Arthritis and arthralgia three years after Sindbis virus infection: clinical follow-up of a cohort of 49 patients

Sindbis virus (SINV) emerges as large human outbreaks in northern Europe every 7 years. Similar to many other alphaviruses, SINV is a mosquito-borne causative agent of a rash-arthritis. Previous reports suggest that in many alphavirus infections joint symptoms might persist for years. A prospective cohort of 49 patients was physically examined 3 y after verified acute SINV infection to reveal persistent joint symptoms. We carefully searched for a temporal association between the infection and current symptoms, and took into account other medical conditions. Sera were collected and analysed with enzyme immunoassays. Arthritis (swelling and tenderness on physical examination) was diagnosed in 4.1% (2/49) of the patients. Tenderness on palpation or in movement of a joint was found in 14.3% of the patients in the rheumatological examination, and an additional 10.2% complained of persisting arthralgia at the interview. Thus, 24.5% of the patients had joint manifestations attributable to the infection 3 y earlier. A positive IgM antibody response persisted in 3/49 of the patients; both patients with arthritis were in this group. As one-quarter of the patients were symptomatic 3 y after infection, it seems that persistent symptoms of SINV infection have considerable public health implications in areas with high seroprevalence.