Seroprevalence of Sindbis virus and associated risk factors in northern Sweden

Mosquito-borne Sindbis virus (SINV) cause disease characterized by rash, fever and arthritis which often leads to long-lasting arthralgia. To determine the seroprevalence of SINV and associated risk factors in northern Sweden, a randomly selected population aged between 25 and 74 years were invited to join the MONICA study. Serum from 1611 samples were analysed for specific IgG antibodies. Overall, 2.9% had IgG against SINV. More men (3.7%) than women (2.0%) were SINV seropositive (P=0.047) and it was more common in subjects with a lower educational level (P=0.013) and living in small, rural communities (P<0.001). Seropositivity was associated with higher waist circumference (P=0.1), elevated diastolic blood pressure (P=0.037), and history of a previous stroke (P=0.011). In a multiple logistic regression analysis, adjusting for known risk factors for stroke, seropositivity for SINV was an independent predictor of having had a stroke (odds ratio 4.3, 95% confidence interval 1.4-13.0, P=0.011).