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Histopathologic evaluation of livers of pregnant hamsters infected with Leptospira canicola.

Pregnant hamsters were inoculated with Leptospira canicola by an intraperitoneal route. Grossly, the livers were enlarged and pale yellow. On light microscopic examination, disruption of the hepatic cords, as well as granulation of hepatocyte cytoplasm, was evident. On electron microscopic examination, the livers had evidence of severe cellular degradation as early as post-inoculation hour (PIH) 24. At PIH 96, pathologic changes were more pronounced. The rough endoplasmic reticulum was swollen and there was membrane disruption. These changes were not observed in the livers of control animals. In addition, livers of the fetuses at PIH 72 exhibited severe degenerative changes.

Animals↗

Characterization of the outer membrane proteome of Leptospira interrogans expressed during acute lethal infection.

Pathogenic Leptospira species adapt to a wide range of environmental conditions during disease transmission and infection. While the proteome of in vitro cultivated Leptospira has been characterized in several studies to date, relatively little is known of the proteome as expressed by Leptospira during disease processes. Isolates of Leptospira obtained from patients suffering the severe pulmonary form of leptospirosis cause acute lethal infection in guinea pigs and chronic asymptomatic infection in rats. Recent studies have demonstrated that protein and lipopolysaccharide constituents of Leptospira recovered from acutely infected guinea pig tissue differ from that of Leptospira in chronically infected rat tissue and in vitro cultivated Leptospira (J. E. Nally, E. Chow, M. C. Fishbein, D. R. Blanco, and M. A. Lovett, Infect. Immun. 73:3251-3260, 2005). In the current study, the proteome of Leptospira expressed during disease processes was characterized relative to that of in vitro cultivated Leptospira (IVCL) after enrichment for hydrophobic membrane proteins with Triton X-114. Protein samples were separated by two-dimensional gel electrophoresis, and antigens expressed during infection were identified by immunoblotting with monospecific antiserum and convalescent rat serum in addition to mass spectrometry. Results suggest a significant increase in the expression of the outer membrane protein Loa22 during acute infection of guinea pigs relative to other outer membrane proteins, whose expression is generally diminished relative to expression in IVCL. Significant amounts of LipL32 are also expressed by Leptospira during acute infection of guinea pigs.

Adaptation, Physiological↗

Leptospira interrogans serovar grippotyphosa infection in dogs.

Leptospirosis attributed to infection with serovar grippotyphosa was diagnosed in 11 dogs. In naturally and experimentally infected dogs, a stereotypic serologic response to infection with Leptospira serovar grippotyphosa was detected. Although the highest serum antibody titers developed against serovar grippotyphosa, most dogs also had lower titers against serovars bratislava and pomona. Acute renal failure was evident in 10 dogs. One dog died prior to initiation of treatment; the remaining 10 dogs were treated with antibiotics and fluids. Two dogs were euthanatized, 2 dogs recovered without clinical or biochemical evidence of residual renal dysfunction, and 6 dogs recovered but had varying degrees of renal insufficiency. Hepatic involvement appeared to be a minor component of the disease in these dogs. Our results indicate that Leptospira serovar grippotyphosa infection is an important problem in dogs and should be considered when evaluating a dog with renal failure.

Acute Kidney Injury↗

Evaluation of usefulness of 2-mercapto-ethanol treatment in serodiagnosis of swine leptospirosis.

Serum samples of piglets infected artificially or naturally, respectively, with Leptospira pomona were treated with 2-mercapto-ethanol (ME) and tested in the microscopic agglutination test in comparison with untreated sera. Serum-treatment with ME showed two beneficial effects, one being the total elimination of heterotypic reactions, the other the reduction or elimination, respectively, of early antibodies, presumably belonging to the IgM class. Accordingly, two practical implications can be derived from our results. The ratio of ME-sensitive and ME-resistant antibody titers allows the recognition of early leptospira infections. The total suppression by ME of heterotypic agglutination eliminates the danger of determining the wrong leptospira type as causative agent, a crucial problem encountered not infrequently with agglutination testing of untreated sera. Recognition of early cases of swine leptospirosis by ME-treatment of sera is particularly useful, as the complement fixative reaction, successfully used in other species for the same purpose, is inappropriate in swine sera owing to their autolytic properties. Furthermore by elimination of all heterotypic reactions the ME-method gives better chances for the determination of the causative agent and hence for correct interpretation of serological results. ME-treatment is considered as a useful help in serodiagnosis of field samples, in which determination of duration of infection is essential or in which heterotypic agglutination is obscuring the etiological leptospira type.

Agglutination Tests↗

Serovar-specific prevalence and risk factors for leptospirosis among dogs: 90 cases (1997-2002).

OBJECTIVE: To estimate serovar-specific prevalence of leptospirosis by use of veterinary teaching hospital and laboratory submission data; describe annual and seasonal patterns of leptospirosis; and identify risk factors for age, sex, and breed. DESIGN: Retrospective study. ANIMALS: 90 dogs with leptospirosis. PROCEDURES: Hospital records of dogs examined at Purdue University Veterinary Teaching Hospital with a diagnosis of leptospirosis and laboratory records of dogs from which sera were tested for antibodies against Leptospira spp at Purdue University Animal Disease Diagnostic Laboratory from 1997 through 2002 were reviewed. The likely infecting Leptospira serovar was identified. Seasonal and annual prevalences were calculated by use of hospital population at risk (hospital cases) or serologic testing submissions (diagnostic laboratory cases). Age-, sex-, and breed-specific risk factors for hospital cases were estimated by odds ratios. RESULTS: Of the 39 hospitalized dogs identified, 34 had been serologically tested, and 22 of those were infected with Leptospira kirschneri serovar grippotyphosa. Of the 51 diagnostic laboratory cases, 59% had a reciprocal titer > or = 800 against serovar grippotyphosa. Diagnostic laboratory cases were more common in summer, whereas hospital cases of leptospirosis were more common in fall. Male dogs were at significantly greater risk of leptospirosis than female dogs; and dogs 4 to 6.9 years old were at significantly greater risk than dogs < 1 year old. CONCLUSIONS AND CLINICAL RELEVANCE: L kirschneri serovar grippotyphosa infection was associated with most cases of leptospirosis in dogs. Use of an effective vaccine that includes this serovar is advisable for dogs at risk of leptospirosis.

Age Factors↗

[Epidemiology of leptospirosis in a livestock production area of the Andes].

A cross-sectional study was conducted to estimate the prevalence of Leptospira infection in populations of workers, cattle, and pigs in livestock operations and to explore some environmental and production system variables associated with seropositivity. The research was done between November 1997 and February 1998 in the municipality of Don Matías, in the northern part of the department of Antioquia, Colombia. The area has a cold climate, and there is a "pigs-grasses-milk" production system that utilizes pig dung to fertilize grazing pastures. A total of 23 farms were studied, and blood samples were obtained from 67 dairy and pig-raising workers, 174 dairy cows, 68 pigs for fattening, and 214 pigs for breeding. The microagglutination test (MAT) was used for six Leptospira serotypes. The seropositivity prevalence was 22.4% among the workers (95% confidence interval: 13.1% to 34.2%), 60.9% among the dairy cows (95% CI: 53.2% to 68.2%), 10.3% in the fattening pigs, and 25.7% in the breeding pigs. Four logistic regression models were constructed to identify the variables that predicted infection in the workers and in the dairy cows. A high prevalence of infection with Leptospira (serotypes pomona, bratislava, and hardjo) was found in this production system, where conditions are favorable for transmitting this microorganism to the different animal species and to humans.

Adult↗

Leptospirosis renal disease.

Leptospirosis is a re-emerging infectious disease, affecting both animals and humans worldwide. Multiple organ involvement may be encountered in leptospirosis, and early renal involvement is very common, characterized by tubulo-interstitial nephritis and tubular dysfunction. All 12 patients diagnosed in Chang Gung Memorial Hospital (Taiwan) between 1997 and 1999 had acute renal failure, with five patients requiring dialysis. Leptospira shermani is the main serovar encountered in Taiwan, and penicillin may dramatically rescue patients from multiple organ failure provided it is given early. To understand the mechanism behind tubular injuries by leptospira infection, outer membrane proteins (OMPs) extracted from pathogenic leptospira were given to tubular cells in culture. Our in vitro experiment showed that OMPs of pathogenic leptospira activate nuclear NFkappaB binding and stimulate downstream inducible nitric oxide (iNOS), monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-alpha) expression. These results indicate that leptospiral infection may induce tubulo-interstitial nephritis through a toxic component in the outer membrane followed by expression of inflammatory genes.

Acute Kidney Injury↗

Antibody isotypes in sera of equine fetuses aborted due to Leptospira interrogans serovar pomona-type kennewicki infection.

Leptospira-specific antibody isotypes in sera of late term equine fetuses aborted due to Leptospira interrogans serovar pomona-type kennewicki infection were characterized and compared with those of their dams. IgM was the dominant Leptospira-Specific isotype in both fetuses and mares. However, IgGa was the isotype in highest concentration in petal sera and strong Leptospira-specific IgGa but no IgGb and little or no IgG(T) were detected. In contrast, although IgGb was quantitatively the dominant isotype in mares serum, Leptospira-specific serum IgG in aborting mares was dominated by IgG(T) but also included large amounts of IgGa and IgGb. IgGa and IgGb were quantitatively the dominant isotypes in sera of fetuses and mares, respectively. Affinity purified IgGa from fetuses did not agglutinate leptospires but serum devoid of IgGa did, suggesting that IgM is the principal agglutinating antibody. It is concluded that the equine fetus is deficient in IgGb and IgG(T) synthesis.

Abortion, Veterinary↗

Leptospirosis in Kuala Lumpur and the comparative evaluation of two rapid commercial diagnostic kits against the MAT test for the detection of antibodies to leptospira interrogans.

The aim of the study was to look into the epidemiology of serodiagnosed cases of leptospirosis at the University Hospital and compare two commercial ELISA Assays to the Microscopic Agglutination Test (MAT). Demographic data for all serodiagnosed cases for the years 1991-1997 were collected. From this data, 104 sera (n = 104) were selected as samples for comparative evaluation of the commercial ELISAs (INDX Dip-S-Ticks and PanBio ELISA) to the MAT test. Thirty two (n = 32) negative control sera were selected from serodiagnosed cases of other differential diagnosis of leptospira infection. The MAT test is a standard test that detects agglutination antibodies to leptospira biflexa, while the INDX Dip-S-Ticks is an ELISA dot test assaying for total anti-leptospira antibodies. The PanBio ELISA is a colorometric assay in test well strips to detect anti-leptospira IgM. The sensitivity, specificity, and efficiency of tests were calculated at a MAT cut-off value of 1:320. Demographic data showed that leptospirosis peaks during March-May and Aug-Nov coinciding with the inter-monsoon period with more men being infected than women and more adults than children. The sensitivity, specificity, and efficiency of test for the INDX Dip-S-Ticks were 83.3%, 93.8% and 87.5% while the values for the PanBio ELISA were 54.2%, 96.9% and 71.3%. The suboptimal PanBio result could be related to the blocking effect of high IgG titres or could be related to the diagnostic MAT cut-off values used in this study. The data hence reflects a pattern of transmission that is related to "wet" occupational risk factors. The commercial assays evaluated, are easier to perform but interpretation of results should be based on level of endemicity. The INDX Dip-S-Ticks allows this flexibility and is a practical alternative to the MAT test.

Adult↗

Evaluation of environmental risk factors for leptospirosis in dogs: 36 cases (1997-2002).

OBJECTIVE: To identify environmental risk factors for leptospirosis. DESIGN: Retrospective study. ANIMALS: 36 dogs with leptospirosis and 138 dogs seronegative for leptospirosis as determined by microscopic agglutination test for antibodies against Leptospira spp. PROCEDURES: Medical records of dogs evaluated for leptospirosis from 1997 though 2002 were identified. Owner address was used to geocode locations of dogs, and location-specific environmental risk factor data were obtained by use of a geographic information system. Risk of leptospirosis was estimated by odds ratios, controlling for potential confounding by dog age, sex, and breed. RESULTS: Leptospirosis in 19 of the 30 dogs in which an infecting Leptospira serovar could be identified was associated with Leptospira kirschneri serovar grippotyphosa infection. Dogs in which a diagnosis of leptospirosis was made, and dogs with leptospirosis caused by L kirschneri serovar grippotyphosa, were more likely to have addresses located in areas classified as rural in 1990 but urban in 2000. By use of information on recent urbanization and a logistic regression model, the status of 81.6% and 89.8% of dogs with leptospirosis and leptospirosis caused by serovar grippotyphosa, respectively, were correctly classified. Other environmental variables (proximity to streams, recreational areas, farmland, wetlands, areas subject to flooding, and areas with poor drainage; annual rainfall; and county cattle or pig population) did not significantly improve accuracy of classification. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs in periurban areas are at greater risk of leptospirosis. Vaccination of dogs in these areas to protect against leptospirosis should be considered.

Animals↗

Serological study of leptospiral infections and endogenous uveitis among horses and ponies in the United Kingdom.

The prevalence of antibody titres to a range of 20 leptospira antigens in the serum of horses and ponies with no ophthalmic abnormalities and with ophthalmoscopic evidence of endogenous uveal inflammatory disease was determined using a microscopic agglutination technique. Titres against leptospira antigens were observed in 13 out of 138 (9.1 per cent) animals with no ophthalmic abnormalities, and in three out of 27 (11.1 per cent) animals with anterior uveitis. Serovar sejroe was common to all seropositive animals with anterior uveitis. The results show that leptospira infection is not a major factor in the aetiology of equine anterior uveitis in the UK, but suggests that the organism may be associated with some cases of recurrent anterior uveitis.

Animals↗

[The noncorrespondence of the geographic ranges of the host and the causative agent].

For the first time the experimental and field studies of Leptospira infections, carried out over the period of 6 years, have revealed that the habitat of striped field mice (Apodemus agrarius Pallas 1778) serving as a host for Leptospira pomona, serovar mozdok, is much wider than the habitat of the infective agent proper. The presence of an animal species highly sensitive to a definite leptospiral serovar and serving as its reservoir at a given locality cannot be regarded as a proof of the presence of the epizootic process without bacteriological confirmation. But, in the absence of homologous Leptospira carriage, intensive leptospiral seroconversion can be attributed to a population other than that of the host.

Animals↗

Leptospirosis.

Equine clinical leptospirosis has been primarily related to uveitis and the often recurrent sequelae of ocular changes. Reports of equine hepatic and renal involvement are sporadic. More recently, serovar bratislava has been identified as a host-adapted serovar in the horse. More significantly, reports of equine abortion and stillbirth have become more frequent in the literature. This is more than likely a result of improved diagnostic techniques, not of increased prevalence of disease. In addition to abortion, equine neonatal disease is becoming more frequently recognized in association with leptospira infection. Whether leptospiral infection results in abortion or diseased foals may depend upon the stage of gestation when the mare is exposed and host immune status. Antibiotic of choice for treatment of equine leptospirosis remains speculative, as specific equine studies have not been performed. Extrapolation from other species suggests that the use of streptomycin remains a good choice of therapy for the chronic shedding state and may be used in combination with other antimicrobials for treatment of acute disease. Penicillin or potentiated penicillins and tetracycline at appropriate to high end dosages are logical choices for the treatment of acute leptospirosis.

Abortion, Veterinary↗

[Observation on the antigenic affinity of Leptospira and Brucella in the serological examination of cattle].

36,9% bovine serums which showed a non-specific reaction in examination for brucellosis had titre greater than or equal to 1:400 leptospirosis agglutinins. 15.1% of the serums showed a positive reaction (greater than 1:800), mostly those against L. sejroe and L. grippotyphosa. The cross reactions, found in individual cases within up to 39 days since the first reaction to brucellosis in cattle may signalize early Leptospira infections.

Agglutination Tests↗

LipL32, an outer membrane protein of Leptospira, as an antigen in a dipstick assay for diagnosis of leptospirosis.

Microscopic agglutination test (MAT), as well as other serological assays that aimed at detecting antibodies to Leptospira, supplements the leptospirosis diagnosis based on the clinical features. Nevertheless, false positive results have been occasionally reported when the crude antigen was used in those antibody-based tests due either to the presence of antibodies stimulated by other antigenically related pathogens in the patient's serum, or the antibodies in the serum may be stimulated by a previously unrecognized Leptospira infection, especially in the disease endemic areas. Thus, the more refined antigen should improve the serodiagnostic accuracy. Among Leptospira spp., LipL32, which is a pathogenic Leptospira outer membrane protein (OMP), expressed by the bacteria grown both in vitro and in vivo. In this study, recombinant LipL32 protein was tested by a dipstick method for its potential in serodiagnosis of leptospirosis. Preliminary results suggest that the recombinant LipL32 is a good diagnostic detection reagent for specific Leptospira IgG. Diagnostic sensitivity and specificity of the Lip32 dipstick assay, when compared to those of MAT, were 100% and 98.33%, respectively.

Agglutination Tests↗