Epidemiology and Infection

Research Article

Geographical and temporal distribution of Ockelbo disease in Sweden

J. O. Lundströma1a2, S. Venea1, Å. Espmarka1, M. Engvalla1 and B. Niklassona1a3

a1 Department of Virology, National Bacteriological Laboratory, S-10521 Stockholm, Sweden

a2 Department of Virology, Karolinska Institute, c/o National Bacteriological Laboratory, S-10521 Stockholm, Sweden

a3 National Defence Research Establishment, FOA-5, S-17290 Sundyberg,Sweden

Abstract

The incidence of Ockelbo disease and the prevalence of Ockelbo virus neutralizing antibodies were investigated in a sample of the Swedish population. The disease occurs throughout most of Sweden but with higher incidence and antibody prevalence rates in the central part of the country. It generally affects middle-aged men and women, with equal incidence between sexes, and is uncommon in people younger than 20 years of age. The disease occurs during a short period each year between the third week of July and the first week of October, with a peak during the second half of August. During the 8 years studied (1981–8), an average of 31 Ockelbo patients/year were diagnosed. The antibody prevalence rates in the oldest age groups were 20–40 times higher than the accumulated life-risk of being diagnosed and reported as an Ockelbo disease patient, which suggests that many cases are asymptomatic and/or unreported.

(Accepted January 15 1991)

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