Causative Agent
Chikungunya virus
Incubation Period
Average 3 – 7 days (range 2 – 12 days)
Infectious Period
From up to 2 days before illness onset to 5 days after illness onset.
Epidemiology
Chikungunya means “that which bends up” in the East African/Mozambique
Makonde language. Regular outbreaks in East and West Africa, Indian Ocean
islands, Asia, and more recently southern Europe.
In Singapore, the first outbreak of chikungunya fever was reported in Jan 2008 in Little India where Aedes aegypti was the vector implicated in transmission. A few local cases resurfaced in May and June 2008 in suburban residential areas. A sharp increase in local cases occurred again in July 2008 in rural industrial and farming areas where Aedes albopictus was the predominant vector, and coincided with the rise in imported from Malaysia. A total of 718 laboratory confirmed cases (181 imported) were reported in 2008. Following aggressive vector control measures, cases subsided rapidly in Feb 2009 with 341 cases (66 imported) reported in 2009. In the first 9 months of 2010, 7 local and 18 imported were reported.The incidence rate among indigenous cases was highest in the 35-44 year age group with a male to female ratio of 3.9:1.
Asymptomatic infections do occur but how common this is remains to be determined. Infection is thought to result in lifelong immunity. In older reports chikungunya fever has been described as a self-limited illness, although severe complications and death have been reported in the more recent outbreaks. Pregnant women can be infected with chikungunya virus. Most infections will not be transmitted to the foetus. There are, however, rare reports of first trimester abortions occuring after chikungunya infection. There is no evidence that the virus can be transmitted through breast milk.
