Evaluation of two screening tests for human leptospirosis.

Leptospirosis is prevalent in Thailand but its diagnosis depends primarily on clinical awareness. Serodiagnosis is of great assistance in the diagnosis of leptospirosis but in Thailand microagglutination (MA) is the only serodiagnosis available. MA is not rapid and it is used mainly in the referent laboratory. In addition, its roles in early diagnosis are rarely available. Rapid screening serological test which is sensitive early in the infection is needed. Latex agglutination (LA), indirect hemagglutination (IHA) were developed and evaluated in 100 MA positive sera and 200 blood donors. Later on, IHA and LA were compared with MA in 30 patients with a clinical picture compatible with leptospirosis. IHA and LA had sensitivities of 94 and 98 per cent respectively in MA positive sera. The specificity of IHA and LA in 200 blood donors was 99 and 100 per cent respectively. The study in 30 patients showed that LA and IHA were definitely more sensitive than MA test in sera collected within two weeks after the onset of fever. LA is also one of the most rapid tests for leptospirosis. With either LA or IHA human leptospirosis will be diagnosed more readily and more accurately.