Seroprevalence, Risk Factors, and Rodent Reservoirs of Leptospirosis in an Urban Community of Puerto Rico, 2015

Abstract

Background: The burden of leptospirosis in Puerto Rico remains unclear due to underreporting.

Methods: A cross-sectional survey and rodent trapping was performed in a community within San Juan, Puerto Rico to determine the seroprevalence and risk factors for Leptospira infection. The microscopic agglutination test was used to detect anti-Leptospira antibodies as a marker of previous infection. We evaluated Leptospira carriage by quantitative polymerase chain reaction among rodents trapped at the community site.

Results: Of 202 study participants, 55 (27.2%) had Leptospira agglutinating antibodies. Among the 55 seropositive individuals, antibodies were directed most frequently against serogroups Icterohaemorrhagiae (22.0%) and Autumnalis (10.6%). Of 18 captured rodents, 11 (61.1%) carried pathogenic Leptospira (Leptospira borgpetersenii, 7 and Leptospira interrogans, 2). Four participants showed their highest titer against an isolate obtained from a rodent (serogroup Ballum). Increasing household distance to the canal that runs through the community was associated with decreased risk of infection (odds ratio = 0.934 per 10-meter increase; 95% confidence interval, .952-.992).

Conclusions: There are high levels of Leptospira exposure in an urban setting in Puerto Rico, for which rodents may be an important reservoir for transmission. Our findings indicate that prevention should focus on mitigating risk posed by infrastructure deficiencies such as the canal.

Keywords: Puerto Rico; leptospirosis; public health; rodent; seroprevalence.

Figure 1.

(A) Satellite image of the city of San Juan, Puerto Rico, with a black rectangle delineating the Caño Martín Peña neighborhood. (B) Satellite image of the 4 sampled census tracts (purple) along the canal (blue). The number of subjects and the proportion of seropositive subjects within each studied block are indicated in colored circles. (C) An image of the canal showing accumulation of vegetation and debris and the close distance to households.

Figure 2.

Distribution of microscopic agglutination test titers for 202 subjects from the Caño Martín Peña neighborhood. Labels above the bars indicate the number of subjects (% of total), according to their highest microscopic agglutination test (MAT) titer.

Figure 3.

Seroprevalence of Leptospira antibodies in human participants in Caño Martín Peña in 2015 by age and sex, with 95% confidence intervals.