The clinical picture of the various arboviral infections

• Viral encephalitis (inflammation of the brain) e.g. Japanese Encephalitis, Venezuelan Equine Encephalitis (=VEE), West Nile virus. St Louis Encephalitis, Eastern and Western Equine Encephalitis (EEE and WEE) occur in the USA. Murray River Valley is a cause in Australia. Tick-borne encephalitis (TBE) is a name which covers both Central European encephalitis (CEE) and Russian spring-summer encephalitis (RSSE).

• Viral haemorrhagic fever e.g. Yellow Fever, Crimean-Congo Haemorrhagic Fever, Dengue Haemorrhagic Fever

• Mostly aspecific viral fever with or without exanthema and a flu-like syndrome e.g. classical Dengue, West Nile Fever, Rift Valley Fever, Chikungunya Fever (the last two can take a haemorrhagic course)

• Flu-like syndrome with skin rash and severe joint pain and arthritis occur in Australia in infections with Ross River virus (RRV) and Barmah Forest virus (BFV). Arthritis frequently occurs in RRV while a rash is more frequent in BFV, but in practice in individual cases, no clinical distinction can be made between the viruses. Arthralgia, myalgia and lethargy can be present for 6 months in 50% of the RRV patients and in 10% of the BFV patients. Chikungunya Fever is also responsible for severe joint aches (esp. Middle East and Southeast Asia). There are plenty of arboviruses which fall in this clinical group. E.g. Sindsbis and the related Pogosta disease, Ockelbo disease and Karelian fever are all arboviroses characterized by arthritis, maculopapular rash, low fever, fatigue and muscle ache.

• Teratogenic syndrome: Some viruses, such as Main Drain virus and Cache Valley virus, a Bunyavirus, are associated with congenital abnormalities in animals such as sheep and other ruminants (congenital arthrogryphosis and hydrocephalus). Whether this risk also applies for man is unclear at present and is currently being studied.

Category: Microbiology Notes