An outbreak of acute jaundice syndrome (AJS) among the Rohingya refugees in Cox's Bazar, Bangladesh: Findings from enhanced epidemiological surveillance.

In the summer of 2017, an estimated 745,000 Rohingya fled to Bangladesh in what has been described as one of the largest and fastest growing refugee crises in the world. Among numerous health concerns, an outbreak of acute jaundice syndrome (AJS) was detected by the disease surveillance system in early 2018 among the refugee population. This paper describes the investigation into the increase in AJS cases, the process and results of the investigation, which were strongly suggestive of a large outbreak due to hepatitis A virus (HAV). An enhanced serological investigation was conducted between 28 February to 26 March 2018 to determine the etiologies and risk factors associated with the outbreak. A total of 275 samples were collected from 18 health facilities reporting AJS cases. Blood samples were collected from all patients fulfilling the study specific case definition and inclusion criteria, and tested for antibody responses using enzyme-linked immunosorbent assay (ELISA). Out of the 275 samples, 206 were positive for one of the agents tested. The laboratory results confirmed multiple etiologies including 154 (56%) samples tested positive for hepatitis A, 1 (0.4%) positive for hepatitis E, 36 (13%) positive for hepatitis B, 25 (9%) positive for hepatitis C, and 14 (5%) positive for leptospirosis. Among all specimens tested 24 (9%) showed evidence of co-infections with multiple etiologies. Hepatitis A and E are commonly found in refugee camps and have similar clinical presentations. In the absence of robust testing capacity when the epidemic was identified through syndromic reporting, a particular concern was that of a hepatitis E outbreak, for which immunity tends to be limited, and which may be particularly severe among pregnant women. This report highlights the challenges of identifying causative agents in such settings and the resources required to do so. Results from the month-long enhanced investigation did not point out widespread hepatitis E virus (HEV) transmission, but instead strongly suggested a large-scale hepatitis A outbreak of milder consequences, and highlighted a number of other concomitant causes of AJS (acute hepatitis B, hepatitis C, Leptospirosis), albeit most likely at sporadic level. Results strengthen the need for further water and sanitation interventions and are a stark reminder of the risk of other epidemics transmitted through similar routes in such settings, particularly dysentery and cholera. It also highlights the need to ensure clinical management capacity for potentially chronic conditions in this vulnerable population.

Didelphis albiventris as a carrier of Leptospira sp. in the central nervous tissue in the semiarid region of Northeast, Brazil.

Leptospirosis has been investigated in several species of wild animals. The white-eared opossum (Didelphis albiventris) is a mammal common in the brazilian semi-arid, so, this study aimed to investigate its role in the occurrence of the leptospirosis in the region Northeast of Brazil. 12 animals were used, from which samples were collected for the attempt of isolation, molecular detection and serological examination. There was no microbial growth, nor were any anti-Leptospira sp. antibodies found in the serological samples. The PCR detected leptospiric DNA in the central nervous system (CNS) of five animals (41.7 %). The gene in one of the samples was sequenced and showed identity with Leptospira interrogans. The presence of Leptospira sp. in the CNS of Didelphis albiventris does not allow the characterization of the studied animals as reservoirs with potential for transmission of the pathogen in the region, however it represents a site that needs to be further investigated.

Development of real-time loop-mediated isothermal amplification (RealAmp) method for sensitive and rapid detection of pathogenic and nonpathogenic Leptospira.

Leptospirosis is a zoonotic disease that is spread through water contaminated with the spirochete Leptospira. In our study, RealAmp (real-time loop-mediated isothermal amplification) was developed to distinguish between pathogenic and nonpathogenic Leptospira spp. Melt curve analysis of RealAmp showed two distinct melt curves for pathogenic and nonpathogenic Leptospira spp with a Tm value of 90 ± 2 and 88 ± 2°C. The sensitivity of the developed method is as low as 1 pg µl-1 of Leptospira DNA. Specificity was achieved to distinguish Leptospira species using the marker genes (lipL32 and lipL21). Different environmental water samples collected from cattle shelter, pisciculture and stagnant water were tested using this RealAmp method. Pisciculture water samples were found to be highly contaminated with both pathogenic and nonpathogenic Leptospira spp (50%), followed by cattle shelter and stagnant water samples (15%). SIGNIFICANCE AND IMPACT OF THE STUDY: The occurrence of pathogenic Leptospira in the environment is a threat to humans and animals. Molecular-based differentiation of the pathogenic and nonpathogenic Leptospria is essential for environmental monitoring; however, the currently available detection methods fail to distinguish between these species. We report here a real-time loop-mediated isothermal amplification-based method that differentiates between the pathogenic and nonpathogenic Leptospira based on the melt curve analysis of the marker genes lipL32 and lipL21. The method was successfully tested with a variety of environmental water samples to study the prevalence of Leptospira in the environment.

Sex Matters: Male Hamsters Are More Susceptible to Lethal Infection with Lower Doses of Pathogenic Leptospira than Female Hamsters.

A somewhat contradictory published body of evidence suggests that sex impacts severity outcomes of human leptospirosis. In this study, we used an acute animal model of disease to analyze leptospirosis in male and female hamsters infected side by side with low but increasing doses of Leptospira interrogans serovar Copenhageni. We found that male hamsters were considerably more susceptible to leptospirosis, given that only 6.3% survived infection, whereas 68.7% of the females survived the same infection doses. In contrast to the females, male hamsters had high burdens of L. interrogans in kidney and high histopathological scores after exposure to low infection doses (∼103 bacteria). In hamsters infected with higher doses of L. interrogans (∼104 bacteria), differences in pathogen burdens as well as cytokine and fibrosis transcript levels in kidney were not distinct between sexes. Our results indicate that male hamsters infected with L. interrogans are more susceptible to severe leptospirosis after exposure to lower infectious doses than females.

Investigation of infectious reproductive pathogens of large ruminants: Are neosporosis, brucellosis, leptospirosis and BVDV of relevance in Lao PDR?

N. caninum, bovine viral diarrhoea virus, Brucella abortus and Leptospira interrogans serovar Hardjo are globally significant reproductive pathogens that cause abortion and reproductive loss in large ruminants. Prevalence information is lacking in Lao People's Democratic Republic (Laos) despite the poor reproductive performance of cattle and buffalo. Serological examination of frozen cattle (n=90) and buffalo (n=61) sera by commercially available enzyme-linked immunosorbent assays provided the first reported screening of some of these pathogens in Laos. Seroprevalence differed amongst these large ruminant species, with N. caninum, BVDV and L. interrogans serovar Hardjo antibodies found in 68.9% (95% CI±11.6), 4.9% (95% CI±5.4) and 3.3% (95% CI±4.5) of buffalo sera, respectively, and in 7.8% (95% CI±5.5), 10.0% (95% CI±6.2) and 22.2% (95% CI±8.6) of cattle sera, respectively. Buffalo sera had a significantly higher seroprevalence of N. caninum compared to cattle (p<0.001) and cattle sera had a significantly higher seroprevalence of L. interrogans serovar Hardjo compared to buffalo (p=0.003). Variability was also observed across provinces for N. caninum in buffalo (p=0.007) and for L. interrogans serovar Hardjo in cattle (p=0.071), suggesting provincial risk factors conducive to pathogen transmission. BVDV and N. caninum seropositivity were negatively associated in buffalo (p=0.018) and cattle (p=0.003). In buffalo, L. interrogans serovar Hardjo and BVDV seropositivity were associated (p=0.035, p=0.039). The identification of antibodies against three major abortifacient pathogens in Laos prompts further research to determine if infection is associated with low reproductive efficiency and the risk factors for infection. This is needed for the development of evidence based prevention strategies for improved large ruminant reproductive management among smallholders in Laos.

Unusual presentation of cyathostomiasis in an adult Thoroughbred mare.

A recently purchased 16-year-old Thoroughbred mare with a history of recurrent colic and low body weight, also had lameness in 3 limbs, pain at the sacro-iliac joint, and increased corneal opacity of the right eye. Response to supportive therapy was poor and euthanasia was elected. A postmortem examination and histopathology confirmed cyathostomiasis within the large colon and cecum and chronic anterior uveitis of the right eye.

Présentation inhabituelle de la cyathostomose chez une jument adulte Thoroughbred. Une jument Thoroughbred, âgée de 16 ans et récemment achetée, avec une anamnèse de coliques récurrentes et de faible poids corporel souffrait aussi de boiterie à trois membres, de douleurs dans l'articulation sacro-iliaque et d'opacité cornéenne accrue de l'oeil droit. La réponse à une thérapie de soutien a été mauvaise et l'euthanasie a été choisie. Un examen post mortem et l'histopathologie ont confirmé une cyathostomose dans le gros côlon et le cæcum ainsi qu'une uvéite antérieure chronique de l'oeil droit.(Traduit par Isabelle Vallières).

Increased levels of soluble forms of E-selectin and ICAM-1 adhesion molecules during human leptospirosis.

Leptospirosis is a multisystemic zoonotic disease with infiltration of visceral organs by Leptospira. The capacity of the vascular endothelium to grant immune cell recruitment and activation in target organs during the disease course remains poorly characterized. We ascertained the levels of expression of several soluble cell adhesion molecules (CAM) notably expressed by endothelial cells in human leptospirosis. We prospectively enrolled 20 hospitalized patients and compared them to 10 healthy controls. Disease severity was defined by one or more organ failures, or death. Plasmatic concentrations of soluble CAM were assessed by multiplex bead assay at the time of patient presentation (M0) and 1 month after hospital discharge. The levels of soluble E-selectin (sCD62E) and soluble intercellular adhesion molecule 1 (sICAM-1, sCD53) were significantly increased in patients compared to controls (p<0.0001) and at 1 month (p<0.0001) with median values at 978 ng/ml (interquartile ranges 787-1164; sCD62E) and 1021 ng/ml (690-1428; sCD53). At M0, Soluble P-selectin level (sCD62P) was found to be decreased with levels at 60 ng/ml (0-631) versus 711 ng/ml (343-1113) for healthy controls (p<0.05). Levels of sICAM-3 (sCD50), sVCAM-1 (vascular cell adhesion molecule, sCD106) and sPECAM-1 (platelet endothelial cell adhesion molecule, sCD31) were not different from healthy subjects at M0. This study shows that two adhesion molecules, shed as soluble forms, are elevated during the acute phase of leptospirosis: E-selectin and s-ICAM1. These molecules may interfere with the process of immune cell recruitment to clear Leptospira at tissue levels.

Adipose tissue is the first colonization site of Leptospira interrogans in subcutaneously infected hamsters.

Leptospirosis is one of the most widespread zoonoses in the world, and its most severe form in humans, "Weil's disease," may lead to jaundice, hemorrhage, renal failure, pulmonary hemorrhage syndrome, and sometimes,fatal multiple organ failure. Although the mechanisms underlying jaundice in leptospirosis have been gradually unraveled, the pathophysiology and distribution of leptospires during the early stage of infection are not well understood. Therefore, we investigated the hamster leptospirosis model, which is the accepted animal model of human Weil's disease, by using an in vivo imaging system to observe the whole bodies of animals infected with Leptospira interrogans and to identify the colonization and growth sites of the leptospires during the early phase of infection. Hamsters, infected subcutaneously with 104 bioluminescent leptospires, were analyzed by in vivo imaging, organ culture, and microscopy. The results showed that the luminescence from the leptospires spread through each hamster's body sequentially. The luminescence was first detected at the injection site only, and finally spread to the central abdomen, in the liver area. Additionally, the luminescence observed in the adipose tissue was the earliest detectable compared with the other organs, indicating that the leptospires colonized the adipose tissue at the early stage of leptospirosis. Adipose tissue cultures of the leptospires became positive earlier than the blood cultures. Microscopic analysis revealed that the leptospires colonized the inner walls of the blood vessels in the adipose tissue. In conclusion, this is the first study to report that adipose tissue is an important colonization site for leptospires, as demonstrated by microscopy and culture analyses of adipose tissue in the hamster model of Weil's disease.

High-Throughput Parallel Sequencing to Measure Fitness of Leptospira interrogans Transposon Insertion Mutants during Acute Infection.

Pathogenic species of Leptospira are the causative agents of leptospirosis, a zoonotic disease that causes mortality and morbidity worldwide. The understanding of the virulence mechanisms of Leptospira spp is still at an early stage due to the limited number of genetic tools available for this microorganism. The development of random transposon mutagenesis in pathogenic strains a decade ago has contributed to the identification of several virulence factors. In this study, we used the transposon sequencing (Tn-Seq) technique, which combines transposon mutagenesis with massive parallel sequencing, to study the in vivo fitness of a pool of Leptospira interrogans mutants. We infected hamsters with a pool of 42 mutants (input pool), which included control mutants with insertions in four genes previously analyzed by virulence testing (loa22, ligB, flaA1, and lic20111) and 23 mutants with disrupted signal transduction genes. We quantified the mutants in different tissues (blood, kidney and liver) at 4 days post-challenge by high-throughput sequencing and compared the frequencies of mutants recovered from tissues to their frequencies in the input pool. Control mutants that were less fit in the Tn-Seq experiment were attenuated for virulence when tested separately in the hamster model of lethal leptospirosis. Control mutants with unaltered fitness were as virulent as the wild-type strain. We identified two mutants with the transposon inserted in the same putative adenylate/guanylate cyclase gene (lic12327) that had reduced in vivo fitness in blood, kidney and liver. Both lic12327 mutants were attenuated for virulence when tested individually in hamsters. Growth of the control mutants and lic12327 mutants in culture medium were similar to that of the wild-type strain. These results demonstrate the feasibility of screening large pools of L. interrogans transposon mutants for those with altered fitness, and potentially attenuated virulence, by transposon sequencing.

Distribution and Diversity of Pathogenic Leptospira Species in Peri-domestic Surface Waters from South Central Chile.

BACKGROUND: Leptospirosis is a neglected zoonosis affecting animals and humans caused by infection with Leptospira. The bacteria can survive outside of hosts for long periods of time in soil and water. While identification of Leptospira species from human cases and animal reservoirs are increasingly reported, little is known about the diversity of pathogenic Leptospira species in the environment and how surveillance of the environment might be used for monitoring and controlling disease. METHODS AND FINDINGS: Water samples (n = 104) were collected from the peri-domestic environment of 422 households from farms, rural villages, and urban slums participating in a broader study on the eco-epidemiology of leptospirosis in the Los Rios Region, Chile, between October 2010 and April 2012. The secY region of samples, previously detected as pathogenic Leptospira by PCR, was amplified and sequenced. Sequences were aligned using ClustalW in MEGA, and a minimum spanning tree was created in PHYLOViZ using the goeBURST algorithm to assess sequence similarity. Sequences from four clinical isolates, 17 rodents, and 20 reference strains were also included in the analysis. Overall, water samples contained L. interrogans, L. kirschneri, and L. weilii, with descending frequency. All species were found in each community type. The distribution of the species differed by the season in which the water samples were obtained. There was no evidence that community-level prevalence of Leptospira in dogs, rodents, or livestock influenced pathogen diversity in the water samples. CONCLUSIONS: This study reports the presence of pathogenic Leptospira in the peri-domestic environment of households in three community types and the differences in Leptospira diversity at the community level. Systematic environmental surveillance of Leptospira can be used for detecting changes in pathogen diversity and to identify and monitor contaminated areas where an increased risk of human infection exists.

A cross sectional study of leptospirosis and fetal death in Yucatan, Mexico.

INTRODUCTION: Leptospirosis is a zoonotic disease affecting mainly to low income human population. Acute leptospiral infection during pregnancy has been associated with spontaneous abortion and fetal death during the first trimester and the abortion may occur as consequence of systemic failure. OBJECTIVE: To estimate the frequency of Leptospira interrogans infection in women with spontaneous abortion in the state of Yucatan, Mexico. METHODS: A cross sectional study on women with spontaneous abortion was conducted. Serum samples were tested for Leptospirosis by the microaglutination test, to estimate the frequency of the infecting serovar. The indirect ELISA IgM was used to detect recent infection by L. interrogans. DNA was extracted from paraffin-embedded tissue of placenta for PCR detection of L. interrogans. RESULTS: Overall frequency of infection with L. interrogans in the 81 women with abortion was 13.6%. Five of the 12 serovars evaluated were found and included. Two of the 11 women with abortion and positive to microaglutination test were also positive to the ELISA IgM test. None samples were positive for PCR Leptospira diagnosis. CONCLUSION: two women could be associated with spontaneous abortion due to leptospirosis, because they showed antibodies against L. interrogans in the microaglutination test and ELISA IgM assays. Differences between regions were found with respect to the prevalences of lesptospirosis.

INTRODUCCIÓN: Leptospirosis es una enfermedad zoonótica que afecta principalmente la población humana de bajos recursos. Infección aguda por leptospirosis durante el embarazo se ha asociado con aborto espontáneo y muerte fetal durante el primer trimestre del embarazo. OBJETIVO: Estimar la frecuencia de infección por Leptospira interrogans en mujeres con aborto espontáneo en el estado de Yucatán, México. MÉTODOS: Se efectuó un estudio transversal en 81 mujeres con aborto espontáneo. La prueba de referencia para Leptospirosis, prueba de microaglutinación, se utilizó para estimar la frecuencia de la serovar infectante. El ELISA IgM indirecto se utilizó para detectar infección reciente por L. interrogans. Se extrajo ADN a partir de tejido embebido en parafina de placenta para la detección de L. interrogans por PCR. RESULTADOS: La frecuencia global de la infección con L. interrogans en 81 mujeres con aborto, fue del 13.6%. Se encontró cinco de 12 serovares de Leptospira. Dos de las 11 mujeres con aborto espontáneo y positivo a microaglutinación también fueron positivas a la prueba ELISA IgM. Ninguna muestra fue positiva hacia el diagnóstico PCR de Leptospira. CONCLUSION: Dos mujeres podrían estar asociados con el aborto espontáneo debido a la leptospirosis, porque mostraron anticuerpos contra L. interrogans en la microaglutinación y ensayos de ELISA IgM. Diferencias entre regiones fueron encontradas con respecto a las prevalencias de leptospirosis.

A cross sectional study of leptospirosis and fetal death in Yucatan, Mexico / Estudio transversal de leptospirosis y muerte fetal en Yucatán, México

Introduction: Leptospirosis is a zoonotic disease affecting mainly to low income human population. Acute leptospiral infection during pregnancy has been associated with spontaneous abortion and fetal death during the first trimester and the abortion may occur as consequence of systemic failure. Objective: To estimate the frequency of Leptospira interrogans infection in women with spontaneous abortion in the state of Yucatan, Mexico. Methods: A cross sectional study on women with spontaneous abortion was conducted. Serum samples were tested for Leptospirosis by the microaglutination test, to estimate the frequency of the infecting serovar. The indirect ELISA IgM was used to detect recent infection by L. interrogans. DNA was extracted from paraffin-embedded tissue of placenta for PCR detection of L. interrogans. Results: Overall frequency of infection with L. interrogans in the 81 women with abortion was 13.6%. Five of the 12 serovars evaluated were found and included. Two of the 11 women with abortion and positive to microaglutination test were also positive to the ELISA IgM test. None samples were positive for PCR Leptospira diagnosis. Conclusion: two women could be associated with spontaneous abortion due to leptospirosis, because they showed antibodies against L. interrogans in the microaglutination test and ELISA IgM assays. Differences between regions were found with respect to the prevalences of lesptospirosis.

Introducción: Leptospirosis es una enfermedad zoonótica que afecta principalmente la población humana de bajos recursos. Infección aguda por leptospirosis durante el embarazo se ha asociado con aborto espontáneo y muerte fetal durante el primer trimestre del embarazo. Objetivo: Estimar la frecuencia de infección por Leptospira interrogans en mujeres con aborto espontáneo en el estado de Yucatán, México. Métodos: Se efectuó un estudio trasversal en 81 mujeres con aborto espontáneo. La prueba de referencia para Leptospirosis, prueba de microaglutinación, se utilizó para estimar la frecuencia de la serovar infectante. El ELISA IgM indirecto se utilizó para detectar infección reciente por L. interrogans. Se extrajo ADN a partir de tejido embebido en parafina de placenta para la detección de L. interrogans por PCR. Resultados: La frecuencia global de la infección con L. interrogans en 81 mujeres con aborto, fue del 13.6%. Se encontró cinco de 12 serovares de Leptospira. Dos de las 11 mujeres con aborto espontáneo y positivo a microaglutinación también fueron positivas a la prueba ELISA IgM. Ninguna muestra fue positiva hacia el diagnóstico PCR de Leptospira. Conclusion: Dos mujeres podrían estar asociados con el aborto espontáneo debido a la leptospirosis, porque mostraron anticuerpos contra L. interrogans en la microaglutinación y ensayos de ELISA IgM. Diferencias entre regiones fueron encontradas con respecto a las prevalencias de leptospirosis.

Identificação de biofilme renal em ratos naturalmente infectados por Leptospira interrogans através de técnicas histoquímicas e de microscopia eletrônica de varredura, Brasil / Identification of renal biofilm in rats naturally infected with Leptospira interrogans using histochemical and scanning electron microscopy techniques, Brazil

INTRODUÇÃO: A leptospirose é um importante agravo de saúde pública e afeta ao menos um milhão de humanos por ano no mundo. Ratos de esgoto (Rattus norvegicus) são os principais reservatórios de leptospiras patogênicas nas áreas urbanas e excretam, através da urina, elevadas quantidades de bactérias diariamente. As leptospiras sobrevivem no ambiente e são transmitidas para novos hospedeiros através do contato com mucosas e pele. Leptospiras patogênicas formam densos biofilmes in vitro. A patogênese da leptospirose em reservatórios crônicos é pouco conhecida. OBJETIVO: Estudar a formação de biofilme por Leptospira interrogans em R. norvegicus capturados em uma área hiperendêmica de Salvador, Bahia, Brasil. MATERIAIS E MÉTODOS: Capturamos 86 ratos, dos quais 76 (88,4%) foram considerados portadores de L. interrogans através da avaliação por imunohistoquímica (IHQ) anti-L. interrogans e/ou Reação em Cadeia da Polimerase quantitativa em Tempo Real (RT-qPCR) utilizando iniciadores específicos para o gene lipL32. RESULTADOS: Ao exame de IHQ anti-L. interrogans, 69 ratos foram positivos. Destes, 24 (35%)...

INTRODUCTION: Leptospirosis is an important public health problem and affects at least one million people each year worldwide. Norway rats (Rattus norvegicus) are the main reservoir hosts of leptospires in urban environments. They excrete large amounts of bacteria daily. Leptospires survive in the environment and are transmitted to new hosts by contact with mucous membranes and skin. Pathogenic leptospires form dense biofilms in vitro. The pathogenesis of chronic leptospirosis in reservoirs is largely unknown. The aim of this work was to study biofilm formation by Leptospira interrogans in R. norvegicus caught in a hyperendemic area in Salvador, Bahia, Brazil. MATERIAL AND METHODS: We caught 86 rats, out of which 76 (88.4%) were carriers of L. interrogans according to immunohistochemistry (IHC) anti-L. interrogans and/or quantitative real time PCR (RT-qPCR) using LipL32 primers. RESULTS: From the 69 rats positive for IHC anti-L. interrogans, 24 (35%)...

[Content of some pro- and anti-inflammatory cytokines in blood sera of leptospirosis patients].

AIM: Study the content of some pro- and anti-inflammatory cytokines in blood sera of leptospirosis patients in dynamics of infectious process and the role of these cytokines in the disease immunopathogenesis. MATERIALS AND METHODS: The content of cytokines in blood sera was determined by a method based on xMAP technology with a standard panel consisting of 9 analytes: TNF-α, MCP-1, IL-8, IL-4, IL-6, IL-10, IL-1Ra, IL-12 (p70), IFN-γ. RESULTS: A significantly increased level of IL-8, IL-10, TNF-α was confirmed and the increased content of MCP-1 in leptospirosis patients compared with practically healthy donors was established for the first time. Correlations between cytokines during leptospirosis were detected. CONCLUSION: The data obtained show that cytokines play an important role in leptospirosis immunopathogenesis.

Avanços no conhecimento da imunopatogênese da leptospirose e a aplicação do método do imprint como ferramenta qualitativa e quantitativa de leptospiras / Advances in understanding the immunopathogenesis of leptospirosis and application of the imprint method as a qualitative and quantitative tool leptospires

A leptospirose é uma zoonose causada por espiroquetas patogênicas pertencentes ao gênero Leptospira. O modelo da doença em camundongos tem vantagens devido à ampla gama de ferramentas genéticas e imunológicas disponíveis para pesquisas básicas. A maior limitação na conduta clínica e na pesquisa experimental da leptospirose é o fraco desempenho dos métodos disponíveis para detecção direta e para quantificação de leptospiras. Foi incluído nesta tese um conjunto de três manuscritos que visam investigar o desfecho da infecção pela cepa virulenta de Leptospira interrogans nas linhagens de camundongos selvagens (A, CBA, BALB/c e C57BL/6)...

Leptospirosis is a zoonosis caused by pathogenic spirochaetes belonging to the genus Leptospira. The mouse disease model is advantagous due to the broad array of immunological and genetic tools available for basic research. A major limitation in the clinical management and experimental research of leptospirosis is the poor performance of the available methods in the direct detection and quantification of leptospires. This thesis includes three manuscripts that investigate the outcome of infection by a virulent strain of Leptospira interrogans in wildtype mice strains: A, CBA, BALB/c and C57BL/6; in iNOS knockout (KO) mice, recombination activating gene 1 (RAG1) KO mice and CB17 severe combined immunodeficiency (SCID) mice. To investigate whether the imprint method (IM) of quantification was reliable we compared it with against real time PCR (qPCR) for the detection and quantification of leptospires in kidney samples from rats and hamsters. As expected, none of the wildtype mice were susceptible to lethal leptospirosis. The A and C57BL/6 strains exhibited high leptospiral loads in the kidney samples and the CBA and C57BL/6...

Seroprevalence of Leptospira spp. in clinically healthy racing horses in Korea.

Leptospirosis is a zoonotic disease of global importance, and has a worldwide distribution. The present study aimed to determine leptospiral seroprevalence in clinically healthy racing horses from all three racecourses in Korea. Serum samples from 1,226 racing horses were examined using a microscopic agglutination test to detect the presence of antibodies against 18 Leptospira serovars. Of the tested samples, 307 (25.0%) were found to be positive. The distribution of seroprevalence differed significantly by racecourse (P=0.004); the Jeju course had the highest incidence (31.1%), followed by the Seoul (25.2%) and Busan (19.5%) racecourses. Seasonal variation in seropositivity was also apparent (P=0.000), being lower in spring (13.0%) and winter (12.5%), and higher in summer (36.7%) and autumn (34.7%). No significant age- or gender-related difference in seroprevalence was noted in this study (P>0.05). Seroprevalence was higher (P=0.006) among ponies than among thoroughbreds. Sejroe was the most frequently detected serovar (n=236), followed by Bratislava (n=35), Ballum (n=16), Autumnalis (n=10), and Canicola (n=10). The majority of serum titers were relatively low; most values ranged from 1:100 (n=217) to 1:200 (n=69). These results suggest that the Sejroe serovar may be maintained in the racing horse population in Korea.

Serum sialic acid and oxidative stress parameters changes in cattle with leptospirosis.

This study was designed to disclose some indicators of oxidative stress and inflammation in natural cases of bovine leptospirosis. For this purpose, 12 bulls exhibiting clinical signs of leptospirosis and 10 healthy bulls were used. Animals were subjected to thorough clinical examination and the clinical signs were recorded. All animals were blood sampled in order to determine serum total sialic acid (TSA), lipid bound sialic acid (LBSA), malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), uric acid (UA), total protein (TP), albumin and glucose. Urine samples were collected from each animal and examined under dark-field microscope to observe spirochetes. Diseased animals exhibited clinical signs suggesting leptospirosis and the diagnosis was supported by positive dark-field microscope examination. Mean TSA (mmol/L), LBSA (mmol/L), TP (g/dl), albumin (g/dl), glucose (mg/dl), MDA (micromol/L), GSH (mg/dl), NO (nmol/ml), and UA (mg/L) levels were 1.63 +/- 0.02, 0.40 +/- 0.10, 7.18 +/- 0.24, 3.23 +/- 0.5, 64.96 +/- 1.88, 5.71 +/- 0.11, 78.68 +/- 0.72, 7.94 +/- 0.34, and 8.75 +/- 0.41 in healthy bulls, and 2.50 +/- 0.05, 0.70 +/- 0.2, 9.27 +/- 0.17, 2.55 +/- 0.62, 107.93 +/- 2.52, 8.82 +/- 0.14, 47.85 +/- 1.85, 14.57 +/- 0.63 and 15.85 +/- 0.80 in leptospirosis cases, respectively. The differences between the two groups were statistically significant (P < 0.001). Increased TSA, LBSA, MDA, NO, UA, TP, glucose and decreased GSH and albumin concentrations were suggestive of inflammation and oxidative stress in diseased bulls. The results obtained may suggest that oxidative damage along with other mechanisms might have taken part in the pathogenesis of bovine leptospirosis and further detailed studies are needed to fully understand the mechanism(s) of the disease.

Severe sepsis due to severe falciparum malaria and leptospirosis co-infection treated with activated protein C.

Co-infection with falciparum malaria and leptospirosis is uncommon. The aim of this study is to report a case of severe sepsis secondary to dual infection with falciparum malaria and leptospirosis. The literature is also reviewed on the clinical course of such co-infections, and the possible mechanisms and treatment of patients with life-threatening malaria and leptospirosis with activated protein C. The patient was a 25-year old male admitted in the Respiratory Intensive Care Unit (RICU) with fever, haemolysis, acute renal failure, hepatitis, acute lung injury (ALI) and altered sensorium. A syndromic evaluation was done and investigations revealed falciparum parasitaemia. He was treated with parenteral artesunate, ceftriaxone and doxycycline, and adjunctive therapies as for severe sepsis. Infusion of activated protein C was started 20 hours after onset of organ dysfunction, and intensive haemodialysis was instituted. Over the next four days the patient became afebrile with progressive resolution of ALI, renal failure and hepatitis. His Leptospira serology (requested as part of the evaluation) was reported positive on day 5. Dual infections are common and under-recognized in the tropics. Failure to treat potential co-infections may lead to poor outcomes. Acute lung injury in falciparum malaria has high mortality rates and therapy as for severe sepsis may improve survival. Adjunctive therapies, including activated protein C, cannot replace source eradication.

A model of Leptospirosis infection in an African rodent to determine risk to humans: seasonal fluctuations and the impact of rodent control.

Human leptospirosis (Leptospira spp. infection) is a worldwide public health problem that is of greatest concern for humid tropical and subtropical regions. The magnitude of the problem in these areas is larger because of the climatic and environmental conditions the bacterium face outside their hosts but also because of the frequency of contacts between people and sources of infection. Rodents are thought to play the most important role in the transmission of human leptospirosis. We here model the dynamics of infection in an African rodent (Mastomys natalensis) that is thought to be the principal source of infection in parts of Tanzania. Our model, representing the climatic conditions in central Tanzania, suggests a strong seasonality in the force of infection on humans with a peak in the abundance of infectious mice between January and April in agricultural environments. In urban areas the dynamics are predicted to be more stable and the period of high numbers of infectious animals runs from February to July. Our results indicate that removal of animals by trapping rather than reducing the suitability of the environment for rodents will have the greater impact on reducing human cases of leptospirosis.