Prevalence of leptospiral agglutinins among conservancy workers in Madras City, India.

In a study of 584 Corporation conservancy (sanitation) workers who lived mostly in slums, and who worked in four Corporation Circles of Madras City, India, 192 (32.9%) were found to be positive for agglutinins to Leptospira interrogans. Seropositivity prevalence increased with age, but was similar in males and females except in the youngest age group, where males predominated. Prevalence in the four study areas ranged between 17.8 and 40.5% (P < 0.01). Among 152 sera in which one serogroup predominated, Autumnalis was the most commonly recorded (33.6%), followed by Icterohaemorrhagiae (15.1%), Panama (15.1%), Sejroe (14.5%) and others (21.7%). Forty sera reacted to two or more serogroups at the same (highest) titre, most frequently to the first three serogroups above. The titre range was 1:50-1:3200 (geometric mean titre 149). Among a group of 46 male automobile industry workers who lived in middle-class housing, seropositivity prevalence (17.4%) was approximately half that of the sanitation workers (P < 0.05), and the titre range was lower (1:50-1:200, GMT 84). The predominating serogroups were those found in the sanitation workers. Bearing in mind that sanitation workers are the urban group probably at highest risk of leptospiral infection, the prevalence rate (< 33%) found in our study is not considered to be particularly high.