Pinnipeds carriers of pathogenic Leptospira: New data based on molecular characterization

Leptospira borgptersenii and Leptospira interrogans identified in wild mammals in Rio Grande do Sul, Brazil

Leptospira spp. are bacteria responsible for leptospirosis, a zoonotic disease with considerable impacts on the economy, animal health, and public health. This disease has a global distribution and is particularly prevalent in Brazil. Both rural and urban environments are habitats for Leptospira spp., which are primarily transmitted through contact with the urine of infected animals. Consequently, domestic and wild species can harbor these prokaryotes and serve as infection sources for other hosts. In the context of wild animals, there is a dearth of molecular studies elucidating the roles of various animal and bacterial species in the epidemiology of leptospirosis. Therefore, this study aimed to evaluate the presence of Leptospira spp. DNA in different species of free-living and captive wild animals and to assess the phylogenetic relationships of the identified microorganisms in Rio Grande do Sul, Brazil. The samples were evaluated for the presence of the gene lipL32 by polymerase chain reaction (PCR) and sequencing of the amplified fragment after which phylogenetic analyzes were carried out. DNA from Leptospira spp. was extracted from kidney tissue from wild animals (Mammalia class). Pathogenic Leptospira spp. DNA was detected in 9.6% (11/114) of the samples, originating from nine species of wild animals, including the white-eared opossum (Didelphis albiventris), skunk (Conepatus chinga), geoffroy's cat (Leopardus geoffroyi), margay (Leopardus wiedii), pampas fox (Lycalopex gymnocercus), capybara (Hydrochoerus hydrochaeris), common marmoset (Callithrix jacchus), neotropical river otter (Lontra longicaudis), and european hare (Lepus europaeus). Phylogenetic analysis revealed the presence of Leptospira borgpetersenii and Leptospira interrogans in these animals. This research is the first study contributing to the epidemiology of leptospirosis by identifying L. borgpetersenii and L. interrogans in free-living and captive wild animals in Rio Grande do Sul, Brazil, potentially acting as bacterial reservoirs. Additionally, our findings can inform sanitary measures for controlling and preventing the disease, thereby safeguarding public health.

Detection of pathogenic Leptospira spp. in unconventional pets

Leptospirosis is a disease caused by Leptospira spp. responsible for considerable impacts on the public and animal health. In the past two decades, non-domesticated species of pets (unconventional pets) have become popular. However, the role of these unconventional pets on maintaining diseases still unclear. Therefore, the objective of this study was to survey the presence of Leptospira spp. DNA in unconventional pets. Samples of kidney tissues from 29 animals belonging to the Mammalia class (including Orders Carnivora, Lagomorpha and Rodentia) were analyzed for the presence of the gene lipL32. As a result, DNA of pathogenic Leptospira spp. from specie L. interrogans was detected in four (13,80%) of the analyzed samples: three from Oryctolagus cuniculus and one from Mesocricetus auratus. This study highlights the importance of epidemiological surveillance of leptospirosis, as it identified in species of unconventional pets, that may possibly act as reservoirs of Leptospira spp.

Bat-Associated Pathogenic Leptospira spp. from Forest Fragments in Southwestern Brazilian Amazonia

Bats are known as potential carriers of different pathogens; these animals have been identified worldwide as an important reservoir of different species of Leptospira. Therefore, there has been an increasing interest in studying leptospirosis in neotropical bats in the Amazon. This region is a fertile ground for zoonotic diseases, given the intense process of deforestation, urbanization, opening of new agricultural frontiers, predatory hunting, effects of climate change, and loss of biodiversity. Based on this, the aim of the present study was to investigate the frequency of infection associated with the genetic characterization of pathogenic Leptospira spp. in bats inhabiting diverse landscapes in the southwestern region of the Amazon. To conduct the study, mist nets were installed to capture bats. Kidney samples were submitted to LipL32-polymerase chain reaction and secY gene sequencing. Our results showed that 21% of neotropical evaluated bats in Southwestern Amazon were infected with Leptospira spp. Positive animals were found in rural, urban, periurban, and control areas. Sanguinivores had the highest frequency of positives, followed by insectivores and frugivorous bats. The species of L. interrogans and a potential new Leptospira species were identified. The frequency of Leptospira in bats was not influenced by landscape type, suggesting these pathogens may not be affected by landscape changes. The findings suggest that bats may serve as potential reservoirs of Leptospira in diverse landscapes. The presence of Leptospira in bats appears to be independent of the type of land use, implying that these pathogens may not be affected by small-scale changes in the environment.

Genetic Evidence for a Potentially New Pathogenic Leptospira sp. Circulating in Bats from Brazilian Amazon

Leptospirosis is a neglected zoonosis frequently reported worldwide, caused by a spirochete of the genus Leptospira. It is capable of infecting domestic animals, free-living animals, and humans. Among wild animals, the role of bats in the epidemiology of leptospirosis has been investigated but is far from being elucidated. The Amazonian biome has the ideal conditions for maintaining and disseminating leptospires and, despite efforts that have been made to better understand leptospires' occurrence in wild animals in the region, few studies aimed to explore and genetically characterize leptospires in bats. Based on this, the aim of the present study is to deeper investigate and genetically characterize leptospires detected in bats from the southwest Amazon. Animals were trapped by mist netting at five sites in the state of Acre, Brazil. Kidney samples were obtained and stored for molecular analysis. Polymerase chain reaction (PCR) was conducted first based on the LipL32 gene, and positive samples were submitted to rrs and secY-PCR and sequencing. Sequences were then submitted to phylogenetic analyses through multiple bioinformatic tools. The rrs sequences from the present study formed one single haplotype, different from any other previously deposited, grouped in a highly supported cluster with sequences from bats from Madagascar and China. The initial secY screening revealed no identity with previously deposited sequences. The phylogenetic trees revealed the sequences from the present study in an isolated branch, clearly separated from all previously known pathogenic Leptospira spp., suggesting the existence of a potentially undescribed species. The haplotype network including only leptospires from the Amazon region confirmed two new haplotypes from the same taxon unity, isolated from the others, with a probable origin of the species from L. noguchii. The characterization of this potentially new species in bats reinforces the complexity of the transmission dynamics of leptospires, including wild, periurban, and urban environments, emphasizing the need for an integrative look at leptospirosis vigilance within the context of One Health.

Molecular Epidemiology of Pathogenic Leptospira spp. Infecting Dogs in Latin America

Canine leptospirosis is a bacterial disease caused by spirochetes of the genus Leptospira. Infections can vary from asymptomatic and chronic infections to clinical acute diseases. The disease is endemic in tropical areas, such as Latin American countries, but a broad understanding of the dynamics of circulation of strains, based on molecular data, has not yet been performed. Based on in silico analyses, the present study aims to analyze the genetic diversity and circulation patterns of haplotypes from pathogenic leptospires infecting dogs in Latin America. DNA sequences were obtained from GenBank platform, curated, and aligned. Genetic distances were calculated, and a maximum likelihood tree and haplotype network were constructed. According to the inclusion criteria adopted, a total of 148 sequences were identified. Most of the records were from Brazil, including sequences from L. interrogans serogroup Icterohaemorrhagiae. Phylogenetic analysis showed a genetically closely related cluster, consisting of a larger haplogroup that includes the reference strain Fiocruz L1-130, known to be the major circulating strain in humans. Moreover, no genetic variations were observed according to clinical history and/or geographical localization. We described the molecular epidemiology of leptospires circulating among dogs in Latin America and demonstrated a very genetically homogeneous group, elucidating its ubiquitous circulation pattern and drawing attention to the important role of dogs in the One Health transmission dynamics of leptospirosis.

Molecular Detection of Pathogenic Leptospira sp. in Cetaceans from the Brazilian Coast

Leptospirosis is a zoonosis with ubiquitous distribution caused by spirochetes belonging to the genus Leptospira sp., endemic mainly in tropical and subtropical regions of the world and capable of infecting domestic animals, free-living animals, and humans. Although well documented in terrestrial animals and humans, little information is available on its distribution and impact on marine animals. There are few studies assessing cetaceans' health status, and even scarcer are those focused on leptospirosis research. In this context, considering the One Health approach, the present study aimed to investigate the occurrence of pathogenic Leptospira sp. in cetaceans on the Brazilian coast. Kidneys of 142 cetaceans belonging to 19 species were collected. DNA was extracted, and the diagnosis was performed by LipL32-polymerase chain reaction. Genetic characterization was conducted based on secY gene sequencing. Pathogenic Leptospira sp. DNA was detected in 14.8% (21/142) of the tested cetaceans, with coastal species presenting a significantly higher frequency (p-value = 0.03) of infected individuals (25%, 17/68) than oceanic species (7.5%, 4/53). It was possible to amplify and sequence three strains (one for Sotalia guianensis, one for Stenella clymene, and one for Pontoporia blainvillei), all of them identified as Leptospira interrogans, with high similarity with sequences from Icterohaemorrhagiae serogroup. Phylogenetic analysis revealed sequences from the present study grouped in species-specific unique clusters but very close to pinnipeds in the same area, evidencing the presence of two distinct haplotypes circulating on marine mammals in the region. We could demonstrate that cetaceans can act as carriers of pathogenic leptospires. Moreover, the proximity with anthropogenic areas could play an important role in leptospirosis' dynamics of transmission in a One Health context.