Clinical distinction and evaluation of leptospirosis in Taiwan - A case-control study

Background: Leptospirosis is the most widespread zoonosis. Leptospirosis remains underreported in Taiwan because of ignorance and the broad spectrum of clinical manifestations. Acute renal failure (ARF) is a prominent feature of leptospirosis. This investigation conducted a case-control study to obtain information to distinguish leptospirosis from other conditions with similar presentations. Methods: Leptospirosis surveillance was performed at Chang Gung Memorial Hospital, Taiwan, between September 2000 and December 2001. Suspected clinical cases were included in the sample and investigated. Diagnosis was confirmed with four-fold or greater increase of microscopic agglutination test (MAT) titer in paired sera; positive immunoglobulin M (IgM) dipstick with single MAT≥400; or isolation of leptospira. Cases were classified as excluded based on confirmed etiology other than leptospirosis or negative paired serologic test. Results: Twenty-two confirmed cases and 21 excluded cases of leptospirosis were identified from among 169 suspected cases. An outbreak was observed during the flooding from Typhoon Nali. L. shermani, the most common serovar in Taiwan, was identified in 78.5% of confirmed cases. In the confirmed group, mean age was 44 ± 14.5 (21-66) yrs similar to that of the excluded group, with male predominance (86.4 vs. 57. 1%, p