Dengue fever imported to Norway. Serologically confirmed cases 1991-96

With up to 100 million cases annually, dengue fever is today's most important arboviral disease. Dengue fever is endemic in many parts of South-East Asia, the Indian subcontinent, Oceania and the Americas. The disease mainly affects the local population, but occasionally also visitors from non-endemic areas. In this article we present epidemiological and clinical data on all 26 cases with serological confirmed dengue fever diagnosed in Norway in 1991-1996. 21 patients (81%) were infected in Asia. Typical exanthema, leucopenia, and thrombocytopenia were seen in 71%, 79% and 84% of the cases, respectively. A 37-year-old Indian-born woman developed dengue haemorrhagic fever grade 1 after a visit to New Delhi, while the remaining 25 patients had classical dengue fever. Postinfectious complications were common, and four weeks after the acute illness, hair loss, mental depression and asthenia were reported by 45%, 50% and 100% of the cases, respectively.