Seroprevalence and association with abortion of leptospirosis in cattle in Ontario.

Sera were collected using a systematic random sampling from 348 cattle herds in Ontario, in proportion to the cattle population in different areas. One cow in five from 296 dairy herds and one in three from 52 beef herds were sampled. The sera were analyzed for prevalence of antibodies to Leptospira interrogans serovar grippotyphosa, hardjo, icterohaemorhagiae and pomona using the microscopic agglutination test. Herd seroprevalence (one or more animals with titer greater than or equal to 80) in beef and dairy herds combined was grippotyphosa 2%, hardjo 13.8%, icterohaemorrhagiae 10.1% and pomona 25.8%; 39% of all herds showed evidence of leptospiral infection with one or more serovars; 44.2% of 52 beef herds had serological evidence of infection with serovar hardjo compared to 8.4% of 296 dairy herds (P less than 0.0001). Seroprevalence of other serovars was not significantly different between beef and dairy herds. The proportion of beef animals seropositive for hardjo and for pomona increased with age, particularly for hardjo; 26.5% of beef animals aged nine years or over were seropositive for hardjo. Dairy animals showed a significant rise of hardjo but not pomona titers with age. The seroprevalence of pomona infection was significantly higher in dairy cattle in eastern Ontario than in other regions. Thirty-four (6.1%) of 553 aborted bovine fetuses had leptospires detected by immunofluorescence techniques. Sixty-five percent of these fetuses were from submissions made between November and January. Leptospires were identified as serovar hardjo by specific immunofluorescence. There appeared, however, to be a paradoxical serological response in that eight aborting cows had antibody titers to pomona rather than hardjo.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bovine abortion associated with Leptospira interrogans serovar hardjo infection

During 1981, 265 bovine abortions were investigated by serological and histological methods for evidence of leptospiral infection. Leptospires were demonstrated in the tissues of 10 foetuses by a Levaditi silver impregnation technique. Serological testing of maternal sera indicated that Leptospira interrogans serovar hardjo was associated with 5 of the abortions while the remaining 5 were due to L. interrogans serovar pomona infection. In cases of abortion associated with L. interrogans serovar hardjo leptospires were readily demonstrated in foetal liver, kidney, intestine and heart. They were demonstrated less often in lung and placenta and could not be found in foetal brain. Autolysis did not appear to interfere with the demonstration of leptospires by silver impregnation. No lesions attributable to leptospiral infection were seen in placentas but mild interstitial nephritis was found in some of the foetuses. Fourteen other cows had serological evidence of recent leptospiral infection but leptospires were not detected in foetal tissues. Histological examination of silver impregnated foetal tissues in combination with the microscopic agglutination test was shown to be an effective method for diagnosing abortion associated with L. interrogans serovar hardjo in cattle.     

Experimental infection of lactating goats with Leptospira interrogans serovars pomona and hardjo

Pathogenesis of Leptospira interrogans serovars pomona and hardjo was evaluated in 14 lactating goats. Although mild clinical signs of leptospiral infection characterized by pyrexia and reduction in milk yield appeared in some animals, a consistent clinical pattern was not observed in the inoculated animals. The pomona serovar was isolated from the kidney of 1 of the 4 goats inoculated with serovar pomona. The hardjo serovar (strain UI 750) was isolated in the rabbit serum-supplemented bovine albumin polysorbate-80 liquid medium only from the mammary gland of 1 of 4 goats at 13 days after inoculation with serovar hardjo. The positive culture was detected after an 8-month incubation period.     

Leptospirosis associated with serovars hardjo and pomona in red deer calves (Cervus elaphus)

Four red deer calves (Cervus elaphus) died with severe nephritis apparently associated with infection by Leptospira interrogans serovar pomona. The sera of 12 in-contact red deer calves were examined for leptospiral agglutinins and nine showed titres to pomona consistent with recent infection. Two also showed titres of 1:100 to serovar hardjo. The urine of five of these in-contact calves was examined periodically over a period of nine months. All were initially leptospiruric, four being infected with pomona and one with hardjo. In four animals leptospiruria could only be detected for up to six months, but one animal infected with pomona was leptospiruric for at least eight months. The apparent source of infection was from infected cattle, and it is suggested that deer are unlikely to act as maintenance hosts for serovar pomona.     

Prevalence of antibodies of Leptospira serovars in beef cattle in central Queensland.

OBJECTIVE: To obtain up-to-date data on the prevalence of antibodies to Leptospira serovars in central Queensland beef herds preliminary to assessing their role in bovine subfertility and the role of cattle as a zoonotic reservoir. DESIGN: Sera from 2857 female cattle in 68 central Queensland beef herds were tested for antibodies to 14 Leptospira serovars using the microscopic agglutination test. Vaccination use and age of cattle were collected to enable the calculation of crude and age-stratified seroprevalences. RESULTS: The most commonly detected antibodies were to serovars hardjo (15.8% crude seroprevalence), tarassovi (13.9%), pomona (4.0%) and szwajizak (2.2%). Vaccinates were omitted from the hardjo and pomona seroprevalence data. The seroprevalence for hardjo and pomona tended to increase with age of the animals. CONCLUSION: These results are broadly similar to those of previous serological surveys. The data suggest that serovars other than hardjo, pomona and tarassovi, are unlikely to have a significant role in bovine subfertility and that cattle are unlikely to be a source of human infection with them in central Queensland.     

Development and initial evaluation of an indirect enzyme-linked immunosorbent assay for the detection of Leptospira interrogans serovar hardjo antibodies in bovine sera.

Outer sheath antigen from Leptospira interrogans serovar hardjo type hardjoprajitno and acetic acid extracted antigens from serovar hardjo types hardjoprajitno and hardjobovis were evaluated in an immunoassay for ability to detect hyperimmune rabbit serum to serovar hardjo. The degree of cross-reactivity with hyperimmune rabbit sera to L. interrogans serovars pomona, copenhageni, grippotyphosa, canicola and sejroe, and Leptospira biflexa serovar patoc was also measured for each antigen. All of the antigens reacted with the antiserum to L. interrogans serovar hardjo. The outer sheath antigen however, also showed wide cross-reactivity with the antisera to all of the serovars of L. interrogans tested and with the antiserum to L. biflexa serovar patoc. The acetic acid extracted antigen from either type hardjoprajitno, or type hardjobovis, showed a high degree of specificity for serovar hardjo antiserum. The hardjobovis acetic acid extracted antigen was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting, and was incorporated into an indirect ELISA for detection of anti-serovar hardjo antibodies in bovine serum. This ELISA showed a relative specificity of 100% with 156 bovine sera which were negative at a dilution of 1:100 in the microscopic agglutination test (MAT) for L. interrogans serovars hardjo, pomona, sejroe, icterohaemorrhagiae, copenhageni, canicola, and grippotyphosa. The relative sensitivity of this assay with 192 bovine sera which had serovar hardjo MAT titres of > or = 100 was 95.3% (95% confidence limit = 2.99%). The degree of cross-reactivity with 289 bovine sera which had serovar pomona MAT titres of > or = 100 (with no detectable serovar hardjo MAT titres) was approximately 1.0%. This assay was: easily standardized, scored objectively, repeatable, semi-automated and used a non-hazardous antigen that can be routinely prepared in gram amounts.     

Haemolytic disease associated with Leptospira interrogans serovar pomona in red deer calves (Cervus elaphus)

Three red deer calves (Cervus elaphus) died with a haemolytic disease associated with infection by Leptospira interrogans serovar pomona. Infection within the herd was more prevalent than disease. Sera from 16 herd mates were tested by the microscopic agglutination test (MAT) and 12 had leptospiral titres, the majority to serovar pomona. A few calves had titres to balcunica and hardjo. Urine was obtained for culture from six of these calves and serovar pomona was isolated from five with titres to pomona, and hardjo from one with a titre to hardjo but not pomona. A fourth calf died with severe nephritis but a diagnosis of leptospirosis was not confirmed in this case.     

Leptospirosis: I. Clinical investigation of the infection in dairy cattle in the Waikato district of New Zealand

An investigation was made into the prevalence of leptospiral infection in cattle. An area 50 km radius was selected in a region where leptospirosis was reputedly common. Farmers volunteered 250 herds with 39 500 cows for testing and 7 500 animals were selected and sampled. Twenty-nine cows (0.4%) on 14 (5.6%) of the farms had leptospiruria at the first examination. Leptospirae were cultured from the urines of nine of these animals and all were Leptospira interrogans serovar hardjo. Serologically 12.5% of cows had titres of 1:200 or greater to hardjo and 3.5% titres of 1:200 or greater to pomona. In the Spring of 1977, there was evidence of clinical leptospirosis in calves associated with only one of the herds and no clinical leptospirosis in the 250 lactating herds, although leptospiral titres were found in 88% of them. This indicated that clinical disease was much less common than infection. We concluded that leptospirosis was of minor economic importance in dairy cattle, although it could be significant in individual herds, and a health hazard to farm workers.     

The efficacy of a Leptospira interrogans serovars pomona and copenhageni and L. borgpetersenii serovar hardjo vaccine in cattle

An experimental, trivalent, bovine, leptospiral vaccine, containing inactivated Leptospira interrogans serovars pomona and copenhageni and L. borgpetersenii serovar hardjo Hardjobovis, was developed. The experimental vaccine was shown to protect hamsters against virulent challenge with each of the component serovars. In a serological efficacy test in cattle, the experimental vaccine was compared for bioequivalence with a similar product, registered in New Zealand for veterinary use. The experimental vaccine induced higher titres in cattle than the latter mentioned product.     

Development of a monoclonal antibody-based competitive enzyme-linked immunosorbent assay for the detection of Leptospira borgpetersenii serovar hardjo type hardjobovis antibodies in bovine sera.

A murine monoclonal antibody (designated M553) that binds to an epitope on whole cell antigens prepared from Leptospira borgpetersenii serovar hardjo type hardjobovis and Leptospira interrogans serovar hardjo type hardjoprajitno, was produced and incorporated into a competitive enzyme-linked immunosorbent assay for the detection of bovine antibodies to serovar hardjo. The epitope recognized by M553 was susceptible to periodate oxidation. The M553 antibody was characterized by western blot with hardjobovis whole cell antigen. This antibody does not cross-react with whole cell antigens prepared from 11 other pathogenic Leptospira serovars, or, Leptospira biflexa serovar patoc. The sensitivity estimate of the competitive ELISA was 100% with field sera (n = 165) with serovar hardjo microscopic agglutination test (MAT) titres of > or = 100. The specificity estimate was 100% with sera (n = 128) obtained from a specific pathogen free herd of cattle that were negative in the MAT at a dilution of 1:100 for serovars hardjo, pomona, sejroe, copenhageni, canicola, and grippotyphosa. The specificity estimate with field sera (n = 301) with serovar hardjo MAT titres of < 100, was 98% (95% confidence interval = +/- 1.58%). There was no cross-reactivity with field sera (n = 306) with serovar pomona titres > or = 100 and serovar hardjo titres < 100. The specificity estimate with the combined populations of sera with serovar hardjo MAT titres of < 100 (n = 735) was 99.18% (95% confidence interval = +/- 0.65%). There was a high level of agreement (kappa = 0.977) between the results of the competitive ELISA and those of the MAT.     

Isolation of leptospires from nephritic kidneys of beef cattle at slaughter

Of 955 beef cattle slaughtered at an abattoir in Quebec from May to August 1985, 122 (13%) had lesions of focal interstitial nephritis. Nephritic kidneys were collected for leptospiral culture, and matching blood samples were examined serologically. Leptospires were isolated from the kidneys of 35 (29%) cattle. Antibodies to Leptospira interrogans serovar hardjo were found in 29 (24%) cattle and to pomona in 13 (10%).     

THE PREVALENCE OF ANTIBODIES TO MEMBERS OF LEPTOSPIRA INTERROGANS IN CATTLE

A total of 1,355 random samples taken from bovine serums submitted for brucellosis testing in Victoria were submitted to the microscopic agglutination test for the presence of antibody to 12 serovars of Leptospira interrogans . The most common reaction obtained was to serovar hardjo , although the percentage of reactors varied from 24.8% in the metropolitan area to 56.3% in north-eastern Victoria (mean 40.6%). A total of 86.3% of farms from which 3 or more samples were taken had at least one reactor to serovar hardjo . The prevalence of antibody to other serovars was tarassovi (7.8% of reactors), ballum (3.7%), pomona (2.4%), autumnalis (1.8%) and bataviae (1.2%). Reactions to other serovars were observed in serums of less than 1% of cattle tested; serums from 50.8% of cattle did not react to any antigen.     

A serosurvey for antibodies to Leptospira in dogs in the lower North Island of New Zealand

AIMS: To investigate the prevalence of antibodies to endemic and exotic Leptospira serovars in samples from a serum bank, collected from dogs in the lower North Island of New Zealand. METHODS: Sera (n=466), which had been collected from apparently healthy dogs, were screened using the microscopic agglutination test (MAT) for antibodies to serovars L. borgpeterseni serovar hardjo, L. interrogans serovars pomona, copenhageni and canicola, and L. kirschneri serovar grippotyphosa. RESULTS: Antibody to Leptospiral antigen was found in 14.2% of dogs tested. The highest level of reactivity was with serovar copenhageni, to which 9.5% (41/433) of sera were positive. Antibodies to serovars grippotyphosa and canicola were not detected in this population of dogs. CONCLUSIONS: Leptospira infection is relatively common in dogs in the lower North Island . CLINICAL RELEVANCE: Vaccination of dogs against leptospirosis should be considered using vaccine containing antigen to serovars hardjo, pomona and copenhageni. The presence of moderate levels of copenhageni antibody in dogs in the lower North Island raises the possibility that this serovar has become established in rodent populations in this region.     

The significance of leptospiral titres associated with bovine abortion

To investigate relationships between serological titres to 2 serovars, pomona (L. pomona) and hardjo (L. hardjo), of Leptospira interrogans and abortions, log linear and logit models were fitted to herd and individual cow data from cattle serologically negative for brucellosis. Serological titres to both serovars were significantly related to abortions in individual cows, with L. pomona having a stronger relationship than L. hardjo. L. hardjo was not significant when herd data were analysed. Differences between dairy and beef cattle in the serological titres found to both L. pomona and L. hardjo were detected when data sets of all cattle or cattle with no history of abortion were analysed. The beef/dairy differences may be due to different management practices and/or to different geographical distributions of both serovars and populations of beef and dairy cattle. If there are no cattle in a herd with a reciprocal titre of 3000 or greater for L. pomona, it is unlikely that L. pomona is associated with the abortion problem. There was no specific L. hardjo titre which separated high and low probabilities that the serum came from a cow or herd with an abortion history.     

Survey to estimate prevalence of Leptospira interrogans infection in mature cattle in the United States.

A total of 5,142 kidney tissue samples and 5,111 serum samples from mature cattle in 49 states and Puerto Rico were collected at slaughter. Age of cattle ranged from 1 to 16 years (mean, 6.6 years). Leptospires were isolated from 88 (1.7%) kidney tissues, and 2,493 (49%) sera contained antibodies against 1 or more of 12 Leptospira interrogans serovars. Leptospires were observed by immunofluorescence in 41 (0.8%) kidney tissues. Using agglutinin-absorption tests, 73 (83%) isolates were identified as serovar hardjo, 11 (12.5%) as serovar pomona, and 4 (4.5%) as serovar grippotyphosa. By use of restriction endonuclease analysis studies of chromosomal DNA, all isolates differed from reference serovars but were identical to strains previously isolated from cattle or swine in the United States. Of the serovar hardjo isolates, 85% were identical to restriction endonuclease analysis type (genotype) hardjo-bovis A and 11 (15%) were identical to genotype hardjo-bovis B. Serovar pomona isolates were identical to genotypes kennewicki A (64%) or kennewicki B (36%), and serovar grippotyphosa isolates were identical to the RM 52 strain. Isolation rates were significantly (P less than 0.001) higher for beef cattle than for dairy cattle and were higher (P less than 0.001) for bulls than for cows. Combined culture and immunofluorescence results indicated that 2% of mature cattle were renal carriers of leptospires.     

Serological reactions to Leptospira species in game animals of northern Natal

Fifty sera collected from 12 different species of free-living game animals in game parks in the Northern Natal were tested against 8 Leptospira interrogans antigens using the microscopic agglutination test (MAT). Six out of 50 animals had titres, all less than 100. Three of these animals had titres to serovar mini, 1 animal to tarrasovi, and 3 animals had multi-serovar reactions, 1 to mini and hardjo, and 1 to tarrasovi, copenhageni and pomona.     

Monoclonal antibodies to Leptospira interrogans serovar pomona.

Three monoclonal antibodies produced against Leptospira interrogans serovar pomona have been studied for their diagnostic usefulness. All three monoclonals reacted strongly in the enzyme-linked immunosorbent assay and indirect fluorescent antibody test with serovar pomona and did not react with serovars grippotyphosa, canicola, icterohaemorrhagiae and hardjo.     

Diagnostic specificity, sensitivity and cross-reactivity of an enzyme-linked immunosorbent assay for the detection of antibody against Leptospira interrogans serovars pomona, sejroe and hardjo in cattle.

Outer sheath antigen was prepared from Leptospira interrogans serovars pomona, sejroe and hardjo by treating the organisms with 1.0M NaC1 followed by 0.04% sodium dodecyl sulfate (SDS). Sodium dodecyl sulfate was removed from the SDS-protein complexes by the extraction of dodecyl sulfate anions as ion pairs with triethylammonium cations into an organic solvent. The outer sheath antigen was recovered from the organic solvent as a precipitate and used as the source of leptospiral enzyme-linked immunosorbent assay (ELISA) antigen. Utilizing this antigen, ELISA was adapted to detect bovine serum antibody to L. interrogans serovars pomona, sejroe and hardjo. The specificity of this assay in 344 bovine sera, which were negative in the microscopic agglutination test (MAT) for seven serovars, was 99.4%. In sera from 37 and 87 cattle which revealed MAT titers greater than or equal to 1:50 for L. interrogans serovars pomona and sejroe, the relative sensitivity of the test was 100%. The ELISA also showed a considerable degree of low level cross-reactivity with other serovars. Sixty-six (75.9%) out of 87 bovine sera which were MAT-positive (MAT titer of greater than or equal to 1:50) with serovars sejroe and hardjo only were ELISA positive with heterologous pomona antigen; 16 (43.2%) and six 16.2%) out of 37 bovine sera which were MAT positive MAT titer of greater than or equal to 1:50) with serovar pomona only were ELISA positive with heterologous sejroe and hardjo ELISA antigen respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence and serovars of leptospira involved in equine abortions in central Kentucky during the 1990 foaling season.

A study to determine the prevalence of leptospira-induced abortions in the central Kentucky equine population during the 1990 foaling season and to determine the leptospira serovars responsible was conducted. From July 1, 1989 through June 30, 1990, 32 (4.4%) of 726 submissions (fetuses, stillborn foals, and/or placentas) were diagnosed as leptospirosis by the fluorescent antibody test and/or microscopic agglutination test. Attempts were made to isolate leptospires from the fetal tissues and/or the dam's urine in 31 of these cases. Leptospira interrogans serovar kennewicki was isolated from 11 (35.5%) and serovar grippotyphosa from 2 (6.5%) of the 31 cases. Of 12 cases that were culture negative with serologically positive fetal fluids, 8 had titers against serovar pomona, 1 against bratislava, 1 against grippotyphosa, 1 against hardjo, and 1 against both bratislava and pomona.     

Prevalence of Leptospira interrogans serovar hardjo in the genital and urinary tracts of non-pregnant cattle

In a bacteriological investigation of 60 cows and heifers from an abattoir Leptospira interrogans serovar hardjo was isolated from 39 (65 per cent) animals. The genital tract (57 per cent) appeared to be as important a site of hardjo localisation as the urinary tract (62 per cent). This is believed to be the first report of genital hardjo infection in naturally infected cattle.