Jamie K. Morton

Experimental infection of reindeer with bovine viral diarrhea virus.

Two 8-month reindeer ( Rangifer tarandus ) and a 1-month-old Hereford-Holstein calf ( Bos taurus ) were inoculated intranasally with the Singer (cytopathogenic) strain of bovine viral diarrhea (BVD) virus. Clinical signs in reindeer included loose stools containing blood and mucus, and transient laminitis or coronitis. Signs in the calf were limited to bloody mucus in the stool and lesions in the nasal mucosa. Antibody titers to BVD virus in the reindeer were intermittent, and titers in the calf persisted from days 14 to 63 post-inoculation (PI). Viremia was detected on PI day 4 in one reindeer, days 3-7 in the other, and days 2-7 in the calf. Bovine viral diarrhea virus was isolated from the lung of the calf at necropsy (PI day 63).

BRUCELLOSIS IN ELK III. SEROLOGIC EVALUATION

The efficacy of the standard plate agglutination (SPT), buffered Brucella antigen rapid card (BBA), rivanol (Riv) and complement fixation (CFT) tests was statistically evaluated and correlated with known brucellosis infections in elk. Low titers on the SPT were detected in artificially exposed mature cow elk 2 weeks postinoculation and other tests began detecting antibodies at 3 weeks. Titers on all tests were detected as long as 4 years postinoculation. Serologic response was similar in artificially and naturally infected cows. Bulls did not maintain serologic titers as long as cows. The SPT at 1:25 or higher most frequently detected Brucella antibodies in infected elk, while the SPT at 1:100 or more least frequently detected antibodies. The percent of elk reacting at 1:100 or greater on the SPT declined rapidly after 6 months postinoculation. Combinations of any 2 of the 4 tests used had close agreement in concurrently identifying infected elk. The CFT correctly identified the greatest number (93%) of elk which were culture positive at necropsy and CFT titers persisted longer than those of the other tests. A CFT reaction persisted longer (average 10.7 weeks) than that of any other test in calves that demonstrated postnatal titers. The serologic responses of calves which acquired active infections were similar to adults. Criteria for identifying seropositive elk are discussed.

THE PATHOGENICITY OF BRUCELLA SUIS BIOVAR 4 FOR BISON

The pathogenicity of Brucella suis biovar 4 for bison (Bison bison) was evaluated by inoculation of 2.1 × 107 colony forming units (CFU) in 0.1 ml saline into the conjunctival sac of six pregnant cows. Six pregnant bison were inoculated with 1.27 × 107 CFU of Brucella abortus strain 2308 as a positive control. Bison were inoculated on 23 January 1992, and observed until calving or abortion after which they were euthanized, and necropsied. Bacteriological and histological examinations were conducted on lymph nodes, reproductive tract, mammary gland, and internal organs. Terminal serum samples from calves and cows were evaluated by card, rivanol precipitation, standard tube agglutination, cold complement fixation tube, indirect bison conjugated enzyme linked immunosorbent assay (ELISA), competitive ELISA, and particle-concentration fluorescence immunoassay. No clinical signs of brucellosis were seen in bison inoculated with B. suis biovar 4, and infection was found only in lymph nodes of two animals. There was no evidence of metastasis of this organism to the mammary gland or the reproductive tract. There were no detectable levels of antibodies to Brucella spp. in terminal blood samples taken from B. suis biovar 4-challenged bison. Brucella abortus was isolated from several tissues in all control bison. All B. abortus-challenged animals developed uterine infection and five developed mam-mary gland infection. Reproductive disease resulted in abortions in five B. abortus-challenged bison and neonatal death in the remaining calf. Brucella suis biovar 4 does not appear to be pathogenic for bison.

Trypanosoma cervi from Alaskan reindeer, Rangifer tarandus.

Twenty-nine (64.4%) or 45 reindeer, Rangifer tarandus, examined over a two-year period were infected with trypanosomes. Trypomastigotes and dividing epimastigotes were found in the blood of fawns, cows, and bulls. Morphometric analysis of bloodstream trypomastigotes from reindeer and comparison of these parasites with similar stages of trypanosomes from elk, mule deer, and white-tailed deer from the continuous United States proved them conspecific; the trypanosomes from these members of the Cervidae are identified as Trypanosoma cervi Kingston & Morton, 1975. This is the first report of trypanosomes from reindeer. No pathogenic effects are known to be caused by these parasites.

Experimental Brucella suis biovar 4 infection in a moose.

A moose (Alces alces gigas) was inoculated with Brucella suis biovar 4 to better understand the effects of brucellosis in this species. Serum antibody titers increased rapidly and peaked within 21 to 56 days. Fever, leukocytosis, recumbency, anorexia and depression were observed starting 42 days post inoculation. Brucella suis biovar 4 was isolated from blood, lymph nodes, liver and spleen.

AVIAN POX INFECTION IN AN AMERICAN GREEN-WINGED TEAL (Anas crecca carolinensis) IN ALASKA

Poxvirus infection was diagnosed on the basis of gross and microscopic appearance plus the presence of typical inclusion bodies in a juvenile American green-winged teal (Anas crecca carolinensis) in Alaska. This constitutes the first known report of avian pox in migratory ducks and the first report of poxvirus infection in wild birds in Alaska.

SEROLOGIC SURVEY FOR ACTINOBACILLUS CAPSULATUS IN FREE-RANGING SNOWSHOE HARES (LEPUS AMERICANUS) FROM ALASKA AND ALBERTA

A plate agglutination method was developed to test sera from free-ranging snowshoe hares (Lepus americanus) captured in Alaska (USA) or Alberta (Canada) for antibody against Actinobacillus capsulatus. Antiserum against A. capsulatus was prepared in a domestic rabbit. A concentrated suspension of formalin-killed A. capsulatus was prepared for use as an antigen. Serum antibody prevalence for hares was 98 of 239 (41%) in Alaska and 51 of 111 (46%) in Alberta. Prevalence in Alaska peaked in 1981 corresponding to a peak in hare population density. Seasonal prevalence peaked in May in Alaska. Prevalence at one capture site in Alaska was significantly higher than at four other sites. There was no difference in sex-specific prevalence for either Alaska or Alberta.

Effects of live Brucella abortus strain 19 vaccine on reindeer later challenge exposed with Brucella suis type 4

Twelve reindeer (Rangifer tarandus) were vaccinated with Brucella abortus strain 19 vaccine and challenge exposed with B. suis type 4 two and one-half months later during mid-gestation. An additional 10 reindeer served as non-vaccinated controls. A sharp serologic titer response was observed in both vaccinates and controls. Brucella suis type 4 was isolated from tissues and blood from most controls (8 of 10, and 7 of 10 respectively). Seven of 11 vaccinated cows aborted, gave birth to weak fawns that died, or were not pregnant at the completion of the experiment. Brucella suis type 4 was isolated from the tissue of 4 of 12 vaccinates at necropsy. It was concluded that, under the conditions of this experiment, B. abortus strain 19 vaccine in reindeer did not provide adequate protection against challenge exposure with virulent B. suis type 4 organisms.

Effects of live Brucella abortus strain 19 vaccine on reindeer

Twenty female and seven male reindeer (Rangifer tarandus) were vaccinated subcutaneously in the right shoulder with a 1-ml dose of approximately 1.2 x 108 colony forming units of Brucella abortus strain 19, the standard reduced dose for cattle. An additional three females and one male served as non-vaccinated sentinels. Brucella abortus strain 19 was isolated from two of three fetuses aborted by vaccinated females during the first of two fawning seasons. Serologic titers to brucellosis in the vaccinates peaked by 46 days post-vaccination. Shedding of B. abortus strain 19 by vaccinated animals was indicated by seroconversion of all four sentinels. Titers in the sentinels were low and sporadic. Brucella abortus strain 19 was isolated from the tissues and fetus of a pregnant female 51 days post-vaccination and from the carpal joint of another female 7 months post-vaccination. Based on these results and a previous challenge experiment, it was concluded that Brucella abortus strain 19 is not a suitable vaccine to use in a brucellosis control program in reindeer.