Positive Microscopic Agglutination Test Research Articles

Acute leptospirosis in horses: A retrospective study of 11 cases (2015-2023).

Reports of leptospirosis in horses are limited. To describe the clinical and diagnostic findings of acute systemic leptospirosis in horses. Eleven client-owned horses presented to an equine hospital because of acute onset of disease between 2015 and 2023. Retrospective case series. Horses diagnosed with leptospirosis by 1 or more of urine PCR, serologic microscopic agglutination test (MAT), and histopathology. Common clinical signs included lethargy (10), anorexia (10), fever (9), tachypnea (9), abnormal lung sounds (9), and epistaxis (6). Acute kidney injury was present in all cases. Evidence of pulmonary hemorrhage and liver disease was found in 8 (73%) and 6 (55%) horses, respectively. In 6 (55%) horses, kidneys, lungs, and liver were affected. Urine quantitative polymerase chain reaction for detection of pathogenic Leptospira spp. was positive in 6 (55%) cases. On serology Leptospira interrogans serovar Australis, Autumnalis, and Bratislava accounted for 86% of all titers ≥1 : 800. Overall case fatality rate was 4/11 (36%). Main findings on necropsy were tubular necrosis, interstitial nephritis, hemorrhage in the alveoli, pulmonary edema, periportal hepatitis and necrosis, cholestasis, and cholangitis. Leptospirosis should be considered as a differential diagnosis in horses with evidence of acute systemic inflammation and acute renal injury, epistaxis, or hepatic disease. For increased likelihood of identifying positive cases, both MAT serology and urine PCR should be performed.

Modern Features of Pathogenic Leptospira Isolation and Identification in Siberia and the Far East

Recently, pathogenic Leptospira culture isolation is an extremely rare phenomenon in Russia.The aim of our work was to synthesize the lessons learned at the Irkutsk Anti-Plague Institute from Leptospira culture isolation and identification since 2011.Materials and methods. Material from eight individuals with suspected leptospirosis and from 942 small mammals (SM) was examined using PCR and microscopic agglutination test (MAT), from humans and 260 SM, applying bacteriological method. Bacteriological temperature test, MAT, PCR, MLST and MALDI-TOF mass spectrometry with the original Leptospira protein profiles base were used to identify cultures. Six complete genomes were generated at the Central Research Institute of Epidemiology of the Rospotrebnadzor.Results and discussion. Leptospira have not been isolated from humans against the background of taking antibiotics, despite the positive PCR and MAT results. Four cultures of Leptospira borgpetersenii of the Javanica serogroup and three L. kirschneri (Grippotyphosa) have been isolated from SM. The results of identification using MLST scheme No. 1 and MALDI-TOF MS are identical. MLST in silico has shown the uniformity of two Grippotyphosa serogroup strains from Primorie and Khabarovsk with a sequence-type (ST) profile 110:100:94. ST146 is determined in four Javanica serogroup strains according to scheme No. 1, and unique single nucleotide polymorphisms are detected according to schemes No. 2–3. Thus, in Siberia and the Far East, between 2012 and 2016, seven pathogenic Leptospira cultures were isolated from carriers in natural foci; carrier infection rate being12.0–48.9 %. Javanica serogroup strains differ in the MLST profile characteristics and adapt to nutrient media for a longer time than Grippotyphosa serogroup strains.

The Evaluation of the Diagnostic Value of a PCR Assay When Compared to a Serologic Micro-Agglutination Test for Canine Leptospirosis.

ObjectiveTo evaluate PCR assay sensitivity and specificity compared to that of microscopic agglutination test (MAT) for diagnosis of canine leptospirosis. Electronic records search was performed to identify dogs with results for both PCR and MAT testing for leptospirosis.MethodsAll dogs were clinically ill. Diagnosis of leptospirosis was defined as an unvaccinated dog with a positive MAT titer of ≥1:800 or a vaccinated dog or dog with an unknown vaccination status with a positive MAT titer of ≥1:1,600. Diagnosis of leptospirosis was excluded based on MAT titer <1:800 on both the initial and convalescent samples or an initial MAT titer <1:800 and an alternative definitive diagnosis.ResultsForty-nine samples (urine, n = 39; blood, n = 10) were evaluated. Leptospirosis was diagnosed in 17 dogs and excluded in 26 dogs. Urine PCR assay demonstrated sensitivity of 69.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 86.6%. Blood PCR assay demonstrated sensitivity of 25%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 25%. Overall PCR sensitivity was 52.4%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 73.7%.ConclusionsPCR assay performed on urine or blood has high specificity and positive predictive value when compared to MAT for diagnosis of clinical canine leptospirosis. Sensitivity and negative predictive value are moderate to low, so PCR testing should be performed in conjunction with paired MAT testing for canine leptospirosis. Prior antibiotic therapy does not preclude the use of the PCR test.

Can cytokines response play a role in the treatment of fatal leptospirosis?

Background:The northern coastal regions of Iran are endemic for leptospirosis which may range from a subclinical illness to a progressively fatal disease. There has been growing evidence that inflammatory markers play a significant role in the severity and prognosis of leptospirosis. This study aimed to investigate inflammatory cytokines in patients with leptospirosis.Methods:This descriptive-analytical prospective study was performed in 75 patients over 18 years old who had a positive microscopic agglutination test (MAT) titer from January to June 2019. SPSS software Version 20 was used for statistical analysis and the significance level was considered as p<0.05.Results:The patients’ age enrolled in this study are from 21 to 75 years with a mean and standard deviation of 48.6±14.0. The male to female ratio in our participants was 54/21. Fever was the most common symptoms in 66 (88.0%) patients, followed by myalgia in 62 (82.7%) cases. The level of interleukin 10 was significantly higher in severe illness (P=0.003) and fatal cases (p<0.028) compared with recovered patients. The level of TNF-α level was also higher in the severe illness and Weil's syndrome compared with the mild kind (P=0.022).Conclusion:Our results showed that the levels of TNF-α and IL-10 significantly increased in severe leptospirosis. Also, IL-10 was significantly higher in fatal cases. The inhibition of IL-10 production might play an important role in decreasing the risk of fatal outcomes in leptospirosis.

Seroepidemiological Analysis of Leptospiral infection using MAT in Stray Dogs in Alborz, Iran.

Leptospirosis is a zoonotic disease with global importance, and the animals are the source of transmission of this disease through shedding in their urine. Accordingly, it is essential to conduct epidemiological studies of leptospirosis in order to diagnose this disease in dogs and reduce the risk of transmission to humans. This study aimed to perform a seroepidemiological analysis of Leptospiral infection in stray dogs in Alborz, Iran, using the Microscopic Agglutination Test (MAT). In total, 110 blood samples were collected from stray dogs to detect the antibodies against leptospira interrogans serovarsby the MAT. The prevalence rate of positive MAT tests in stray dogs was estimated at 21.84%. The following protocol confirmed that the most common titers were 1:200 (50%) and 1:400 (25%). In addition, the most prevalent Leptospira serovars were L. Canicola (33.33%), and the lowest belonged to L. Pomona (4.1%). Moreover, no significant difference was observed between the age and gender of the dogs regarding their MAT titer (P&amp;gt;0.05). The results also showed a high prevalence of leptospirosis in stray dogs of Koohsar in Alborz province, Iran. Since Leptospirosis is a zoonosis disease, it should be studied continuously in humans and animals, especially dogs.

Acute undifferentiated fever in India: a multicentre study of aetiology and diagnostic accuracy

BackgroundThe objectives of this study were to determine the proportion of malaria, bacteraemia, scrub typhus, leptospirosis, chikungunya and dengue among hospitalized patients with acute undifferentiated fever in India, and to describe the performance of standard diagnostic methods.MethodsDuring April 2011–November 2012, 1564 patients aged ≥5 years with febrile illness for 2–14 days were consecutively included in an observational study at seven community hospitals in six states in India.Malaria microscopy, blood culture, Dengue rapid NS1 antigen and IgM Combo test, Leptospira IgM ELISA, Scrub typhus IgM ELISA and Chikungunya IgM ELISA were routinely performed at the hospitals.Second line testing, Dengue IgM capture ELISA (MAC-ELISA), Scrub typhus immunofluorescence (IFA), Leptospira Microscopic Agglutination Test (MAT), malaria PCR and malaria immunochromatographic rapid diagnostic test (RDT) Parahit Total™ were performed at the coordinating centre. Convalescence samples were not available.Case definitions were as follows: Leptospirosis: Positive ELISA and positive MAT. Scrub typhus: Positive ELISA and positive IFA. Dengue: Positive RDT and/or positive MAC-ELISA. Chikungunya: Positive ELISA. Bacteraemia: Growth in blood culture excluding those defined as contaminants. Malaria: Positive genus-specific PCR.ResultsMalaria was diagnosed in 17% (268/1564) and among these 54% had P. falciparum. Dengue was diagnosed in 16% (244/1564). Bacteraemia was found in 8% (124/1564), and among these Salmonella typhi or S. paratyphi constituted 35%. Scrub typhus was diagnosed in 10%, leptospirosis in 7% and chikungunya in 6%. Fulfilling more than one case definition was common, most frequent in chikungunya where 26% (25/98) also had positive dengue test.ConclusionsMalaria and dengue were the most common causes of fever in this study. A high overlap between case definitions probably reflects high prevalence of prior infections, cross reactivity and subclinical infections, rather than high prevalence of coinfections. Low accuracy of routine diagnostic tests should be taken into consideration when approaching the patient with acute undifferentiated fever in India.

Clinical, serological and echocardiographic examination of healthy field dogs before and after vaccination with a commercial tetravalent leptospirosis vaccine

BackgroundLeptospirosis is a re-emerging bacterial zoonosis caused by spirochetes of the genus Leptospira. Severe disease has been reported in dogs in Europe despite vaccination with bivalent Leptospira vaccines. Recently, a tetravalent canine Leptospira vaccine (Nobivac® L4) was licenced in Europe. The goal of this study was to investigate clinical signs, microscopic agglutination test (MAT) titres, haematology, blood biochemistry, cardiac (c) Troponin I levels and echocardiography before and after vaccination with this tetravalent vaccine. Forty-eight healthy dogs were prospectively enrolled and vaccinated twice, 3–4 weeks apart (T0 and T1). Before vaccination (T0) and 16–31 days after the second vaccination (T2), MAT (n = 48), haematology (n = 48), blood biochemistry (n = 36) and cTroponin I measurements (n = 29) were performed, and MAT was repeated 347–413 days after the second vaccination (T3, n = 44). Echocardiography was performed before the first and second vaccination (T0 and T1, n = 24).ResultsMild and transient clinical signs within 5 days following the first and second vaccination occurred in 23% and 10% of the dogs, respectively. Before the first vaccination (T0), all dogs showed negative MAT titres for the tested serovars except for Canicola (50% with titres 100–400). At T2, positive MAT titres to the serovars Canicola (100%), Australis (89%), Grippotyphosa (86%), Bratislava (60%), Autumnalis (58%), Copenhageni (42%), Pomona (12%), Pyrogenes (8%) and Icterohaemorrhagiae (2%) were found. Median to high titres (≥ 400) were most common to the serovar Canicola (92%) and less common to the serovars Australis (41%), Grippotyphosa (21%), Bratislava (12%), Autumnalis (4%), Pyrogenes (4%) and Pomona (2%). At T3, positive MAT titres (titre range: 100–400) were found in 2–18% of the dogs to serovars of the vaccine serogroups and in 2–18% of the dogs to the non-vaccine serovars Pomona, Autumnalis, Pyrogenes and Ballum. Haematology, blood biochemistry, cTroponin I levels and echocardiography results did not change significantly following vaccination.ConclusionsClinical signs following vaccination with Nobivac® L4 were transient and mild in all cases. Seroconversion differed considerably among individual dogs and among the vaccine serogroups.

Serogroups and genotypes of Leptospira spp. strains from bovine aborted foetuses.

Leptospirosis is a global disease of animals, with potential major economic impact on livestock industry and important zoonotic capacities. The disease represents a major challenge in the developing countries as humans and animals frequently live in close association. The serovar Hardjo of Leptospira whose primary host is cattle has been studied extensively, but few data exist on other current circulating or emerging serotypes. To better understand the disease in cattle and how to prevent and/or control it, it is necessary to identify the genotype and the serotype of circulating Leptospira. This study presents results of several investigations performed on a historical Belgian collection of congenital jaundice in bovine aborted foetuses coming from the leptospirosis emerging episode of 2014 (Delooz etal., Transboundary and Emerging Diseases, 62, 2015, 124). The results revealed that L.Grippotyphosa and L.Australis were the most prevalent serogroups with, respectively, 17/42 and 13/42 positive microscopic agglutination test (MAT) during this emerging event associated with the same clinical pattern. The study also confirms that congenital jaundice is associated with L.kirscheneri and L.interrogans and provides the genotyping of DNA obtained from these two species.

Hotspots of canine leptospirosis in the United States of America

Leptospirosis is a widespread zoonotic disease that causes hepatic and renal disease in dogs and human beings. The incidence of leptospirosis in dogs in the USA appears to be increasing. This study used 14 years of canine leptospirosis testing data across 3109 counties in the USA to analyze environmental and socio-economic correlates with rates of infection and to produce a map of locations of increased risk for canine leptospirosis. Boosted regression trees were used to identify the probability of a dog testing positive for leptospirosis based on microscopic agglutination test (MAT) results, and environmental and socio-economic data. The Midwest, East and Southwest were more likely to yield positive tests for leptospirosis, although specific counties in Appalachia had some of the highest predicted probabilities. Location (suburban areas or areas with deciduous forest) and climate (precipitation and temperature) were predictors for positive MAT results for leptospirosis, although the precise direction and strength of the effects was difficult to interpret. Wide geographic variation in predicted risk was identified. This risk mapping approach may provide opportunities for improved diagnosis, control and prevention of leptospirosis in dogs.

Pathology of leptospirosis: autopsy study

Autopsy studies were performed on 4 cases who had clinical and epidemiological data suggestive of leptospirosis complicated with multiorgan involvement. The diagnosis of leptospirosis was confirmed by strongly positive microscopic agglutination test. The immunoblotting data revealed antibodies against more than one serovar of leptospires. All patients were males who presented with fever, myalgia, hypotension, breathlessness, oliguria and one out of 4 had also icterus. All 4 cases died one to four days after admission. Pancarditis, arteritis of coronary arteries, intra-alveolar hemorrhage of both lungs, acute interstitial nephritis with focal tubular necrosis and occasional acute proliferative glomerulonephritis were present in every case. Two cases showed also acute meningitis and choroid plexitis. Acute hemorrhagic splenitis with severe lymphoid depletion and triaditis of portal tracts of the liver with focal acute hemorrhagic pancreatitis were also seen in one case.

Usefulness of real-time PCR assay targeting lipL32 gene for diagnosis of human leptospirosis in Uruguay

Assays based on DNA amplification can provide information that contributes to the initial management of patients with leptospirosis. However, these have not been adopted in Uruguay. Our aim was to evaluate the performance of the lipL32 real-time PCR (qPCR) for diagnosis of leptospirosis. We analyzed by microscopic agglutination test (MAT) and lipL32 qPCR serum samples from 183 patients with suspected leptospirosis. To establish the analytical sensitivity of the qPCR, experimentally spiked samples with known amounts of Leptospira interrogans were analyzed. The analytical sensitivity of the qPCR was 102 leptospires/mL. In 98 patients MAT results were negative meanwhile 85 showed positive reactions, revealing acute infections. Twenty six acute-phase sera of these 85 patients showed a positive signal by qPCR (diagnostic sensitivity 30%). In these patients the average time between onset of symptoms and collection of the first sample was 8 days. In patients with negative results for qPCR and positive MAT results (n=59) the average interval between onset of symptoms and collection of the first sample was 13 days. The qPCR did not yield false positive results. The qPCR had a lower diagnostic sensitivity than MAT and a higher cost. However, it allowed to make an early diagnosis in 26 patients. In patients with confirmed acute infections and negative results by qPCR, more than 8 days had elapsed between the onset of the illness and extraction of the first serum sample. Our data support that the qPCR from sera have clinical utility within the first week of illness.

A leptospirosis case presenting with thrombotic thrombocytopenic purpura.

Leptospirosis is a zoonotic disease caused by spirochetes of the genus Leptospira. While the majority of leptospirosis cases occur in the tropics, some cases are also observed in temperate regions of developing countries. The disease has various clinical presentations ranging from a mild influenza-like form to a severe potentially fatal illness accompanied by multi-organ failure. However, atypical presentations of leptospirosis have occasionally been described. Here, a case of leptospirosis presenting as thrombotic thrombocytopenic purpura (TTP) is reported. A 58-years-old male presented with fever, oliguria, darkening of urine, and visual hallucinations. Laboratory investigations revealed anaemia, severe thrombocytopaenia, elevated total bilirubin with indirect predominance, high lactate dehydrogenase, and increased urea (293 mg/dL) and creatinine (7.6 mg/dL) levels. He was diagnosed with TTP. Patient was thought leptospirosis due to atypical clinical manifestations. Leptospirosis was confirmed by strongly positive Microscopic Agglutination Test. Patient recovered completely with antibiotics and plasmapheresis. Leptospirosis may be accompanied by thrombotic thrombocytopenic purpura in particular subtropic regions.

Clinicopathologic and atypical features of naturally occurring leptospirosis in dogs: 51 cases (2000–2010)

To determine clinicopathologic features, percentage of atypical abnormalities, antibody titers against Leptospira serogroups, and importance of convalescent titers in dogs with leptospirosis. Retrospective case series. 51 dogs with leptospirosis. Criteria for inclusion were at least 1 positive microscopic agglutination test (MAT) result (titer ≥ 1:1,600 in vaccinated dogs, titer ≥ 1:800 in nonvaccinated dogs, or ≥ 4-fold increase in convalescent titer), a complete medical record (including leptospirosis vaccination date, reason for initial evaluation, and CBC, serum biochemical analysis, and urinalysis results), and clinical signs or laboratory findings consistent with leptospirosis. Initial clinical signs, temporal distribution, and signalment were similar to previous reports. Convalescent MAT titers were necessary for diagnosis in 45% of cases. Atypical abnormalities included radiographic evidence of pulmonary disease in 10 of 23 dogs and hepatic involvement alone in 7 of 51 dogs. Other abnormalities included proteinuria in 34 of 51 dogs, thrombocytopenia in 26 of 51, coagulopathy in 7 of 24 dogs, hypoalbuminemia in 14 of 51 dogs, and glucosuria in 9 of 51 dogs. Significant associations were found between antibodies against serogroup Grippotyphosa and renal involvement and serogroup Icterohaemorrhagiae and hepatic involvement. Increased awareness of atypical abnormalities may decrease misdiagnosis of leptospirosis in dogs. Results of concurrent infectious disease testing should be interpreted with caution; misdiagnosis of leptospirosis could pose a public health risk. Convalescent titers were necessary to identify infection when acute testing results were negative. Further research is needed to determine the true associations between antibodies against identified serogroups and clinical features.

Pancreatitis and myocarditis followed by pulmonary hemorrhage, a rare presentation of leptospirosis- A case report and literature survey

BackgroundLeptospirosis is a potentially fatal disease which can cause multi-organ dysfunction. It can rarely present as acute pancreatitis. This is the first ever report of leptospirosis presenting with acute pancreatitis and myocarditis followed by diffuse pulmonary hemorrhages to the best of our knowledge.Case presentationA 15-year-old South Asian boy presented with high grade fever, epigastric discomfort and was anicteric on admission. He developed tachycardia, transient hypotension, changes of electro-cardiogram and positive troponin I suggestive of myocarditis. Acute pancreatitis was diagnosed with 12 fold high serum amylase and with the evidence of computerized tomography. Then he developed diffuse pulmonary hemorrhages and later acute renal failure. Leptospirosis was confirmed by positive leptospira IgM, negative IgG and strongly positive Microscopic Agglutination Test. Other possible infective and autoimmune causes were excluded. Patient recovered completely with antibiotics and the supportive care.ConclusionThis case illustrates diagnostic difficulties especially in resource poor settings where leptospirosis is common. Additionally it highlights the fact that leptospirosis should be considered in patients presenting with pancreatitis which can be complicated with myocarditis and diffuse pulmonary hemorrhages. We hypothesize that Toll like receptors may play a role in such systemic involvement.

Risk factors of leptospirosis among febrile hospital admissions in northeastern Malaysia

BackgroundLeptospirosis is a worldwide zoonotic disease. Risk factors for the disease may vary among countries. ObjectiveThis study was conducted to determine the risk factors of leptospirosis among febrile cases. Materials and methodsA hospital-based cross-sectional study was conducted among 999 febrile patients admitted to 10 hospitals in northeastern Malaysia, from August 2010 to February 2011. An interviewer-guided proforma sheet on sociodemography, type of occupation and social history data was distributed to all adult patients with fever on admission. Serum sample for leptospirosis was screened by IgM Enzyme-linked Immunosorbent Assay (IgM ELISA) test and confirmed by Microscopic Agglutination Test (MAT). The cut-off point for positive MAT was ≥1:400 titer in single acute specimens. ResultsSeroprevalence of leptospirosis was 8.4% (95% CI: 6.8, 10.3) (n=84/999) by MAT. Multiple logistic regression analysis showed that the high risk occupation group (OR: 1.95, 95% CI: 1.22, 3.13) (p=0.005) and history of recent recreational activity (OR: 2.36, 95% CI: 1.46, 3.85) (p<0.001) were significant associated factors for leptospirosis. ConclusionThis study shows a relatively high seroprevalence of leptospirosis in northeastern Malaysia. Identification of high risk occupational group and history of recent recreational activity will help to increase the index of suspicion to diagnose leptospirosis among febrile inpatients due to its mimicking other common febrile illnesses in Malaysia.

A serological survey of leptospiral antibodies in dogs in New Zealand

AIM: To investigate the prevalence of titres to four endemic leptospiral serovars in dog sera from the lower half of the North Island, and the South Island of New Zealand submitted to diagnostic laboratories, and to explore the association between the prevalence of seropositive samples to leptospirosis and breed group, age group and sex. METHODS: Serum samples from 655 dogs residing in the central and lower North Island and from the South Island of New Zealand were sourced from the Massey University Veterinary Teaching Hospital and from submissions to New Zealand Veterinary Pathology in 2005. They were screened by the Microscopic Agglutination Test (MAT) against Leptospira interrogans serovars Copenhageni and Pomona and L. borgpetersenii serovars Hardjo and Ballum. Titres greater or equal to 96 were considered positive. Variables investigated for their association with the prevalence of seropositive samples to leptospirosis included serovar, breed, North vs. South Island, age and sex. RESULTS: Positive MAT titres to Leptospira interrogans serovar Copenhageni were found in 10.3 % of dogs (95% CI=8.1–12.9), and were more common than positive titres to other leptospiral serovars. Small breeds did not have a lower prevalence of Copenhageni titres than other breeds. Positive titres to Leptospira borgpetersenii serovar Hardjo were associated with breeds of dogs used as farm working dogs. There was no significant difference in the prevalence of positive leptospiral titres between dogs from the North or South Islands. Dogs greater than 12 years of age were less likely to have positive titres to Leptospira than younger dogs. No association was found between positive titres and sex. CONCLUSIONS: Breeds of dogs used as farm working were at greater risk of exposure to Leptospira borgpetersenii serovar Hardjo. Small breeds did not have a lower risk of seropositivity to Copenhageni than farm working breeds. Further study should be undertaken to confirm the prevalence of positive titres to leptospirosis in farm dogs and dogs resident in the South Island. CLINICAL RELEVANCE: The risk of dogs being exposed to Leptospira interrogans serovar Copenhageni, and requirement for vaccination against serovar Copenhageni, cannot be determined by geographical location or breed group. Vaccination against Leptospira borgpetersenii serovar Hardjo is likely to be beneficial in working dogs.

Spatial and spatio-temporal clustering of overall and serovar-specific Leptospira microscopic agglutination test (MAT) seropositivity among dogs in the United States from 2000 through 2007

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 246.5 km 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 (29–335 km 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.

An Emerging Pulmonary Haemorrhagic Syndrome in Dogs: Similar to the Human Leptospiral Pulmonary Haemorrhagic Syndrome?

Severe pulmonary haemorrhage is a rare necropsy finding in dogs but the leptospiral pulmonary haemorrhagic syndrome (LPHS) is a well recognized disease in humans. Here we report a pulmonary haemorrhagic syndrome in dogs that closely resembles the human disease. All 15 dogs had massive, pulmonary haemorrhage affecting all lung lobes while haemorrhage in other organs was minimal. Histologically, pulmonary lesions were characterized by acute, alveolar haemorrhage without identifiable vascular lesions. Seven dogs had mild alveolar wall necrosis with hyaline membranes and minimal intraalveolar fibrin. In addition, eight dogs had acute renal tubular necrosis. Six dogs had a clinical diagnosis of leptospirosis based on renal and hepatic failure, positive microscopic agglutination test (MAT) and/or positive blood/urine Leptospira-specific PCR. Leptospira could not be cultured post mortem from the lungs or kidneys. However, Leptospira-specific PCR was positive in lung, liver or kidneys of three dogs. In summary, a novel pulmonary haemorrhagic syndrome was identified in dogs but the mechanism of the massive pulmonary erythrocyte extravasation remains elusive. The lack of a consistent post mortem identification of Leptospira spp. in dogs with pulmonary haemorrhage raise questions as to whether additional factors besides Leptospira may cause this as yet unrecognized entity in dogs.

DISTRIBUIÇÃO DE ANTICORPOS PARA Leptospira sp EM BÚFALOS (Bubalus bubalis) DA REGIÃO NORDESTE DO ESTADO DO PARÁ, BRASIL

This study investigates the occurrence of leptospirosis in buffaloes (Bubalus bubalis) from the northeast region of Para, Brazil. Sera samples from 127 animals were tested by microscopic agglutination test (MAT) with live antigens using reference strains of 24 different leptospiral serovars, which was carried out in the Laboratory of Bacterial Zoonosis (FMVZ/USP). Positive MAT titres (between 100 and 3,200) were found. A total of 67,72% of samples were reactive to one or more Leptospira spp. serovars, of which serovar Hardjo genotype hardjioprajitno was the most common (15,75%), followed by serovars grippotyphosa, pomona (11,81% each), and wolffi (7,09%). Research findings were very similar to those of other studies in Brazil, although some differences were observed as regards predominant serovars in buffaloes. We conclude that the prevalence of Leptospira spp. in the herds studied is probably due to the region's climate, which facilitates the spread of bacteria.

Evaluation of surveillance case definition in the diagnosis of leptospirosis, using the Microscopic Agglutination Test: a validation study

BackgroundLeptospirosis is endemic in both urban and rural areas of Sri Lanka and there had been many out breaks in the recent past. This study was aimed at validating the leptospirosis surveillance case definition, using the Microscopic Agglutination Test (MAT).MethodsThe study population consisted of patients with undiagnosed acute febrile illness who were admitted to the medical wards of the Teaching Hospital Kandy, from 1st July 2007 to 31st July 2008. The subjects were screened to diagnose leptospirosis according to the leptospirosis case definition. MAT was performed on blood samples taken from each patient on the 7th day of fever. Leptospirosis case definition was evaluated in regard to sensitivity, specificity and predictive values, using a MAT titre ≥ 1:800 for confirming leptospirosis.ResultsA total of 123 patients were initially recruited of which 73 had clinical features compatible with the surveillance case definition. Out of the 73 only 57 had a positive MAT result (true positives) leaving 16 as false positives. Out of the 50 who didn't have clinical features compatible with the case definition 45 had a negative MAT as well (true negatives), therefore 5 were false negatives. Total number of MAT positives was 62 out of 123. According to these results the test sensitivity was 91.94%, specificity 73.77%, positive predictive value and negative predictive values were 78.08% and 90% respectively. Diagnostic accuracy of the test was 82.93%.ConclusionThis study confirms that the surveillance case definition has a very high sensitivity and negative predictive value with an average specificity in diagnosing leptospirosis, based on a MAT titre of ≥ 1: 800.