International multi-centre evaluation of a dipstick assay for human leptospirosis

A dipstick assay for the detection of Leptospira-specific immunoglobulin M (IgM) antibodies in human sera was evaluated in 27 laboratories in 23 count ries. 873 serum samples from 711 patients including 329 laboratory-confirme d leptospirosis case patients, 239 noncase patients and 69 patients with vi ral infections causing heamorrhagic fever were tested. Relative to the resu lts of the reference leptospirosis test, the sensitivity of the dipstick as say was 84.5% for serum samples collected during the first 10 days of the d isease and 92.1% for serum samples collected 10-30 days after the onset of disease. The specificity was 87.5% and 94.4%, respectively Similar to viral haemorrhagic fevers, leptospirosis may cause bleeding. A small number of s erum samples from patients with haemorrhagic viral infections gave a weak ( 1 +) stain. All other samples were negative. In conclusion, the dipstick as say is sensitive and specific and reacts well with serum samples from patie nts infected with a range of leptospiral strains. It is also easy to use an d does not require special equipment or refrigeration. Therefore the assay is ideal for use in developing countries and rural settings.