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.     

Leptospira interrogans serovar hardjo Infection in Cattle in the South Okanagan District of British Columbia

An outbreak of leptospirosis due to Leptospira interrogans serovar hardjo in the South Okanagan District of British Columbia was investigated. The infection was associated primarily with bulls, but serovar hardjo was isolated from both bulls and cows at slaughter. Kidney and cerebrospinal fluid were found to contain leptospires, independently of the presence and level of serum agglutinins. Treatment of a bull twice in six months with dihydrostreptomycin failed to diminish an agglutinin titer (1/200) which persisted for two years without reexposure of the bull. A serological survey of cull cows sold through a central auction mart revealed the presence of hardjo agglutinins in 15.4% of 1300 sera representing 163 herds in 20 locations. Thirty percent of these herds contained reactor cattle. The number of premises from which reactor cattle came in a given locality varied from 4% to 67.7%. Measures to control leptospirosis in the study are suggested.     

Isolation of Leptospira interrogans serovar bratislava from stillborn and weak pigs in Iowa

Leptospira interrogans serovar bratislava was isolated from a herd of swine in Iowa with a history of stillborn and weak neonatal pigs. Placentas, kidneys, and lungs of stillborn and weak pigs from 3 litters were processed to detect leptospires by use of bacteriologic culture and fluorescent antibody testing. Sera from stillborn and weak pigs were tested to detect agglutinating antibody against leptospires. A low antibody titer against L interrogans serovar bratislava was detected in the sera of stillborn and weak pigs. Small numbers of leptospires were sometimes detected in tissues by use of the fluorescent antibody test. Serovar bratislava was isolated from placentas, stillborn pigs or weak pigs from each of the 3 litters.     

Bovine leptospirosis: Microbiological and histological findings in cattle slaughter

Kidneys from cattle at slaughter were examined for the presence of leptospires. Of 218 (8.3%) kidneys leptospires were isolated from 18; all were identified as Leptospira interrogans serovar hardjo. None of the leptospire-infected kidneys had histopathological lesions indicative of leptospirosis and leptospires were demonstrated in only 2 by immunogold silver staining. Leptospires infected kidneys remained viable for at least 21 days when stored at 4 degrees but became non-viable within 14 days when stored frozen at -15 degrees.     

Comparison of polymerase chain reaction assay,bacteriologic culture,and serologic testing in assessment of prevalence of urinary shedding of leptospires in dogs

OBJECTIVE: To compare results of polymerase chain reaction (PCR) testing of urine samples, serologic testing, and bacteriologic culture of urine to determine prevalence of urinary shedding of leptospires in dogs. DESIGN: Serial case study. ANIMALS: 500 dogs evaluated serially without regard to health status. PROCEDURE: Urine samples were examined via PCR assay and bacteriologic culture for leptospires. Blood samples were analyzed for antibodies against serovars canicola, bratislava, pomona, icterohemorrhagiae, grippotyphosa, and hardjo. RESULTS: Titers > or = 1:100 against at least 1 serovar were detected in 104 (20.8%) dogs, and titers > or = 1:400 were detected in 41 (8.2%) dogs. High titers were detected most commonly to serovar grippotyphosa, followed by icterohemorrhagiae, canicola, pomona, bratislava, and hardjo. High titers to > 1 serovar were detected in 14 dogs. A positive PCR assay result was obtained in 41 (8.2%) dogs, only 9 of which had a titer > or = 1:100. Leptospires were not cultured from the urine of any dog. Only 4 dogs had clinical leptospirosis. Overall disease prevalence was 0.8% for the 6-month evaluation period. Compared with PCR assay, serologic testing for predicting shedding had a sensitivity of 22%, specificity of 79%, positive predictive value of 9%, and negative predictive value of 92%. CONCLUSIONS AND CLINICAL RELEVANCE: Irrespective of health status, 8.2% of dogs were shedding pathogenic leptospires. Serologic testing was a poor predictor of urinary shedding. Clinically normal dogs that shed leptospires may pose a zoonotic risk to their owners.     

Diagnosis and prevalence of leptospira infection in aborted and stillborn horses

A study was conducted to evaluate a recently available fluorescent antibody test (FAT) conjugate for the detection of leptospires in tissues of aborted and stillborn horses, to determine the leptospira antibody titers and compare serologic test results with FAT results, and to determine the prevalence of leptospira-induced abortions and stillbirths in the equine population of central Kentucky. From July 1, 1988 through June 30, 1989, 15 (2.5%) of 594 submissions (fetuses, stillborn foals, and/or placentas) were diagnosed as leptospirosis by the FAT (14 of 15 tested) and/or microscopic agglutination test (12 of 14 tested). Of the 12 serologically positive fetal fluids, 10 had high tigers against Leptospira interrogans serovar pomona and 2 against serovar grippotyphosa.     

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.     

Effect of maternal vaccination on the susceptibility of growing pigs to leptospiral infection

Serum samples were collected from 30 piglets, derived from 17 litters, whose dams had been vaccinated against leptospirosis. Microscopic agglutination test (MAT) titres against Leptospira interrogans serovar pomona varied greatly from pig to pig; there was less variation among littermates. Titres declined between 4 and 10 weeks of age, with an uncorrected half-life of 15.5 days, consistent with IgG being the main antibody class involved. Twelve pigs, 4 derived from unvaccinated sows and 8 from sows vaccinated against leptospirosis, were challenged intravenously at 8 weeks of age with leptospires of serovar pomona. Colostrum-derived antibody protected 4 out of 8 pigs, and in 1 of the remaining 4 the serological response was reduced. Three of the protected pigs showed reduced serological responses and in the fourth the response was strong, but delayed. All of the pigs derived from unvaccinated sows developed leptospiraemia and leptospiruria and showed strong serological responses. Protection by colostrum-derived antibody bore an inexact relationship to MAT titre, but a titre of 16 appeared to be sufficient for protection.     

Leptospirosis in beef herds from western Canada: serum antibody titers and vaccination practices

One study described the frequency of pre-breeding vaccination for leptospirosis in 205 cow-calf herds from across western Canada and the prevalence of positive Leptospira antibody titers in unvaccinated, weaned calves from 61 of these herds. The percentages of herds vaccinated for leptospirosis were 13.7% in 2001 and 8.4% in 2002. Of 1539 calves examined, 13 (0.8%) had a positive antibody titer for a Leptospira serovar; the most common serovar detected was hardjo. A second study examined the prevalence of positive Leptospira antibody titers during the summer grazing season in 313 vaccinated and 478 unvaccinated cows from 40 cow-calf herds in southern Saskatchewan. Antibody titers for 7 Leptospira serovars were measured during the grazing season. Of the non-vaccinated cows, 9.6% were positive in the spring for serovar pomona, 6.7% for serovar grippotyphosa, and 6.1% for serovar icterohaemorrhagiae; the corresponding percentages for the fall were 5.5%, 3.0%, and 1.3%, respectively. Of 781 vaccinated and unvaccinated cows that were sampled twice, 11.3% of vaccinated cows and 2.3% of unvaccinated cows had increases in Leptospira antibody titers during the grazing season.     

Effect of vaccination with a bacterin containing Leptospira interrogans serovar bratislava on the breeding performance of swine herds

Swine herds suspected to be infected with Leptospira interrogans serovar bratislava were vaccinated with bacterins containing 5 or 6 leptospiral serovars in which serovar bratislava was the unique component. The principal diagnostic feature indicating an infection by this organism was demonstration of antibody against serovar bratislava in sera from stillborn pigs. For 1 breeding cycle after vaccination of herds on 3 farms, 255 of 266 (95.9%) sows and gilts given the 6-serovar bacterin farrowed. In contrast, 233 of 311 (74.9%) sows and gilts given the 5-serovar bacterin farrowed. These results, as evaluated by analysis of variance techniques, showed a significant improvement (P less than 0.01) in reproductive performance for groups vaccinated against serovar bratislava.     

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.     

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)     

Reproductive failure associated with Leptospira interrogans serovar bratislava infection of swine

Specimens from 17 swine herds experiencing reproductive failure were examined for Leptospira interrogans serovar bratislava. Clinical signs observed in these herds included stillborn pigs, weak neonatal pigs, and abortion. Diagnostic tests used to determine L. interrogans serovar bratislava infection were bacteriologic culture, serologic assays to detect antibodies, and immunofluorescence. Examination of fetal serum for antibodies against serovar bratislava and a fluorescent antibody test were the most practical diagnostic procedures.     

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.     

Immunological and molecular characterization of Leptospira interrogans isolated from a bovine foetus

Cattle are commonly infected with pathogenic leptospires, and similarly to rodents, they excrete the bacteria in their urine and can transmit the pathogen from animal to animal or animal to human. Thus, surveillance and monitoring systems for detection of new Leptospira serovars are important for the control of leptospirosis. Here, we report the isolation of a spirochete from a stillborn bovine foetus and its characterization by immunological and molecular techniques. A variable number tandem repeat profile using seven discriminatory primers identified the spirochete as belonging to species Leptospira interrogans serogroup Australis serovar Muenchen. A phenotypic analysis using monoclonal antibodies (mAbs) against leptospiral membrane-associated proteins confirmed the expression of important virulence and pathogenicity factors (LipL32 and LigBrep). Out of 120 reference sera tested, 22 positive (36.66%) and 9 negative (15%) also reacted with the new isolate. Furthermore, the serovar Muenchen isolate was virulent in hamster model. The animal inoculated developed acute lethal infection characterized by hepatic, pulmonary and renal lesions. Local isolates exhibited unique characteristics that differed from those of reference strains; therefore, isolation of leptospires is useful in the surveillance of local pathogenic serovars. In conclusion, the data obtained from this study can contribute to the epidemiological understanding and control of leptospirosis in southern Brazil.     

Prevalence of leptospirosis among animal herds of north eastern provinces of India

Serum samples from 840 animals were examined for Leptospira spp. antibodies by microscopic agglutination test (MAT) to assess the risk factors and the prevalence of leptospirosis among animal herds of Assam, Meghalaya, Mizoram the north eastern (NER) provinces. They were compared with Tamilnadu (TN) the southern province of India for the serovar and risk factor inconsistency. Serovar Ballum was reported to be prevalent (28.1 %) in Assam and Grippotyphosa (16.1 %) in Tamilnadu. The overall seropositivity observed was 36.8 %(206/560) from NER and 30.7 %(86/280) from TN. In this study, the higher seroprevalence was observed in pigs (42.6 %), cattle (39.8 %) and goats (26 %) in NER. Cattle (36.4 %) and goat (17.6 %) showed higher prevalence in TN. The presence of rodents in pig herds was found to be significant (P = 0.0088) in NER and it was for cattle in TN (P = 0.0063). We suggest that a program of rodent control should be included in the flock management practices aiming to reduce transmission of the leptospires.     

Sporadic cases and an outbreak of leptospirosis probably associated with recreational activities in rivers in the northern part of Okinawa Main Island

In the summer of 2003, sporadic cases and an outbreak of human leptospirosis probably related to recreation in rivers occurred in the northern part of Okinawa Main Island. Sixteen of 22 suspected cases were definitely diagnosed as leptospirosis by serological test or isolation. The infective leptospiral serovar in 14 cases was presumed to be Hebdomadis. Transmission was thought to occur by exposure to river water that was contaminated by the urine of infected animals. The findings indicate that recreation in rivers in this area is a significant risk factor for infection with leptospires.     

Leptospirosis in sheep and goats under tropical conditions

Inadequate management practices and poor reproductive performance have been reported as fundamental factors on reducing the levels of productivity in livestock. Different pathogens have been reported in small ruminants' herds/flocks with reproductive failures. The aim of the present study was to review aspects of leptospirosis in small ruminants, mainly its impact on reproduction and consequently on productivity of the herds/flocks under tropical conditions. Leptospiral infection in goats and sheep is common in several countries, and those species can also act as carriers of leptospires. Severe disease is often associated to young animals and is frequently associated to incidental serovars. In contrast, subclinical infection is mainly characterized by reproductive problems, such as infertility, abortion, occurrence of stillbirths, and weak lambs/goat kids. Moreover, laboratorial tests are essential to achieve an accurate diagnosis of the infection. Microscopic agglutination test is the most common indirect test of leptospirosis, being used worldwide. In small ruminants, PCR consists on a recommendable method for diagnosing animals that carry leptospires. Control of leptospirosis in small ruminants involves measures such as the identification and treatment of the carriers and other sources of infection, quarantine in acquired animals, and systematic immunization with commercial vaccines containing the circulating serovars in the herd/flock. Productivity of small ruminant breeding can dramatically increase with adequate sanitary conditions and control of leptospirosis. Immunization of all the animals combined to the treatment of carriers may successfully control the infection and importantly reduce the economic reproductive hazards that are observed under tropical conditions.     

Serodiagnosis of leptospirosis in pigs using an axial filament enzyme-linked immunosorbent assay.

The axial filament (AF) from Leptospira interrogans serovar canicola was isolated by cesium chloride density gradient centrifugation of 2% sarcosyl treated whole cells. Isolation of AF was confirmed by electron microscopic examination, by protein-A immunogold labelling, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), and immunoblotting. Analysis by SDS-PAGE of the purified preparation showed relatively weak bands of molecular size 41 kDa and 21 kDa, and strong bands of 35 kDa and 34.5 kDa. Immunoblot analysis using antiserum to the AF against sonicated leptospires of a variety of serovars showed prominent reaction against the 41, 35, and 34.5 kDa protein bands, as well as against minor bands of molecular weight 43, 39, and 37 kDa. Antisera prepared against leptospiral serovars also identified minor bands at 33 and 32 kDa. Immunoblots with antiserum to whole cells of serovar bratislava detected the 35 and 34.5 kDa AF bands of Borrelia burgdorferi moderately and of Treponema hyodysenteriae only slightly in comparison to leptospiral AF. Antibody to B. burgdorferi did not detect the leptospiral AF antigen. Immunoblots with antiserum to T. hyodysenteriae showed a marked reaction with a 41 kDa band of B. burgdorferi but only a very minor reaction with leptospiral AF. The AF was tested in an AF-ELISA against sera from 260 pigs, many of which reacted in the microscopic agglutination test (MAT) against one or more leptospiral serovars. A sensitivity of 97.1% and a specificity of 93.1% was determined in comparison to the MAT. Only moderate correlation was observed between titres detected in the AF-ELISA and the MAT (r = 0.4). When sonicated whole cells (WC) of serovar canicola were used in an ELISA (WC-ELISA), high correlation was observed between AF-ELISA and WC-ELISA (r = 0.97). These findings show that the AF-ELISA can be used effectively as a species-specific antigen for the serological diagnosis of leptospirosis in swine and that sonicated whole cells can substitute excellently for purified AF as the antigen source. These findings may be extrapolated to the use of AF in immunodiagnosis of leptospirosis in other species.     

Observations of leptospirosis in farmed deer

AIMS: Slaughterhouse and on-farm surveys were undertaken to investigate some aspects of leptospirosis (Leptospira interrogans) in farmed deer in the lower North Island of New Zealand. METHODS: Blood samples and kidneys were collected at slaughter from 601 l-year and older red and red X Wapiti stags and 21 adult hinds from 53 farms (10 or 12 deer per farm). Serum samples were analysed for up to seven Leptospiral serovars. Gross and histological examinations of kidneys were undertaken. Kidneys from 202 deer were cultured for leptospires. A follow-up postal questionnaire (68% response) indicated one herd had been vaccinated prior to the survey. Serological analyses were also carried out on serum bank samples from a previous on-farm survey involving male and female weaner, yearling and adult red deer from 16 commercial deer farms in March and November. RESULTS: Serological reactions at titres > or = 96 to serovar hardjo were present in 73.6%, pomona in 41.5%, copenhageni in 11.3% and tarassovi in 15.1% of farms from the slaughterhouse survey. Antibodies to serovars australis, ballam and balanica were present in three, one and four of six herds studied, respectively. Titre prevalence to hardjo was higher than that of pomona and other serovars within farms. Cultures for Leptospira were positive in 10 stags from six lines with similar prevalence across age groups. Histological examination showed many gross lesions were associated with mild interstitial cellular infiltration characteristic of subclinical Leptospiral infections. Some sections from culture-positive kidneys contained spirochetes in renal tubules. The on-farm survey showed a 10-30% within-herd prevalence of pomona and hardjo titres in 56% of 3-month-old deer herds, but by 11 months of age, 100% of herds were titre-positive with high prevalences to one or both serovars. Concurrently, herds of 1-year-old and adult deer on the same farms were all seropositive. CONCLUSION: This study has shown that Leptospiral infections are common in farmed deer in the survey area.