Diseases of wapiti utilizing cattle range in southwestern Alberta.

Specimens from 28 wapiti (Cervus elaphus canadensis) were collected by hunters in southwestern Alberta in 1984. Various tests were performed to detect infections and conditions that could affect cattle sharing the range or cause disease in wapiti. Serum antibodies were present against leptospiral serovars autumnalis (25%), bratislava (4%), and icterohaemorrhagiae (8%), and the viruses of bovine virus diarrhea (52%), infectious bovine rhinotracheitis (45%), and parainfluenza type 3 (13%). No serological evidence of bovine respiratory syncytial virus, Brucella, Anaplasma, bluetongue virus, or epizootic hemorrhagic disease virus was found, nor were any lesions of vesicular diseases, necrotic stomatitis or nutritional myopathy evident. Focal interstitial nephritis and sarcocystosis were diagnosed histologically in 40% and 75%, respectively, of the wapiti tested. The prevalence of giant liver flukes (Fascioloides magna) was 50% and of lungworms (Dictyocaulus viviparus) 32%. Leptospiral serology on cattle in the area did not indicate that wapiti or cattle were a serious source of infection to each other. The giant liver fluke was the parasite most likely to be amplified by wapiti for cattle. Within the limits of this study, the results indicated that wapiti in the Waterton area do not pose a disease threat to the cattle with which they range, but periodic observational studies in these wapiti would be a useful means of early detection of any changes in the interspecies relationship.

The Successful Management of Leptospirosa hardjo Infection in a Beef Herd in Northern Ontario.

Abortion, premature calving, hemolytic anemia and fatal hematuria were associated with high levels (titer > 10(-4)) of antibody to Leptospira interrogans serovar hardjo and with isolation of hardjo in a herd of 265 beef cattle in the Great Clay Belt of northern Ontario. This herd was bred by artificial insemination, after heat detection by vasectomized bulls. The antibody prevalence rate in the herd was 54 to 60% over a five year period. The rate tended to reach 100% by age three years and to be below 5% in yearlings, which were raised in isolation from older cattle. Hardjo was isolated from the urine of a cow that aborted in the eighth month of pregnancy, and from kidneys of yearling steers which had been exposed to an older cow. Maternal antibody levels in calves paralleled those in their dams, protecting calves while they were being naturally exposed to infection, thus contributing to the achievement of balance between host and parasite. A controlled vaccination trial was conducted in 50 initially seronegative yearling steers and heifers. Serological response to vaccine was limited to a maximum agglutinin titer of 10(-2) in 8% of vaccinated cattle. Vaccination reduced the infection rate from 86% in the controls to 46% in the treated group, indirectly reducing the number of calves for which colostral antibody against hardjo would be available. A vaccination program was not implemented in the herd. Hardjo infection appeared to die out over a period of six years following the initial five year study period, with antibody prevalence falling from 60% to 0.7% and reactors persisting only in two eight year old cows. Decline in infection was coincident with changes in management which protected heifers from exposure to infection until their third pregnancy, and which probably lowered the reservoir of infection by increased culling from older age classes.

Leptospirosa pomona Abortion Storm in a Cattle Herd in Saskatchewan.

Abortions occurred in 18% of 131 beef cows and heifers during two months, on a farm in southern Saskatchewan. The losses began two weeks after acute febrile illness and agalactia in a dairy cow to which the beef herd had been exposed. A diagnosis of Leptospira interrogans serovar pomona infection was made on the basis of serology in cows and the finding of leptospires in fetal tissues by fluorescent antibody test. Tentative diagnosis of infectious bovine rhinotracheitis delayed treatment and prophylaxis until infection attained high intensity in the herd and severe losses to the farmer occurred. Abortions ceased after vaccination against pomona and oxytetracycline treatment of pregnant cows, although chronic debility followed the acute phase of the disease in some cows. Recrudescence of infection was suspected four months later, when acute agalactia occurred in one cow and debility in calves and cows was recurring. Pomona infection was not proven, but dihydrostreptomycin treatment and revaccination were applied to the whole herd. Seroconversion and IgM antibody continued to indicate a persistent source of infection and susceptibility in a minority of the population one year after onset. The source of the original infection is believed to have been a carrier beef cow, or a dairy cow which was leptospiruric at the time of contact with the beef herd. With the exception of one aborted calf, no evidence of pomona infection was found outside the farm, in cattle or wild mammals tested serologically within a radius of 30 km, during one year following the outbreak.

Antibodies to bovine bacterial and viral pathogens in pronghorns in Alberta, 1983.

Sera from 210 pronghorns (Antilocapra americana) ranging in southeastern Alberta were tested for antibodies to disease agents present in indigenous cattle. No antibodies to Brucella abortus, Leptospira interrogans serovars pomona, hardjo, or grippotyphosa, or infectious bovine rhinotracheitis virus were found. Antibodies at prevalences of 43.8% and 49.2% were detected to bovine virus diarrhea (BVD) and parainfluenza type 3 (PI-3) viruses, respectively. The much higher prevalence of BVD virus antibodies in cattle than in pronghorns, and the occurrence of clinical bovine PI-3 infection in the study area, suggest that cattle may be a source of infection to the pronghorns.

Leptospirosis in red foxes in Ontario.

The role of the red fox (Vulpes vulpes) in the epizootiology of leptospirosis in southwestern Ontario was investigated in 1973-1974. Leptospira interrogans serovar pomona (kennewicki by DNA analysis) was isolated from the kidneys of three of eight foxes tested. Severe hemorrhagic nephritis and interstitial nephritis were common to these foxes and to five others out of nine foxes examined. Autumnalis antibodies were detected at titers 10(-2) to 10(-5) in 12 of 100 fox sera. Pomona antibodies occurred in 6% of the sera, always accompanied by autumnalis antibodies, and at titers never exceeding the autumnalis titers. Cultural, serological, and pathological findings together indicated that the red fox could have been acting as an amplifier host, but not as a maintenance host, for pomona.

Leptospirosis outbreak in a piggery in southern alberta.

Fourteen abortions, stillbirths and neonatal deaths occurred over an interval of one month in crated sows in a farrow-to-finish swine operation. Leptospira interrogans serovar pomona (kennewicki by DNA analysis) was demonstrated by culture and fluorescent antibody test to be present in sows, piglets, boars, feeders, drinking water and skunks on the premises.Antibody was found in all clinically affected sows, at serum dilutions ranging from 1/800 to 1/25,600, and in all breeding boars at titers from 1/50 to 1/1600. Pomona antibody was present in 118 sow sera collected nine months before the outbreak, at a prevalence of 21.3%. Parvovirus infection in fetuses was intercurrent with the leptospirosis epizootic, despite vaccination for the former. Environmental contamination, feedback through skunks via drinking water, and dissemination through the piggery are discussed.

Leptospirosis: an occupational hazard to veterinarians.

Leptospirosis occurred in two veterinarians in Alberta, following their exposure to leptospires of domestic animal origin. The disease at onset resembled "flu" with fever, muscle and joint pain, and lassitude. It progressed through an extremely debilitating period with mild to severe hepatic and renal dysfunction, icterus and hemorrhage in one case, and cerebral meningitis in the other. Both patients were hospitalized for 11 to 14 days, where they responded to supportive and specific antibiotic and steroid therapy (penicillin G 10(6) IU q.i.d. and steroids, or tetracycline 500 mg q.i.d.). Diagnosis rested in one case on clinical signs and the observation of leptospires in blood and urine. In the other case, a tentative diagnosis of leptospirosis based on history and clinical signs was confirmed by serological test results and by the isolation of Leptospira interrogans serovar pomona from the patient's blood on day 6. Current occurrences of leptospirosis in man are reviewed. Convenient diagnostic methods, treatment and behavioural sequellae of leptospirosis are discussed.

Reclassification of North American leptospiral isolates belonging to serogroups Mini and Sejroe by restriction endonuclease analysis.

The genomes of North American strains of leptospires belonging to serogroups Mini and Sejroe were analyzed and compared with those of reference strains by cleavage with restriction endonucleases. The isolates selected for this study, when typed by the serologic method, were identified as serovars szwajizak, hardjo, and balcanica. However, the results of restriction endonuclease analysis (REA) indicated that a different classification existed. The 2 isolates typed as serovar szwajizak seem to be georgia by REA. Isolates belonging to serovars balcanica and hardjo had REA patterns that differed from both reference strains. Differences were not observed in the REA patterns between balcanica and hardjo isolates. All hardjo and balcanica isolates examined are suggested to be classified into a previously described hardjo, REA subtype hardjobovis. Using the enzyme Hha1, these isolates were subdivided into 3 subgroups. When examining the REA pattern of the 17 reference strains in serogroup Sejroe, 3 identical pairs were observed: wolffi and roumanica; sejroe and polonica; and istrica and nyanza. The REA again indicated that it will be a valuable method for the classification of leptospires.

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.

Diagnosis of Leptospira serovar hardjo Infection in Cattle in Canada.

The investigations described were designed to identify the cause of serological reactions to Leptospira interrogans serovars hardjo and sejroe in Canadian cattle, and to confirm by culture a diagnosis of leptospirosis in cases of reproductive failure and atypical mastitis.Leptospires were detected in ten of 64 urine cultures, nine of 18 kidney cultures, and one of nine cerebrospinal fluid cultures. Twelve strains were purified. All were placed in the serogroup which contains serovars hardjo and sejroe. The nine strains which were fully serotyped were considered to be identical with serovar hardjo strain hardjoprajitno. Hardjo was isolated from cattle in the presence or absence of clinical disease and of antibody detectable by the microscopic agglutination test. Hardjo antigen was more sensitive than sejroe in detecting agglutinins in 58% of actively infected cattle and equal in 25%, as shown by comparative serum titrations.

The relationship of serology and nasal microbiology to pulmonary lesions in feedlot cattle.

A group of 62 beef calves, born and raised in an institutional herd, were transferred at nine months of age to a commercial feedlot where they remained until slaughter seven months later. Clinical, immunological and microbiological monitoring was carried out during this period. No serious clinical illness occurred. One hundred percent seroconversion to bovine virus diarrhea virus took place after introduction of the calves into the feedlot as well as almost complete (59/62) seroconversion to bovine herpesvirus 1, a proportion of which could be related to a single vaccination. Significant increases in recoveries of Mycoplasma spp. from nasal swabs also occurred in the feedlot. At slaughter, the lungs of all animals were recovered and examined for pathological lesions: 23 were completely normal and 39 showed minor histological changes chiefly characterized by areas of lobular to sublobular atelectasis. For this group of calves, no relationship was found between the presence of potential pathogens in nasal mucus and the occurrence of lesions in the lung. The serological results are discussed in terms of vaccinations and other known events that occurred during the study period.

Correlation of bedrock type with the geography of leptospirosis.

Leptospirosis occurs enzootically over most of Southern Ontario. Leptospira pomona is the serotype most commonly found in outbreaks. Antibodies to L. pomona occur frequently in the sera of deer in wilderness areas. The geographic location of leptospirosis presents a pattern which closely parallels the distribution of Paleozoic bedrock. By contrast, L. pomona infection is absent from areas underlain by Precambrian bedrock. Comparisons of water chemistry, soil type, habitat, and host and pathogen availability in these two geologically distinct environments have not defined the mechanisms involved in the disease pattern. Leptospires resembling saphophytic strains occur widely, regardless of bedrock type. High titers to L. biflexa, a saprophytic serotype, were found frequently in deer sera from a Precambrian area which was surveyed intensively. Antibodies to L. hardjo and L. sejroe occur in many bovine sera from a predominantly Precambrian area where Paleozoic outliers are numerous. Colloidal clay is common to leptospiral habitats. A microenvironment structured by the surface activity of clay is likely to be a key ecological factor in the landscape epizootiology of leptospirosis. In Ontario, bedrock composed of limestone and dolomite formed in the Paleozoic era appears to be a reliable ecological marker for Leptospira pomona infection.