Mixed Leptospira Infections in a Diverse Reservoir Host Community, Madagascar, 2013-2015

Mixed Leptospira infections in domestic animals from a rural community with high leptospirosis endemicity

BACKGROUND

Leptospirosis is one of the most common zoonoses in the world which is associated with a severe febrile disease in humans causing a variety of syndromes including meningitis, interstitial nephritis, hepatitis, and sometimes death. Leptospirosis is caused by different pathogenic Leptospira species divided into almost 30 serogroups and more than 300 serovars which are carried by some animal asymptomatic chronic infections. Humans can become infected through direct contact with animal urine or indirectly by coming into contact with fresh water or mud contaminated with urine.

METHODOLOGY/PRINCIPAL FINDINGS

In this research, we looked for leptospiral DNA in urine samples from dogs living in a rural, low-income and highly endemic community in the coast of Ecuador. We used molecular biology and next-generation sequencing for the detection. Our results showed evidence of two Leptospira species, L interrogans and L. santarosai, genomes in three dogs.

CONCLUSIONS/SIGNIFICANCE

It has been widely known that animal carriers are typically infected with a single leptospiral strain. However, recent reports, including the present one, indicate that carrier animals may be coinfected with two or more leptospiral species.

Identifying the Drivers Related to Animal Reservoirs, Environment, and Socio-Demography of Human Leptospirosis in Different Community Types of Southern Chile: An Application of Machine Learning Algorithm in One Health Perspective

Leptospirosis is a zoonosis with global public health impact, particularly in poor socio-economic settings in tropical regions. Transmitted through urine-contaminated water or soil from rodents, dogs, and livestock, leptospirosis causes over a million clinical cases annually. Risk factors include outdoor activities, livestock production, and substandard housing that foster high densities of animal reservoirs. This One Health study in southern Chile examined Leptospira serological evidence of exposure in people from urban slums, semi-rural settings, and farm settings, using the Extreme Gradient Boosting algorithm to identify key influencing factors. In urban slums, age, shrub terrain, distance to Leptospira-positive households, and neighborhood housing density were contributing factors. Human exposure in semi-rural communities was linked to environmental factors (trees, shrubs, and lower vegetation terrain) and animal variables (Leptospira-positive dogs and rodents and proximity to Leptospira-positive households). On farms, dog counts, animal Leptospira prevalence, and proximity to Leptospira-contaminated water samples were significant drivers. The study underscores that disease dynamics vary across landscapes, with distinct drivers in each community setting. This case study demonstrates how the integration of machine learning with comprehensive cross-sectional epidemiological and geospatial data provides valuable insights into leptospirosis eco-epidemiology. These insights are crucial for informing targeted public health strategies and generating hypotheses for future research.

Prevalence, genetic diversity and eco-epidemiology of pathogenic Leptospira species in small mammal communities in urban parks Lyon city, France

Rodents are recognized as the main reservoirs of Leptospira spp. Rats, in particular, serve as hosts for the widely predominant Leptospira interrogans serovar Icterohaemorrhagiae, found worldwide. Several studies have shown the importance of other reservoirs, such as mice or hedgehogs, which harbor other leptospires' serovars. Nevertheless, our knowledge of circulating Leptospira spp. in reservoirs other than rats remains limited. In this context, we proposed an eco-health approach to assess the health hazard associated with leptospires in urban green spaces, where contacts between human/small mammals and domestic animals are likely. We studied the prevalence, the diversity of circulating strains, and epidemiology of pathogenic Leptospira species in small terrestrial mammal communities (rodents and shrews), between 2020-2022, in two parks in Lyon metropolis, France. Our study showed a significant carriage of Leptospira spp. in small terrestrial mammals in these parks and unveiled a global prevalence rate of 11.4%. Significant variations of prevalence were observed among the small mammal species (from 0 to 26.1%), with Rattus norvegicus exhibiting the highest infection levels (26.1%). We also observed strong spatio-temporal variations in Leptospira spp. circulation in its reservoirs. Prevalence seems to be higher in the peri-urban park and in autumn in 2021 and 2022. This is potentially due to differences in landscape, abiotic conditions and small mammal communities' composition. Our study suggests an important public health relevance of rats and in a lesser extent of other rodents (Apodemus spp., Clethrionomys glareolus and Mus musculus) as reservoirs of L. interrogans, with rodent species carrying specific serogroups/serovars. We also emphasize the potential hazard associated between the shrew Crocidura russula and L. kirschneri. Altogether, these results improve our knowledge about the prevalence of leptospirosis in an urban environment, which is an essential prerequisite for the implementation of prevention of associated risks.

Concurrent colonization of rodent kidneys with multiple species and serogroups of pathogenic Leptospira

Rodents are important reservoir hosts of pathogenic leptospires in the US Virgin Islands. Our previous work determined that trapped rodents were colonized with Leptospira borgpetersenii serogroup Ballum (n = 48) and/or Leptospira kirschneri serogroup Icterohaemorrhagiae (n = 3). In addition, nine rodents appeared to be colonized with a mixed population comprising more than one species/serogroup. The aim of this study was to validate this finding by characterizing clonal isolates derived from cultures of mixed species. Cultures of presumptive mixed species (designated LR1, LR5, LR37, LR57, LR60, LR61, LR68, LR70, and LR72) were propagated in different media including Hornsby-Alt-Nally (HAN) media, incubated at both 29℃ and 37℃, and T80/40/LH incubated at 29℃. Polyclonal reference antisera specific for serogroup Ballum and Icterohaemorrhagiae were used to enrich for different serogroups followed by subculture on agar plates. Individual colonies were then selected for genotyping and serotyping. Of the nine cultures of mixed species/serogroups, a single clonal isolate was separated in five of them: L. borgpetersenii serogroup Ballum in LR1, LR5, and LR37, and L. kirschneri serogroup Icterohaemorrhagiae in LR60 and LR72. In four of the cultures with mixed species (LR57, LR61, LR68, and LR70), clonal isolates of both L. borgpetersenii serogroup Ballum and L. kirschneri serogroup Icterohaemorrhagiae were recovered. Our results definitively establish that rodents can be colonized with more than one species/serogroup of Leptospira concurrently. The identification and characterization of multiple species/serogroups of Leptospira from individual reservoir hosts of infection are essential to understand the epidemiology and transmission of disease to both human and domestic animal populations.IMPORTANCEPathogenic Leptospira, the causative agent of human and animal leptospirosis, comprise a diverse genus of species/serogroups which are inherently difficult to isolate from mammalian hosts due to fastidious growth requirements. Molecular evidence has indicated that reservoir hosts of Leptospira may shed multiple species concurrently. However, evidence of this phenomena by culture has been lacking. Culture is definitive and is essential for comprehensive characterization of recovered isolates by high-resolution genome sequencing and serotyping. In this work, a protocol using recently developed novel media formulations, in conjunction with reference antisera, was developed and validated to demonstrate the recovery of multiple species/serogroups of pathogenic Leptospira from the same host. The identification and characterization of multiple species/serogroups of Leptospira from individual reservoir hosts of infection are essential to understand the epidemiology and transmission of disease to both human and domestic animal populations.

Ancestral African Bats Brought Their Cargo of Pathogenic Leptospira to Madagascar under Cover of Colonization Events

Madagascar is home to an extraordinary diversity of endemic mammals hosting several zoonotic pathogens. Although the African origin of Malagasy mammals has been addressed for a number of volant and terrestrial taxa, the origin of their hosted zoonotic pathogens is currently unknown. Using bats and Leptospira infections as a model system, we tested whether Malagasy mammal hosts acquired these infections on the island following colonization events, or alternatively brought these bacteria from continental Africa. We first described the genetic diversity of pathogenic Leptospira infecting bats from Mozambique and then tested through analyses of molecular variance (AMOVA) whether the genetic diversity of Leptospira hosted by bats from Mozambique, Madagascar and Comoros is structured by geography or by their host phylogeny. This study reveals a wide diversity of Leptospira lineages shed by bats from Mozambique. AMOVA strongly supports that the diversity of Leptospira sequences obtained from bats sampled in Mozambique, Madagascar, and Comoros is structured according to bat phylogeny. Presented data show that a number of Leptospira lineages detected in bat congeners from continental Africa and Madagascar are imbedded within monophyletic clades, strongly suggesting that bat colonists have indeed originally crossed the Mozambique Channel while infected with pathogenic Leptospira.

Fine-scale prevalence and genetic diversity of urban small mammal-borne pathogenic Leptospira in Africa: A spatiotemporal survey within Cotonou, Benin

Leptospirosis is a zoonotic disease that is caused by spirochete bacteria of the genus Leptospira. Around the world, one million people each year are infected, leading to 60,000 deaths. Infection occurs through contact with environmental pathogens excreted by mammals (notably rodents). Data on Leptospira and leptospirosis in Africa are rather scarce, especially in urban habitats though these appear to be favourable environments for the pathogen circulation and human contamination. Using qPCR, DNA sequencing as well as MST/VNTR approaches, we examined Leptospira occurrence and genetic diversity in 779 commensal small mammals that were sampled over 2 years in the city centre of Cotonou, Benin, from three neighbourhoods with contrasting socio-environmental conditions. Overall prevalence reached 9.1%. However, very marked variations in both space and time were observed, with local peaks of high prevalence but no clear seasonal pattern. In most sites that could be regularly sampled, Leptospira-positive rodents were found at least once, thus confirming the widespread circulation of the pathogen within small mammal communities of Cotonou. Interestingly, an unusual diversity of small mammal-borne Leptospira species and genotypes was retrieved, with up to four species and three different genovars within the same neighbourhood, and even instances of two species and two genovars identified simultaneously within the same household. To our knowledge, such a high genetic diversity has never been described at such a fine scale, a fortiori in Africa and, more generally, within an urban environment. Altogether, our results underline that much remains unknown about leptospirosis as well as the associated infectious risk in African cities where the disease may be massively over-looked.

Co-Radiation of Leptospira and Tenrecidae (Afrotheria) on Madagascar

Leptospirosis is a bacterial zoonosis caused by pathogenic Leptospira that are maintained in the kidney lumen of infected animals acting as reservoirs and contaminating the environment via infected urine. The investigation of leptospirosis through a One Health framework has been stimulated by notable genetic diversity of pathogenic Leptospira combined with a high infection prevalence in certain animal reservoirs. Studies of Madagascar’s native mammal fauna have revealed a diversity of Leptospira with high levels of host-specificity. Native rodents, tenrecids, and bats shelter several distinct lineages and species of Leptospira, some of which have also been detected in acute human cases. Specifically, L. mayottensis, first discovered in humans on Mayotte, an island neighboring Madagascar, was subsequently identified in a few species of tenrecids on the latter island, which comprise an endemic family of small mammals. Distinct L. mayottensis lineages were identified in shrew tenrecs (Microgale cowani and Nesogale dobsoni) on Madagascar, and later in an introduced population of spiny tenrecs (Tenrec ecaudatus) on Mayotte. These findings suggest that L. mayottensis (i) has co-radiated with tenrecids on Madagascar, and (ii) has recently emerged in human populations on Mayotte following the introduction of T. ecaudatus from Madagascar. Hitherto, L. mayottensis has not been detected in spiny tenrecs on Madagascar. In the present study, we broaden the investigation of Malagasy tenrecids and test the emergence of L. mayottensis in humans as a result of the introduction of T. ecaudatus on Mayotte. We screened by PCR 55 tenrecid samples from Madagascar, including kidney tissues from 24 individual T. ecaudatus. We describe the presence of L. mayottensis in Malagasy T. ecaudatus in agreement with the aforementioned hypothesis, as well as in M. thomasi, a tenrecid species that has not been explored thus far for Leptospira carriage.

Ocular leptospirosis: a review of current state of art of a neglected disease

Introduction: Leptospirosis is a neglected and re-emerging zoonotic disease that may cause ocular involvement, uveitis being the main complication of the systemic disease. Aim: The purpose of this review was to raise awareness and update on uveitis caused by leptospirosis, which is a challenging pathology because it can mimic other types of uveitis. Materials and methods: An article review, was conducted by searching PubMed (MEDLINE), Scielo, Cochrane Library databases using the following MeSH and DeCS terms: "leptospirosis", "uveitis", "ocular", "eye" and "human". The inclusion criteria were articles between 2000 and 2021 in English, Spanish, French or Portuguese. Results and Discussion: A total of 49 articles were obtained with the mentioned inclusion criteria, and additionally 5 articles before the year 2000, which were considered due to their relevance and scarcity of articles on the pathology. Afterwards, a description of the disease was made. Conclusion: This literature review was steered to raise awareness and to apprise physicians and ophthalmologists about a pathology that is becoming increasingly relevant, but underdiagnosed, even in developed countries. Abbreviations: REU = recurrent equine uveitis, MAT = microagglutination.

Fatal Rodentborne Leptospirosis in Prison Inmates, South Africa, 2015

Leptospirosis is a neglected zoonotic disease. In 2015, leptospirosis was diagnosed in 2 prison inmates in South Africa. Using real-time PCR and DNA sequencing, we identified Leptospira interrogans serogroup Icterohaemorrhagiae in rodents and water samples within the prison. Leptospirosis might be frequently underdiagnosed in South Africa.

Ecological and Socio-Economic Determinants of Livestock Animal Leptospirosis in the Russian Arctic

Leptospirosis is a re-emerging zoonotic infectious disease caused by pathogenic bacteria of the genus Leptospira. Regional differences in the disease manifestation and the role of ecological factors, specifically in regions with a subarctic and arctic climate, remain poorly understood. We here explored environmental and socio-economic features associated with leptospirosis cases in livestock animals in the Russian Arctic during 2000–2019. Spatial analysis suggested that the locations of the majority of 808 cases were in “boreal” or “polar” climate regions, with “cropland,” “forest,” “shrubland,” or “settlements” land-cover type, with a predominance of “Polar Moist Cropland on Plain” ecosystem. The cases demonstrated seasonality, with peaks in March, June, and August, corresponding to the livestock pasturing practices. We applied the Forest-based Classification and Regression algorithm to explore the relationships between the cumulative leptospirosis incidence per unit area by municipal districts (G-rate) and a number of socio-economic, landscape, and climatic factors. The model demonstrated satisfactory performance in explaining the observed disease distribution (R² = 0.82, p < 0.01), with human population density, livestock units density, the proportion of crop area, and budgetary investments into agriculture per unit area being the most influential socio-economic variables. Climatic factors demonstrated a significantly weaker influence, with nearly similar contributions of mean yearly precipitation and air temperature and number of days with above-zero temperatures. Using a projected climate by 2100 according to the RCP8.5 scenario, we predict a climate-related rise of expected disease incidence across most of the study area, with an up to 4.4-fold increase in the G-rate. These results demonstrated the predominant influence of the population and agricultural production factors on the observed increase in leptospirosis cases in livestock animals in the Russian Arctic. These findings may contribute to improvement in the regional system of anti-leptospirosis measures and may be used for further studies of livestock leptospirosis epidemiology at a finer scale.

Effects of land use, habitat characteristics, and small mammal community composition on Leptospira prevalence in northeast Madagascar

Human activities can increase or decrease risks of acquiring a zoonotic disease, notably by affecting the composition and abundance of hosts. This study investigated the links between land use and infectious disease risk in northeast Madagascar, where human subsistence activities and population growth are encroaching on native habitats and the associated biota. We collected new data on pathogenic Leptospira, which are bacteria maintained in small mammal reservoirs. Transmission can occur through close contact, but most frequently through indirect contact with water contaminated by the urine of infected hosts. The probability of infection and prevalence was compared across a gradient of natural moist evergreen forest, nearby forest fragments, flooded rice and other types of agricultural fields, and in homes in a rural village. Using these data, we tested specific hypotheses for how land use alters ecological communities and influences disease transmission. The relative abundance and proportion of exotic species was highest in the anthropogenic habitats, while the relative abundance of native species was highest in the forested habitats. Prevalence of Leptospira was significantly higher in introduced compared to endemic species. Lastly, the probability of infection with Leptospira was highest in introduced small mammal species, and lower in forest fragments compared to other habitat types. Our results highlight how human land use affects the small mammal community composition and in turn disease dynamics. Introduced species likely transmit Leptospira to native species where they co-occur, and may displace the Leptospira species naturally occurring in Madagascar. The frequent spatial overlap of people and introduced species likely also has consequences for public health.

Many neglected tropical diseases have reservoirs in wildlife. The effects of human activities on wildlife include changes in species abundance, community composition, and the transmission dynamics of parasites. Introduced species, especially black rats (Rattus rattus) are known to transmit zoonotic diseases among wildlife species and people. Leptospira, a water-borne bacterium that infects wildlife and people, is an important pathogen in the tropics, and in Madagascar, multiple strains and hosts have been identified. We tested how land use gradients in a forest-frontier agricultural system affect the composition of small mammal communities, and in turn the prevalence of Leptospira. We investigated 11 species of small mammals, including native rodents and tenrecs, as well as introduced rodents and shrews, in old growth forest, forest fragments, agricultural fields, and in a village. Leptospira prevalence and infection risk were highest in introduced species compared to native species and lower in forest fragments. The results highlight how the introduction of non-native species affects the variation in disease prevalence in small mammals, with potential consequences for spill-over to people.

Amplification of pathogenic Leptospira infection with greater abundance and co-occurrence of rodent hosts across a counter-urbanizing landscape

Land use change can elevate disease risk by creating conditions beneficial to species that carry zoonotic pathogens. Observations of concordant global trends in increased pathogen prevalence or disease incidence and landscape change have generated concerns that urbanization could increase transmission risk of some pathogens. Yet host-pathogen relationships underlying transmission risk have not been well characterized within cities, even where contact between humans and species capable of transmitting pathogens of concern occurs. We addressed this deficit by testing the hypothesis that areas in cities experiencing greater population loss and infrastructure decline (i.e., counter-urbanization) can support a greater diversity of host species and a larger and more diverse pool of pathogens. We did so by characterizing pathogenic Leptospira infection relative to rodent host richness and abundance across a mosaic of abandonment in post-Katrina New Orleans (Louisiana, USA). We found that Leptospira infection loads were highest in areas that harboured increased rodent species richness (which ranged from one to four rodent species detected). Areas with greater host co-occurrence also harboured a greater abundance of hosts, including the host species most likely to carry high infection loads, indicating that Leptospira infection can be amplified by increases in overall and relative host abundance. Evidence of shared infection among rodent host species indicates that cross-species transmission of Leptospira probably increases infection at sites with greater host richness. Additionally, evidence that rodent co-occurrence and abundance and Leptospira infection load parallel abandonment suggests that counter-urbanization can elevate zoonotic disease risk within cities, particularly in underserved communities that are burdened with disproportionate concentrations of derelict properties.

Multi-locus sequence analyses reveal a clonal L. borgpetersenii genotype in a heterogeneous invasive Rattus spp. community across the City of Johannesburg, South Africa

BACKGROUND

Rattus spp. are frequently implicated as key reservoir hosts for leptospirosis, one of the most common, but neglected, bacterial zoonoses in the world. Although leptospirosis is predicted to be a significant public health threat in Africa, studies from the continent are limited.

METHODS

Rattus spp. (n = 171) were sampled (January-May 2016) across the City of Johannesburg, South Africa's largest inland metropole. Rattus spp. genetic diversity was evaluated by full length (1140 bp) cyt b sequencing of 42 samples. For comparison, a further 12 Rattus norvegicus samples collected in Cape Town, South Africa's largest coastal metropole, were also genotyped. Leptospira infections were identified and genotyped using real-time PCR and multi-locus (lfb1, secY and lipL41) DNA sequencing.

RESULTS

Five R. norvegicus haplotypes were identified across Johannesburg, four of which have not previously been detected in South Africa, and one in Cape Town. Across Johannesburg we identified a Leptospira spp. infection prevalence of 44% (75/171) and noted significant differences in the prevalence between administrative regions within the metropole. Multi-locus sequence analyses identified a clonal genotype consistent with L. borgpetersenii serogroup Javanica (serovar Ceylonica).

DISCUSSION

The prevalence of infection identified in this study is amongst the highest detected in Rattus spp. in similar contexts across Africa. Despite the complex invasion history suggested by the heterogeneity in R. norvegicus haplotypes identified in Johannesburg, a single L. borgpetersenii genotype was identified in all infected rodents. The lack of L. interrogans in a rodent community dominated by R. norvegicus is notable, given the widely recognised host-pathogen association between these species and evidence for L. interrogans infection in R. norvegicus in Cape Town. It is likely that environmental conditions (cold, dry winters) in Johannesburg may limit the transmission of L. interrogans. Spatial heterogeneity in prevalence suggest that local factors, such as land use, influence disease risk in the metropole.

CONCLUSIONS

In South Africa, as in other African countries, leptospirosis is likely underdiagnosed. The high prevalence of infection in urban rodents in Johannesburg suggest that further work is urgently needed to understand the potential public health risk posed by this neglected zoonotic pathogen.

Wild rodents and insectivores as carriers of pathogenic Leptospira and Toxoplasma gondii in The Netherlands

Small mammals such as rodents can to carry zoonotic pathogens. Currently, there is impaired knowledge on zoonotic pathogens in rodents and insectivores in the Netherlands. This limits opportunities for preventive measures and complicates risk-assessments for zoonotic transmission to humans. Leptospira spp. and Toxoplasma gondii are present on a list of prioritized emerging pathogens in the Netherlands and were therefore the focus of this study. Both pathogens have the ability to survive under moist environmental conditions. In total, a group of 379 small mammals (rodents & insectivores) were tested on pathogenic Leptospira spp., and 312 on T. gondii. Rodents and insectivores were trapped at various sites, but mostly on pig and dairy farms throughout the country. Over five percent of the animals (5.3%, n = 379) tested positive for Leptospira DNA, and five of the animals (1.6%, n = 312) tested were positive for T. gondii DNA. The animals positive for T.gondii were all brown rats and the ones for Leptospira spp. were various species. Our results show that insectivores and rodents might be used as an indicator for the environmental contamination and/or the contamination in wildlife for Leptospira spp.

Pathogenic Leptospira and their animal reservoirs: testing host specificity through experimental infection

Leptospirosis is caused by pathogenic Leptospira transmitted through contact with contaminated environments. Most mammalian species are infectable by Leptospira but only few act as efficient reservoir being capable of establishing long term kidney colonization and shedding Leptospira in urine. In Madagascar, a large diversity of pathogenic Leptospira display a tight specificity towards their endemic volant or terrestrial mammalian hosts. The basis of this specificity is unknown: it may indicate some genetically determined compatibility between host cells and bacteria or only reflect ecological constraints preventing contacts between specific hosts. In this study, Rattus norvegicus was experimentally infected with either Leptospira interrogans, Leptospira borgpetersenii or Leptospira mayottensis isolated from rats, bats or tenrecs, respectively. Leptospira borgpetersenii and L. mayottensis do not support renal colonization as featured by no shedding of live bacteria in urine and low level and sporadic detection of Leptospira DNA in kidneys. In contrast 2 out of the 7 R. norvegicus challenged with L. interrogans developed renal colonization and intense Leptospira shedding in urine throughout the 3 months of experimental infection. These data suggest that host-Leptospira specificity in this biodiversity hotspot is driven at least in part by genetic determinants likely resulting from long-term co-diversification processes.

Prevalence and risk factors of Leptospira infection in urban brown rats (Rattus norvegicus), Vienna, Austria

Leptospirosis is a worldwide bacterial zoonosis which incidence is expected to increase in conjunction with global change. In urban ecosystems, synanthropic rats are the key source of Leptospira infection in humans and other animals. Risk assessment and prediction of human leptospirosis require investigations of the environment associated with the bacteria and infection patterns in the reservoir hosts. The objective of this study was to address the prevalence of mixed Leptospira infection in the lungs and kidneys of brown rats captured in three sites of the city centre of Vienna, Austria, between 2016 and 2018. A total of 96 brown rats were examined for the presence of Leptospira using PCR. Occurrence of mixed Leptospira infections was explored through next-generation sequencing (NGS). A logistic regression model was built to predict the individual infection status using morphological and land-use data. Overall, the prevalence of Leptospira interrogans in the kidney was 25% but varied among sites (0–36%). We did not evidence any pulmonary nor mixed infections. Host body mass and sex were strong predictors of Leptospira carriage in the sampled rats (relative variable importance (RVI) = 0.98 and 0.89, respectively) while the presence of water affected it moderately (RVI = 0.44). Our findings demonstrate that NGS is an unbiased approach to the direct characterisation of mixed leptospiral infections that could provide further insights into the ecology of Leptospira. Future surveillance programmes should consider the use of rats as sentinels for the early detection of emerging pathogenic Leptospira in urban ecosystems.

Detection and Characterization of Leptospira Infection and Exposure in Rats on the Caribbean Island of Saint Kitts

In this study, we detected and characterized Leptospira infection and exposure in rats on the Caribbean island of Saint Kitts for the first time. We detected Leptospira infection in 17/29 (59%), 14/29 (48)%, and 11/29 (38)% of rats by RT-PCR, culture, and immunofluorescence assay, respectively. Whole genome sequencing (WGS) and analysis and serogrouping of 17 Leptospira strains isolated from rats revealed their close relationship with L. interrogans serogroup Icterohaemorrhagiae (n = 10) and L. borgpetersenii serogroup Ballum (n = 7). WGS, serogrouping, and additional PCR tests on rat kidneys confirmed mixed infections with L. interrogans and L. borgpetersenii in the kidneys of three rats. Microscopic agglutination test (MAT) was positive for 25/29 (87%) of the rats tested, and the response was restricted to serovars Icterohaemorrhagiae {24/29(83%)}, Mankarso {4/29(14%)}, Copenhageni {4/29(14%)}, Grippotyphosa {2/29(7%)}, and Wolffi {1/29(3%)}. Interestingly, there was no agglutinating antibody response to serovar Ballum. We observed a similar pattern in the serologic response using Leptospira isolates obtained from this study with each of the rat sera, with strong response to L. interrogans isolates but minimal reactivity to L. borgpetersenii isolates. Our findings suggest the use of multiple complementary diagnostic tests for Leptospira surveillance and diagnosis to improve the accuracy of the data.

High Prevalence of Leptospira spp. in Rodents in an Urban Setting in Madagascar

Leptospirosis is a neglected zoonotic bacterial disease caused by pathogenic Leptospira spp. Only limited studies have been conducted on the presence of Leptospira spp. in rats in Antananarivo, the capital city of Madagascar. We assessed Leptospira prevalence in small mammals in urban areas of Antananarivo where sanitation is inadequate and there is risk of flooding during the rainy season. We captured rodents and shrews at two sites and examined kidney samples from 114 animals using culture and a real-time polymerase chain reaction (PCR) assay specific to pathogenic Leptospira spp. We identified 23 positive samples containing Leptospira interrogans and Leptospira borgpetersenii, with a high prevalence in Rattus norvegicus (44.9%). Our results indicate that small mammals, in particular R. norvegicus, present a major public health risk for acquiring leptospirosis in Antananarivo.

Leptospira in livestock in Madagascar: uncultured strains, mixed infections and small mammal-livestock transmission highlight challenges in controlling and diagnosing leptospirosis in the developing world

In developing countries, estimates of the prevalence and diversity of Leptospira infections in livestock, an important but neglected zoonotic pathogen and cause of livestock productivity loss, are lacking. In Madagascar, abattoir sampling of cattle and pigs demonstrated a prevalence of infection of 20% in cattle and 5% in pigs by real-time PCR. In cattle, amplification and sequencing of the Leptospira-specific lfb1 gene revealed novel genotypes, mixed infections of two or more Leptospira species and evidence for potential transmission between small mammals and cattle. Sequencing of the secY gene demonstrated genetic similarities between Leptospira detected in Madagascar and, as yet, uncultured Leptospira strains identified in Tanzania, Reunion and Brazil. Detection of Leptospira DNA in the same animal was more likely in urine samples or pooled samples from four kidney lobes relative to samples collected from a single kidney lobe, suggesting an effect of sampling method on detection. In pigs, no molecular typing of positive samples was possible. Further research into the epidemiology of livestock leptospirosis in developing countries is needed to inform efforts to reduce human infections and to improve livestock productivity.

Resistance to anticoagulant rodenticides in Martinique could lead to inefficient rodent control in a context of endemic leptospirosis

Leptospirosis is a re-emergent worldwide zoonosis. It is endemic in Martinique where transmission conditions are favourable. Humans are usually infected through contact with water contaminated with urine of rodents. Recent human leptospirosis outbreaks in Martinique require today effective rodent management to prevent leptospirosis transmission. Nowadays, use of anticoagulant rodenticides (AR) is the main method implemented to control rodent populations. Nevertheless, intensive use of these AR has selected worldwide many VKORC1-based resistant rodent strains to AR. Our aim was to characterize the sensitivity of Martinique commensal rodents to AR to better prevent leptospirosis transmission. Resistance of house mice to first-generation and in rare cases even to second-generation ARs were clearly demonstrated in Martinique with the detection of the Y139C mutation with a very high allelic frequency of 40% and the A26T/Y139C double-mutation with an allelic frequency of 0.9%. In black rat, the most prevalent rodent in Martinique, 3 new Vkorc1 coding mutations were detected, the H68N, A115T and S149N mutations associated with moderate resistance to first generation AR. Therefore, rodent management in Martinique must be carried carefully to avoid resistance diffusion and maintain long-term effective rodent management, to be able to efficiently prevent leptospirosis transmission.