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ARBOVIRUSES By: Dr. Malak El Hazmi Assistant Professor & Consultant Virologist College of Medicine & KKUH.

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Presentation on theme: "ARBOVIRUSES By: Dr. Malak El Hazmi Assistant Professor & Consultant Virologist College of Medicine & KKUH."— Presentation transcript:

1 ARBOVIRUSES By: Dr. Malak El Hazmi Assistant Professor & Consultant Virologist College of Medicine & KKUH

2 Viral Zoonoses Non arthropod-borne zoonosesArthropod-borne Vs Mosquito-borne Vs –Yellow Fever V –Dengue V Rabies V. Ebola V. Marburg V. Lassa V. Hantaviruses Tick-borne Vs –Tick-borne encephalitis Vs –Colorado tick fever Fly-borne Vs –Sandfly fever V.

3 Arboviruses: Def Etiology Epidemiology Diseases Dengue Yellow Fever Rift Valley Fever Dx. Rx Prevention

4 Arthropod –borne Viruses Arboviruses > 500 Vs Classification – –Togaviridae * – –Flaviviridae * – –Bunyaviridae * – –Reoviridae – –Orthomyxoviridae – –Rhabdoviridae

5 Characteristic Properties of Arboviruses PropertyTogaFlaviBunyaRhabdoReo * Ortho SymmetryCubic HelicalBulletCubic Diameter (nm) x Nucleic acid (+)ss RNA (+)ss RNA (-)ss RNA (-) ss RNA ds RNA (-) ss RNA No. of Vs * Non-enveloped

6 Epidemiology: Reservoir: Wild birds & Mammals Vector: Mosquito, tick & Sandfly Transmission: bite of infected vector Natural Cycles 1. 1.Human-mosquito cycle Dengue + Urban yellow fever 2. 2.Mosquito - bird cycle West Nile Vs 3. 3.Mosquito-mammal cycle Venezuelan equine encephalitis

7 Life cycle of arboviruses

8 Epidemiology: Reservoir: Wild birds & Mammals Vector: Mosquito, ticks& Sandfly Transmission: bite of infected vector

9 Life cycle of arboviruses

10 Epidemiology: Natural cycles 1. Arthropod - bird cycle West Nile Vs,EEEV, WEEV

11 2. Arthropod -mammal cycle Venezuelan equine encephalitis Epidemiology: Natural cycles

12 3. Human- Arthropod cycle Dengue & Urban yellow fever

13 Epidemiology: Natural cycles 2.Arthropod- mammal cycle 1. Arthropod - bird cycle 3. Human- arthropod cycle

14 Diseases Asymptomatic Infections* Diseases 1) 1)CNS disease ( encephalitis) 2) 2)Fever, Rash & arthralgia 3) 3)Hemorrhagic fever ± hepatitis

15 * ArboVs associated with CNS disease: VirusVectorReservoirDistribution Eastern equine encephalitis EEEV Mosquito BirdsAmerica Western equine encephalitis WEEV Mosquito BirdsAmerica Venezuelan equine encephalitis VEEV Mosquito RodentAmerica Japanese encephalitis V MosquitoBirds PigsOrient Murray Valley encephalitis V Mosquito BirdsAustralia West Nile V Mosquito BirdsEurope, Africa Middle East Asia, America

16 West Nile virus Flaviviridae Flaviviridae Febrile illness encephalitis Febrile illness encephalitis

17 Eastern equine encephalitis virus Eastern equine encephalitis virusEEEV Togaviridae Killed vaccine for horses Western equine encephalitis virus Western equine encephalitis virus WEEV WEEV Severe Encephalitis EEEV &WEEV EEEV &WEEV less severe

18 Togaviridae Togaviridae Febrile illness Febrile illness encephalitis encephalitis Venezuelan equine encephalitis virus VEEV

19 *ArboVs associated with Hemorrhagic Fever Virus VirusVectorReservoirDistribution Crimean Congo VirusTickMammalsAfrica, Asia & Europe Rift Valley fever virusMosquitoSheep cattle Africa Yellow Fever virusMosquitoMonkeys Man Africa & South America Dengue VirusMosquitoManEntire tropical zone

20 * ArboVs associated with Fever-rash-arthralgia VirusVectorReservoirDistribution West Nile virusMosquitoBirdsAfrica, Europe, America Rift Valley Fever VirusMosquitoSheep Cattle Africa Dengue VirusMosquitoManEntire tropical zone Sandfly fever VirusSandflyManMediterranean

21 Yellow Fever Flaviviridae Asymptomatic to Jaundice + Fever ± hemorrhage ± renal failure Epidemiology Tropical Africa & South America Jungle Yellow Fever Urban Yellow Fever

22 Jungle Yellow Fever: Vector: mosquito Reservoir: Monkeys Accidental host: humans It is a disease of Monkeys Urban Yellow Fever: Vector: mosquito Reservoir: human It is a disease of humans

23 Dengue Virus Vector : Mosquito Reservoir : human Tropical parts of the world Diseases The classic dengue fever 2. Dengue Hemorrhagic Fever

24 Dengue Virus 1. 1.The classic dengue fever Fever – rash – arthralgia Break bone fever Self-limiting 2. 2.Dengue Hemorrhagic Fever Severe disease Mortality rate 15% C/F - F-R-A - Hemorrhage (GI, skin)

25 Rift Valley Fever Bunyaviridae Sheep, Cattle, etc Spread Mosquitoes Infected animal blood or tissue Raw milk

26 Diseases Febrile disease* Retinitis Fulminant disease with Hge + Jaundice + Hepatitis Rarely: encephalitis

27 Reference Lab Lab. Methods : A. A.Isolation (Good standard ) Samples: blood, CSF, Viscera. Cell culture CPE Identify by IF B -IgM -AB * - EIEA, IF: (most used) C - Arbovirus RNA by RT-PCR Dx. Rx. Ribavirin (some bunyavirus & Togavirus)

28 Prevention 1. 1.Vector Control: Elimination of vector breading sites using insecticides Avoidance contact with vectors ( repellants, net ) 2. 2.Vaccines:

29 2- Vaccines: 1. 1.Yellow Fever vaccine (LAV, 17D strain, one dose /10 yrs) 2. 2.Tick-borne encephalitis vaccine (killed, 2 doses,3 rd doses after 1 yr. booster every 3-5 yrs) 3. 3.Japanese encephalitis (killed, LAV)


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