The Survey of Seroprevalence of Leptospirosis in Mazandaran Province of Iran Using Microscopic Agglutination Test and Indirect Immunofluorescence Assay

Leptospirosis is a worldwide zoonotic disease with a much greater incidence in tropical and temperate regions. It has now been identified as one of the emerging infectious diseases. Since, the incidence of Leptospirosis is significantly high in temperate regions among rice field workers and livestock animals at Mazandaran province, it is neccessery to evaluate condition of Leptospirosis that will help to recognize the most prevalent for vaccine development. In this survey, 127 serum samples of suspected human were collected from different parts of Mazandaran during eight months (during november 2006 to july 2007) and were tested by indirect immunoflurescence assay (IFA) in Amol Branch, Institute Pasteur of Iran. To recognize common pathogenic serotypes, collected samples were tested using Microscopic agglutination test (MAT) in Leptospira Research Laboratory, Faculty of Veterinary Medicine, University of Tehran. Prevalence rate of Leptospirosis in Mazandaran province was 58.26% using IFA and MAT. In this survey, 74 samples were positive which 82.43% of them were belonged to male and 17.52% to female. Rice field workers showed the most frequent occurrence of infection, so among positive cases 66.22% were to the rice field workers and showed significant difference with other occupations (P=0.007). Among 107 samples that were collected from males and 20 from females, 57% and 65% samples were positive, respectively. There was no significant difference between gender and Leptospirosis (P>0.05). Living place (urban or rural) and contact with animals did show no significant difference with Leptospirosis. The most positive cases were found in age range of 40-50 years (25.67%). The most prevalent serotypes which were recognized in Mazandaran province using MAT, included, Ballum (16.77%), Sejroe (14.29%), Tarassovi (13.64%), Australis (11.69%), Pyrogenes (7.79%), Javanica (6.5%), Icterohaemorrhagiae (6.5%). Using a MAT titer of ≥ 1:100 as the gold standard, The sensitivity of IFA for the detection of Leptospirosis was 38.8%, the specificity was 88.33%, the positive predictive value was 78.78%, and the negative predictive value was 56.38%. It seems that Leptospifrosis is widespread in Mazandaran province and the authorities should pursue prevention and control measures of this multifaceted disease with more enthusiasm to prevent spread of the disease. Demographic analysis of the results indicates that leptospirosis is typically an occupational disease in the region.