Evaluation of an IgM-ELISA test for the diagnosis of human leptospirosis

Leptospirosis is a zoonosis with a worldwide distribution very common in most countries. In Italy this acute febrile illness is more frequent in the Northern than in the Southern regions. In the period 1994-1996, the number of cases of Leptospirosis in Sicily was lower with respect to the northern-central regions (7.2% and 73.4% respectively). Between January 1990 and December 1999, a total of 9 leptospirosis cases were observed in the Regional Centre for Leptospirosis of Palermo. The patients were all males (age between 22 and 59 years) and their occupations varied. Laboratory diagnosis is performed by the classical microagglutination microscopical (MAT) but this test is very complex and time-consuming. This study compared the classical MAT with ELISA IgM by using 19 serum samples from 9 patients with confirmed leptospirosis. We also tested 23 serum samples from blood-donors and 29 serum samples from patients with other infectious diseases. By the MAT and the PanBio IgM ELISA all sera from patients were found to be positive. Our results indicate that MAT represents the test with the highest degree of specificity (100%), but ELISA is simpler to perform, considering the favourable degree of sensitivity (100%) and specificity (95.9%).