Seroprevalence, distribution, and risk factors for human leptospirosis in the United States Virgin Islands

Abstract

Background: The first documented human leptospirosis cases in the U.S. Virgin Islands (USVI) occurred following 2017 Hurricanes Irma and Maria. We conducted a representative serosurvey in USVI to estimate the seroprevalence and distribution of human leptospirosis and evaluate local risk factors associated with seropositivity. Methodology/Principal findings: A stratified, two-stage cluster sampling design was used and consisted of three island strata and random selection of census blocks and then households. All eligible members of selected households were invited to participate (≥5 years old, resided in USVI ≥6 months and ≥6 months/year). Household and individual-level questionnaires were completed, and serum collected from each enrolled individual. Microscopic agglutination test serology was conducted, and bivariate and logistic regression analyses completed to identify risk factors for seropositivity. Conclusions/Significance: Leptospirosis seropositivity of 4% across USVI demonstrates an important human disease that was previously unrecognized and emphasizes the importance of continued leptospirosis surveillance and investigation. Local risk factors identified may help guide future human and animal leptospirosis studies in USVI, strengthen leptospirosis public health surveillance and treatment timeliness, and inform targeted education, prevention, and control efforts. Author summary: We established that in 2019, four percent of the population in the U.S. Virgin Islands (USVI) had evidence of previous exposure to Leptospira bacteria. There were no human cases of leptospirosis documented in USVI before the 2017 hurricanes, however due to the prevalence of the disease in other Caribbean localities, the post-hurricane cases, and the evidence of exposure demonstrated in this investigation, it is likely that leptospirosis has been a previously unrecognized problem in the territory. We demonstrated that contact with rodents or their body fluids or seeing rodents/evidence of rodents, contact with cows, increasing age, and not being part or full Caucasian/White race are independently associated with previous exposure to Leptospira spp. in USVI. These findings highlight the importance of continuing leptospirosis surveillance in USVI, considering leptospirosis as a diagnosis in patients with acute febrile illness and/or compatible exposures, and further investigating the epidemiology, ecology, and clinical features of leptospirosis in USVI. Our investigation also supports the need to investigate leptospirosis, and consider it a potential diagnosis, in locations with environmental conditions the bacteria favor (tropical and subtropical areas), even if leptospirosis has not been previously documented in those areas, and especially if it has not been previously investigated.

Publication information

Originally published in PLOS Neglected Tropical Diseases on 2022-11-15. Original DOI: 10.1371/journal.pntd.0010880.

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