Chikungunya

Chikungunya is an arboviral disease transmitted by aedes mosquitoes. The virus was first isolated in 1953 in Tanzania.

The disease typically consists of an acute illness characterized by fever, rash, and incapacitating arthralgia. The word chikungunya, used for both the virus and the disease, means “to walk bent over” in some east African languages, and refers to the effect of the joint pains that characterise this dengue-like infection.

Chikungunya is a specifically tropical disease, but it is geographically restricted, and outbreaks are relatively uncommon. It is only occasionally observed in travellers and military personnel. More than 266 000 people have been infected during the ongoing outbreak in Réunion, in which Aedes albopictus is the presumed vector. In the ongoing Indian outbreak, in which Aedes aegypti is the presumed vector, 1 400 000 cases of chikungunya were reported during 2006.

The reasons for the re-emergence of chikungunya on the Indian subcontinent, and for its unprecedented incidence rate in the Indian Ocean region, are unclear. Plausible explanations include increased tourism, chikungunya virus introduction into a naive population, and viral mutation.

Re-emerging

In the past decade, chikungunya—a virus transmitted by Aedes spp mosquitoes has re-emerged in Africa, southern and southeastern Asia, and the Indian Ocean Islands as the cause of large outbreaks of human disease. The disease is characterised by fever, headache, myalgia, rash, and both acute and persistent arthralgia. The disease can cause severe morbidity and, since 2005, fatality. The virus is endemic to tropical regions, but the spread of Aedes albopictus into Europe and the Americas coupled with high viraemia in infected travellers returning from endemic areas increases the risk that this virus could establish itself in new endemic regions. This Seminar focuses on the re-emergence of this disease, the clinical manifestations, pathogenesis of virus-induced arthralgia, diagnostic techniques, and various treatment modalities.

In Sri Lanka

Chikungunya (CHIKV) is a crippling mosquito-borne disease caused by the chikungunya virus that has recently emerged as a significant public health problem in Sri Lanka.

The re-emergence of CHIKV in Sri Lanka was confirmed in November 2006 (Hapuarachchi et al., 2008), after four decades of absence (Munasinghe et al., 1966). The estimated figures indicate that approximately 40 000 individuals in Sri Lanka were affected during 2006–2007 and a similar number in 2008. Yet, Chikungunya virus is not a stranger to Sri Lanka as the first epidemic was reported in the early 1960s, followed by quiescence until the epidemic which started in mid-October 2006. There were more than 37, 000 cases reported in first few months from different parts of the island.

The disease is transmitted by Aedes mosquito, which is the vector of Dengue fever and chikungunya, found in Sri Lanka. It is an urban mosquito and breeds in clear water. However, overcrowding of houses would have led to poor hygiene and prevalence of mosquito breeding sites. A study done in India showed that high population density, lack of adequate vector control, and poor hygiene were important risk factors in the population.

The outbreak of chikungunya in 1965 had reported less joint disease and nonarthritic complications than in 2006. Plausible explanations for the increased morbidity of the infection include mutations of the virus, absence of herd immunity, lack of vector control, and globalization of travel and trade. Sri Lanka records high incidence of chikungunya among the regions during the epidemic in the Indian Ocean in 2006.

Unfortunately, there is no evidence based-treatment policy for the management of chronic arthritic disability except for its natural healing and alleviation of symptoms. Hence, proper understanding of the pathophysiology of chronic disability and development of an effective treatment regimen would be an urgent task.

Hapuarachchi, H.C., Bandara, K.B.A.T., Sumanadasa, S.D.M., Hapugoda, M.D., Lai, Y.L., Lee, K.S., Tan, L.K., Lin, R.T., Ng, L.F., Bucht, G. and Abeyewickreme, W., 2010. Re-emergence of Chikungunya virus in South-east Asia: virological evidence from Sri Lanka and Singapore. Journal of General Virology, 91(4), pp.1067-1076.
Kularatne, S.A.M., Gihan, M.C., Weerasinghe, S.C. and Gunasena, S., 2009. Concurrent outbreaks of Chikungunya and Dengue fever in Kandy, Sri Lanka, 2006–07: a comparative analysis of clinical and laboratory features. Postgraduate medical journal, 85(1005), pp.342-346.
Kularatne, S.A., Weerasinghe, S.C., Gihan, C., Wickramasinghe, S., Dharmarathne, S., Abeyrathna, A. and Jayalath, T., 2012. Epidemiology, clinical manifestations, and long-term outcomes of a major outbreak of chikungunya in a hamlet in Sri Lanka, in 2007: a longitudinal cohort study. Journal of Tropical Medicine, 2012.