The association between rainfall and seropositivity to Leptospira in outdoor reared pigs

Outdoor reared pigs were used as indicators for investigating the effect of weather conditions in the seroprevalence of Leptospira. Over the period February to March 2008, sera from 386 sows on 11 farms in southern Sweden were tested for antibodies to the following Leptospira serovars: L. interrogans serovar (sv) Bratislava, L. kirschneri sv Grippotyphosa, L. interrogans sv Icterohaemorrhagiae, L. interrogans sv Pomona, L. borgpetersenii sv Tarassovi and one domestic strain (mouse 2A) related to L. borgpetersenii sv Sejroe and L. borgpetersenii sv Istrica. The highest seroprevalence was to this strain (8.0%) followed by sv Bratislava (3.9%). Six of the 11 farms had sows which were seropositive to at least one of the Leptospira serovars. Data on rainfall and temperature were retrieved for the respective farms. For each millimetre of extra rainfall, there was an increase in the odds ratio (OR) for seropositivity to sv Bratislava of 4.3 (95% CI 1.9-10), and to strain mouse 2A of 2.5 (95% CI 1.0-6.4). There was no association between seropositivity and temperature. This study indicates that different climate conditions within the northern temperate climate zone may be of importance for the presence of Leptospira-seropositivity in mammals.     

Annual Variations in <Emphasis Type="Italic">Leptospira</Emphasis> Seroprevalence among Sows in Southern Vietnam

A serological survey was conducted among sows in the Mekong delta in southern Vietnam in 1999 to investigate variations in leptospiral Seroprevalence over a one-year period. In this region, leptospirosis is endemic and a high leptospiral Seroprevalence has been shown in the pig population. In this study, the serology of six Leptospira serovars was analysed by the microscopic agglutination test for 429 sows at five large-scale state farms sampled during the dry period, the rainy period and the early dry period. The serovars included were L. interrogans serovar (sv) autumnalis strain Akiyama A, L. interrogans sv bratislava strain Jez, L. interrogans sv icterohaemorrhagiae strain Kantorowicz, L. interrogans sv pomona strain Pomona, L. borgpetersenii sv tarassovi strain Perepelitsin, and L. kirschneri sv grippotyphosa strain Duyster. Variations in Seroprevalence over the year were found for sv bratislava and sv icterohaemorrhagiae: the Seroprevalence was higher during the dry period compared with the rainy period (p = 0.07 and p = 0.005, respectively) and the early dry period (p = 0.00006 and p = 0.0006, respectively). It is concluded that in regions where water is constantly abundant and where animals are exposed to the outdoor environment all year round there are highly significant variations in leptospiral Seroprevalence over the year.     

A serological survey of leptospirosis in Prince Edward Island swine herds and its association with infertility.

A serological survey was undertaken to determine the prevalence of leptospirosis, and to investigate associations between leptospiral antibody titers, and herd measures of reproduction. Production records and leptospirosis serology were analyzed for 25 slaughter hogs from each of eleven randomly sampled farrow-finish operations on Prince Edward Island. The effect of selected leptospiral serovars on nonproductive sow days per parity (NPSD/P) and the proportion of pigs born dead was evaluated. The four most common serovars to which antibodies were detected were Leptospira icterohaemorrhagiae, L. bratislava, L. autumnalis and L. pomona, with respective prevalences of 57.1%, 35.1%, 3.4% and 1.5% of PEI slaughter hogs. None of these serovars was associated with increased frequency of stillbirths (p greater than 0.05). However, farms with a higher prevalence of L. bratislava antibody titers tended to have more infertility, as measured by NPSD/P (r = 0.738, p = 0.036 with Bonferroni adjustment). Also, farms with L. pomona antibody titers had higher NPSD/P than farms without L. pomona antibody titers (p = 0.0008 with Bonferroni adjustment). There was no association between NPSD/P and antibodies to either L. autumnalis or L. icterohaemorrhagiae (p greater than 0.05).     

Leptospirosis in horses in Ontario.

Sera from Thoroughbred and Standardbred horses in southwest Ontario were tested for antibody to seven Leptospira interrogans serovars (autumnalis, bratislava, canicola, grippotyphosa, hardjo, icterohaemorrhagiae, pomona), using the microscopic agglutination test. There was significantly higher seroprevalence of bratislava than of other serovars, in which prevalence was low. Seroprevalence of bratislava increased significantly with age; only 5% of two to three year old horses had titers greater than or equal to 1:80 compared to 52% of horses older than seven years. Eight of 16 foals from two farms seroconverted at low titers to bratislava between four and eight months of age. Leptospires were not detected by immunofluorescence and isolation techniques in 50 kidneys collected from horses at slaughter. Fetal tissues from 52 aborted horse fetuses were also examined by these methods and serovar kennewicki was identified by immunofluorescence and by isolation in one fetus. Serovar bratislava appears to be widespread in horses in Ontario but unimportant in abortion. The clinical significance of this infection in horses in Ontario is unclear.     

Development of an indirect enzyme-linked immunosorbent assay for the detection of leptospiral antibodies in dogs.

Serology plays an important role in the diagnosis of leptospirosis. Few laboratories have the resources, expertise, or facilities to perform the microscopic agglutination test (MAT). Thus, there is a need for a rapid and simple serological test that could be used in any diagnostic laboratory. In this study, a genus-specific, heat-stable antigenic preparation from Leptospira interrogans serovar pomona was used in an enzyme-linked immunosorbent assay (ELISA) for the detection of leptospiral antibodies in dog sera. This antigenic preparation reacted with rabbit antisera against L. interrogans serovars bratislava, autumnalis, icterohaemorrhagiae and pomona and with rabbit antiserum against L. kirschneri serovar grippotyphosa. The ELISA showed a relative specificity of 95.6% with 158 dog sera which were negative at a dilution of 1:100 in the MAT for serovars pomona, bratislava, icterohaemorrhagiae, autumnalis, hardjo, and grippotyphosa. The relative sensitivity of this assay with 21 dog sera that revealed serovars MAT titres of > or =100 to different serovars was 100%. This assay is easily standardized, technically more advantageous than MAT, and uses an antigenic preparation that can be routinely prepared in large amounts. It was concluded that this ELISA is sufficiently sensitive test to be used as an initial screening test for the detection of leptospiral antibodies in canine sera, with subsequent confirmation of positive test results with the MAT.     

Seroprevalence of bovine leptospirosis in Garanhuns Municipal District,Pernambuco State,Brazil

The prevalence of Leptospira interrogans serovars in dairy cattle was determined by analyzing 464 serum samples from cows on 15 properties in Garanhuns municipal district, Pernambuco State, Brazil. A microscopic seroagglutination test including 12 serovars of Leptospira interrogans as antigens was used. Samples with titres 100 were considered positive. Two hundred and twenty-one (47.63%) of the samples were positive to one or more serovars. The prevalence of the serovars was hardjo (21.98%), bratislava (15.73%), castellonis (11.64%), tarassovi (10.56%), pyrogenes (1.72%), icterohaemorrhagiae (1.08%), pomona (0.86%), wolffi (0.86%), grippotyphosa (0.86%), djasiman (0.43%), canicola (0.21 %), and copenhageni (0.21%).     

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.     

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)     

Serological survey of leptospirosis in sows with premature birth and stillbirth in Chiba and Gunma prefectures of Japan

In 1996 and 1997, the seroprevalence against Leptospira in parturient sows with premature birth or stillbirth from two herds was investigated. In three out of four sow serum samples obtained in Gunma Prefecture, the antibody titers to Leptospira interrogans serovar copenhageni (M20) were higher than 10,000 (the reciprocal of the serum dilution). Furthermore, the antibody titers to L. interrogans serovar canicola (Hond Utrecht IV) were significantly high in the three sows and the titers ranged from 1,000 to 3,000. In sows obtained in Chiba Prefecture, significantly high antibody titers to serovar copenhageni (M20) were confirmed in eight out of 40 sows, and antibody titers greater than 10,000 in six of them. Significantly high antibody titers to L. interrogans serovar icterohaemorrhagiae (RGA) and L. canicola (Hond Utrecht IV) were confirmed in four and 18 out of the 40 sows, respectively, compared with the titers to the other serovars. These findings may indicate the prevalence of leptospirosis in pig herds in both Gunma and Chiba Prefectures.     

An old disease with a new face: canine leptospirosis does not lose its relevance

The clinical features of the disease are presented based on retrospective analysis of the records of eleven dogs diagnosed with leptospirosis using clinical signs and results of the microagglutination test (MAT) between 1991 and 1996. Additionally, Leptospira titres were determined in 30 healthy dogs and 20 hospitalised dogs without clinical or laboratory evidence of leptospirosis. A positive titre for L. grippotyphosa, L. pomona, L. bratislava, L. australis, L. icterohaemorrhagiae and/or L. canicola was found in 16 normal dogs and only one hospitalised patient. Eight of these dogs had titres of > or = 1:800. Only one of them had been vaccinated shortly before sampling. These results suggest that many dogs from the surroundings of Bern, Switzerland have contact with various Leptospira interrogans serovars. In ten healthy dogs, the Leptospira titre was determined before and four weeks after vaccination with leptospiral antigen. Only two of the dogs showed a serologically measurable response to the antigen contained in the vaccine. In dogs MAT titers presumably do not reliably reflect the immune status against leptospiral infections.     

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.     

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.     

Survey of leptospiral agglutinins in the sera of swine of southeastern Alabama

The occurrence of leptospirosis in swine of southeastern Alabama was determined. A total of 627 sera were tested, using the microscopic agglutination method, with live antigens of 12 serovars. Of the sera tested, 121 (19.3%) had a titer of 1:100 or greater to the serovars employed. The percentage distribution of sera with titers of greater than or equal to 1:100 among serovars most commonly reported was as follows: Leptospira interrogans serovars pomona, 3.8%; icterohaemorrhagiae, 3.3%; canicola, 1.6%; hardjo, 0.7%; and grippotyphosa, 0.16%. Of the less commonly recognized leptospiral serovars, the percentages reacting were as follows: ballum, 4.9%; autumnalis, 3.2%; pyrogenes, 1.1%; and bataviae, 0.4%. None of the sera reacted with antigen of serovars australis, tarassovi, or wolffi.     

Herd-level risk factors associated with Leptospira spp. seroprevalence in dairy and beef cattle in Spain.

Our aim in this cross-sectional study was to investigate the seroprevalence of Leptospira spp. infection in herds and cattle and the relationships between seroprevalence and beef versus dairy, size, replacement policy and grazing management in a representative area of beef- and dairy-cattle production in Spain. Herds were the initial sampling unit. Blood samples were collected from 762 dairy cattle belonging to 81 herds and 1238 beef cattle from 134 herds; sera were tested for antibodies against 11 serovars of Leptospira (autumnalis, ballum, bratislava, canicola, castellonis, copenhagheni, grippotyphosa, hardjo, louisiana, pomona and tarassovi) using the microagglutination test. Forty-three percent (36.2-49.5%) of the herds and 8% (6.4-8.8%) of the individuals were seropositive against one or more of the serovars studied. Bratislava was the most-prevalent serovar (24% of the herds and 4% of the individuals) followed by hardjo (11 and 1%, respectively). Grippotyphosa, copenhagheni and tarassovi were more prevalent in dairy than in beef herds (P<0.001, P<0.05, P<0.05, respectively) -- but no significant association was found between herd-size and Leptospira seroprevalence for any of the serovars considered.     

Serologic survey for leptospirosis in coyotes in northcentral Kansas

During 1975 to 1977, serum samples were collected from 101 adult coyotes (Canis latrans) captured in northcentral Kansas. Ten samples were seropositive by microagglutination testing and six of those samples were seropositive for multiple serovars. Titers for Leptospira interrogans serovars grippotyphosa, pyrogenes, djasiman, butembo, and pomona were demonstrated.     

Three case studies involving Leptospira interrogans serovar pomona infection in mixed farming units

Three case studies involving Leptospira interrogans serovar pomona outbreaks within mixed farming systems in South Africa are described. On 2 farms, pigs constituted the main enterprise with cattle and sheep of secondary importance. On each of these 2 farms, abortion due to L. pomona in sows was confirmed by culture, and antibody titres to pomona were detected in cattle, sheep, horses and dogs. On the 3rd farm, a piggery was of secondary importance to cattle farming. Abortion and death in cows occurred on this farm and serology showed titres to various serovars, including pomona. L. pomona was also isolated from bovine urine, an aborted bovine foetus and kidneys from slaughtered pigs. This particular case study was regarded as clinically atypical in that adult Jersey cattle died of acute leptospirosis in a semiarid region of South Africa. In all 3 case studies, the poor management of pig effluent and of the drinking water and its sources played a pivotal role in the transmission of the disease. Inadequate vaccination of animals against Leptospira and poor record-keeping within the secondary farming enterprises were also contributing factors to the spread of leptospirosis.     

Experimental canine leptospirosis caused by Leptospira interrogans serovars pomona and bratislava

OBJECTIVE: To evaluate gross, histopathologic, and serum biochemical findings caused by Leptospira interrogans serovars pomona and bratislava inoculated in dogs. ANIMALS: Twenty-seven 8-week-old female Beagles. PROCEDURE: Dogs were randomly assigned to challenge or control groups. Challenge groups were conjunctivally inoculated on 3 successive days with 5 x 10(7) L interrogans serovar pomona (n = 12) or serovar bratislava (11). Clinical signs were recorded throughout the experiment, and clinical pathology assays, bacteriologic culture, and necropsies (6 or 7 dogs necropsied at each time point) were done on postinoculation day (PID) 7, 10, 14, and 20. RESULTS: Infection could not be confirmed in any serovar bratislava-inoculated dog, and control dogs remained healthy throughout the experiment. Positive culture and fluorescent antibody test results were confirmed in 11 of 12 serovar pomona-inoculated dogs. Fever and lethargy starting at PID 7 were the most common clinical signs in serovar pomona-infected dogs. On day 10, gross lesions included multifocal renal and pulmonary hemorrhage and perirenal edema. Serovar pomona-inoculated dogs had histopathologic lesions including hepatitis, interstitial nephritis, and pneumonia at PID 7, 10, 14, and 20. Increases in BUN, anion gap, and bilirubin concentration occurred on PID 10, 14, and 20. Platelet counts in dogs with positive results of bacteriologic culture were decreased from baseline values on PID 10, 12, and 14. CONCLUSIONS AND CLINICAL RELEVANCE: Conjunctival inoculation with L interrogans serovar pomona resulted in a high rate of infection with concomitant hemorrhagic and inflammatory lesions of the kidneys, liver, and lungs.     

Preliminary study on differentiation of Leptospira grippotyphosa and Leptospira sejroe from other common pathogenic leptospiral serovars in canine urine by polymerase chain reaction assay.

A multiplex polymerase chain reaction (PCR) method using primer sets of G1/G2 and B64-I/B64-II was validated to detect pathogenic leptospira serovars from canine urine samples. The PCR method was found to be specific and sensitive with a detection limit of 100 cells of Leptospira icterohaemorrhagiae per milliliter of urine. The primer set previously designated and erroneously transcribed B64-I/B64-II amplified a DNA fragment of 352 base pairs from Leptospira grippotyphosa and Leptospira sejroe but not from Leptospira autumnalis, Leptospira bratislava, Leptospira canicola, Leptospira hardjo, Leptospira icterohaemorrhagiae, and Leptospira pomona. From 100 diagnostic canine urine samples, 5 were found positive for Leptospira grippotyphosalsejroe with a PCR product of 352 base pairs and 6 were positive for other pathogenic leptospira serovars with a PCR product of 285 base pairs. One 285-base pair product was sequenced and found to be 99.3% homologous to the G1/G2 PCR fragment sequence reported previously. All 352-base pair PCR products of clinical samples and pure cultures of L. grippotyphosa and L. sejroe were sequenced. The 352-base pair fragment sequences of L. grippotyphosa and L sejroe were identical. Only 2 base pairs were found different between the sequences from pure cultures and those from clinical samples. Serum samples from 3 positive cases that generated a PCR product of 352 base pairs were tested by the microscopic agglutination test, and 2 were found to be positive for L. grippotyphosa (1:10,240 and 1:5,120), 1 was positive for L. grippotyphosa (1:320) or L. icterohaemorrhagiae (1:320). The results of this study suggest that the multiplex PCR with the primer set G1/G2 and the erroneously transcribed B64-I/B64-II may be able to differentiate L. grippotyphosa or L. sejroe from other pathogenic leptospira serovars commonly tested for in Canadian diagnostic laboratories.     

The prevalence of leptospirosis and its association with multifocal interstitial nephritis in swine at slaughter.

An abattoir survey was undertaken to determine the prevalence of leptospirosis and its association with lesions of multifocal interstitial nephritis (so-called "white spotted kidneys") in swine at slaughter. Both cross-sectional and case-control study designs were used. Of 197 kidneys from hogs randomly selected at slaughter, 11 (5.6%) had generalized grey-white foci typical of multifocal interstitial nephritis (MFIN). Antibody titers greater than or equal to 1:80 against Leptospira pomona were detected in nine (4.6%) hogs and against L. bratislava in 63 (32%) of these hogs. Leptospira pomona (kennewicki) was detected by immunofluorescence in 5/197 (2.5%) of randomly selected hogs. Leptospires identified as genotype kennewicki were isolated from six (9.8%) of 61 kidneys cultured. Leptospira bratislava was not detected by immunofluorescence or culture. There was a highly significant (p = 0.00) and strong association (odds ratio (OR) = 195) between high L. pomona titer (greater than or equal to 1:80) and the presence of leptospires in the kidneys, as detected by culture. There was also a significant (p = 0.046) and strong (OR = 8.10) association between multifocal interstitial nephritis and the presence of renal leptospires as detected by culture. The association between leptospiral titer and MFIN lesions in the prevalence survey group of animals was statistically significant (p = 0.031), but this association was not significant in the case-control study group (p = 0.071) The failure to identify L. bratislava despite serological evidence of infection suggests that some of these seropositive animals may have been transiently infected at an early age, that serological findings were falsely positive, or that immunofluorescence and isolation attempts failed to detect L. bratislava if they were indeed present in the kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)