VECTOR-BORNE VIRAL DISEASES IN SWEDEN - A SHORT REVIEW

Ockelbo disease, caused by a Sindbis-related virus transmitted to man by mosquitoes, was first described in the central part of Sweden in th e 1960s as clusters of patients with fever, arthralgia and rash. An av erage annual rate of 30 cases was recorded in the 1980s but no cases h ave been diagnosed during the last few years. Nephropathia epidemica ( NE) characterized by fever, abdominal pain and renal dysfunction has b een known to cause considerable morbidity in Sweden during the last 60 years but the etiologic agent (Puumala virus) was not isolated until 1983. This virus's main reservoir is the bank vole (Clethrionomys glar eolus). NE is endemic in the northern two thirds of Sweden where more than a hundred cases are diagnosed each year. Tick-borne encephalitis transmitted by Ixodes ricinus ticks is restricted to the archipelago a nd Lake Malaren on the east coast close to Stockholm. Between 30 and 1 10 cases are diagnosed every year. Inkoo virus, a California encephali tis group virus, has been isolated from mosquitoes in Sweden. The anti body prevalence to Inkoo virus is very high in a normal population, bu t no disease has as yet been associated with this virus in Sweden. Amo ng the vector-borne virus diseases imported to Sweden, dengue is the m ost important, with approximately 50 cases recorded every year.