Chikungunya epidemic: an Indian perspective.

Chikungunya, caused by the chikungunya virus, recently emerged as an important public health problem in the Indian Ocean Islands and India. In 2006, an estimated 1.38 million people across southern and central India developed symptomatic disease. The incidence of the disease may have been higher but may have been underreported due to lack of accurate reporting. First isolated in Tanzania in 1953, the chikungunya virus belongs to the family Togaviridae (single-stranded RNA alphaviruses) and has 3 distinct genotypes: East African, West African and Asian. Previous outbreaks in India (1963 and 1973) were caused by the Asian genotypes, but the 2005 epidemic in the Indian Ocean islands and the 2006 epidemic in India have been attributed to the East African genotype. The virus is transmitted to humans by the bites of mosquitoes of the species Aedes aegypti and A. albopictus. Researchers speculate that mutation of the virus, absence of herd immunity, lack of vector control, and globalization of trade and travel might have contributed to the resurgence of the infection. Chikungunya is characterized by high fever, severe arthralgia and rash. Although viral diagnostics (culture, serological tests and polymerase chain reaction tests) can be used to confirm the infection, these tests are not accessible during outbreaks to the majority of the population. The disease is a self-limiting febrile illness and treatment is symptomatic. As no effective vaccine or antiviral drugs are available, mosquito control by evidence-based interventions is the most appropriate strategy to contain the epidemic and pre-empt future outbreaks.