Prevalence of Trichinella nativa in lynx (Felis lynx) from Alaska, 1988-1993.

Lynx (Felis lynx) carcasses were collected during the 1989 to 1990 through 1992 to 1993 trapping seasons in Alaska (USA). Seven areas were represented. Tongue samples were removed from 1,065 carcasses. Specimens were examined for the presence of Trichinella nativa larvae by means of enzymatic digestion. Overall prevalence was 21%. Both prevalence and number of larvae per gram of host tissue were directly related to age of the host. Age-specific prevalence ranged from 4% for kittens up to 59% for lynx 5 yr of age and older. For infected lynx, intensity ranged from 0.27 larvae per gram of host tissue for kittens up to 2.35 larvae per gram for lynx 3 yr of age and older. Location-specific prevalence ranged from 19% to 27%. Year-specific prevalence ranged from 13% to 26%. Prevalence in both males and females was 21%.

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.

Bovine herpesvirus-1 and Pasteurella haemolytica aerobiology in experimentally infected calves.

Eight calves (2 calves in each of 4 groups) were exposed to an aerosol of bovine herpesvirus-1 (BHV-1) and 4 days later to an aerosol of Pasteurella haemolytica. Samples of tracheal and exhaled air were taken simultaneously beginning 1 day before viral exposure and once a day up to 3 to 4 days after the bacterial exposure. Samples were also taken during the period of aerosol exposure. Only 0.04% to 0.42% of P haemolytica-carrying droplets of the bacterial aerosol passed beyond the cranial part of the respiratory tract to the trachea. Nevertheless, numbers of bacteria as few as 1 bacterium/L of tracheal air were sufficient to produce fatal disease in the lungs of BHV-1-infected calves. In 1 of 4 groups, BHV-1 was isolated from most daily samples of exhaled and tracheal air. Pasteurella haemolytica was isolated 7 times more frequently from air when calves were kept at 1 C than when calves were kept at 23 C. The number of P haemolytica-carrying droplets in exhaled air was low (less than 1/L of air); however, samples obtained during the time that calves were coughing contained up to 10 P haemolytica-carrying droplets/L of air. It was learned that the cranial part of the respiratory tract serves as an efficient filter on inhalation and exhalation, but this filter is deficient in the animal when coughing occurs. This process expels infective droplets of size suitable for inhalation by other cattle in close proximity.

Resistance to Eimeria bovis produced after chemotherapy of experimental infections in calves.

Eighteen Holstein-Friesian four week old calves were inoculated with 5 X 10(5) sporocysts of Eimeria bovis by stomach tube. The calves were divided into three equal groups. The first group was treated with monensin, 1 mg kg-1 body weight daily, from the 10th-20th day inclusive after infection; the second group was treated with amprolium, 10 mg kg-1 body weight daily, for the same period of time and the third group acted as infected controls. Both drugs were for the most part effective in preventing clinical signs, in suppressing reduced rates of weight and in reducing oocyst production. The calves of all three groups were resistant to the second infection given 35 days after the first infection with E. bovis as measured by rates of weight gain, fecal oocyst output and lack of clinical signs.