Arbovirus infections Flashcards
over 500 viruses transmitted by arthropods such as ticks, mosquitoes, sandflies.
What is general life cycle of arboviruses?
Arthropod takes blood meal from infected vertebrae
passes through gut wall to reach salivary gland, where replication takes place
1-2 weeks later arthropod is infectious, and can transmit at next blood meal
Certain viruses that infect ticks, can be transmitted directly from adult to egg (transovarial transmission). Future generations are infected without need for vertebrate host
Sometimes humans are dead end host, and are not naturally part of life cycle e.g equine encephalitis/ WNV
What are arboviruses which cause fever and haemorrhagic disease?
Togavirus
Flavivirus
Bunyavirus
Reovirus
Togavirus - Ross river (alphavirus)
Flavivirus -
Dengue
Yellowfever
Kyasanur forest
Omsk haemorrhagic fever
Bunyavirus - Rift Valley Sandfly fever CCHF La crosse
Reovirus -
Colorado tick fever
Many other less important causes. e.g almost 200 bunyaviruses, 40 may occasssionally cause human disease
Which arboviruses cause fever/ arthalgia/ rash?
Togavirus -
chikungunya
O’nyong nyong
Ross River
Flavivirus -
Dengue
Zika
West Nile
Bunyavirus -
Toscana
Which arboviruses cause encephalitis?
Fatality rate can vary up to 70%. However in most cases, very few people infected actually develop infection
Togavirus -
Eastern Equine encephalitis
Western Equine encephalitis
Venezuelan encephalitis
Flavivirus - West Nile encephalitis St Louis encephalitis Japanese encephalitis Murray Valley encephalitis Tick borne encephalitis Powassan
Bunyavirus -
California encephalitis
Most transmitted by mosquito, except -
tick borne encephalitis
Powassan - tick
6/10 of these viruses present in USA
Diseases such as Nipah are not transmitted by arthropods
Arboviruses which cause haemorrhagic disease.
What is vector for these viruses?
Yellow fever Dengue Kyasanur forest Omsk Ross river Rift Valley Sandfly fever CCHF Colorado tick fever La Crosse
Mosquito - Yellow fever - aedes Dengue Ross river Rift Valley La Crosse
Tick - Kyasanur forest Omsk CCHF Colorado tick fever
Sandfly -
Sicilian Sandfly fever
What is nuclear material of arboviruses?
Togaviridae - family
Alphavirus - genus
Flaviviridae - family
Flavivirus - genus
Togaviridae - family
Alphavirus - genus
+ssRNA (IV)
Flaviviridae - family
Flavivirus - genus
+ssRNA (IV)
What is nuclear material of arboviruses?
Bunyaviridiae - family
Orthobunyavirus - genus
Reoviridae - family
Orbivirus/ Coltivirus - genus
Bunyaviridiae - family
Orthobunyavirus - genus
-ssRNA (V)
Reoviridae - family
Orbivirus/ Coltivirus - genus
dsRNA (III)
Which arbovirus infections are present in Europe?
West Nile TBE Dengue CCHF Toscana Scicilian sandlfly Chikungunya
How is Zika transmitted?
Aedes aegypti mosquito
Can also occur via sexual transmission or blood transfusion.
What are symptoms of zika?
fever arthalgia rash - maculopapular myalgia conjunctivitis
What are complications for pregnant women infected with Zika?
Microcephaly
facial disproportion
spasticity
seizures
How to diagnose zika infection?
reverse-transcriptase PCR of viral RNA using seum/ saliva/ urine
IgM/IgG - note cross-reactivity can occur with other flavivirus antibodies
Arboviruses which cause encephalitis.
Which viruses have vaccines available?
JE
WEE
EEE
VEE
Except JE, vaccines only available for laboratory staff
What is the definition of this word:
Enzootic
Enzootic is the non-human version of endemic in animals
e.g WNV persisting life cycle in birds
What is the definition of this word:
Epizootic
Epizootic disease is a disease event in an animal population akin to an epidemic in humans. It generally refers to outbreaks of disease which cause serious economic or public health issues and are of major importance in the international trade of animals and animal products.
Examples of epizootic disease include avian influenza, swine fever and foot and mouth disease
Epizootic example may be WNV spread from birds enzootic cycle to horses
