An unusual enterovirus outbreak in Denmark: clinical characteristics and molecular epidemiology

In 2000, a large enterovirus (EV) outbreak was seen in Denmark; the number of patients with a verified EV infection was 3-fold higher compared to previous y. Echovirus 30 (E30) was the dominant EV type and was detected in 31% of all 306 EV positive patients and in 61% of the 155 patients in whom typing was successful. The outbreak started in February and peaked in June, which is unusually early in a temperate climate and not registered before in Denmark. The age distribution of the patients also differed from previous y with a significantly higher proportion of older children and adults being affected. The patients had mainly symptoms consistent with aseptic meningitis. A phylogenetic analysis based upon a part of the VP1 structural gene of 21 E30 isolates showed that the Danish isolates belonged to the E30 genotype which has prevailed in Europe during the last few years. However, they constituted a separated cluster compared with 2 other outbreaks in other parts of Europe in 2000.