Leptospirosis in dogs: a serologic survey and case series 1996 to 2001

All leptospirosis microscopic agglutination test titers for the Leptospira serovars icterohaemorrhagiae, canicola, grippotyphosa, bratislava, hardjo, and pomona conducted on 1,260 blood samples from dogs at the University of Illinois Veterinary Diagnostic Laboratory between March 1996 and March 2001 were evaluated. Low titers (1:100 to 1:400) were predominantly L. icterohaemorrhagiae and L. canicola, which represented the predominant serovars (65.4%) among all positive samples with low titers. L. grippotyphosa was the predominant serovar (72.1%) among samples with clinically significant titers (greater than 1:800). The medical records of 87 dogs with a titer greater than 1:800 that were patients at the Veterinary Teaching Hospital of the University of Illinois were reviewed. A clinical diagnosis of leptospirosis was made in 15 cases (17.2%) based on the elevated titer, appropriate clinical signs, lack of recent vaccination, and lack of concurrent disease that could explain the clinical signs present. Renal disease was present in 10 of the cases, concurrent renal and hepatic disease in two, and hepatic disease in three. In 12 cases, the predominant serovar was L. grippotyphosa; titers to L. grippotyphosa and L. bratislava were equal in magnitude in three cases.     

Leptospira interrogans serovar bratislava infection in two dogs

Two dogs with clinical histories suggestive of leptospirosis were examined serologically and culturally for evidence of leptospiral infection. Antibodies to Leptospira interrogans serovar bratislava were detected in serum from one dog, and the organism was isolated from urine of that dog. In a serologic survey of dogs in the state of Illinois, reactor rates to bratislava were higher than those to canicola or icterohaemorrhagiae. In cases of suspect canine leptospirosis, serovars such as bratislava, not contained in canine vaccines, should be considered in a differential diagnosis.     

Leptospira antibody detection in dog serum in the years 1985 to 1988

In 1985-1988, 993 serum samples of dogs from Southern Bavaria and 408 samples from Northern Bavaria and from several Lands of the Federal Republic of Germany were tested for antibodies against the serovars canicola, icterohaemorrhagiae, grippotyphosa, bratislava, pomona, saxkoebing, sejroe and hardjo by using the microscopic agglutination test (MAT). 683 seras (48.75%) out of altogether 1401 samples showed a reaction against one up to seven serovars. The mostly low canicola- and icterohaemorrhagiae titers, having been proved in over 30% of the samples, can be put down to the fact, that usually the dogs had been vaccinated. Most frequently titers were found with the serovars grippotyphosa and bratislava--in Southern Bavaria 28.3%, in Northern Bavaria and other Lands of the Federal Republic of Germany 18.6%. The prevalence of titers against serovar saxkoebing, with or without a reaction against other serovars out of homologous and heterologous serogroups, reach up to 3.2% in sendings coming from Southern Bavaria and in other sendings up to 6.1%.     

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.     

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.     

Treatment and outcome of dogs with leptospirosis: 36 cases (1990-1998)

OBJECTIVE: To characterize serologic and clinical features and outcome of dogs with leptospirosis that were treated conservatively (i.e., medical management alone) or with hemodialysis. DESIGN: Retrospective study. ANIMALS: 36 dogs with leptospirosis. PROCEDURE: History; results of physical examinations, ultrasonography, and serologic, hematologic, and serum biochemical analyses; time to resolution of azotemia; and outcome were obtained from medical records. Dogs were treated conservatively (n = 22) or with hemodialysis (14). RESULTS: Between 1990 and 1998, amount of rainfall was positively correlated with number of cases of leptospirosis identified per year. Serum antibodies against 6 Leptospira serovars were measured, and titers were highest to Leptospira pomona in 16 (44%) dogs, L bratislava in 9 (25%) dogs, and L hardjo in 1 (3%) dog. Eight (22%) dogs had equally high titers to L pomona and L bratislava, 1 (3%) had equally high titers to L grippotyphosa and L canicola, and 1 (3%) had high titers to L grippotyphosa, L pomona, L canicola, and L bratislava. During initial evaluation, all dogs were azotemic. Thirty (83%) dogs survived, including 12 of 14 (86%) dogs treated with hemodialysis and 18 of 22 (82%) treated conservatively. Serum creatinine concentration was similar in both groups after resolution of clinical signs. CONCLUSIONS AND CLINICAL RELEVANCE: Infection with L pomona and L bratislava was recognized as a cause of leptospirosis in dogs, and resulted in development of acute renal failure with various degrees of azotemia. Prognosis for dogs with mild to moderate azotemia was good with conservative treatment, whereas treatment with hemodialysis appeared to improve prognosis for dogs with severe azotemia.     

Serological findings in cases of acute leptospirosis in the dog

Fourteen dogs which had died from acute leptospirosis, three dogs which survived an acute attack of leptospirosis and seven healthy dogs living in close contact with the animals which died were examined for the presence of lepto-spiral antibodies by the microscopic agglutination test. Twelve dogs had titres of 1:3200 or greater. The predominant titre was directed against serovar bratislava in seven cases, serovar grippothyphosa in two cases and both these serovars in two cases. In one case the predominant titre was directed against serovars bratislava, grippothyphosa, copenhageni (serogroup icterohaemorrhagiae) and pomona. The present study and other recent reports suggest that the epidemiology of canine leptospirosis is changing with the emergence of serovars differing from those typically infecting dogs, namely canicola and icterohaemorrhagiae.     

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.     

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.     

Sero-epidemiology of canine leptospirosis in Trinidad: serovars, implications for vaccination and public health

A sero-epidemiological study on canine leptospirosis was conducted in house, stray, farm and hunting dogs, as well as in suspect cases of clinical canine leptospirosis. Serum samples were collected from apparently healthy (vaccinated and non-vaccinated), house dogs. A questionnaire was administered to the owners to elicit information on risk factors for leptospirosis. The microscopic agglutination test was used to screen for leptospirosis using 17 international serovars. Reciprocal titres of between 100 and <800 were considered as evidence of past exposure while reciprocal titres of 800 or greater were classified as suggestive of acute/current infection. Of a total of 419 serum samples tested, 61 (14.6%) were seropositive for Leptospira agglutinins, 23 (5.5%) had mixed infections and 16 (3.8%) had current infection. Amongst 50 suspected cases of clinical leptospirosis, 24 (48.0%) were seropositive and only 13 (26.0%) had current infection compared with 10 (6.3%) and three (1.9%) of 160 apparently healthy house dogs respectively. The difference was statistically significant (P < 0.05; chi2). Twelve (25.5%) of 47 hunting dogs, 10 (20.4%) of 49 farm dogs and five (4.4%) of 113 stray dogs were seropositive (P < 0.05; chi2). Overall, a total of nine serovars were detected with serovars mankarso, icterohaemorrhagiae RGA, autumnalis and copenhageni being involved in 29 (47.5%), 20 (32.8%), 25 (41.0%) and 10 (16.4%) respectively in 61 seropositive dogs (P < 0.05; chi2). Serovar mankarso was most predominant in seropositive apparently healthy dogs, 37.8% (14/37), suspected clinical cases of leptospirosis, 62.5% (15/24) compared with serovar icterohaemorrhagiae with a frequency of 21.6% (8/37) and 50.0% (12/24), the difference being statistically significant (P < 0.05; chi2). Although all vaccines used for prevention of canine leptospirosis in the country contain serovars canicola and icterohaemorrhagiae, serovar mankarso was mostly associated with infection and disease and may be a good candidate for inclusion in the vaccine used locally. The public health risk posed to owners of dogs infected with Leptospira cannot be over-emphasized considering the zoonotic nature of the disease.     

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.     

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.     

Risk factors associated with the seroprevalence of leptospirosis among students at the veterinary school of Zaragoza University

The prevalence and risk factors associated with leptospirosis were studied in veterinary students in Zaragoza. Sera were collected at the beginning and end of the academic year 1994 to 1995 and were tested by ELISA against a pool of Leptospira interrogans serovars bratislava, canicola, grippotyphosa, hardjo, icterohaemorrhagiae and pomona antigens. At the beginning of the study the prevalence was 8.14 per cent and at the end it was 11.4 per cent. The incidence of the disease during the study was 0.0394. Risk factors associated with leptospirosis included: taking the course specialising in food inspection and technology, on-farm work, contact with pets in general, and particularly carnivores, and contact with animal traders. The symptoms associated with the disease were myalgia and fever, and the treatment of the symptoms provided some protection.     

Clinical application of a polymerase chain reaction assay for diagnosis of leptospirosis in dogs

OBJECTIVE: To evaluate the use of a polymerase chain reaction (PCR) assay on urine samples for diagnosis of leptospirosis in dogs. DESIGN: Prospective case study. ANIMALS: 132 dogs with clinical signs suggestive of leptospirosis and 13 healthy dogs. PROCEDURE: PCR testing was performed on urine samples to detect leptospiral DNA; results were compared with results of conventional criteria for the diagnosis of leptospirosis. RESULTS: Leptospirosis was diagnosed in 8 dogs via established criteria; all these dogs had positive results of PCR assay, including 1 dog with positive results before seroconversion developed. A positive PCR assay result was also obtained in 16 dogs that did not have a confirmed diagnosis of leptospirosis. In the 8 dogs that had a confirmed diagnosis of leptospirosis, serovars pomona (n = 3 dogs), grippotyphosa (2), canicola (2), and bratislava (1) were identified serologically. The remaining 121 dogs all had a diagnosis other than leptospirosis or were healthy. For PCR testing on urine, sensitivity was 100%, specificity was 88.3%, positive predictive value was 33%, and negative predictive value was 100%. CONCLUSIONS AND CLINICAL RELEVANCE: Positive PCR test results prior to seroconversion may have value in establishing an early diagnosis. Positive results in dogs that had signs consistent with leptospirosis despite failing to meet established criteria for leptospirosis raise questions regarding the sensitivity of serologic testing in diagnosis of leptospirosis. Serovars pomona, grippotyphosa, and canicola were most common.     

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.     

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.     

Sero‐epidemiology of Canine Leptospirosis in Trinidad: Serovars,Implications for Vaccination and Public Health

A sero‐epidemiological study on canine leptospirosis was conducted in house, stray, farm and hunting dogs, as well as in suspect cases of clinical canine leptospirosis. Serum samples were collected from apparently healthy (vaccinated and non‐vaccinated), house dogs. A questionnaire was administered to the owners to elicit information on risk factors for leptospirosis. The microscopic agglutination test was used to screen for leptospirosis using 17 international serovars. Reciprocal titres of between 100 and <800 were considered as evidence of past exposure while reciprocal titres of 800 or greater were classified as suggestive of acute/current infection. Of a total of 419 serum samples tested, 61 (14.6%) were seropositive for Leptospira agglutinins, 23 (5.5%) had mixed infections and 16 (3.8%) had current infection. Amongst 50 suspected cases of clinical leptospirosis, 24 (48.0%) were seropositive and only 13 (26.0%) had current infection compared with 10 (6.3%) and three (1.9%) of 160 apparently healthy house dogs respectively. The difference was statistically significant (P < 0.05; χ²). Twelve (25.5%) of 47 hunting dogs, 10 (20.4%) of 49 farm dogs and five (4.4%) of 113 stray dogs were seropositive (P < 0.05; χ²). Overall, a total of nine serovars were detected with serovars mankarso, icterohaemorrhagiae RGA, autumnalis and copenhageni being involved in 29 (47.5%), 20 (32.8%), 25 (41.0%) and 10 (16.4%) respectively in 61 seropositive dogs (P < 0.05; χ²). Serovar mankarso was most predominant in seropositive apparently healthy dogs, 37.8% (14/37), suspected clinical cases of leptospirosis, 62.5% (15/24) compared with serovar icterohaemorrhagiae with a frequency of 21.6% (8/37) and 50.0% (12/24), the difference being statistically significant (P < 0.05; χ²). Although all vaccines used for prevention of canine leptospirosis in the country contain serovars canicola and icterohaemorrhagiae, serovar mankarso was mostly associated with infection and disease and may be a good candidate for inclusion in the vaccine used locally. The public health risk posed to owners of dogs infected with Leptospira cannot be over‐emphasized considering the zoonotic nature of the disease.     

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.     

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 infection in domestic and wild animals in Fiji

Clinical and serological evidence has indicated that human leptospirosis in Fiji is an important disease, and the prevalence of antibody is exceptionally high. A serological survey of the rural population showed that only 12% of the people studied did not have complement fixing (CF) leptospiral antibody. As the origin of this infection could not be explained by the known distribution of leptospiral infection in domestic and wild animals, a serological survey using the complement fixation test (CFT) was undertaken as the first stage of an epidemiological investigation into human and animal leptospirosis. Sera from domestic and wild animals were tested for CF antibody to 12 leptospiral serovars, namely: pomona, copenhageni, grippotyphosa, hardjo, ballum, tarassovi, canicola, australis, bratislava, autumnalis, pyrogenes and bataviae. Antibody was detected in 27.5% of 480 cattle, 17.1% of 70 sheep, 10.3% of 252 goats, 10.0% of 480 pigs, 57.0% of 100 dogs, 55.8% of 34 rats (Rattus rattus, R. frugivorus, R. exulans and R. norvegicus), 53.1% of 32 mongooses (Herpestes auropunctatus) and 40.0% of 10 mice (species unknown.) Cross-reactivity precluded the identification of infecting serogroups with the exception of pomona in pigs and icterohaemorrhagiae, ballum and australis in dogs. Infection of dogs with a serovar of the australis serogroup may explain the predominance of serological reactions to bratislava in man. The survey revealed a significant level of leptospiral antibody in the animal populations of Fiji and indicated that cattle, dogs, rats, mongooses and mice are probably the most important maintenance hosts. Consequently, further investigation will concentrate on the attempted isolation of leptospires from these species.