Chikungunya Virus

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Chikungunya Virus.

Classification

GROUP: GROUP IV SINGLE STRANDED POSITIVE SENSE RNA

FAMILY: Togaviridae

GENUS: Alphavirus

SPECIES: Chikungunya virus

ORDER: not assigned

VIRUS ACCESSION NUMBER: 73001507

ICTVdB VIRUS CODE: 00.073.0.01.007.00.000.002.

ICTV approved acronym: CHIKV

Description and significance:

Chikungunya virus is an arthropod borne virus from the genus Alphavirus and family Togaviridae. It was first isolated in Tanzania, Africa in 1953 and has sporadically caused human epidemics in South-east Asia, southern India. Chikungunya is a zoonotic virus with a life cycle that principally involves primates and the Aedes mosquitoes. Humans that are infected may develop relatively high viremias and fever that can elevate up to 104 degrees Fahrenheit. Aedes aegypti (also called the yellow fever mosquito) is the primary transmission agent for Chikungunya. It is usually found in tropics and that is the reason it is predominantly seen in Asian countries. Chikungunya has also spread across the globe in recent years and remains a viral disease with no anti-viral medication available. The clinical picture is characterized by a sudden onset of fever, rash and severe pain in the joints. The name Chikungunya comes from the Swahili language for stooped walk, reflecting the physique of a person suffering from the disease. Chikungunya fever is also called the “bone-breaker fever”. The family Togaviridae includes viruses like O’nyong nyong and Igba Oro, which are closely related to Chikungunya and induce the same disease in humans.

Natural Host:

The virus is transmitted by Aedes aegypti and Aedes albopictus. Virus infects during its life cycle arthropod and vertebrate hosts. Viral host belongs to the Domain Eucarya, Kingdom Animalia, Phylum Arthropoda and Chordata, Subphylum Hexapoda; Class Insecta; Subclass Pterygota; Order Diptera.

Severity and Occurence of the Disease

Infection can affect the nervous system or the musculo-skeletal system. General symptoms include fever, headache, maculopapular rash, arthralgia, myalgia, photophobia, lymphadenopathy. Infection is usually acute or chronic, more than 12% of patients with Chikungunya develop chronic joint pain. Prevalence of viral infection is seasonally dependent and incidences of the virus are usually noticeable in summer and wet seasons. The incubation period lasts usually two to four days followed by a recovery in five to seven days. The virus can be detected during the first 48 hours of disease and maybe detected as late as four days in some patients. The virus is known to occur in tropical regions. Viral host lives under aerobic conditions and lives in the atmosphere where it is wet. During 2005-2006 twelve cases of Chikungunya fever were diagnosed in the United States (ProMED 2006a). In India there have been at least hundred thousand cases reported with two confirmed fatalities. Infections may occur in areas that are not considered endemic but travel and globalization increases the possibility of epidemic outbreaks in other regions around the globe. Below is a list of some Chikungunya outbreaks: • Tanzania in 1953 (first recoded outbreak) • Kolkata, India in 1963 • Port Klang, Malaysia in 1999 • 237 deaths and 33% of people infected in Reunion islands in 2006-2007 • Italy in 2007 • Kerala in 2007

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