Homologous microscopic agglutinating antibodies after natural infection with leptospires – results from a long term follow up of a cohort living in an endemic area

Abstract

AbstractThe present study was undertaken to determine the level and duration of persistence of antibodies against autologous, homologous and heterologous strains of Leptospira among the individuals naturally infected with Leptospira. A cohort of patients, who were culture positive for Leptospira were serologically followed up by microscopic agglutination test, using the infecting strain and the representative strains of homologous and heterologous serogroups as antigens. The case distribution, using the titre levels against the three antigens was studied. Duration of the persistence of antibodies was analyzed by Kaplan-Meier survival analysis. Fourteen culture positive cases were followed up for four years. The antibody titre against the infecting strain peaked at one month, and lasted up to four years, at a median titre of 1 in 100. The median titre of antibody against the representative strain of homologous serogroup dropped below 1 in 40 by the end of two years. Antibodies against the heterologous sero...