Clinical Chikungunya cases A followup serology after 1-2 years

Objective To evaluate the prevalence, persistence of Chikungunya virus (CHIKV) IgM, risk factors and the impact of the mysterious febrile arthralgia epidemic associated with suspected cases of CHIKV infection in and around Tirunelveli,a southern district of Tamilnadu, an area hit much during 2009.Materials and methods A total of 102 patients of more than 15 yrs of age with complaints of arthralgia and with past history suggestive of CHIKV infection during 2009-2010 epidemic were included. Assessment was done to evaluate the risk factors, and to detect CHIKV specific IgM antibodies by ELISA.Results Out of 102 patients,14 were positive for CHIKV IgM antibodies, of which 11(79) were female 3(21) were male. Among the 14 IgM positive patients, 10(71) had arthralgia even before CHIKV infection. Of this, 4 (29) were serologically proved in 2010 and they still remain positive.Of the 14 IgM positive patients, 10(71) showed involvement of more than one joint and of the 88 IgM negative patients, 28(32) showed involvement of more than one joint. Diabetes and hypertension were the comorbid medical conditions associated in IgM positive patients with persistent arthralgia. There was no significant correlation between IgM serology and comorbidity.Conclusion Long term detection of IgM antibodies after acute infection could be an indication of virus or viral antigenic persistence in tissue sanctuaries with continuing humoral response which can explain the long term sequelae.