicephalus appendiculatus) Africa, Asia
- 38. ORTHOBUNYAVIRUS- CALIFORNIA ENCEPHALITIS • Virus was discovered in Kern County, California. • The La Crosse Virus from the same genus is also a common cause of encephalitis. • Total 3 cases were reported, and all three cases were residents of Kern County in the Central Valley of California. • Mortality rates are less than 1%. • The incubation period is usually 3–7 days.
- 39. PHLEBOVIRUS- RIFT VALLEY FEVER • The disease was first reported among livestock in Rift Valley of Kenya in the early 1900s and the virus was first isolated in 1931.
- 40. • Disease of sheep and cattle. • Humans: Asymptomatic-to-mild. • Rare VHF, encephalitis, retinitis.
- 41. • Transmission: – Animal contact (birthing or blood) – Laboratory aerosol • Mortality 1% overall. • Ribavirin, an antiviral drug, has shown promise in animal trials. Interferon, immune modulators, and convalescent- phase plasma may possibly help in the treatment of RVF. • Live-attenuated vaccine (MP-12) undergoing trials. 41
- 42. CLINICAL FEATURES • 3-7 day incubation, 3-5 day duration. • Asymptomatic or mild illness. Fever, myalgia, weakness, weight loss • Photophobia, conjunctivitis • Encephalitis • <5% hemorrhagic fever • 1-10% vision loss (retinal hemorrhage, vasculitis) 42
- 43. NAIROVIRUS- CRIMEAN CONGO HEMORRHAGIC FEVER (CCHF) • Extensive geographic distribution(Africa, Balkans, and western Asia) • An outbreak was recorded recently in parts of Gujarat, claiming four lives in 2010–12 period. • Transmission: – Tick-borne (Hyalomma spp.) – Contact with animal blood or products – Person-to-person transmission by contact with infectious body fluids – Laboratory worker transmission documented • Mortality 15-40% • Therapy: Ribavirin 43
- 45. PATHOGENESIS • Viremia present throughout disease. • Virus grows in macrophages and other cells. • Recovery may be due to CMI or neutralizing antibodies. • DIC often present. • Poor prognosis signaled by early elevated AST(Aspartate aminotransferase) and clotting time. 45
- 46. CLINICAL FEATURES • 4-12 day incubation after tick bite exposure. • 2-7day incubation after direct contact with infected fluids. • Abrupt onset fever, chills, myalgia, severe headache. • Malaise, GI symptoms, anorexia. • Leukopenia, thrombocytopenia, hemoconcentration, proteinuria, elevated AST. • Hemorrhages may be profuse (hematomas, ecchymoses) 46
- 47. Signs of Crimean-Congo Hemorrhagic Fever
- 49. REOVIRIDAE • REO=Respiratory Enteric Orphan Virus • Non-enveloped • Icosahedral • RNA ds • Segmented • Human Diseases – Coltivirus – Orbivirus
- 50. Coltivirus Colorado Tick Fever • Transmitted from the bite of an infected Rocky Mountain wood tick (Dermacentor andersoni). • The disease develops from March to September, with the highest infections occurring in June. • The disease is found almost exclusively in the western United States and Canada, mostly in high mountain areas such as Colorado and Idaho. • Small mammals serve as the amplifying host. • The CTFV was first isolated from human blood in 1944.
- 51. • Disease usually lasts 7-10 days.& often biphagic. • The virus infects erythroblasts and prolonged intra-erythrocytic viremia lasts up to several months. • Symptoms – fever – Myalgia – Meningoencephalitis – Photophobia – Rash – Hemorrhage
- 52. ORBIVIRUS Kemerovo tickborne viral fever • The causative agent is a zoonotic Orbivirus. • Transmitted by ticks. • Associated with fever and neurological symptoms. • First described in 1963 in western Siberia,Russia. • Rodents and birds are the primary hosts.
- 53. SUMMARY
- 54. CLINICAL PRESENTATION • Fevers with or without a maculopapular rash . • Hemorrhagic fevers • Encephalitis • Some arboviruses may be associated with more than one syndrome (eg, dengue).
- 55. DIAGNOSIS • Clinical manifestations. • History of known exposure • Serologic tests include the – ELISA – Complement fixation group reactivity – Fluorescent antibody – Neutralization specific – Hemagglutination inhibition tests. • The diagnosis is confirmed only by detecting a rise in antibody titers (IgM, IgG) or by isolating the virus. • Polymerase chain reaction(PCR)
- 56. TREATMENT • No specific therapy. • Hospitalization, intravenous fluids, respiratory support, prevention of secondary infections, and good nursing care are primary treatment. • Some antiviral drugs eg; Ribavirin, and immuno modulators eg; Interferon are under trial.
- 57. • Vaccines - under trial phase. • Rift Valley fever vaccines are used in Africa to immunize sheep and cattle and hence to stop the transmission cycle to humans. • A human vaccine for Crimean-Congo hemorrhagic fever is used in Soviet Union and Bulgaria.
- 58. PREVENTION MOSQUITO CONTROL Anti-larval measures 1.Environmental control(source reduction)- Drainage of breeding places, and water management. Elimination of stagnant water at home, schools and work place to avoid breeding of mosquitoes. Getting rid of any container capable of retaining water in the outdoor surroundings (used tyres, food cans, garbage, saucers under flower pots, flower vases, Desert coolers etc) Covering water tanks so that mosquitoes cannot get in & breed 2. Chemical control- Mineral oils, Paris green, synthetic (abate, malathion) 3. Biological control- Gambusia and Lebister fishes. • Bacillus thuringiensis var. israelensis, Serotype H-14, Strain 164.& 12AS (Aqueous Suspension).
- 59. Anti-adult measures Residual spray-DDT(Dichlorodiphenyltrichloroethane) (1-2 gm/m²) Space spray- Pyrethrem (1 oz/1000c.ft) Genetic control THERMO FOGGING -Aerosol spray of ultra low volume [ULV] of MALATHION or SUMITHION 250 ml/hectare is effective in interrupting transmission and stopping epidemics. ULV treatments 10 days apart has shown to reduce mosquito densities more than 98%.
- 60. Protection against mosquito bites • Using insect repellents (Diethyltolumide) over the exposed parts of the body. • Using mosquito screens or nets • Wearing the long sleeved clothes like long trousers of a light shade for protection against mosquitoes.
- 62. RESIDUAL SPACE SPRAY FOGGING
- 63. CONTROL OF SANDFLY • Control of sandflies by insecticides such as DDT and Malathion. • Sanitation –filling up cracks and cervices in walls and floors and location of a cattle sheds and poultry house at a fair distance from human habitations.
- 64. PREVENTION OF TICK • DEET(N,N-Diethyl-meta-toluamide) or diethyltoluamide repellents for skin • Permethrin repellents for clothing – (0.5% permethrin should be applied to clothing ONLY) • Check for and remove ticks at least twice daily. • If a tick attaches, do not injure or rupture the tick. Remove ticks by grasping mouthparts at the skin surface using forceps and apply steady traction. 64
- 66. GROUP A OTHERS (ALPHAVIRUSE) UMBRE SINDBIS SATHUPRI CHIKUNGUNYA CHANDIPURA CHITTOR GANJAM MINNAL GROUP B VENKATAPURAM (FLAVIVIRUS) DHORI DENGUE KAISODI KFD SANDFLY FEVER JE AFRICAN HORSE SICKNESS WEST NILE VELLORE Some Arboviruses known to be prevalent in india