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

Viral Zoonoses Arthropod-borne Vs Non arthropod-borne zoonoses 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.

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

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

Characteristic Properties of Arboviruses Property Toga Flavi Bunya Rhabdo Reo* Ortho Symmetry Cubic Helical Bullet Diameter (nm) 70 40-60 80-100 180 x 85 60-80 15-120 Nucleic acid (+)ss RNA (-)ss (-) ss ds No. of Vs 29 68 318 63 77 2 *Non-enveloped

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

Life cycle of arboviruses

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

Life cycle of arboviruses

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

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

Epidemiology: Natural cycles 3. Human- Arthropod cycle Dengue & Urban yellow fever

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

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

*ArboVs associated with CNS disease: Virus Vector Reservoir Distribution Eastern equine encephalitis EEEV Mosquito Birds America Western equine encephalitis WEEV Venezuelan equine encephalitis VEEV Rodent Japanese encephalitis V Birds Pigs Orient Murray Valley encephalitis V Australia West Nile V Europe, Africa Middle East Asia, America

West Nile virus Flaviviridae Febrile illness encephalitis

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

Venezuelan equine encephalitis virus VEEV Togaviridae Febrile illness encephalitis

*ArboVs associated with Hemorrhagic Fever Virus Vector Reservoir Distribution Crimean Congo Virus Tick Mammals Africa , Asia & Europe Rift Valley fever virus Mosquito Sheep cattle Africa Yellow Fever virus Monkeys Man Africa & South America Dengue Virus Man Entire tropical zone

*ArboVs associated with Fever-rash-arthralgia Virus Vector Reservoir Distribution West Nile virus Mosquito Birds Africa, Europe, America Rift Valley Fever Virus Sheep Cattle Africa Dengue Virus Man Entire tropical zone Sandfly fever Virus Sandfly Mediterranean

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

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

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

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

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

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

Dx. Rx. Reference Lab Lab. Methods : 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 Rx. Ribavirin (some bunyavirus & Togavirus)

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

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