in Black-tailed Prairie Dogs ( Cynomys ludovicianus ) and Beavers ( Castor canadensis ) in Northwestern Mexico

Leptospirosis and the Environment: A Review and Future Directions

Leptospirosis is a zoonotic disease of global importance with significant morbidity and mortality. However, the disease is frequently overlooked and underdiagnosed, leading to uncertainty of the true scale and severity of the disease. A neglected tropical disease, leptospirosis disproportionately impacts disadvantaged socioeconomic communities most vulnerable to outbreaks of zoonotic disease, due to contact with infectious animals and contaminated soils and waters. With growing evidence that Leptospira survives, persists, and reproduces in the environment, this paper reviews the current understanding of the pathogen in the environment and highlights the unknowns that are most important for future study. Through a systematic Boolean review of the literature, our study finds that detailed field-based study of Leptospira prevalence, survival, and transmission in natural waters and soils is lacking from the current literature. This review identified a strong need for assessment of physical characteristics and biogeochemical processes that support long-term viability of Leptospira in the environment followed by epidemiological assessment of the transmission and movement of the same strains of Leptospira in the present wildlife and livestock as the first steps in improving our understanding of the environmental stage of the leptospirosis transmission cycle.

Health Screening of American Beavers (Castor canadensis) in Utah, USA

American beavers (Castor canadensis), trapped between 2017 and 2020 for the purpose of translocation, underwent hematologic, serologic, and fecal examinations. Eight of 73 beavers were seropositive for Leptospira spp. and 1/49 seropositive for Toxoplasma gondii. Two of 40 beavers tested positive for Giardia spp., and 22/44 beavers had strongyle-type ova in the feces; one was positive for coccidia. Hematologic variables were largely within published reference ranges for captive beavers. Within the specific ecosystems sampled, the disease prevalence in beavers appeared low; however, prophylactic deworming is recommended prior to translocation. Further, appropriate personal protective equipment should be used when handling beavers, to prevent zoonotic infection with Giardia spp.

Molecular Detection of Leptospira interrogans and Borrelia burgdorferi in Wild Rodents from Mexico

Leptospirosis and Lyme borreliosis are zoonotic emerging diseases of global importance and wide distribution. The aim of this study was to detect by molecular testing to Leptospira interrogans and Borrelia burgdorferi sensu lato in wild rodents from Nuevo Leon, Quintana Roo, and Campeche, Mexico. This study is the first in report to Chaetodipus nelsoni, Dipodomys merriami, and Peromyscus eremicus infected with L. interrogans in Mexico. Besides, Chaetodipus hispidus, Heteromys gaumeri, Heteromys irroratus, Neotoma micropus, Peromyscus leucopus, Peromyscus maniculatus, and Sigmodon hispidus infected with B. burgdorferi s.l. in Mexico. Also, is the first report in identify coinfection of L. interrogans and B. burgdorferi s.l. in wild rodents such as H. irroratus and S. hispidus in Nuevo Leon, and H. gaumeri in Quintana Roo, Mexico. These wild rodent species infected represent a risk factor for the exposed population in these sylvatic and rural areas of Mexico.

Evidence of Leptospira species and their significance during reintroduction of Eurasian beavers (Castor fiber) to Great Britain

The Scottish Beaver Trial (SBT) reintroduced the Eurasian beaver (Castor fiber) in 2009 using wild-caught Norwegian beavers. This included a six-month prerelease quarantine in Devon, England. The International Union for Conservation of Nature (IUCN) and government guidelines for health screening were followed, including testing for Leptospira species. Unlicensed beavers, from Germany, were also identified in Scotland (Tayside) and Devon (later forming the River Otter Beaver Trial (ROBT)) and were health-screened under licence. Due to positive Leptospira species results and lack of prerelease screening in ROBT and Tayside, beavers from Germany and Norway (range sources) were screened. One hundred and fifty-six samples from 151 beavers were analysed by Leptospira species quantitative PCR (qPCR) (n=73 kidney (postmortem)/urine samples (antemortem)) or microscopic agglutination test (MAT, Leptospira pools 1-6) (n=83 serum samples). No beavers from Norway (95 per cent confidence interval (CI) 0-5.6 per cent, n=52), Tayside or SBT postrelease (95 per cent CI 0-4.6 per cent, n=63) tested positive. Seven beavers from Germany and Devon were positive. This gives an overall 9.3 per cent (95 per cent CI 5.2-15.1 per cent) exposure level, of which 4.6 per cent (95 per cent CI 1.9-9.3 per cent) suggested infection on a positive qPCR (n=1) or MAT titre of at least 1/400 (n=6), although none had abnormal physical, biochemical or haematological changes. This study suggests that Leptospira species infection in wild Eurasian beavers occurs at a low level, has no sex bias and does not appear to cause significant morbidity or mortality.

Fatal leptospirosis in free-ranging Eurasian beavers (Castor fiber L.), Switzerland

Leptospirosis was first diagnosed in free-ranging Eurasian beavers (Castor fiber L.) in Switzerland in 2010. Pathologic, serologic, molecular and epidemiologic analyses were carried out on 13 animals submitted for necropsy from 2010 through 2014. Typical lesions included alveolar haemorrhages in the lungs, tubular degeneration and interstitial nephritis in the kidneys. Microscopic agglutination test results were positive for serogroups Icterohaemorrhagiae, Australis, Autumnalis and Sejroe. Molecular analysis identified four distinct profiles belonging to serovar Icterohaemorrhagiae or Copenhageni. The severity and features of the lesions were consistent with a fatal disease associated with leptospires similarly to what has been reported in other animals and humans. The spatiotemporal occurrence of leptospirosis in beavers suggested an upstream spread of the bacteria and coincided with an increased incidence of leptospirosis in dogs and a case cluster in humans. However, an epidemiologic link among beaver cases and among species was not supported neither by the serologic nor molecular data.

Detection of pathogenic Leptospira species associated with phyllostomid bats (Mammalia: Chiroptera) from Veracruz, Mexico

The genus Leptospira encompass 22 species of spirochaetes, with ten pathogenic species that have been recorded in more than 160 mammals worldwide. In the last two decades, the numbers of records of these agents associated with bats have increased exponentially, particularly in America. Although order Chiroptera represents the second most diverse order of mammals in Mexico, and leptospirosis represents a human and veterinary problem in the country, few studies have been conducted to identify potential wildlife reservoirs. The aim of this study was to detect the presence and diversity of Leptospira sp. in communities of bats in an endemic state of leptospirosis in Mexico. During January to September 2016, 81 bats of ten species from three localities of Veracruz, Mexico, were collected with mist nets. Kidney samples were obtained from all specimens. For the detection of Leptospira sp., we amplified several genes using specific primers. Amplicons of the expected size were submitted to sequencing, and sequences recovered were compared with those of reference deposited in GenBank using the BLAST tool. To identify their phylogenetic position, we realized a reconstruction using maximum-likelihood (ML) method. Twenty-five samples from three bat species (Artibeus lituratus, Choeroniscus godmani and Desmodus rotundus) showed the presence of Leptospira DNA. Sequences recovered were close to Leptospira noguchii, Leptospira weilii and Leptospira interrogans. Our results include the first record of Leptospira in bats from Mexico and exhibit a high diversity of these pathogens circulating in the state. Due to the finding of a large number of positive wild animals, it is necessary to implement a surveillance system in populations of the positive bats as well as in related species, in order to understand their role as carriers of this bacterial genus.