Autochthonous leptospirosis in South-East Austria, 2004-2012

Leptospirosis is one of the world's mostly spread zoonoses causing acute fever. Over years, leptospirosis has been reported to occur rarely in Austria and Germany (annual incidence of 0.06/100,000 in Germany). Only imported cases have been on the increase. Objectives of this case-series study were to retrospectively assess epidemiologic and clinical characteristics of leptospirosis illnesses in South-East Austria, to describe risk exposures for autochthonous infections, and to compare patients with imported versus autochthonous infection.

During the 9-year period between 2004 and 2012, 127 adult patients (49 females, 78 males) who tested positive by rapid point-of-care test for Leptospira-specific IgM (Leptocheck®) were identified through electronic hospital databases. Follow-up telephone interviews were conducted with 82 patients. A total of 114 (89.8%) of the 127 patients enrolled had acquired leptospirosis within Austria and 13 (10.2%) had potentially imported infections. Most autochthonous cases were diagnosed during the months of June and July, whereas fewest were diagnosed during the winter months. Exposure to rodents, recreational activities in woods or wet areas, gardening, cleaning of basements or huts were the most common risk exposures found in autochthonous infection. Serogroups Australis (n = 23), Sejroe (n = 22), and Icterohaemorrhagiae (n = 11) were identified most frequently by MAT testing in autochthonous infections. Patients with imported leptospirosis were significantly younger, less likely to be icteric and had significantly lower liver transaminase levels (p = 0.004) than those with autochthonous infections.

Leptospirosis is endemic in South-East Austria. In contrast to reports from other countries we found a relatively high proportion of leptospirosis cases to be female (39% vs. ∼ 10%), likely the result of differing risk exposures for South-East Austria.