Emergence of chikungunya virus in Indian subcontinent after 32 years: A review.

An outbreak of chikungunya virus is currently ongoing in many countries in Indian Ocean since January 2005. The current outbreak appears to be the most severe and one of the biggest outbreaks caused by this virus. India, where this virus was last reported in 1973, is also amongst affected countries. Chikungunya virus has affected millions of the people in Africa and Southeast Asia, since it was first reported in 1952 in Tanzania. Even then, natural history of this disease is not fully understood. The intra-outbreak studies, point towards recent changes in the viral genome facilitating the rapid spread and enhanced pathogenecity. The available published scientific literature on chikungunya virus was searched to understand the natural history of this disease, reasons for the current outbreak and the causes behind re-emergence of the virus in India. The paucity of the scientific information on various epidemiological aspects of chikungunya virus threatens off an epidemic as control of spread of virus might be difficult in the absence of appropriate knowledge. There is an immediate need of the research on chikungunya virus, for an effective vaccine besides strengthening the existing diagnostic laboratory facilities. The current outbreak can also be taken as a lesson for establishment of a system for continuous surveillance of diseases, considered disappeared from the countries. The re-emergence and epidemics are unpredictable phenomena but the impact of such events can be ameliorated by appropriate knowledge and by being in the right state of preparedness.