Factors associated with differential seropositivity to Leptospira interrogans and Leptospira kirschneri in a high transmission urban setting for leptospirosis in Brazil.

BACKGROUND: Leptospirosis is a zoonosis caused by pathogenic species of bacteria belonging to the genus Leptospira. Most studies infer the epidemiological patterns of a single serogroup or aggregate all serogroups to estimate overall seropositivity, thus not exploring the risks of exposure to distinct serogroups. The present study aims to delineate the demographic, socioeconomic and environmental factors associated with seropositivity of Leptospira serogroup Icterohaemorraghiae and serogroup Cynopteri in an urban high transmission setting for leptospirosis in Brazil. METHODS/PRINCIPAL FINDINGS: We performed a cross-sectional serological study in five informal urban communities in the city of Salvador, Brazil. During the years 2018, 2020 2021, we recruited 2.808 residents and collected blood samples for serological analysis using microagglutination assays. We used a fixed-effect multinomial logistic regression model to identify risk factors associated with seropositivity for each serogroup. Seropositivity to Cynopteri increased with each year of age (OR 1.03; 95% CI 1.01-1.06) and was higher in those living in houses with unplastered walls (exposed brick) (OR 1.68; 95% CI 1.09-2.59) and where cats were present near the household (OR 2.00; 95% CI 1.03-3.88). Seropositivity to Icterohaemorrhagiae also increased with each year of age (OR 1.02; 95% CI 1.01-1.03) and was higher in males (OR 1.51; 95% CI 1.09-2.10), in those with work-related exposures (OR 1.71; 95% CI 1.10-2.66) or who had contact with sewage (OR 1.42; 95% CI 1.00-2.03). Spatial analysis showed differences in distribution of seropositivity to serogroups Icterohaemorrhagiae and Cynopteri within the five districts where study communities were situated. CONCLUSIONS/SIGNIFICANCE: Our data suggest distinct epidemiological patterns associated with the Icterohaemorrhagiae and Cynopteri serogroups in the urban environment at high risk for leptospirosis and with differences in spatial niches. We emphasize the need for studies that accurately identify the different pathogenic serogroups that circulate and infect residents of low-income areas.

Bacterial community profiles within the water samples of leptospirosis outbreak areas.

Background: Leptospirosis is a water-related zoonotic disease. The disease is primarily transmitted from animals to humans through pathogenic Leptospira bacteria in contaminated water and soil. Rivers have a critical role in Leptospira transmissions, while co-infection potentials with other waterborne bacteria might increase the severity and death risk of the disease. Methods: The water samples evaluated in this study were collected from four recreational forest rivers, Sungai Congkak, Sungai Lopo, Hulu Perdik, and Gunung Nuang. The samples were subjected to next-generation sequencing (NGS) for the 16S rRNA and in-depth metagenomic analysis of the bacterial communities. Results: The water samples recorded various bacterial diversity. The samples from the Hulu Perdik and Sungai Lopo downstream sampling sites had a more significant diversity, followed by Sungai Congkak. Conversely, the upstream samples from Gunung Nuang exhibited the lowest bacterial diversity. Proteobacteria, Firmicutes, and Acidobacteria were the dominant phyla detected in downstream areas. Potential pathogenic bacteria belonging to the genera Burkholderiales and Serratia were also identified, raising concerns about co-infection possibilities. Nevertheless, Leptospira pathogenic bacteria were absent from all sites, which is attributable to its limited persistence. The bacteria might also be washed to other locations, contributing to the reduced environmental bacterial load. Conclusion: The present study established the presence of pathogenic bacteria in the river ecosystems assessed. The findings offer valuable insights for designing strategies for preventing pathogenic bacteria environmental contamination and managing leptospirosis co-infections with other human diseases. Furthermore, closely monitoring water sample compositions with diverse approaches, including sentinel programs, wastewater-based epidemiology, and clinical surveillance, enables disease transmission and outbreak early detections. The data also provides valuable information for suitable treatments and long-term strategies for combating infectious diseases.

The role of small ruminants in the epidemiology of leptospirosis.

Leptospirosis is a common global zoonotic disease of man and all farm animals. Although most leptospiral infections in sheep and goats are asymptomatic, they may play a role in the epidemiology of the disease by the spread of Leptospira through the urine. This study was carried out to evaluate the role of sheep and goats in the epidemiology of leptospirosis. Blood and urine samples were taken from 210 goats and 246 sheep. To detect antibodies, sera samples were tested with 8 live serovars of L. interrogans (Hardjo, Pomona, Grippotyphosa, Canicola, Ballum, Icterhemorrhagiae, Tarasovi, and Australis) by MAT. Then, urine samples were tested by Nested PCR targeting 16S rRNA gene for detection of pathogenic Leptospira. Results of MAT showed that 10.95% of goats and 8.53% of sheep had antibodies against at least one examined serovars. In both species, the highest reacting was L. i. Pomona with a rate of 68.18% and 56% in sheep and goats, respectively. Moreover, in PCR, 2 (0.95%) urine samples of goat and 12 (4.87%) urine samples of sheep were positive. All of the MAT positive studied animals were PCR negative and, statistical analysis showed that there was no relationship and agreement between the results of PCR and MAT in sheep (kappa = - 0.07, p > 0.05) and goats (kappa = - 0.02, p > 0.05). Finally, it is concluded that sheep and goats can excrete L. interrogans in the urine and thus transmit them to other animals and humans.

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

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.

Sero-prevalence of anti-Leptospira antibodies and associated risk factors in rural Rwanda: A cross-sectional study.

BACKGROUND: Leptospirosis is a zoonotic disease transmitted through the urine of wild and domestic animals, and is responsible for over 50,000 deaths each year. In East Africa, prevalence varies greatly, from as low as 7% in Kenya to 37% in Somalia. Transmission epidemiology also varies around the world, with research in Nicaragua showing that rodents are the most clinically important, while studies in Egypt and Chile suggest that dogs may play a more important role. There are no published studies of leptospirosis in Rwanda. METHODS & FINDINGS: We performed a cross-sectional survey of asymptomatic adults recruited from five occupational categories. Serum samples were tested using ELISA and Microscopic Agglutination Test (MAT). We found that 40.1% (151/377) of asymptomatic adults had been exposed to Leptospira spp. Almost 36.3% of positive subjects reported contact with rats (137/377) which represent 90.7% among positive leptospira serology compared with 48.2% of negative subjects (182/377) which represent 80.5% among negative leptospira serology (OR 2.37, CI 1.25-4.49) and 1.7 fold on prevalence ratio and 2.37 of odd ratio. Furthermore, being a crop farmer was significantly associated with leptospirosis (OR 2.06, CI 1.29-3.28). We identified 6 asymptomatic subjects (1.6%) who met criteria for acute infection. CONCLUSIONS: This study demonstrates a high prevalence of leptospiral antibodies infection among asymptomatic adults in rural Rwanda, particularly relative to neighboring countries. Although positive subjects were more likely to report rat contact, we found no independent association between rats and leptospirosis infection. Nonetheless, exposure was high among crop farmers, which is supportive of the hypothesis that rats together with domestic livestock might contribute to the transmission. Further studies are needed to understand infecting Leptospira servers and elucidate the transmission epidemiology in Rwanda and identify means of host transmitters.

Mongooses (Urva auropunctata) as reservoir hosts of Leptospira species in the United States Virgin Islands, 2019-2020.

During 2019-2020, the Virgin Islands Department of Health investigated potential animal reservoirs of Leptospira spp., the bacteria that cause leptospirosis. In this cross-sectional study, we investigated Leptospira spp. exposure and carriage in the small Indian mongoose (Urva auropunctata, syn: Herpestes auropunctatus), an invasive animal species. This study was conducted across the three main islands of the U.S. Virgin Islands (USVI), which are St. Croix, St. Thomas, and St. John. We used the microscopic agglutination test (MAT), fluorescent antibody test (FAT), real-time polymerase chain reaction (lipl32 rt-PCR), and bacterial culture to evaluate serum and kidney specimens and compared the sensitivity, specificity, positive predictive value, and negative predictive value of these laboratory methods. Mongooses (n = 274) were live-trapped at 31 field sites in ten regions across USVI and humanely euthanized for Leptospira spp. testing. Bacterial isolates were sequenced and evaluated for species and phylogenetic analysis using the ppk gene. Anti-Leptospira spp. antibodies were detected in 34% (87/256) of mongooses. Reactions were observed with the following serogroups: Sejroe, Icterohaemorrhagiae, Pyrogenes, Mini, Cynopteri, Australis, Hebdomadis, Autumnalis, Mankarso, Pomona, and Ballum. Of the kidney specimens examined, 5.8% (16/270) were FAT-positive, 10% (27/274) were culture-positive, and 12.4% (34/274) were positive by rt-PCR. Of the Leptospira spp. isolated from mongooses, 25 were L. borgpetersenii, one was L. interrogans, and one was L. kirschneri. Positive predictive values of FAT and rt-PCR testing for predicting successful isolation of Leptospira by culture were 88% and 65%, respectively. The isolation and identification of Leptospira spp. in mongooses highlights the potential role of mongooses as a wildlife reservoir of leptospirosis; mongooses could be a source of Leptospira spp. infections for other wildlife, domestic animals, and humans.

Poverty, sanitation, and Leptospira transmission pathways in residents from four Brazilian slums.

Residents of urban slums suffer from a high burden of zoonotic diseases due to individual, socioeconomic, and environmental factors. We conducted a cross-sectional sero-survey in four urban slums in Salvador, Brazil, to characterize how poverty and sanitation contribute to the transmission of rat-borne leptospirosis. Sero-prevalence in the 1,318 participants ranged between 10.0 and 13.3%. We found that contact with environmental sources of contamination, rather than presence of rat reservoirs, is what leads to higher risk for residents living in areas with inadequate sanitation. Further, poorer residents may be exposed away from the household, and ongoing governmental interventions were not associated with lower transmission risk. Residents at higher risk were aware of their vulnerability, and their efforts improved the physical environment near their household, but did not reduce their infection chances. This study highlights the importance of understanding the socioeconomic and environmental determinants of risk, which ought to guide intervention efforts.

Leptospira spp. Antibody in Wild Boars (Sus scrofa), Hunting Dogs (Canis lupus familiaris), and Hunters of Brazil.

Hunting activities are a potential risk factor for human infection with Leptospira spp. and, although wild boar seroprevalence has been studied, there are no concurrent serosurveys of wild boars (Sus scrofa), hunting dogs (Canis lupus familiaris), and hunters. The aim of our study was to assess the seroprevalence of Leptospira spp. antibodies in free-ranging wild boars, hunting dogs, and hunters, and risk factors associated with exposure in southern and central-western Brazil. Leptospira spp. antibodies were serologically detected using the microscopic agglutination test, with a total 30 serovars. Overall, 12.2% (9/74) of wild boars and 10.6% (16/170) of hunting dogs were seropositive for at least one serovar and all hunters 0.0% (0/49) were seronegative for Leptospira spp. Seropositivity was statistically higher in 42.1% (8/19) wild boars from natural areas when compared to 2.4% (1/41) from anthropized areas (P<0.001), with prevalence ratio of 17.14 (95% confidence interval: 2.29-128.36). Despite the limited sample size, our findings showed that hunters may be less exposed to Leptospira spp. than are wild boars, particularly in natural areas where Leptospira spp. may be maintained by wild reservoirs. In addition to acting as sentinels, hunting dogs may play a role in disease transmission of sylvatic leptospiral serovars.

High exposure to pathogenic leptospires by the population residing in dairy farms in Hidalgo, Mexico.

Leptospirosis is a neglected zoonotic disease of unknown magnitude that has been overlooked and underreported, influenced by complex interactions established among humans, animals, and the environment; certain occupations, such as working with livestock, have an increased risk of exposure. We conducted a cross trans-sectional study in 374 serum samples obtained from workers and residents of dairy farms in the Tizayuca Basin, Hidalgo, Mexico, to determine the prevalence of anti-Leptospira antibody and the risk factors associated to this type of environment. The determination of anti-Leptospira antibodies was obtained by microscopic agglutination test. Seropositivity was defined from titles > 1:100. Seropositivity of anti-Leptospira antibodies among the population was 46.8% (176/374) (95% Cl 41.9-52.1). Thirty-nine percent (146/74) of the analyzed serum reacted to the Hardjo serovar (Sejröe serogroup). Eighty-eight percent (8/9) slaughterhouse workers tested were seropositive. Those who belonged to an ethnic group had OR 1.78 (IC 1.02-3.11, P = 0.041). Seropositivity was associated with having a secondary school level or lower, with OR 1.79 (IC 0.97-3.29, P = 0.058). Exposure to Leptospira in a dairy production farm is a risk factor for humans. Our findings can contribute to strengthening the intervention of the Public Health System to prevent this zoonosis that prevails in dairy farm environments.

A Mouse Model of Sublethal Leptospirosis: Protocols for Infection with Leptospira Through Natural Transmission Routes, for Monitoring Clinical and Molecular Scores of Disease, and for Evaluation of the Host Immune Response.

Leptospirosis is a zoonotic disease caused by pathogenic Leptospira species that are maintained in sylvatic and domestic environments by transmission among rodents and other carriers. Humans become infected after contact of breached skin or mucosa with contaminated water or soil. Understanding persistent or sublethal infection in a host is critical for controlling human risk of exposure to pathogenic Leptospira. Animal models that recapitulate disease progression after infection via natural transmission routes are more appropriate for validation of vaccines and therapeutics. Furthermore, the ability to measure shedding of live Leptospira in urine of reservoir and carrier hosts can be used to develop new diagnostic assays and sensors to evaluate human risk of exposure. We developed inbred mouse models of Leptospirosis, that bypass survival as a criterion, in which we can analyze both pathogen and host factors affecting sublethal infection (<1 month), including shedding of Leptospira in urine. Mice are infected with pathogenic Leptospira using a physiologic route, and the clinical, histological, and molecular scores of disease are measured. Furthermore, the host immune response to Leptospira is evaluated. This mouse model also provides a tool in which to test fundamental hypotheses related to host-pathogen interactions and the immune mechanisms engaged in protective and pathogenic immune responses. © 2020 Wiley Periodicals LLC Basic Protocol 1: Culture and maintenance of virulent Leptospira Basic Protocol 2: Infection of mice through a physiologic route and collection of clinical scores and biological samples Basic Protocol 3: Analysis of pathogenesis after Leptospira infection.

Cats shedding pathogenic Leptospira spp.-An underestimated zoonotic risk?

Shedding of DNA of pathogenic Leptospira spp. has been documented in naturally infected cats in several countries, but urinary shedding of infectious Leptospira spp. has only recently been proven. The climate in Southern Chile is temperate rainy with high annual precipitations which represents ideal preconditions for survival of Leptospira spp., especially during spring and summer. The aims of this study were to investigate shedding of pathogenic Leptospira spp. in outdoor cats in Southern Chile, to perform molecular characterization of isolates growing in culture, and to assess potential risk factors associated with shedding. Urine samples of 231 outdoor cats from rural and urban areas in southern Chile were collected. Urine samples were investigated for pathogenic Leptospira spp. by 4 techniques: qPCR targeting the lipL32 gene, immunomagnetic separation (IMS)-coupled qPCR (IMS-qPCR), direct culture and IMS-coupled culture. Positive urine cultures were additionally confirmed by PCR. Multilocus sequence typing (MLST) was used to molecularly characterize isolates obtained from positive cultures. Overall, 36 urine samples (15.6%, 95% confidence interval (CI) 11.4-20.9) showed positive results. Eighteen (7.8%, 95% CI 4.9-12.1), 30 (13%, 95% CI 9.2-18), 3 (1.3%, 0.3-3.9) and 4 cats (1.7%; 95% CI 0.5-4.5) were positive in qPCR, IMS-qPCR, conventional culture, and IMS-coupled culture, respectively. MLST results of 7 culture-positive cats revealed sequences that could be assigned to sequence type 17 (6 cats) and sequence type 27 (1 cat) corresponding to L. interrogans (Pathogenic Leptospira Subgroup 1). Shedding of pathogenic Leptospira spp. by cats might be an underestimated source of infection for other species including humans. The present study is the first one reporting growth of leptospires from feline urine in culture in naturally infected cats in South-America and characterisation of culture-derived isolates. So far, very few cases of successful attempts to culture leptospires from naturally infected cats are described worldwide.

Circulating genotypes of Leptospira in French Polynesia : An 9-year molecular epidemiology surveillance follow-up study.

BACKGROUND: Leptospirosis is a widespread zoonosis with global impact, particularly among vulnerable populations in resource-poor settings in tropical countries. Rodents have been considered to be the main reservoir of the disease; however, a wide variety of mammals can act as hosts as well. Here we examine the genetic diversity of Leptospira strains from biological samples of patients and animals in French Polynesia (FP) from 2011 to 2019. METHODOLOGY/PRINCIPAL FINDINGS: From 2011 to 2019, we have collected 444 blood samples from patients diagnosed as having leptospirosis. The limited volume of clinical material and low amount of leptospiral DNA in blood samples led us to develop a nested PCR targeting the secY locus that enabled us to amplify and sequence 244 samples (55%). In addition, 20 Leptospira strains recovered from the blood of patients from 2002 to 2011 were sequenced and fully characterized at the serogroup level and used as reference strains for the association of different phylogenetic branches with respective serogroups. The secY sequences were compared with publicly available sequences from patients and animal reservoirs in FP (n = 79). We identified rats as the main source of infection for L. borgpetersenii serogroup Ballum and L. interrogans serogroup Icterohaemorrhagiae, dogs as the main source of infection for L. interrogans serogroup Australis, and farm pigs as the main source of infection for L. interrogans serogroups Pomona or Canicola. L. interrogans was associated with the most severe infections with 10 and 5 fatal cases due to serogroups Icterohaemorrhagiae and Australis, respectively. Mortality was significantly associated with older age (p-value < 0.001). CONCLUSIONS/SIGNIFICANCE: We described the population dynamics of leptospires circulating among patients in FP, including two patients who were reinfected with unrelated Leptospira genotypes, and clarified the local role of the animal reservoirs in the transmission route of leptospirosis to humans. Routine Leptospira genotyping directly on biological samples should allow the epidemiological follow-up of circulating strains and assess the impact of control interventions on disease transmission.

Leptospira sp. vertical transmission in ewes maintained in semiarid conditions.

Leptospirosis is a globally distributed disease associated with reproductive failures in livestock; however, its pathogenesis has not been fully elucidated. Results from the present study indicate there is a presence of Leptospira sp. in organs and fluids of fetuses from ewes slaughtered in the semiarid region of Brazil. Twenty-nine fetuses from 23 ewes determined to be Leptospira sp.-positive using PCR were sampled (14 and 15 in dry and rainy seasons, respectively). Fetal samples of blood, central nervous system (CNS), lung, liver, spleen, stomach contents, peritoneal fluid, kidney, bladder, urine and reproductive system were collected. Diagnostic methods included the microscopic agglutination test (MAT), polymerase chain reaction (PCR) and bacterial isolation. Of the 29 fetuses, 24 (82.8 %) had at least one Leptospira sp.-positive organ or fluid, as determined using PCR, and of a total of 209 samples, 62 (29.7 %) contained leptospiral DNA. Of the 99 samples collected during the dry season, 42 (42.4 %) were positive, and of 110 samples collected during the rainy season, 20 (18.2 %) were positive (P = 0.0001). There was deoxyribonucleic acid (DNA) sequencing of three samples of kidney, CNS and liver, and in all of these, there was 99.3 % similarity with Leptospira interrogans. Leptospires were present in cultures of pooled samples from fetuses with deformities. Results indicate there is vertical (maternal-to-fetus) transmission which would represent an alternative transmission route for the spread of Leptospira sp. in ewes, suggesting molecular detection is essential in the investigation of leptospirosis in fetuses to identify animals that have been infected with this bacterium.

Molecular Detection and Typing of Pathogenic Leptospira in Febrile Patients and Phylogenetic Comparison with Leptospira Detected among Animals in Tanzania.

Molecular data are required to improve our understanding of the epidemiology of leptospirosis in Africa and to identify sources of human infection. We applied molecular methods to identify the infecting Leptospira species and genotypes among patients hospitalized with fever in Tanzania and compared these with Leptospira genotypes detected among animals in Tanzania to infer potential sources of human infection. We performed lipL32 real-time PCR to detect the presence of pathogenic Leptospira in acute-phase plasma, serum, and urine samples obtained from study participants with serologically confirmed leptospirosis and participants who had died with febrile illness. Leptospira blood culture was also performed. In positive specimens, we performed species-specific PCR and compared participant Leptospira secY sequences with Leptospira reference sequences and sequences previously obtained from animals in Tanzania. We detected Leptospira DNA in four (3.6%) of 111 participant blood samples. We detected Leptospira borgpetersenii (one participant, 25.0%), Leptospira interrogans (one participant, 25.0%), and Leptospira kirschneri (one participant, 25.0%) (one [25%] undetermined). Phylogenetic comparison of secY sequence from the L. borgpetersenii and L. kirschneri genotypes detected from participants was closely related to but distinct from genotypes detected among local livestock species. Our results indicate that a diverse range of Leptospira species is causing human infection. Although our analysis suggests a close relationship between Leptospira genotypes found in people and livestock, continued efforts are needed to obtain more Leptospira genetic material from human leptospirosis cases to help prioritize Leptospira species and genotypes for control.

An Observational Study of Human Leptospirosis in Seychelles.

A 1-year population-based prospective study was launched in Seychelles, a country with one of the highest human incidence of leptospirosis worldwide, to describe the characteristic features of the epidemiology of the disease and highlight the most prominent risk factors. Diagnosis was based on the IgM enzyme-linked immunosorbent assay, microscopic agglutination test, and real-time PCR. A standardized questionnaire was administered to 219 patients aged ≥ 13 years consulting for acute febrile illness. The high incidence of leptospirosis in Seychelles was confirmed. The disease was particularly severe, as the case fatality rate was 11.8%. Leptospirosis was positively associated in univariate analysis with socio-professional and clinical variables including gardening/farming, oliguria, jaundice, conjunctivitis, history of hepatitis C virus infection, anemia, thrombocytopenia, and/or biological renal failure. Epidemiological analyses of the questionnaires highlighted a link of the disease with living in houses (versus apartment), the presence of animals around and in houses, gardening, and misuse of personal protective equipment. Multivariate analyses indicated that being a farmer/landscaper and having cattle and cats around the home are the most significant drivers of leptospirosis. Biological features most associated with leptospirosis were thrombocytopenia, leukocytosis, high values for renal function tests, and elevated total bilirubin. We report changes in behavior and exposure compared with data collected on leptospirosis 25 years ago, with indication that healthcare development has lowered case fatality. Continuous health education campaigns are recommended as well as further studies to clarify the epidemiology of human leptospirosis, especially the role of domestic animals.

M16-Type Metallopeptidases Are Involved in Virulence for Invasiveness and Diffusion of Leptospira interrogans and Transmission of Leptospirosis.

BACKGROUND: Leptospirosis is a global zoonotic infectious disease caused by Leptospira interrogans. The pathogen rapidly invades into hosts and diffuses from bloodstream into internal organs and excretes from urine to cause transmission of leptospirosis. However, the mechanism of leptospiral invasiveness remains poorly understood. METHODS: Proteolytic activity of M16-type metallopeptidases (Lep-MP1/2/3) of L. interrogans was determined by spectrophotometry. Expression and secretion of Lep-MP1/2/3 during infection of cells were detected by quantitative reverse-transcription polymerase chain reaction, Western blot assay, and confocal microscopy. Deletion and complementation mutants of the genes encoding Lep-MP1/2/3 were generated to determine the roles of Lep-MP1/2/3 in invasiveness using transwell assay and virulence in hamsters. RESULTS: Leptospira interrogans but not saprophytic Leptospira biflexa strains were detectable for Lep-MP-1/2/3-encoding genes. rLep-MP1/2/3 hydrolyzed extracellular matrix proteins, but rLep-MP1/3 displayed stronger proteolysis than rLep-MP2, with 123.179/340.136 µmol/L Km and 0.154/0.159 s-1 Kcat values. Expression, secretion and translocation of Lep-MP1/2/3 during infection of cells were increased. ΔMP1/3 but not ΔMP2 mutant presented attenuated transmigration through cell monolayers, decreased leptospiral loading in the blood, lungs, liver, kidneys, and urine, and 10/13-fold decreased 50% lethal dose and milder histopathologic injury in hamsters. CONCLUSIONS: Lep-MP1 and 3 are involved in virulence of L. interrogans in invasion into hosts and diffusion in vivo, and transmission of leptospirosis.

A systematic review of Leptospira in water and soil environments.

BACKGROUND: Leptospirosis, caused by pathogenic Leptospira, is a zoonosis of global distribution. This infectious disease is mainly transmitted by indirect exposure to urine of asymptomatic animals via the environment. As human cases generally occur after heavy rain, an emerging hypothesis suggests that rainfall re-suspend leptospires together with soil particles. Bacteria are then carried to surface water, where humans get exposed. It is currently assumed that pathogenic leptospires can survive in the environment but do not multiply. However, little is known on their capacity to survive in a soil and freshwater environment. METHODS: We conducted a systematic review on Leptospira and leptospirosis in the environment in order to collect current knowledge on the lifestyle of Leptospira in soil and water. In total, 86 scientific articles retrieved from online databases or institutional libraries were included in this study. PRINCIPALS FINDINGS/SIGNIFICANCE: This work identified evidence of survival of Leptospira in the environment but major gaps remain about the survival of virulent species associated with human and animal diseases. Studies providing quantitative data on Leptospira in soil and water are a very recent trend, but must be interpreted with caution because of the uncertainty in the species identification. Several studies mentioned the presence of Leptospira in soils more frequently than in waters, supporting the hypothesis of the soil habitat and dispersion of Leptospira with re-suspended soil particles during heavy rain. In a near future, the growing use of high throughput sequencing will offer new opportunities to improve our understanding of the habitat of Leptospira in the environment. This better insight into the risk of leptospirosis will allow implementing efficient control measures and prevention for the human and animal populations exposed.

The route of infection with Leptospira interrogans serovar Copenhageni affects the kinetics of bacterial dissemination and kidney colonization.

The goal of this study was to characterize how natural routes of infection affect the kinetics of pathogenic Leptospira dissemination to blood and kidney. C3H/HeJ mice were sublethally infected with L. interrogans serovar Copenhageni FioCruz L1-130 (Leptospira) through exposure of a dermis wound and through oral and nasal mucosa, in comparison to uninfected mice and to mice infected via standard intraperitoneal inoculation. In striking contrast to oral mucosa inoculation, transdermal and nasal mucosa infections led to weight loss, renal colonization and inflammation, as previously observed for conjunctival and intraperitoneal infections. However, the timing at which Leptospira gained access to blood, as well as Leptospira' colonization of the kidney and shedding in urine, differed from intraperitoneal infection. Furthermore, a comparative analysis of transcription of pro-inflammatory mediators in kidney and total immunoglobulin isotyping in serum from infected mice, showed increased innate immune response markers (KC, MIP-2, TNF-α) and lower Th1 associated IFN-γ in kidney, as well as lower Th1 associated IgG2a in mice infected through the nasal mucosa as compared to intraperitoneal infection. We conclude that the route of infection affects the timing at which Leptospira gains access to blood for dissemination, as well as the dynamics of colonization and inflammation of the kidney.

Leptospirosis: a neglected tropical zoonotic infection of public health importance-an updated review.

Leptospirosis is a zoonotic and waterborne disease worldwide. It is a neglected, reemerging disease of global public health importance with respect to morbidity and mortality both in humans and animals. Due to negligence, rapid, unplanned urbanization, and poor sanitation, leptospirosis emerges as a leading cause of acute febrile illness in many of the developing countries. Every individual has a risk of getting infected as domestic and wild animals carry leptospires; the at-risk population varies from the healthcare professionals, animal caretakers, farmers and agricultural workers, fishermen, rodent catchers, water sports people, National Disaster Response Force (NDRF) personnel, people who volunteer rescue operations in flood-affected areas, sanitary workers, sewage workers, etc. The clinical manifestations of leptospirosis range from flu-like illness to acute kidney failure (AKF), pneumonia, jaundice, pulmonary hemorrhages, etc. But many rare and uncommon clinical manifestations are being reported worldwide. This review will cover all possible updates in leptospirosis from occurrence, transmission, rare clinical manifestations, diagnosis, treatment, and prophylactic measures that are currently available, their advantages and the future perspectives, elaborately. There are less or very few reviews on leptospirosis in recent years. Thus, this work will serve as background knowledge for the current understanding of leptospirosis for researchers. This will provide a detailed analysis of leptospirosis and also help in finding research gaps and areas to focus on regarding future research perspectives.