Serogroup Icterohaemorrhagiae Research Articles

Short communication: Uterine leptospiral infection is strongly associated to strains of serogroup Sejroe on experimentally infected hamsters

Leptospira infection is influenced by the host species and the bacterial strain involved. Important differences on their tissue distribution are referred, also depending on the host and the studied strain. Considering tissue distribution of leptospires the majority of the studies focus on a single strain, or strains from the same serogroup with different inoculation doses. Nevertheless, none had associated different serogroups with their tissue distribution. Thus, the present study aims to investigate the hypothesis that tissue distribution of Leptospira spp. on experimentally infected hamsters may vary according to the strain serogroup. Females of Golden Syrian hamsters were used for the experimental infection with Leptospira isolates (n = 13) belonging to serogroups Icterohaemorrhagiae (n = 8) and Sejroe (n = 5). PCRs were conducted in renal, hepatic and uterine tissue. Seven out of the thirteen studied hamsters presented acute clinical signs and were euthanized before the 21° day p.i. (strains VF237, VF52, U81, UFF-SG001, UFF-G19, UFF-B15, L1-130), while the others presented a subclinical infection. Regarding to the PCR results it was possible to observe that, all but one strain (UFF-SG001), which was detected on all the studied tissues, presented some differences on their tissue distribution. All strains could be detected on at least one tissue and a significant association was observed for the occurrence of the strains of serogroup Sejroe in uterus (p = 0.044). The results of the present study indicate that strains of serogroup Sejroe are strongly associated to uterine infection on experimentally infected hamsters.

Potential antileptospiral constituents from Phyllanthus amarus

Background: Phyllanthus amarus (PA) is a well-known herb for its medicinal properties and widely used worldwide. PA has a significant role in Indian Ayurveda system of medicine for treating various ailments such as gonorrhea, menorrhagia, and other genital infections. Objectives: The aim of the study is to investigate antileptospiral activity and isolate the potential antileptospiral constituents of the methanol extract of PA (MPA). Materials and Methods: The primary pharmacological tests for leptospirosis were investigated by test tube dilution technique and microdilution technique. To examine the morphogenesis of experimental leptospirosis by morphologic and histological methods, albino mice were inoculated intraperitoneally with Leptospira interrogans sero group Icterohaemorrhagiae strains. Results: The activity-guided repeated fractionation for MPA through silica gel column chromatography yielded three compounds that exhibited antioxidant and in vitro, in vivo, and in silico antileptospiral activities. Based on diverse physicochemical and spectroscopic analyses (viz.,13C NMR,1H NMR, ultraviolet [UV], IR, and mass spectroscopy), the potential constituents were elucidated as 5-(3-(3,4-dimethoxybenzyl)-4-methoxy-2-(methoxymethyl)butyl)-4,7-dimethoxybenzo[d][1,3]dioxole(C1),1-(3-(3,4-dimethoxybenzyl)-4-methoxy-2-(methoxymethyl)butyl)-2,3,4,5tetramethoxybenzene(C2), and 4-(3-(3,4dimethoxybenzyl)-4-methoxy-2-(methoxymethyl)butyl)-3,6-dimethoxybenzene-1,2-diol (C3). The histopathological examinations of both kidney and liver showed promising activity with C3 at 75 and 100 μg/mL, respectively. Conclusion: The in vitro , in vivo, and in silico studies revealed that benzo methoxy class of compounds has great potential as antileptospiral agents.

Leptospirosis in donkeys (Equus asinus) destined for slaughter and export

Brazil is the eighth largest exporter of equidae meat in the world. Most donkey meat is obtained from discarded animals, raising concerns about their health status, particularly regarding zoonotic infections such as leptospirosis. Thus, this study aimed to determine the frequency of anti-Leptospira sp. antibodies in Northeastern donkeys at two properties specializing in producing donkeys for slaughter and export to the Chinese market, in the municipalities of Parnamirim (A) and Araripina (B), both located in the mesoregion of the Sertão of Pernambuco, Northeastern Brazil. The serum of 349 donkeys was collected, including 147 males and 202 females, aged 3 to 12 years. All animals were subjected to the Microscopic Agglutination Test (MAT) using a cut-off point of 1:50. A total of 19.8% seropositive animals were obtained. The Icterohaemorrhagiae serogroup was the most found in this study (40.6%), followed by Australis (27.5%), Autumnalis (8.7%), Sejroe (8.7%), Pomona (8.7%), Celledoni (2.9%), and Tarassovi (2.9%). A higher overall rate of seropositivity was found in donkeys from property B (2.2.4%) in the municipality of Araripina. In the association analysis, it was observed that animals less than 9 years of age were more likely to be seropositive, this may be due to the acquisition of resistance to Leptospira sp. as age advances. A significant number of donkeys seropositive for Leptospira sp. was found, thus, breeding these animals for slaughter and export requires implementing prophylactic measures.

Seroprevalence, Risk Factors, and Rodent Reservoirs of Leptospirosis in an Urban Community of Puerto Rico, 2015.

The burden of leptospirosis in Puerto Rico remains unclear due to underreporting. A cross-sectional survey and rodent trapping was performed in a community within San Juan, Puerto Rico to determine the seroprevalence and risk factors for Leptospira infection. The microscopic agglutination test was used to detect anti-Leptospira antibodies as a marker of previous infection. We evaluated Leptospira carriage by quantitative polymerase chain reaction among rodents trapped at the community site. Of 202 study participants, 55 (27.2%) had Leptospira agglutinating antibodies. Among the 55 seropositive individuals, antibodies were directed most frequently against serogroups Icterohaemorrhagiae (22.0%) and Autumnalis (10.6%). Of 18 captured rodents, 11 (61.1%) carried pathogenic Leptospira (Leptospira borgpetersenii, 7 and Leptospira interrogans, 2). Four participants showed their highest titer against an isolate obtained from a rodent (serogroup Ballum). Increasing household distance to the canal that runs through the community was associated with decreased risk of infection (odds ratio = 0.934 per 10-meter increase; 95% confidence interval, .952-.992). There are high levels of Leptospira exposure in an urban setting in Puerto Rico, for which rodents may be an important reservoir for transmission. Our findings indicate that prevention should focus on mitigating risk posed by infrastructure deficiencies such as the canal.

Genetic characteristics of pathogenic Leptospira in wild small animals and livestock in Jiangxi Province, China, 2002–2015

BackgroundLeptospirosis is one of the most important neglected tropical bacterial diseases worldwide. However, there is limited information on the genetic diversity and host selectivity of pathogenic Leptospira in wild small mammal populations.Methodology/Principal findingsJiangxi Province, located in southern China, is a region highly endemic for leptospirosis. In this study, among a total of 3,531 trapped rodents dominated by Apodemus agrarius (59.7%), 330 Leptospira strains were successfully isolated from six different sites in Jiangxi between 2002 and 2015. Adding 71 local strains from humans, various kinds of livestock and wild animals in Jiangxi, a total of 401 epidemic strains were characterized using 16S rRNA gene senquencing, multilocus sequence typing (MLST) and the microscopic agglutination test (MAT). Among them, the most prevalent serogroup was Icterohaemorrhagiae (61.10%), followed by Javanica (19.20%) and Australis (9.73%); the remaining five serogroups, Canicola, Autumnalis, Grippotyphosa, Hebdomadis and Pomona, accounted for 9.97%. Species identification revealed that 325 were L. interrogans and 76 were L. borgpetersenii. Moreover, L. interrogans was the only pathogenic species in Fuliang and Shanggao and was predominant in Shangrao (95.0%); L. borgpetersenii was the most common in the remaining three sites. Twenty-one sequence types (STs) were identified. Similarly, ST1 and serogroup Icterohaemorrhagiae were most prevalent in Shangrao (86.0% and 86.4%) and Fuliang (90.4% and 90.4%), ST143 and serogroup Javanica in Shangyou (88.5% and 90.4%) and Longnan (73.1% and 73.1%), and ST105 and serogroup Australis in Shanggao (46.3% and 56.1%). Serogroup Icterohaemorhagiae primarily linked to A. agrarius (86.9%), serogroup Canicola to dogs (83.3%). There were significant differences in the distribution of leptospiral species/serogroups/STs prevalence across host species/collected locations among the 394 animal-associated strains (Fisher’s exact test, p<0.001).Conclusions/SignificanceOur study demonstrated high genetic diversity of pathogenic Leptospira strains from wild small animals in Jiangxi from 2002 to 2015. A. agrarius was the most abundantly trapped animal reservoir, and serogroup Icterohaemorrhagiae and ST1 were the most dominant in Jiangxi. Significant geographic variation and host diversity in the distribution of dominant species, STs and serogroups were observed. Moreover, rat-to-human transmission might play a crucial role in the circulation of Leptospirosis in Jiangxi. Details of the serological and molecular characteristics circulating in this region will be essential in implementing prevention and intervention measures to reduce the risk of disease transmission in China. However, phylogenetic analysis of more Leptospira isolates should explore the impact of ecological change on leptospirosis transmission dynamics and investigate how such new knowledge might better impact environmental monitoring for disease control and prevention at a public health level.

Anti-Leptospira spp. Antibodies in Pigs Slaughtered in the Agreste Region of Pernambuco, Brazil

Background: Swine production and productivity rates can be influenced by several factors, such as genetics, environmental conditions, nutritional factors, previous infections and others. Among infectious diseases, leptospirosis is a well-known cause of reproductive disorders in pigs. These animals are considered carriers of the disease when they are in the terminal stage of the infection and the Veterinary Inspection Service has not been notified when they are slaughtered. Considering the lack of epidemiological information on Leptospira infection in pigs in the state of Pernambuco, the aim of this study was to investigate anti-Leptospira antibodies in pigs slaughtered in the Agreste region of the state of Pernambuco, Brazil.Materials, Methods &amp; Results: Blood samples were collected from 305 pigs in 11 municipalities in the Agreste region of Pernambuco. The animals had no history of vaccination, and were raised on subsistence-oriented family farms. The sera were subjected to the Microscopic Agglutination Test (MAT) for the detection of antibodies. The serovars used in the MAT were: Icterohaemorrhagiae, Copenhageni, Javanica, Canicola, Castellonis, Pyrogenenes, Cynopteri, Autumnalis, Sentot, Djasiman, Australis, Pomona, Grippotyphosa, Hebdomadis, Wolffi, Sejroe, Saxkoebing, Bataviae, Tarassovi, Panama, Patoc, Andamana, Celledoni, Shermani, Brastilava and Hardjo. Sera showing titers of ≥100 were considered positive. The MAT results indicated that 78/305 (25.57%) of the samples were positive, and were distributed in the 11 municipalities. The most frequent serovars were Icterohaemorrhagiae, Copenhageni, and Djasiman, with frequencies of 55.13%, 17.95% and 6.41%, respectively.Discussion: Swine infected with leptospirosis showed few or no signs of the disease. However, the bacteria can be carried for long periods in convoluted tubules of the kidney and their urinary excretion may last for years. A study of Leptospira spp. risk factors on pig farms in the state of Alagoas revealed an absence of rodent control, suggesting that this was the probable cause of infection by this serovar, Icterohaemorrhagiae. Farms that did not control their rodent populations showed a 7.8-fold higher risk of infection among their swine. This exposure poses a problem, since these animals can contaminate the environment, as well as food and water, making them an important source of infection of other animals. The findings of this study indicate that the pigs were exposed to Leptospira spp. The reason that some atypical serovars were identified in this study may be have been incidental infection, since these animals came from a non-technified system, putting them at greater risk of contact with other animal species. This may also be a reason for the identification of the other serovars in this research. Although the serovar Copenhagen is part of the Icterohaemorrhagiae serogroup, few studies have described its importance. The main reservoirs of Copenhageni are also synanthropic rodents, which underscores the importance of these animals as possible sources of contamination on farms that supply pigs to the slaughterhouses of the region under study. The data obtained here indicate the need for animal health surveillance programs in the region. Moreover, they may also be a source of infection of the professionals directly involved in handling and slaughtering pigs. This indicates the need to implement surveillance programs in the region, such as high vaccination coverage at pig farms, as well as integrated pest management against rodents.

Genus-wide Leptospira core genome multilocus sequence typing for strain taxonomy and global surveillance.

Leptospira is a highly heterogeneous bacterial genus that can be divided into three evolutionary lineages and >300 serovars. The causative agents of leptospirosis are responsible of an emerging zoonotic disease worldwide. To advance our understanding of the biodiversity of Leptospira strains at the global level, we evaluated the performance of whole-genome sequencing (WGS) as a genus-wide strain classification and genotyping tool. Herein we propose a set of 545 highly conserved loci as a core genome MLST (cgMLST) genotyping scheme applicable to the entire Leptospira genus, including non-pathogenic species. Evaluation of cgMLST genotyping was undertaken with 509 genomes, including 327 newly sequenced genomes, from diverse species, sources and geographical locations. Phylogenetic analysis showed that cgMLST defines species, clades, subclades, clonal groups and cgMLST sequence types (cgST), with high precision and robustness to missing data. Novel Leptospira species, including a novel subclade named S2 (saprophytes 2), were identified. We defined clonal groups (CG) optimally using a single-linkage clustering threshold of 40 allelic mismatches. While some CGs such as L. interrogans CG6 (serogroup Icterohaemorrhagiae) are globally distributed, others are geographically restricted. cgMLST was congruent with classical MLST schemes, but had greatly improved resolution and broader applicability. Single nucleotide polymorphisms within single cgST groups was limited to <30 SNPs, underlining a potential role for cgMLST in epidemiological surveillance. Finally, cgMLST allowed identification of serogroups and closely related serovars. In conclusion, the proposed cgMLST strategy allows high-resolution genotyping of Leptospira isolates across the phylogenetic breadth of the genus. The unified genomic taxonomy of Leptospira strains, available publicly at http://bigsdb.pasteur.fr/leptospira, will facilitate global harmonization of Leptospira genotyping, strain emergence follow-up and novel collaborative studies of the epidemiology and evolution of this emerging pathogen.

A One Health Approach to Investigating Leptospira Serogroups and Their Spatial Distributions among Humans and Animals in Rio Grande do Sul, Brazil, 2013⁻2015.

Leptospirosis is an endemic zoonotic disease in Brazil and is widespread throughout rural populations in the state of Rio Grande do Sul. This study aimed to identify presumptive infecting Leptospira serogroups in human and animal cases and describe their occurrences within the ecoregions of the state by animal species. Data for human and animal leptospirosis cases were gathered from the government’s passive surveillance systems and presumptive infecting serogroups were identified based on a two-fold titer difference in serogroups in the microscopic agglutination test (MAT) panel. A total of 22 different serogroups were reported across both human and animal cases. Serogroup Icterohaemorrhagiae was the most common among humans, while serogroup Sejroe predominated among animal cases, particularly bovines. Each ecoregion had a large distribution of cases, with 51% of the human cases in the Parana–Paraiba ecoregion, and 81% of the animal cases in the Savannah ecoregion. Identifying and mapping the serogroups circulating using the One Health approach is the first step for further understanding the distribution of the disease in the state. This study has the potential to aid in guiding public health and agricultural practices, furthering the need for a human vaccine in high-risk populations to complement control and prevention efforts.

Geo-Epidemiological Study of Leptospira spp. Infection in Cattle, Feral Cats and Rodents of the Fernando de Noronha Island, Brazil

Background: Leptospirosis is a re-emergent contagious infectious disease, caused by pathogenic leptospires that are transmitted by the urine of infected animals or bacteria-contaminated water and mud. In tropical and subtropical countries it presents high prevalence due to the temperature and humidity conditions that favor the maintenance of the agent in the environment. This disease can affect several species, in Brazilian cattle is an endemic disease, and studies have shown a high occurrence of Leptospira spp. infection in beef and dairy herds. Domestic cats as well as other species of the Family Felidae seem to be resistant to leptospirosis. However, it has been demonstrated under experimental conditions that cats may become infected by ingestion of infected rodents and contaminated water. The present study investigated the occurrence of Leptospira spp. infection in cattle, feral cats and rodents of the Fernando de Noronha Island.Materials, Methods &amp; Results: Fernando de Noronha Island is located 360 km far from Recife and Natal, capitals of the states of Pernambuco and Rio Grande do Norte, Brazil, respectively. It has an area of approximately 18.4 km2 and constitutes the submerged part of a volcanic edifice currently inactive, which base rests 4,000 m deep in the Atlantic Ocean. Blood samples were collected from all the cattle raised in the Island (n = 88), 200 feral cats and 150 rodents, and the sera were screened by MAT (Serogroups: Australis; Autumnalis; Ballum; Bataviae; Canicola; Cynopteri; Djasiman; Grippotyphosa; Hebdomadis; Icterohaemorrhagiae; Icterohaemorrhagiae; Panama; Pomona; Pyrogenes; Sejroe e Tarassovi) for detection of anti-Leptospira spp. antibodies. Initially all sera were screened at 1:100 dilution and those with 50% or more agglutination were titrated at two-fold geometric dilutions. The serum titer was defined as the reciprocal of the highest positive dilution. The plane coordinates obtained by Global Position System (GPS) were used for developing a spatial map of the Fernando de Noronha Island. The geo-referenced data were plotted in the ArcGIS 10.1 software. Approximately 22% (20/88) and 12% (19/150) of the cattle and rodents were serologically reactive against Leptospira spp. antigens, respectively. The antibody titers of cattle ranged from 100 to 800 as shown. All the rodents screened were reactive against only one serovar and their antibody titers ranged from 100 to 3200. None of the serum samples from cats was reactive against the serovars tested. The serogroup Icterohaemorrhagiae predominated among the seropositive cattle, being found in 100% of the reactive samples. In rodents, the serogroups Icterohaemorrhagiae, Djasiman and Australis were responsible for 73.7% (14/19), 21.0% (4/19) and 5.2% (1/19) of the infections, respectively.Discussion: We believe that rodents and cattle play an important role in the dissemination of this disease, thus, it is necessary adopting prophylactic measures aimed at leptospirosis in the study area, in view of the human cases of leptospirosis reported and confirmed in the Island. These results are unprecedented in an insular environment in Brazil. Strategies aimed at better sanitary management of the cattle herds as well as population control of rodents must be implemented in the Fernando de Noronha Island to secure a more sustainable animal production and minimize the risks to public health.

Prevalence and risk factors to &lt;i&gt;Leptospira&lt;/i&gt; sp. infection in dogs attended at veterinary clinics in João Pessoa, Paraíba State, Northeastern Brazil

The aim of this study was to determine the prevalence and risk factors associated with Leptospira sp. in dogs attended at veterinary clinics in the city of João Pessoa, State of Paraíba, Northeast Brazil. A total of 384 blood samples from dogs from 34 veterinary clinics were used from April 2015 to May 2016. The diagnosis of Leptospira sp. was carried out through Microscopic Agglutination Test (MAT), using a collection of 20 pathogenic antigens and adopting a 1: 100 dilution as cutoff point. An epidemiological questionnaire was applied to the owners of the animals to obtain data to be used in the analysis of risk factors. The prevalence of seropositive animals was 11.7% (45/384), with reactions for serogroups Icterohaemorrhagiae (62.3%), Grippotyphosa (22.2%), Canicola (13.3%), Djasiman 2%) and Pomona (2.2%). The following risk factors were identified: age from 49 to 72 months (odds ratio = 2.74), Age &gt; 72 months (odds ratio = 3.22), and monthly cleaning of the environment where the animals are kept (odds ratio = 10,70). It is concluded that dogs attended at veterinary clinics in João Pessoa are exposed to infection by Leptospira sp., with predominance of serogroups kept by wild animals, and it is suggested that the periodic cleaning of the environment where the animals are kept.

MAT cross-reactions or vaccine cross-protection: retrospective study of 863 leptospirosis canine cases

Dogs are naturally exposed to numerous pathogenic serogroups. Leptospirosis vaccines are claimed to afford a clinical protection restricted to the serogroups of which they are composed. ObjectivesDogs exhibiting liver and kidney injury were suspected of having leptospirosis. The purpose of this study was to compare the microscopic agglutination test (MAT) results in naive and vaccinated dogs experiencing leptospirosis outcomes. Only MAT-positive animals were included in the study. MethodsOver five years, 3 512 dogs were suspected of having leptospirosis. For each case, biochemical parameter results were recorded. Leptospirosis involvement was investigated by MAT performed against 6 major serogroups (Icterohaemorrhagiae, Canicola, Australis, Autumnalis, Grippotyphosa and Sejroë). MAT-positive results confirmed leptospirosis cases in 147 naïve dogs and in 580 fully vaccinated dogs. Serological titres of agglutinating antibodies were related to the severity of liver and kidney failure. ResultsThe most prevalent outcome of leptospirosis in unvaccinated dogs was liver failure (57.8%) compared to 51.7% for kidney disease, but the most severe onset (90.8%) was found among the cases of acute kidney injury compared to the severe (42.3%) hepatitis cases. In dogs vaccinated by bivalent Icterohaemorrhagiae and Canicola bacterins, hepatitis decreased from 57.8 to 46.5% and acute kidney injury from 51.7 to 21.6%. The decrease was shown in leptospirosis cases induced by field strains belonging to the six most prevalent serogroups, including the 4 serogroups heterologous to the vaccine. ConclusionCommon vaccination was efficient in decreasing hepatitis and kidney failure induced by field Leptospira spp infection regardless of the MAT-prominent serogroup and limited the disease severity in the remaining cases.

Dealing with leptospirosis in dogs

Leptospirosis is an important bacterial infection which can cause disease in dogs and is zoonotic. Bivalent vaccination (serogroups Canicola and Icterohaemorrhagiae) had been effective at controlling disease, but leptospirosis appears...

Re-evaluating the LD50 requirements in the codified potency testing of veterinary vaccines containing Leptospira (L.) serogroup Icterohaemorrhagiae and L. serogroup Canicola in the United States

Approximately one-third of the reportable USDA Category D and E laboratory animals in the United States are expended on the potency testing of leptospiral vaccines by the codified hamster vaccination-challenge assay. Valid tests require ≥80% of challenge controls to succumb to disease and an LD50 between 10 and 10,000. This work evaluates the risk associated with the removal of LD50 limits; thereby, eliminating back-titration hamsters from in vivo potency assays for Leptospira (L.) serogroups Canicola and Icterohaemorrhagiae. The impact was assessed through 1) retrospective analysis of industry and CVB serial release data from July 2011–April 2015 and 2) evaluation through vaccination-challenge assays. For the initial vaccination-challenge assays (n = 3/serogroup), one group received potent bacterin (PB) and six groups received subpotent bacterins (SB1-SB6). PB and SB1 were challenged with a single dilution of Leptospira between 10 and 10,000 LD50. SB2-SB6 received serial dilutions of more concentrated challenge. Based on the retrospective analysis and in vivo assays, 80% of the challenge controls succumbing to disease reasonably ensured the minimal LD50 was administered. Subpotent vaccines were not at increased risk for being deemed potent when challenged with >10,000 LD50, but potent vaccines were at risk of being deemed subpotent when challenged with >10,000 LD50.

Characterization of the clonal subpopulation Fiocruz L1-130 of Leptospira interrogans in rats and dogs from Brazil.

Leptospira interrogans serogroup Icterohaemorrhagiae strains have been described as causing disease in both humans and animals and as being present worldwide. Icterohaemorrhagiae and Copenhageni serovars are known to cause severe disease in their hosts, and zoonotic outbreaks have been described. The genetic similarity among the strains of these serovars is known. However, it has not yet been demonstrated whether major clonal subpopulation in humans, strain Fiocruz L1-130-like, can circulate among other hosts. We performed genetic characterization of Brazilian serogroup Icterohaemorrhagiae strains of dog and rat origin by secY sequencing, variable-number tandem-repeat, multilocus sequence type and multi-spacer typing analysis. The strains were found to be identical among themselves and to strain Fiocruz L1-130. We suggest that the major strain of L. interrogans serogroup Icterohaemorrhagiae, Fiocruz L1-130, is widely distributed in Brazil in different hosts with substantial zoonotic potential. Understanding the circulation of strain Fiocruz L1-130 is important for the implementation of appropriate control measures. Its circulation highlights the need to treat leptospirosis caused by L. interrogans serogroup Icterohaemorrhagiae as a zoonosis that acts in the human-animal-environment interface, as per the One Health approach.

Diagnosis of acute canine leptospirosis using multiple laboratory tests and characterization of the isolated strains

BackgroundDogs presenting with acute leptospirosis may present non-specific clinical and laboratory findings, and the definitive diagnosis may require additional confirmatory tests, including bacterial culture, for the direct or indirect identification of the pathogen. The present study describes the diagnosis of leptospirosis in suspected dogs based on the use of multiple diagnostic tests, including serological, molecular and bacteriological tests, along with the characterization of the recovered leptospiral strains.ResultsUrine, serum and blood samples were collected from 33 dogs with suspected clinical leptospirosis treated at the University of São Paulo Veterinary Hospital Service (Hovet FMVZ-USP) between 2013 and 2016. Only dogs with high blood urea nitrogen and creatinine levels in association with multiple clinical manifestations of the disease were included. Leptospiral culture, PCR and serology (Microscopic agglutination test - MAT) were performed in blood and urine samples taken from all suspected dogs at clinical presentation, and an additional prospective MAT titration was performed in seven dogs. Infection could be identified exclusively by PCR in 10 dogs (30.3%), exclusively by MAT in four dogs (12.1%) and by both tests in four dogs, totaling 18 dogs (54.5–95%CI: 37.6–71.5). Six out of eight MAT-confirmed cases presented with the highest titers against the Icterohaemorrhagiae serogroup. Leptospires were recovered from urine samples from two PCR-positive dogs, and both strains could be characterized by Multilocus Sequence Analysis and serogrouping as L. interrogans serogroup Icterohaemorrhagiae. Both isolates were shown to be pathogenic in the hamster model.ConclusionsThe simultaneous use of MAT and PCR was able to increase the diagnosis of leptospirosis in clinically suspected cases. Despite the increasing incidence of new serovars affecting dogs being reported in different locations, our results suggest that leptospiral strains belonging to the Icterohaemorrhagiae serogroup are still a major causative agent of canine leptospirosis in São Paulo, Brazil.

Serological and molecular detection of Leptospira spp in dogs.

This study aimed to detect anti-Leptospira spp antibodies and Leptospira DNA in domestic dogs. Blood and urine from 106 dogs were evaluated by microscopic agglutination test (MAT) and polymerase chain reaction (PCR), respectively. Six (5.7%) and one (1%) animals were positive by MAT and PCR, respectively. These results show a low prevalence of infection by Leptospira spp. The absence of positive results for the Icterohaemorrhagiae serogroup indicates the small relevance of these dogs as sources of human leptospirosis.

Pet rodents as possible risk for leptospirosis, Belgium and France, 2009 to 2016.

Leptospirosis is an under-reported and emerging zoonotic disease which is potentially fatal in humans. Rodents are the main reservoirs for pathogenic Leptospira spp., but diagnosis in these animals is difficult, and their infection, which does not induce symptoms, usually goes unoticed. Although the exposures of most human cases of leptospirosis are poorly documented, we were able to identify six human cases of leptospirosis which were associated with direct contact with pet rodents (mice or rats) in Belgium and France between 2009 and 2016. All cases had severe disease and for all, the presence of Leptospira spp. DNA in the kidneys of their pet animals was confirmed, strongly suggesting that excretion of leptospires in urine was the way of transmission. Half of the cases shared the serogroup Icterohaemorrhagiae, which is usually associated with severe disease, with the pet rats which they were in contact with. With the popularity of rats and mice as pets, this study should contribute to raising awareness on asymptomatic pet rodents as a source of Leptospira infections.

A systematic review of leptospirosis on wild animals in Latin America.

Leptospirosis is a bacterial systemic infection which affects domestic animals and wildlife, as well as humans. Many wild animals act as reservoirs of leptospires. Nevertheless, the real role of wildlife animals as source of infection to livestock and humans, as well as the most important reservoirs and leptospiral strains remains unclear. This systematic review assesses the available data about wildlife and their biomes in Latin America, concerning to leptospiral infection. In addition, we discuss the development of the research on leptospirosis in wildlife in this region. After the application of exclusion criteria, 79 papers were analyzed, comprising 186 species, 122 genus, 53 families, and 19 orders from four classes. Mammals were the most studied class, followed by Amphibian, Reptile, and Aves. The Icterohaemorrhagiae serogroup was predominant in most biomes and many orders. A small number of antigens detected the majority of seroreactive animals of each class, and a smaller panel may be used at microscopic agglutination test. Further studies must always consider edaphoclimatic conditions besides only host class or species, in order to obtain a broader understanding of the wild epidemiological cycle of leptospirosis in the region. In conclusion, direct and indirect evidences demonstrate that leptospirosis is largely widespread among wildlife in all biomes of Latin America. Moreover, more research on the role of wildlife on the epidemiology of leptospirosis and its impact on livestock and public health are required, particularly focusing on direct detection of the agent.

High number of asymptomatic dogs as leptospiral carriers in an endemic area indicates a serious public health concern.

Asymptomatic dogs can be potential hosts of leptospirosis. However, the extension of this phenomenon in endemic areas has not yet been clearly defined. This study is aimed at evaluating the role of asymptomatic dogs as carriers of Leptospira in an endemic area of Brazil. A total of 131 male dogs without apparent leptospirosis symptoms were included in the study based on clinical and hematologic exams. Serum and urine samples were collected for microscopic agglutination tests (MAT) and polymerase chain reactions (PCR) targeted the LipL32 gene, respectively. Forty-two dogs (32·1%) presented seroreactivity (titres ⩾100). The serogroup Icterohaemorrhagiae was predominant, representing 92·7% of the seropositive samples. Overall, leptospiral DNA was detected on 26 urine samples (19·8%). PCR positivity was more common (28·6%) on seropositive dogs than on seronegative (15·7%) ones. Nevertheless, MAT was not correlated to PCR (P > 0·05). Age was not associated with seroreactivity, but dogs older than 5 years of age had 4·07 more chances (odds ratio) of being carriers (PCR positive) than younger ones. Although the fact of knowing that asymptomatic dogs can act as leptospiral carriers is not new, the extension of this fact is impressive in an endemic region, and its role and impact on public health cannot be neglected.

The role of capybaras as carriers of leptospires in periurban and rural areas in the western Amazon

Although leptospirosis has been described in capybaras, usually based on serological evidences, bacterial culture of leptospires has been scarcely reported in this species. The western Amazon is a reportedly endemic area where high seroprevalences have been reported in different species of wildlife, domestic animals and in human beings. The present study aimed at investigating the role of capybaras as carriers of leptospires in periurban and rural areas in the western Amazon region. A total of 44 animals were captured, and 41 blood samples (for serology) and 41 urine samples (for PCR and bacterial culture) were obtained. A total of 18/41 (43.9%) of sera were reactive and titers were generally low, indicating chronic infection. PCR was positive in 13/41 (31.7%) samples, isolates were recovered from urine samples belonging to Icterohaemorrhagiae, Grippotyphosa and Shermani serogroups. A high number of carriers (confirmed by PCR) associated to a tendency for harboring Icterohaemorrhagiae serogroup strains could be noticed. Our results suggest that capybaras are massively infected by leptospires. Analogously to Norway rats, capybaras present chronic infection with low titers and long-term bacterial shedding, and may be acting as reservoirs of this bacterium.