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.

Chikungunya outbreaks occurred in the central province, Sri Lanka in 2006. This community-based study reports the epidemiology and the natural history of the infection from an affected village. Of the 199 families and 1001 individuals in the village, 159 (80%) and 513 (51%) were affected, respectively, comprising 237 (46%) males with peak incidence at 40-50 years. The acute illness caused polyarthritis in 233 (46%), and of them 230 (98%) progressed to chronic arthritic disability (CAD). Of the CAD patients, 102 (44%) had recovered in 141 days (range 30-210 days) from the disability state whilst 128 (56%) had persisting disability which lasted 12, 24, and 36 months in 41 (17.8%), 22 (9.5%), and 14 (6.1%) individuals, respectively. Carpal tunnel syndrome (CTS) manifested in 110 (21%). Females showed preponderance for complications over males: acute arthritis 147 versus 86, P = 0.001; CAD 136 versus 84, P = 0.029; CTS 88 versus 22, P = 0.001; relapses 105 versus 68, P = 0.001. Chikungunya was highly communicable and caused lasting crippling complications.