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Background Bacterin-based canine Leptospira vaccines could present a challenge for the use of whole blood real-time polymerase chain reaction ( PCR) as a diagnostic tool. Recent vaccination could induce positive results if the targeted DNA fragment is present within the vaccine and in the blood of the recently vaccinated dog. Objectives The objective of this study was to assess whether 2 available 4-serovar vaccines induce a positive real-time PCR reaction in the blood of healthy recently vaccinated dogs. Animals Twenty healthy dogs. Methods This was a prospective study. Dogs were assigned to 1 of 2 vaccine groups. Both vaccines were culture-based and include Leptospira interrogans serovars Pomona, Canicola, and Icterohaemorrhagiae and Leptospira kirschneri serovar Grippotyphosa. Whole blood for real-time PCR and serum for the microscopic agglutination test ( MAT) were collected prior to and 3 and 7 days after vaccination and weekly thereafter for 8 weeks. Two real-time PCR tests targeting 2 different genes were performed independently in a blinded fashion. Results Both Leptospira vaccines produced positive real-time PCR reactions when assayed undiluted or diluted 1 : 100 in canine blood. However, blood samples drawn from all dogs at all time points after vaccination were negative on PCR. All dogs developed MAT titers. Conclusions and Clinical Importance Recent vaccination with 2 commercially available vaccines does not interfere with the use of real-time PCR for the identification of acute Leptospira infection in dogs. [ABSTRACT FROM AUTHOR]

Leptospirosis is a widely distributed zoonosis that affects several species of domestic and wild animals. Under captive conditions, Leptospirosis is a potential problem because the physical conditions in most zoos and research centers cannot prevent the captive animals from being exposed to rodents, raccoons, opossums, and other local wildlife that are known carriers. Yet, despite the potential risk, animals that are destined for reintroduction into the wild are not routinely tested for anti- Leptospira antibodies before their release. The purpose of this study was to determine the occurrence of anti- Leptospira antibodies in captive New World monkeys that were housed in the Wild Animals Screening Center in Salvador, Brazil. Blood samples were collected from 44 monkeys (28 Callithrix jacchus, eight Callithrix pennicilata, and eight Cebus sp.). The animals were screened for antibodies with the microscopic agglutination test. Twenty-five (56.8%) primates were seroreactive, with Icterohaemorrhagiae being the most frequent serogroup. None of the monkeys, however, presented clinical signs of leptospirosis. Thus, seroreactivity with low titers in asymptomatic animals, as observed in this study, suggests exposure to the agent. The unexpected predominance of the serogroup Icterohaemorrhagiae further suggests that exposure to this serogroup occurred in captivity. Therefore, the dangerous possibility cannot be ignored that reintroduced monkeys will carry the leptospiral serovars into wild populations. In conclusion, primates exposed to urban serovars before their release from captivity represent a potentially significant health risk to wild populations. Am. J. Primatol. 74:8-11, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The article discusses a study of the growth response and shedding of Leptospira spp. in urine following vaccination against leptospirosis in young farmed red deer under pastoral conditions in New Zealand. The researchers enrolled 230 female and 205 male, three-month-old deer from five farms and treated them with streptomycin. They found an induced agglutinating antibody (AA) against Leptospira serovar (LS) Hardjo-bovis in 57 vaccinated deer and an induced AA against LS Pomona in 97 deer.

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A total of 75,206 blood serum samples from dairy cattle and quarantined heifers was collected between 2001 and 2007 and analyzed for bovine leptospirosis by the microscopic agglutination test (MAT). Serovar Hardjo was used for testing of all sera, with the addition of 2 or 3 randomly chosen other serovars (Grippotyphosa, Icterohaemorrhagiae, Pomona, Bataviae, Canicola, and/or Saxcoebing). From the total number of sera tested, 1197 (1.59%) were serologically positive, with a decreasing tendency over the years of research. The most prevalent serovar was Pomona (1.32%), followed by Hardjo (0.52%) and Grippotyphosa (0.37%). The differences among the studied regions in terms of the distribution of serovars and seroprevalence values may be attributed to different farm management approaches and climatic conditions. It is believed that the decrease in seroprevalence toward the last years of investigation may be due to the application of permanent control strategies against leptospirosis and antibiotic therapy for all seropositive animals with an antibody titer equal to or higher than 1:100 [ABSTRACT FROM AUTHOR]

Abstract: Leptospirosis is a worldwide zoonotic disease caused by pathogenic Leptospira spp. Rodent species are the major reservoir hosts that can excrete leptospires in their urine leading to environmental contamination. After gaining entry into the host via skin breaks and mucosa, leptospires disseminate through the bloodstream to target organs causing a wide range of disease manifestations in susceptible mammalian hosts. The crucial step of infection requires host–pathogen interactions. LipL32, the major outer membrane protein (OMP) of pathogenic Leptospira, is conserved among pathogenic leptospires, immunogenic, and expressed in target organs during acute infection in animal models. Therefore, it may play a key role in host–microbe interactions. To identify host proteins that interact with LipL32, phage display technology was employed in our study. Recombinant LipL32 was used as a target molecule for biopanning with a random heptapeptide phage library to enrich for phages expressing peptides with high affinity to LipL32. After three rounds of panning, 44 plaques of eluted phages were subjected to pyrosequencing. Six different peptide sequences were identified and used to search for matching proteins in the database. Putative proteins with potential binding to LipL32 are proteins known to be expressed on the surface of target cells of pathogenic Leptospira such as chloride channel accessory 2, glycoprotein VI, scavenger receptor expressed by endothelial cell isoform I (SREC-I), coronin 2A, laminin alpha 5, collagen XX, and prostaglandin receptor EP1. However, interactions of LipL32 with these host proteins and their role in the pathogenesis of leptospirosis requires experimental confirmation. [Copyright &y& Elsevier]

Abstract: Leptospirosis is the most widespread zoonosis worldwide and is caused by serovars of pathogenic Leptospira species. The understanding of leptospiral pathogenesis lags far behind that of many other bacterial pathogens. Current research is thus directed at identification of leptospiral virulence factors. Saprophytic Leptospira species are environmental organisms that never cause disease. Comparative genomics of pathogens and saprophytes has allowed the identification of more than 900 genes unique to either Leptospira interrogans or Leptospira borgpetersenii; these genes potentially encode virulence-associated proteins. However, genes of unknown function are over-represented in this subset of pathogen-specific genes, accounting for 80% and 60% of open reading frames, respectively. This finding, together with the absence of virulence factor homologues among the proteins of known function, suggests that Leptospira possesses unique virulence mechanisms. Whole genome microarray studies have identified genes whose expression is differentially regulated under a range of simulated in vivo conditions, such as physiological temperature and osmolarity, low iron levels, and the presence of serum. The subset of genes identified by these studies is likely to include virulence factors. However, most such genes encode proteins of unknown function, consistent with the hypothesis that leptospiral virulence genes do not have homologues in other bacterial species. The recent development of mutagenesis systems for pathogenic Leptospira spp. has allowed the screening of defined mutants for attenuation of virulence in animal infection models and has identified definitively for the first time a range of virulence factors, including lipopolysaccharide, flagella, heme oxygenase, and the OmpA-family protein, Loa22. Interestingly, inactivation of a number of genes hypothesised to encode virulence factors based on in vitro virulence-associated properties did not result in attenuation of virulence, suggesting a degree of functional redundancy in leptospiral pathogenic mechanisms. [Copyright &y& Elsevier]

The article describes the case of leptospirosis in a dog with uveitis and presumed cholecystitis. It includes ultrasonographic and clinicopathological findings and outcome. It advises clinicians to consider leptospirosis in cases of uveitis, as well as possible cholecystitis, so that needed testing, therapy, and precautions can be used.

La leptospirosis bovina causa grandes pérdidas económicas a la ganadería por problemas reproductivos y también es un riesgo de salud pública. En México, desde el siglo pasado se ha registrado la presencia de anticuerpos contra serovariedades de Leptospira por la técnica de aglutinación microscópica (AM), en bovinos y otras especies animales. En muy pocos casos, la enfermedad fue demostrada por el aislamiento de Leptospira, y en tales casos, su caracterización se basó en métodos inmunológicos lentos que requirieron la comparación con cepas de referencia y que fueron realizados fuera de México. En el presente trabajo se realizó la caracterización molecular mediante la secuenciación de locus múltiples (MLST), de aislados de Leptospira obtenidos de riñones de bovinos recolectados en rastro, procedentes de las zonas Golfo y sur de México. Se obtuvieron muestras de suero y riñones de 197 bovinos para realizar la AM, y el cultivo en medios específicos EMJH y Fletcher. Se detectó una seropositividad del 60.4% (119 de 197), con títulos desde 1:100 hasta 1:3,200 y se obtuvieron cuatro aislados de Leptospira (2.03%), denominados CAL4, CAL6, CAL7 y MOCA45. Los aislados fueron caracterizados por serología, ribotipificación y MLST, como L. kirschneri serovariedad Grippotyphosa; L. interrogans serovariedad Hardjo; L. santarosai serovariedad Mini y L. santarosai serovariedad Tarassovi, respectivamente. A excepción de la serovariedad Hardjo, los aislados pertenecen a especies y serovariedades no aisladas anteriormente en la República Mexicana, esto sugiere la necesidad de evaluar su diseminación entre bovinos y su potencial efecto en la producción animal y en la salud pública. [ABSTRACT FROM AUTHOR]

Bovine leptospirosis causes high economic losses in cattle mainly due to reproductive failure, as well as representing public health risk. Since the last century, antibody titers against several Leptospira serovars have been detected by the microscopic agglutination test (MAT) in Mexico. With the exception of very few cases, the presence of serovars causing leptospirosis in cattle and other animal species has not been demonstrated by isolation in Mexico, and in such cases characterization had to be done abroad by complex and slow immunological approaches, by comparison with a number of reference strains. The present study was conducted to perform the molecular characterization of Leptospira isolates by multiple locus sequencing typing (MLST). A hundred and ninety seven sera and kidneys samples were collected immediately after slaughter, from grazing cattle coming from the south-eastern states of Mexico. Anti-Leptospira antibodies were detected by the MAT and kidneys were inoculated into EMJH and Fletchers specific medium. A seropositivity of 60.4% (119 out of 197), with titers from 1:100 up to 1:3 200 was detected. Four isolates (2.03%), referred as CAL4, CAL6, CAL7 and MOCA45, were characterized by serology, ribotyping and MLST as L. kirschneri serovar Grippotyphosa; L. interrogans serovar Hardjo; L. santarosai serovar Mini and L. santarosai serovar Tarassovi, respectively. With the exception of serovar Hardjo, the three other isolates belong to serovars and species not previously isolated in Mexico. These findings make it necessary to evaluate the potential distribution of such serovars among cattle and their role on animal production and public health. [ABSTRACT FROM AUTHOR]

Abstract: Associations of land cover/land use variables and the presence of dogs in urban vs. rural address locations were evaluated retrospectively as potential risk factors for canine leptospirosis in Kansas and Nebraska using Geographic Information Systems (GIS). The sample included 94 dogs positive for leptospirosis predominantly based on a positive polymerase chain reaction test for leptospires in urine, isolation of leptospires on urine culture, a single reciprocal serum titer of 12,800 or greater, or a four-fold rise in reciprocal serum titers over a 2–4 weeks period; and 185 dogs negative for leptospirosis based on a negative polymerase chain reaction test and reciprocal serum titers less than 400. Land cover features from 2001 National Land Cover Dataset and 2001 Kansas Gap Analysis Program datasets around geocoded addresses of case/control locations were extracted using 2500m buffers, and the presence of dogs’ address locations within urban vs. rural areas were estimated in GIS. Multivariate logistic models were used to determine the risk of different land cover variables and address locations to dogs. Medium intensity urban areas (OR=1.805, 95% C.I.=1.396, 2.334), urban areas in general (OR=2.021, 95% C.I.=1.360, 3.003), and having urban address locations (OR=3.732, 95% C.I.=1.935, 7.196 entire study region), were significant risk factors for canine leptospirosis. Dogs regardless of age, sex and breed that live in urban areas are at higher risk of leptospirosis and vaccination should be considered. [Copyright &y& Elsevier]

In 2007, a survey was conducted on the prevalence of antibodies to 19 Leptospira serovars in goats in Poland . Sera were collected from adult females of all 49 breeding goat herds in Poland by applying simple random sampling. In total, 736 sera were tested by the microscopic agglutination test. A herd was considered seropositive if at least one goat with a titre of 100 or more was detected. Herd-level seroprevalence of Leptospira was 89.8 per cent and individual-level seroprevalence varied from less than 1.0 to 85.0 per cent among the herds. Antibodies to Leptospira serovars Zanoni, Bratislava, Autumnalis, Australis and Javanica were most frequently detected. Although 40.3 per cent of seropositive goats had high antibody titres (≥400), suggesting recent infection, no relationship with abortions or other clinical manifestation of leptospirosis in goats was detected. [ABSTRACT FROM AUTHOR]

The article compiles the previous reviews and research carried out by the Veterinary Science research group (CIENVET) and international scientific publications. The objective of the research was to describe epidemiologic characteristics of leptospirosis emergence in wildlife and to elucidate their role in disease transmission. An analysis of available information in: Science Direct, SciELO, ProQuest, and PubMed databases, selecting the most relevant articles on leptospirosis according to their relevance and timeliness, to strengthen the critical review disease in wild animals was carried out. Wild animals in the wild or in captivity are crucial components in the epidemiologic cycle of zoonotic diseases, including leptospirosis,acting as reservoirs, maintenance hosts, carriers or accidental hosts, according to factors related to the agent, taxonomic species and the environment, thus participating in the transmission of different serotypes. Since emerging infectious diseases pose a serious threat to wild species, investigations of these diseases in such populations can benefit conservation efforts and provide a connection between serological studies and the well-recognized detection, timely identification and surveillance needs of these diseases. [ABSTRACT FROM AUTHOR]

The study was conducted under CNMP Project No. 61/034/2007, entitled "Innovative Research on prevention and control of zoonoses, bacterial agents of pasteurellosis and leptospirosis in pets and humans in order to achieve effective treatment schemes, in 2009- 2010, at the University of Agricultural Science and Veterinary Medicine, Institute of Comparative Medicine and INCDMI "Cantacuzino", Bucharest, Romania. Samples were collected from patients suspected of the studied zoonoses. The general clinical examination sheet was performed for patients seeking general condition and examining: face, skin, mucous membranes and appendages, lymph node system, muscular system, osteoarticular system, respiratory apparatus, cardiovascular apparatus, digestive system, liver, biliary, spleen, urogenital apparatus, nervous, endocrine system, sense organs. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Investigaciones Veterinarias del Peru is the property of Universidad Nacional Mayor de San Marcos (UNMSM) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article reports on studies conducted in beef herds from western Canada to find out the cause of poor pregnancy rates. It states the first study conducted, describes the frequency of vaccination for leptospirosis in cow-calf herds and the prevalence of positive leptospirosal antibody titers in unvaccinated beef calves. The second study measured leptospirosal antibody titers during the start and ending of the grazing season with the help of serum samples of the herds.

The microscopic agglutination test (MAT) is commonly used for the diagnosis of canine leptospirosis. In dogs it is sometimes suggested that the serogroup with the highest MAT titer is the infecting serogroup; however, this is not true in humans with confirmed leptospirosis. We sought to investigate the value of MAT results in predicting the infecting serogroup by comparing results across several laboratories and within individual dogs over time. To examine the variability in MAT results across different laboratories in dogs recently vaccinated against leptospirosis, and in dogs with clinical leptospirosis, and to investigate variability over time in MAT results in individual dogs with leptospirosis. Eighteen dogs from a research colony, 9 of which had been vaccinated against leptospirosis, and 17 dogs clinically diagnosed with leptospirosis. Serum samples were submitted to up to 5 veterinary diagnostic laboratories for MAT titers from each dog on at least 1 occasion. MAT results also were followed over time in 6 dogs diagnosed with leptospirosis. MAT results were discordant across different laboratories in dogs recently vaccinated against leptospirosis and in dogs with clinical leptospirosis. MAT results varied over time in individual dogs with the disease. The MAT is a valuable test for the diagnosis of leptospirosis in dogs, but it is unlikely that test results can be used to predict the infecting serogroup. Laboratories offering the MAT should consider participation in a proficiency scheme. [ABSTRACT FROM AUTHOR]

Background: Leptospirosis is a zoonotic disease with world-wide distribution, caused by various serovars of Leptospira interrogans and is presumed to be the most widespread zoonosis. Hematological and biochemical changes associated with renal and hepatic pathology are commonly observed in leptospirosis. All leptospires are aerobes and therefore might be expected to generate peroxides during respiration. Enzymatic reduction of H202 by leptospires has been reported by researchers. The pathogenesis may be related to direct effects of leptospiral compounds or inflammatory response due to oxidative stress. The present investigation was designed to study the lipid peroxidation and the activity of antioxidant enzymes in rats experimentally infected with L. interrogans. Materials, Methods & Results: Fifty four male adult rats (Wistar) specific pathogen free, weighing in average 200 grams were used. Rats were divided in nine groups, six animals each group, eight infected groups and one as not infected. Inoculation was performed intraperitoneally (Day 1), using different serovars of L. interrogans distributed by groups: hardjo (group A), wolffi (group B), grippotyphosa (group C), canicola (group D), Icterohaemorrhagiae (group E), bratislava (group F), pomona (group G) and butembo (group H). Group I was composed by not-infected rats, serving as the negative control group. On day 15 PI all animals were anesthetized with isoflurane for blood collection and subsequently decapitated. Liver, spleen, kidney and brain were collected from all animals. Blood was allocated in tube without anticoagulant for serum acquisition to measurement of thiobarbituric acid reactive substances (TBARS). Lipid peroxidation (TBARS levels), superoxide dismutase (SOD), catalase (CAT) and non-protein thiols (NPSH) were measured in the liver, spleen and kidney, and TBARS were also evaluated in serum and brain. Increased lipid peroxidation was observed in all infected groups when compared to not-infected (P<0.05); Increase of TBARS levels were verified in serum of groups F and G; brain of groups E and G; liver and spleen of groups A, B and C; and in the kidneys of all infected groups compared to Group I. SOD activity was increased (P<0.05) in liver samples of groups A and C; and in the kidney samples of groups A to G. Spleen samples did not show statistical differences to SOD activity. We observed increase in CAT activity (P<0.05) in liver samples of groups A, B and G, in spleen samples of groups B and E, and kidney samples of groups A, B, E, F, G and H. NPSH levels increased (P<0.05) in spleen of groups B, D, E and G, and kidney samples of groups A, B, C, D and E. Liver samples had no statistical differences between groups in NPSH levels. Discussion: Based on our results is possible to conclude that the infection by Leptospira interrogans in Wistar rats shows differences between serovars utilized experimentally. The results may suggest that oxidative damage to tissues along with other mechanisms might have taken part in the pathogenesis of leptospirosis and further detailed studies at cellular level are needed to fully understand the pathogenesis and clinical expression of the disease. Kidneys were confirmed as the major host organ to leptospires, resulting in a great stress oxidative response and presenting a high activity of scavenger enzymes, as well as potential generation of oxidative stress to other organs and even to the brain. [ABSTRACT FROM AUTHOR]

Abstract: Leptospirosis is caused by Leptospira, gram negative spirochaetes whose microbiologic identification is difficult due to their low rate of growth and metabolic activity. In Colombia leptospirosis diagnosis is achieved by serological techniques without unified criteria for what positive titers are. In this study we compared polymerase chain reaction (PCR) with microbiological culture and dark field microscopy for the diagnosis of leptospirosis. Microbiological and molecular techniques were performed on 83 samples of urine taken from bovines in the savannahs surrounding Bogotá in Colombia, with presumptive diagnosis of leptospirosis. 117 samples of urine taken from healthy bovines were used as negative controls. 83 samples were MAT positive with titers≥1:50; 81 with titers≥1:100; and 66 with titers≥1:200. 36% of the total samples (73/200) were Leptospira positives by microbiological culture, 32% (63/200) by dark field microscopy and 37% (74/200) by PCR. Amplicons obtained by PCR were 482 base pair long which are Leptospira specific. An amplicon of 262 base pairs typical of pathogenic Leptospira was observed in 71 out of the 74 PCR positive samples. The remaining 3 samples showed a 240 base pair amplicon which is typical of saprophytic Leptospira. PCR as a Leptospira diagnosis technique was 100% sensitive and 99% specific in comparison to microbiological culture. Kappa value of 0.99 indicated an excellent concordance between these techniques. Sensitivity and specificity reported for MAT when compared to microbiological culture was 0.95 and 0.89 with a≥1:50 cut off. PCR was a reliable method for the rapid and precise diagnosis of leptospirosis when compared to traditional techniques in our study. The research presented here will be helpful to improve diagnosis and control of leptospirosis in Colombia and other endemic countries. [Copyright &y& Elsevier]

Abstract: An IgG-ELISA used recombinant antigen and a rapid flow-through enzyme immunoassay were developed for rapid screening of leptospiral antibodies in dogs using recombinant LipL41, which is one of the conserved outer membrane proteins in pathogenic leptospires as the coating antigen. Results from this study were compared with the standard microscopic agglutination test and found that the sensitivity and specificity of the enzyme-linked immunosorbent assay were 75.46% and 93.29% and whereas that of flow-through-based dot-immunobinding assay were 87.73% and 89.63%, respectively. Relative merits of these tests were also assessed. The flow-through-based dot-immunobinding assay was thus proved to be a valid screening test for canine leptospirosis. [Copyright &y& Elsevier]

This report offers a consensus opinion on the diagnosis, epidemiology, treatment, and prevention of leptospirosis in dogs, an important zoonosis. Clinical signs of leptospirosis in dogs relate to development of renal disease, hepatic disease, uveitis, and pulmonary hemorrhage. Disease may follow periods of high rainfall, and can occur in dogs roaming in proximity to water sources, farm animals, or wildlife, or dogs residing in suburban environments. Diagnosis is based on acute and convalescent phase antibody titers by the microscopic agglutination test (MAT), with or without use of polymerase chain reaction assays. There is considerable interlaboratory variation in MAT results, and the MAT does not accurately predict the infecting serogroup. The recommended treatment for optimal clearance of the organism from renal tubules is doxycycline, 5 mg/kg PO q12h, for 14 days. Annual vaccination can prevent leptospirosis caused by serovars included in the vaccine and is recommended for dogs at risk of infection. [ABSTRACT FROM AUTHOR]

Leptospirosis in dogs is a multiorgan disease affecting mostly kidneys and liver. The objective was to characterize prevalence, clinical, and radiological features and outcome of dogs with leptospirosis and pulmonary abnormalities. Fifty dogs with leptospirosis. Medical records of dogs diagnosed with leptospirosis at the Small Animal Clinic, Berlin, were reviewed. Diagnosis was based on microscopic agglutination test, blood or urine polymerase chain reaction, and histopathology. Based on clinical and/or radiological signs, patients were grouped into dogs with lung abnormalities (group 1) or without (group 2). Severity of respiratory distress was scored as mild to moderate (grade 1) or severe (grade 2). Thoracic radiographs were scored based on pulmonary changes and location as grade 1 (caudal interstitial pattern), 2 (generalized mild to moderate reticulonodular interstitial pattern), or 3 (generalized severe reticulonodular interstitial pattern with patchy alveolar consolidations). Results of CBC and biochemistry were compared between groups. Thirty-five dogs had radiological pulmonary changes (grade 1: 5; grade 2: 14; grade 3: 16); 31 of them had pulmonary distress (grade 1: 13, grade 2: 18). Sixty-seven percent of the dogs with dyspnea grade 2 were mainly euthanized because of respiratory distress. Fifteen percent of the dogs with dyspnea grade 1 and 21% without clinical respiratory signs were euthanized because of acute renal failure or sepsis. In 70% of dogs with leptospirosis pulmonary changes were detected. Lung involvement represented a severe complication causing increased case fatality depending on the severity of respiratory distress. [ABSTRACT FROM AUTHOR]

Background: Leptospirosis has long been a major public health concern in the southwestern Indian Ocean. However, in Madagascar, only a few, old studies have provided indirect serological evidence of the disease in humans or animals. Methodology/Principal Findings: We conducted a large animal study focusing on small-mammal populations. Five field trapping surveys were carried out at five sites, from April 2008 to August 2009. Captures consisted of Rattus norvegicus (35.8%), R. rattus (35.1%), Mus musculus (20.5%) and Suncus murinus (8.6%). We used microbiological culture, serodiagnosis tests (MAT) and real-time PCR to assess Leptospira infection. Leptospira carriage was detected by PCR in 91 (33.9%) of the 268 small mammals, by MAT in 17 of the 151 (11.3%) animals for which serum samples were available and by culture in 9 of the 268 animals (3.3%). Rates of infection based on positive PCR results were significantly higher in Moramanga (54%), Toliara (48%) and Mahajanga (47.4%) than in Antsiranana (8.5%) and Toamasina (14%) (p = 0.001). The prevalence of Leptospira carriage was significantly higher in R. norvegicus (48.9%), S. murinus (43.5%) and R. rattus (30.8%) than in M. musculus (9.1%) (p<0.001). The MAT detected antibodies against the serogroups Canicola and Icterohaemorrhagiae. Isolates were characterized by serology, secY sequence-based phylogeny, partial sequencing of rrs, multi-locus VNTR analysis and pulsed field gel electrophoresis. The 10 isolates obtained from nine rats were all identified as species L. interrogans serogroup Canicola serovar Kuwait and all had identical partial rrs and secY sequences. Conclusions/Significance: We present here the first direct evidence of widespread leptospiral carriage in small mammals in Madagascar. Our results strongly suggest a high level of environmental contamination, consistent with probable transmission of the infection to humans. This first isolation of pathogenic Leptospira strains in this country may significantly improve the detection of specific antibodies in human cases. [ABSTRACT FROM AUTHOR]

Leptospirosis is a global zoonotic disease. Pathogenic Leptospira species, the causative agent of leptospirosis, colonize the renal tubules of chronically infected maintenance hosts such as dogs, rats and cattle. Maintenance hosts typically remain clinically asymptomatic and shed leptospires into the environment via urine. In contrast, accidental hosts such as humans can suffer severe acute forms of the disease. Infection results from direct contact with infected urine or indirectly, through contaminated water sources. In this study, a quantitative real-time PCR specific for lipL32 was designed to detect the urinary shedding of leptospires from dogs. The sensitivity and specificity of the assay was evaluated using both a panel of pathogenic Leptospira species and clinical microbial isolates, and samples of urine collected from experimentally infected rats and non-infected controls. The lower limit of detection was approximately 3 genome equivalents per reaction. The assay was applied to canine urine samples collected from local dog sanctuaries and the University Veterinary Hospital (UVH) at University College Dublin. Of 525 canine urine samples assayed, 37 were positive, indicating a prevalence of urinary shedding of leptospires of 7.05%. These results highlight the need to provide effective canine vaccination strategies and raise public health awareness. [ABSTRACT FROM AUTHOR]

Abstract: Leptospirosis is a worldwide zoonosis caused by pathogenic Leptospira. Although several components of this organism have been identified, the molecular mechanisms underlying pathogenesis of this infectious disease are still poorly understood. Besides, direct injury by microbial factors, cytokines produced in response to infection have been proposed to be involved in pathogenesis of leptospirosis. In this study, cytokine gene expression in kidneys was investigated. Hamsters were injected with pathogenic Leptospira interrogans serovar Pyrogenes and were sacrificed on days 3, 5 and 7 after infection. RNA was extracted from kidney tissues. Real-time PCR was performed to demonstrate expression of TNF-α, TGF-β, IP-10 and IL-10 mRNA in kidneys. TNF-α, TGF-β and IP-10 expression could be demonstrated since day 3 post-infection whereas IL-10 expression was detected later on day 5. Leptospira infection resulted in not only expression of a proinflammatory cytokine, TNF-α, but also a T cell chemokine, IP-10. Detection of IP-10 suggested the involvement of T cell recruitment in the immune response or pathology in infected kidneys. Expressions of anti-inflammatory cytokines, TGF-β and IL-10 were also observed. However, the level of TGF-β expression was prominent since day 3 post-infection whereas IL-10 expression was clearly observed on day 5. Further experiments will provide additional information whether there is a correlation between the expression of these cytokines and pathologies found in an affected organ. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge of the intraherd correlation coefficient (ICC) and design (D) effect for infectious diseases could be of interest in sample size calculation and to provide the correct standard errors of prevalence estimates in cluster or two-stage samplings surveys. Information on 813 animals from 48 non-vaccinated cow–calf herds from North-eastern Mexico was used. The ICC for the bovine viral diarrhoea (BVD), infectious bovine rhinotracheitis (IBR), leptospirosis and neosporosis diseases were calculated using a Bayesian approach adjusting for the sensitivity and specificity of the diagnostic tests. The ICC and D values for BVD, IBR, leptospirosis and neosporosis were 0.31 and 5.91, 0.18 and 3.88, 0.22 and 4.53, and 0.11 and 2.68, respectively. The ICC and D values were different from 0 and D greater than 1, therefore large sample sizes are required to obtain the same precision in prevalence estimates than for a random simple sampling design. The report of ICC and D values is of great help in planning and designing two-stage sampling studies. [ABSTRACT FROM AUTHOR]

Leptospirosis, a disease more common in the tropics, can cause a life-threatening multisystemic syndrome in humans and animals. Immunity, whether natural or vaccine-induced, is serogroup-specific with the infecting serovars varying according to geographical locality. In South Africa, in spite of the fact that the bacterin vaccine for some Leptospirn serovars is often used, there is no recent information on the incidence of canine leptospirosis as well as the infecting serovar/s. The aim of this study, which was undertaken on sera collected in 2008 and 2009 from both strays and owned dogs predominantly in the coastal regions of South Africa, was to determine the presence of leptospiral antibodies to 15 serovars known to infect dogs. Of the 530 samples tested, 25 tested positive to 7 different serovars with the microscopic agglutination test (MAT). Nine of the 25 samples tested posi- tive to more than one serovar. The 2 serovars most frequently represented were Canicola, which reacted to 17 sera, and Pyrogenes, which reacted to 10 sera. Currently the only vaccines available in South Africa in different combinations contain serovars Canicola, Icterohaemorrhagiae, Pomona and Grippotyphosa. The results showed that the use of vaccines containing serovar Canicola is still justifiable in certain regions of the country. However, the presence of antibodies to serovar Pyrogenes in several dogs, pending a broader investigation, indicates that this serovar should also be included in the range of Leptospira vaccines for use in South Africa. [ABSTRACT FROM AUTHOR]

The present work was carried out in Havana municipalities, with the objective of characterizing the situation of the leptospirosis in the Human and animal population. The files were revised in the Municipal and Provincial Addresses of the Institute of Municipal Veterinary Medicine and their diagnostic net, as well as the Services of Public Health of identical level. Were determined the reports of leptospirosis cases in the human and animal population from 1993 to 2006 in eight Havana municipalities. It was calculated the percentage value, the relative frequency and the prevalencia of the illness per reports numbers of cases for the population (human and animal), years, species, areas (rural and urban) and the Leptospira serovar involved. The biggest prevalencia in the illness presented it the animal population. The obtained results reveal their utility as a retrospective study that contributes to the knowledge of the indicators related with the analysis of necessary risks for the planning of reduction actions of only sanitary disasters. [ABSTRACT FROM AUTHOR]

Abstract: Leptospirosis is a re-emerging disease of dogs in the United States (U.S.). This paper reports the findings of a retrospective study conducted to determine if seroreactivity to Leptospira microscopic agglutination test (MAT) among dogs in the U.S. clustered in space and time. The study utilized canine sera submitted to a commercial laboratory for leptospiral MAT from January 2000 through December 2007. There were 31,869 serum samples submitted by veterinarians from 3156 zip code locations across the U.S. Results of MAT were considered positive at titers of ≥1:1600. Spatial and spatial-temporal scan statistics were used to identify statistically significant clusters of seroreactivity to Leptospira (overall and individual serovars) using recorded test request dates and locations of the centroid of the zip code reported for each serum sample. There were 2469 positive MAT results with a titer ≥1:1600 to at least one of seven Leptospira serovars. Two relevant spatial clusters of 26.3 and 246.5km radius were identified (P =0.001). The primary cluster was located in the northeastern part of Illinois including Chicago and surrounding areas (232 [14.4%] of 1612 MAT positive; RR=1.95). The secondary cluster covered the central part of Texas (292 [12.62%] of 2314 MAT positive; RR=1.71). Eight space-time clusters of overall MAT positivity were identified (29–335km radius; P =0.001–0.048 and RR=3.98–24.69) that covered different geographic locations for different time points. Spatial and space-time clusters for individual serovars were also identified for six serovars: eight each of Grippotyphosa and Pomona, seven of Bratislava, five of Autumnalis, and three each of Icterohaemorrhagiae and Canicola. In conclusion Leptospira seropositivity in dogs tended to have distinctive clusters in space and space-time. Most of the space-time clusters of overall Leptospira MAT seropositivity were associated with cluster events for individual serovars. Further investigation is warranted to explain individual serovar clusters detected in this study, as a complex interaction of incidental host, environment and reservoir host may be responsible for the occurrence of these serovar clusters. [Copyright &y& Elsevier]

Objective-To use results of microscopic agglutination tests (MATs) conducted at a commercial veterinary diagnostic laboratory to determine temporal and demographic distributions of positive serologic test results for leptospirosis in dogs and identify correlations among results for various Leptospira serovars. Design-Serosurvey. Study Population-MAT results for 33,119 canine serum samples submitted to a commercial veterinary diagnostic laboratory from 2000 through 2007. Procedures-Electronic records of MAT results for dogs were obtained from a veterinary diagnostic laboratory. Seropositivity for antibodies against Leptospira serovars was determined by use of a cutoff titer of ⩾ 1:1,600 to reduce the possible impact of postvaccinal antibodies on results. Correlations between results for all possible pairs of serovars were calculated by ordinal ranking of positive (⩾ 1:100) antibody titer results. Results-2,680 samples (8.1%; 95% confidence interval ICI], 78% to 8.4%) were seropositive for antibodies against Leptospira serovars.The highest percentage of positive MAT results was for the year 2007 (10.2%; 95% Cl, 9.5% to 10.9%) and for the months of November and December during the study period. Antibodies were most common against serovars Autumnalis, Grippotyphosa, Pomona, and Bratislava. Seroprevalence of leptospirosis was lowest for dogs > 10 years of age but was similar across other age strata. Conclusions and Clinical Relevance-Leptospirosis can affect dogs of small and large breeds and various ages. Although an increase in proportions of positive MAT results was evident in the fall, monthly and annual variations suggested potential exposure in all months. Because of the limitations of MAT results and the limited number of serovars used in the test, bacterial culture should be used to identify infective Leptospira serovars. [ABSTRACT FROM AUTHOR]

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The article presents information on a study which took a seroprevalence survey of leptospirosis on deer farms in New Zealand. A selection process for on-farm collection of 12-20 blood samples from hinds predominantly of 9-3 months of age was made to analyze if the deer herds were seropositive to any serovar. Results showed that 81 percent of the herds were seropositive for Leptospira spp. Hardjobovis and that there was a regional difference in the prevalence herds seropositive to both Pomona and Hardjobovis.

Background: Little information is available about experimental induction of leptospirosis in horses. Objectives: Determine serologic, hematologic responses of horses to Leptospira interrogans serovar Kennewicki infection. Animals: Four adult horses seronegative for leptospirosis. Methods: Experimental and observational study. Horses were challenged with an equine isolate of L. interrogans serovar Kennewicki at 2 different doses and different inoculation sites. After challenge, the horses were monitored for 60 days. Blood, urine, and aqueous humor samples were collected at intervals until euthanasia 60 days after infection. Results: Pyrexia (39.3–40°C) occurred as early as 1 day after challenge with 10 × 108 Leptospira divided equally between topical ocular and intraperitoneal injection in 2 horses. Leptospires were recovered from the blood and urine but not from the aqueous humor of the 2 febrile horses. The sera of all 4 challenged horses developed microscopic agglutination test antibody after challenge and remained relatively constant for 21 days. Titer to cross-reacting strains declined earlier than titer to the challenge strain. Conclusions: Clinical disease in experimentally infected horses can be mild or inapparent in Leptospira infected horses. Repeated serologic testing can allow recognition of the infecting serovar. In febrile horses, Leptospira can be isolated from blood while isolation from the urine can occur after fever has subsided. [ABSTRACT FROM AUTHOR]

Abstract: A recombinant leptospiral lipoprotein, LigB, was evaluated for use in the diagnosis of bovine leptospirosis by enzyme-linked immunosorbent assay (rLigB IgG ELISA). The standard reference test (Microscopic agglutination test, MAT) of 200 serum samples from cattle suspected of leptospirosis showed that 95 (47.5%) samples had positive agglutination titres, which ranged from 100 to 1600. In rLigB IgG ELISA, 49% of the samples were positive. Sensitivity of IgG ELISA for 95 bovine sera, which had MAT titres of greater than or equal to 100, were 100%. ELISA showed a specificity of 97.1% with 105 bovine sera, which were negative at a 1:50 dilution in MAT for Leptospira interrogans serovars. The results of ELISA and MAT correspond very good. When analytical specificity of IgG ELISA was evaluated using bovine serum samples from animals showing the serum antibodies to other pathogens, no cross-reaction was observed. Thus the recombinant LigB IgG ELISA can be used instead of the MAT as an aid to the diagnosis of bovine leptospirosis. [Copyright &y& Elsevier]

Copyright of Pratique Medicale et Chirurgicale de l'Animal de Compagnie is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Leptospira is an important infectious Gram-negative bacterium causing Leptospirosis in mammals. Outer membrane proteins (OMPs) are key molecules in the interface between the cell and its environment. A group of putative leptospiral outer membrane proteins with an OmpA-like domain, comprising Lp0056, Lp0222, Lp3615, Lp3685, Lp4337 and Lbp328, were identified by bioinformatic methods and expressed as GST-tag fusion proteins. All these recombinant proteins were screened for immune-protective potential in hamsters challenged with Leptospira interrogans serovar Pomona. Out of these six proteins, three fusion proteins including Lp4337, Lp3685 and Lp0222 were found to be protective on the basis of survival. The immune response generated against these three recombinant proteins was evaluated on the basis of antibody production, lymphocyte proliferation and cytokine profiles in response to recall antigens whereas protective efficacy was assessed on the basis of survival and histopathological lesions in the vital organs (kidney, liver, and lung). Our results show that all three recombinant proteins generated strong immune responses, enhanced survival and reduced the severity of histopathological lesions. Of the proteins studied, Lp4337 generated the strongest immune response and was able to impart maximum protection (75%), followed by Lp3685 (58%), whereas Lp0222 generated lowest immune response correlating to protection (42%) against lethal infection of leptospira in the immunized animals. In contrast, control animals injected with PBS demonstrated low survival and had significant lesions. All these results clearly indicate that these three OmpA-like proteins may serve as novel vaccine candidates for leptospirosis. [Copyright &y& Elsevier]

The article examines the seroprevalence of Leptospira spp. in healthy racing horses in South Korea. The authors mention that the study uses serum samples from 1,226 racing horses that were examined through a microscopic agglutination test to identify the presence of antibodies against 18 Leptospira serovars. They report that 307 or 25.0% of the tested samples were found to be positive. They also found seasonal variation in seropositivity. They reveal that the results indicate that the Sejroe serovar can be maintained in the racing horse population in the country.

Abstract: Leptospirosis is the most wide spread zoonosis worldwide; it is present in all continents except Antarctica and evidence for the carriage of Leptospira has been found in virtually all mammalian species examined. Humans most commonly become infected through occupational, recreational, or domestic contact with the urine of carrier animals, either directly or via contaminated water or soil. Leptospires are thin, helical bacteria classified into at least 12 pathogenic and 4 saprophytic species, with more than 250 pathogenic serovars. Immunity following infection is generally, but not exclusively, mediated by antibody against leptospiral LPS and restricted to antigenically related serovars. Vaccines currently available consist of killed whole cell bacterins which are used widely in animals, but less so in humans. Current work with recombinant protein antigens shows promise for the development of vaccines based on defined protective antigens. The cellular and molecular basis for virulence remains poorly understood, but comparative genomics of pathogenic and saprophytic species suggests that Leptospira expresses unique virulence determinants. However, the recent development of defined mutagenesis systems for Leptospira heralds the potential for gaining a much improved understanding of pathogenesis in leptospirosis. [Copyright &y& Elsevier]

A number of 103 ownerless dogs, not vaccinated against leptospirosis, accommodated at the testing moment in a community shelter in Bucharest, are tested for leptospirosis by the ultramicroscopic agglutination seroreaction with MAR type live antigen The results revealed that 36,89% of these dogs represent for humans and for domestic and farm animals a potential natural reservoir of infection with microorganisms of the Lesptospira genus. The Canicola serotype was identified in 81,57% of the positive cases and the Icterohaemorrhagiae serotype in 18,43% of the positive cases. [ABSTRACT FROM AUTHOR]

Abstract: In poultry farms of central Argentina rodents cause economic losses by the consumption and contamination of chicken food, and also pose a serious sanitary risk as transmitters of several diseases to human and domestic animals, such as leptospirosis, salmonellosis, trichinosis, hantavirus pulmonary syndrome, hantavirus renal syndrome, and Argentine hemorrhagic fever. Because one of the problems in controlling rodents is recolonization from the surroundings, we wanted to assess the effect of control measures applied at different spatial scales on rodent abundance in farm sheds. The treatments applied were the following: anticoagulant application in farms and their surroundings (F + S), anticoagulant application only within farms (F), and standard management (C). Rodent abundance was assessed previous to treatments (t0), at the moment of bait removal (t1), and after 15 (t2), 30 (t3), and 60 days (t4). Differences in rodent abundance between t0 and t1, t2, t3, and t4 were compared among treatments by means of a Kruskal Wallis test. We only found significant differences among treatments between t0 and t2, where F and F + S treatments showed differences with respect to the C treatment. This result suggests that the effect of control measures was due to the control of the perimeter, and not of farther areas. Also, reproduction of remaining individuals may have contributed to the population recovery in sheds of experimental farms. We conclude that more effective control must include the perimeter of the farm, but the effect of control of more distant areas may depend on the characteristics of the particular farm, its surroundings, and the ecology of the species involved. [Copyright &y& Elsevier]

AbstractLeptospirosis is a zoonosis that affects humans, domestic animals, and wildlife. Carnivores are at the top of the feeding chain, thus being exposed to pathogens through their preys. From June 2004 to April 2007, we analyzed for evidences of contact with 14 serovars of Leptospira interrogansSensu Lato serum (analyzed by indirect Microscopic Agglutination Test) and urine or kidney samples (analyzed by microscopic observation, immunostaining and culture) collected from 201 wild and domestic carnivores, including 26 free-living Iberian lynx (Lynx pardinus), 33 red foxes (Vulpes vulpes), 33 Egyptian mongooses (Herpestes ichneumon), 25 common genets (Genetta genetta), two Eurasian badgers (Meles meles) and one Eurasian otter (Lutra lutra), and 53 free-roaming cats and 28 rural dogs in protected areas in Andalusia (southern Spain). Twenty-three percent of the animals presented evidences of contact, being the prevalence similar among wild (23.5%) and domestic species (22.2%). Contact with Lesptospirawas detected in all the species but the otter. Prevalence was: lynx (11% by bacteriological detection, 32% by serology), fox (0%, 47%), mongoose (5%, 20%), genet (0%, 12%), badger (0%, 50%), cat (20%, 14%), dog (only serology: 36%). Serovar Icterohemorragiae accounted for 2/3 of the cases. Serovar Canicola was detected in half of the positive dogs and one lynx. Other serovars detected were Ballum, Sejroë, and Australis. No macroscopic lesions were observed in necropsied animals that showed evidence of contact with the agent, although histopathologic lesions (chiefly chronic interstitial nephritis) were observed in 7 out of the 11 microscopically analyzed individuals. Thus, L. interrogansmay cause previously unrecorded disease in wild carnivores in Spain. Wild and free-roaming carnivores may not act as reservoir of L. interrogansbut as a dead-end hosts, though the dog may act as reservoir of serovar Canicola. Carnivores are apparently good sentinels for the epidemiological monitorization of leptospirosis. [ABSTRACT FROM AUTHOR]

Rats, dogs, cattle, bats and sea lions, exemplify the diversity of mammalian species that can facilitate transmission of the zoonotic disease leptospirosis. The causative agent, pathogenic species of Leptospira, is shed in urine of chronically infected hosts. Direct contact with infected urine, or indirectly with water sources contaminated with infected urine, poses a risk of infection for humans exposed during water-related recreational and occupational activities. New serovars of Leptospira and maintenance hosts continue to be identified. In the western world, incidences of recreational exposure are increasing, while incidences of occupational exposure are decreasing. Adventure travellers returning from tropical regions, are presenting at clinics with symptoms of leptospirosis following participation in high risk activities including white water rafting, triathlons, endurance races and caving. Risks of infection can be reduced with increased awareness of how the disease is contracted, by avoiding contact with high risk water sources and the use of prophylaxis during high risk activities. Molecular techniques can be used to provide risk assessments prior to competition, to supplement epidemiology, and to assess shedding of Leptospira in urine samples. [ABSTRACT FROM AUTHOR]

Copyright of Investigaciones ANDINA is the property of Fundacion Universitaria del Area Andina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents a study which determines the major histocompatibility complex (MHCII) class II antigens expression in leptospiral nephritis in swine. It investigates the renal tissue from 20 8-month-old pigs that have spontaneous nephritis and six control pigs without renal lesions through the use of polymerase chain reaction (PCR) and indirect immunohistochemistry. The results show that MHCII expressions contribute to the inflammatory reaction during porcine leptospiral renal infection.

The article presents a study on how Leptospira in animals induces tubulointerstitial nephritis and how it will evade host immune responses during leptospirosis. Direct damage towards the host tissue by means of the presence of leptospiral antigen or Leptospira substantially causes tubulointerstitial nephritis which are associated with leptospirosis. Leptospires significantly colonize host renal tubules while leptospiruria remains in spite of active immune responses like interstitial nephritis.

Abstract: Few studies were conducted on the diagnosis and control of small ruminants’ leptospirosis. Thirteen goat herds and seven sheep flocks located in the state of Rio de Janeiro, Brazil, were screened for leptospirosis. From the three herds and three flocks with greatest seroreactivity by MAT (Microscopic Agglutination Test), 19 and 40 seropositive goats and sheep, respectively, were selected, and urine samples were collected for bacteriology and PCR. For both species of animals, the most prevalent reactions were due to serogroups Sejroe and Shermani. Although leptospires were observed by darkfield microscopy in eight samples, pure isolates were obtained by bacteriological culture from only two samples. However, twelve urine samples (six goats and six sheep) were positive by PCR. Based on these findings, we consider that the combined use of MAT as a screening test followed by urine PCR for the direct detection of Leptospira spp. DNA was adequate for the identification of carrier animals among goats and sheep. These are valuable tools for the control of leptospirosis in small ruminants. [Copyright &y& Elsevier]

The article focuses on the retrospective case-control study of the re-emergence of seroprevalent cases of canine leptospirosis in Ontario based on serology submission records from 1,406 dogs covering the period from January 1, 1998 to December 31, 2006. Data analysis suggest that dogs in urban areas seemed to be at higher risk to canine leptospirosis than dogs in rural areas. Also noted is the emergence of a distinctive seasonal pattern of leptospirosis, as more cases occur during the summer compared to the fall season.

Abstract: Leptospirosis, an endemic zoonoses, is maintained in the environment by several wildlife species in the Peruvian Amazon. In order to evaluate the possible role of collared peccaries (CP) in the maintenance this disease, two serological surveys of leptospirosis were performed and zootechnical parameters were monitored in a captive CP colony in an interval of 27 months. Total seroprevalence changed from 100% (n =27) to 86.4% (n =22), with reactions to a diversity of serogroups of zoonotic importance. Serological reactions to Leptospira licerasiae serogroup Iquitos, a new species recently identified locally and Leptospira interrogans serogroup Icterohaemorrhagiae were highly prevalent. The observation of leptospiral antibodies in both surveys, changes on serological reactions to different serogroups in large part of the herd and poor reproductive performances, provided an indication of the role of CP farms as a favourable environment for maintaining leptospirosis. Further research regarding the role of CP in the epidemiology of leptospirosis in the Peruvian Amazon is encouraged. [Copyright &y& Elsevier]

Leptospirosis is an extremely widespread zoonotic infection with outcomes ranging from subclinical infection to fatal Weil's syndrome. Despite the global impact of the disease, key aspects of its pathogenesis remain unclear. To examine in detail the earliest steps in the host response to leptospires, we used fluorescently labelled Leptospira interrogans serovar Copenhageni to infect 30 hour post fertilization zebrafish embryos by either the caudal vein or hindbrain ventricle. These embryos have functional innate immunity but have not yet developed an adaptive immune system. Furthermore, they are optically transparent, allowing direct visualization of host-pathogen interactions from the moment of infection. We observed rapid uptake of leptospires by phagocytes, followed by persistent, intracellular infection over the first 48 hours. Phagocytosis of leptospires occasionally resulted in formation of large cellular vesicles consistent with apoptotic bodies. By 24 hours, clusters of infected phagocytes were accumulating lateral to the dorsal artery, presumably in early hematopoietic tissue. Our observations suggest that phagocytosis may be a key defense mechanism in the early stages of leptospirosis, and that phagocytic cells play roles in immunopathogenesis and likely in the dissemination of leptospires to specific target tissues. [ABSTRACT FROM AUTHOR]