Human leptospirosis in Denmark 1970-1996: an epidemiological and clinical study

Epidemiological and clinical aspects of 118 laboratory confirmed cases of human leptospirosis in Denmark from 1970 to 1996 were reviewed. Icterohaemorrhagiae (72%) and sejroe (20%) were the most frequent serovars. The incidence of leptospirosis was 0.09/100,000 inhabitants/y. 93% of the patients were 18-64 y old, 90% were men and 72% of the cases occurred from July to November. Occupational exposure was present in 63% (74/118) of the cases (41% fish farmers, 28%, farmers). Eight percent of the patients had travelled abroad, 7% had been exposed to sewers and 4%, had been exposed through recreational activities (fishing). Initial symptoms were generally non-specific. Weil's disease developed in 63%, of the patients, more often in patients infected with the serovar icterohaemorrhagiae (73%) compared to patients infected with serovars sejroe or saxkoebing (25%). The fatality rate was 7%, all due to icterohaemorrhagiae. Though a rare disease in Denmark, leptospirosis should be considered in certain risk groups as a possible diagnosis in patients with acute febrile illness.