Assessing rodents as carriers of pathogenic Leptospira species in the U.S. Virgin Islands and their risk to animal and public health

Abstract

Leptospirosis is a global zoonotic disease caused by pathogenic bacteria of the genus Leptospira. We sought to determine if rodents in U.S. Virgin Islands (USVI) are carriers of Leptospira. In total, 140 rodents were sampled, including 112 Mus musculus and 28 Rattus rattus. A positive carrier status was identified for 64/140 (45.7%); 49 (35.0%) were positive by dark-field microscopy, 60 (42.9%) by culture, 63 (45.0%) by fluorescent antibody testing, and 61 (43.6%) by real-time polymerase chain reaction (rtPCR). Molecular typing indicated that 48 isolates were L. borgpetersenii and 3 were L. kirschneri; the remaining nine comprised mixed species. In the single culture-negative sample that was rtPCR positive, genotyping directly from the kidney identified L. interrogans. Serotyping of L. borgpetersenii isolates identified serogroup Ballum and L. kirschneri isolates as serogroup Icterohaemorrhagiae. These results demonstrate that rodents are significant Leptospira carriers and adds to understanding the ecoepidemiology of leptospirosis in USVI.

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

“…A recent investigation of rodent Leptospira spp. carriage in USVI identified leptospires in the kidneys of 45.7% of 140 rodents tested from the three main islands [41], which supports the findings in this investigation that rodent exposure is an important risk factor for human leptospirosis in USVI. Leptospira serovars most commonly associated with rodents include Icterohemorrhagiae (rats) and Ballum (mice) [5][6][7]53], which were also the serogroups isolated in the USVI rodent investigation [41].…”

“…carriage in USVI identified leptospires in the kidneys of 45.7% of 140 rodents tested from the three main islands [41], which supports the findings in this investigation that rodent exposure is an important risk factor for human leptospirosis in USVI. Leptospira serovars most commonly associated with rodents include Icterohemorrhagiae (rats) and Ballum (mice) [5][6][7]53], which were also the serogroups isolated in the USVI rodent investigation [41]. Additionally, serogroup Icterohaemorrhagiae was the most common highest reacting serovar in this investigation, further supporting that rodents may be a significant source of Leptospira spp.…”

“…In order to definitively identify which Leptospira serovars are circulating in USVI, as well as which are causing human disease, bacterial isolates need to be obtained and characterized from acutely infected people and animals. It is likely that multiple Leptospira serovars are circulating in USVI, which is supported by isolates obtained in recently published animal surveillance in USVI [ 40 , 41 ], and that seropositive individuals detected were exposed to a variety of serovars through different exposure routes.…”

“…Based on the identification of three locallyacquired human cases of leptospirosis after the 2017 hurricanes [1], a fourth case in 2018 [42], and recent detection of Leptospira spp. DNA and isolates from wild and domestic animals PLOS NEGLECTED TROPICAL DISEASES [40,41,43], leptospirosis is endemic in USVI. Some seropositive participants could have been exposed to Leptospira spp.…”

Leptospira borgpetersenii serovar Hardjo and Leptospira santarosai serogroup Pyrogenes isolated from bovine dairy herds in Puerto Rico

“…Culture of leptospires is a technically difficult and laborious task but the detection of PCR-positive dairy cows prior to culture provides a screening tool to prioritize efforts and optimize successful outcomes. The recent development of new media formulations to support the growth of fastidious leptospires has enabled collection of samples which can now be transported long distances prior to processing (5,6,28). Both L. borgpetersenii and L. santarosai have similar protein profiles and express the pathogen-associated outer membrane protein LipL32.…”