The biochemical, morphological and virulence profiles of Bacillus anthracis isolated in the Kruger National Park

The biochemical, morphological and virulence profiles of 44 Bacillus anthracis isolates, obtained from various localities and carcass remains of wild animals in the Kruger National Park, South Africa, were examined. The morphological characteristics tested for included: the formation of capsules on bicarbonate agar, the motility of the vegetative organism, the presence of haemolysis on blood tryptose agar, the sensitivity of the vegetative organism to bacteriophage, the production of lecithinase on egg yolk agar, the liquefaction (hydrolysis) of gelatine and the capability of each isolate to produce mucoid colonies when grown on bicarbonate agar with horse serum in an atmosphere containing CO2. The API 50CHB and 20E systems were used to evaluate the biochemical activity of each isolate. The virulence of each isolate was determined by its LD50, using an inbred line of Balb/C mice. A clear pattern in the biochemical reactions emerged that appeared to be specific for each isolate. On the API 50CHB test strip, only 2 of the 44 isolates gave a 100% positive reaction to all 10 of the biochemical substances to which it was supposed to react, 9 gave positive results to 90%, 19 were positive to 80%, and 14 were positive to 70%. The reactions on the API 20E were completely different from what was expected, with only 1 of the biochemical activities (gelatinase production) showing a positive reaction to all the isolates. The virulence test indicated that 27/44 isolates could be regarded as highly virulent with a LD50 of less than 1,000 organisms, and the rest of the isolates as virulent with a LD 50 of 1,001-10,000 organisms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Idiopathic gastric rupture in a Friesian foal

Acute idiopathic gastric rupture resulted in sudden death of a 4.5-months-old healthy Friesian foal. No morphological lesions were present which could explain the preceding gastric impaction. In this case hypodypsia may have been (partially) responsible for the impaction as only a mechanical drinking apparatus, unsuitably for horses, was available.     

Excretion of alcelaphine herpesvirus-1 by captive and free-living wildebeest (Connochaetes taurinus)

Excretion of alcelaphine herpesvirus-1 (AHV-1) is for all practical purposes limited to wildebeest calves under the age of 4 months. Sixty-one per cent of calves 1-2 months of age excreted virus with a mean titre of 9.8 X 10(4) cytopathic-forming foci/ml in their ocular fluid. The incidence declined sharply to less than 2% in wildebeest older than 6 months. No difference in age-related excretion of virus could be detected between free-living and captive wildebeest and no virus could be isolated from free-living pregnant wildebeest cows or from captive cows and their calves during the first 4 weeks after birth. The occurrence of wildebeest-derived malignant catarrhal fever (WD MCF) during spring, when wildebeest do not excrete virus, is a strong indication of the existence of an alternative host or an intermediate host capable of biological transfer of AHV-1.     

Actinomycosis of the mandible, mimicking a malignancy in a horse

Osteomyelitis of the mandible with Actinomyces species was diagnosed in a 4-year-old sports horse with radiographic changes suggestive of neoplasia. Surgical debridement, intravenous and local iodine solution treatment were administered. Mandibular Actinomyces infections are reported in humans and ruminants; they have not been previously reported in the horse.     

Cow effects and estimation of success of first and following inseminations in Dutch dairy cows

The objective of this research was to determine the contribution of cow factors to the probability of successful insemination accounting for the serial number of inseminations in analysis. The investigation was performed with 101,297 insemination records in 51,525 lactations of different cows from 1368 herds obtained from the Dutch milk production recording database. Cows that had a first insemination (AI) between 40 and 150 days post-partum with one or more inseminations (≤6 inseminations) were selected. An insemination was defined successful when not followed by another insemination and when the cow calved between 267 and 295 days after insemination, or when the cow was culled between 135 and 295 days after the last insemination. Breed, parity, days in milk, lactation curve characteristics, milk production traits, moment of AI related to peak milk yield time (before or after peak milk yield), the last calf (female, male, twin or stillbirth) and season of insemination were selected as independent parameters for a model with successful rate of insemination as dependent parameter. A multivariable logistic regression model was used within cow and farm as a random effect. The probability of successful insemination was the highest in the first insemination and decreased in the following inseminations. However, the success rate of all inseminations increased in a later stage of lactation. The improvement in the successful inseminations in a later stage of lactation was better in multiparous cows than in first parity cows. Insemination in summer and before peak milk yield time reduced the success of insemination. The success rate was the lowest in 100% Holstein Friesian cows compared with other breeds and was the highest when the last calf was a female calf compared to a male calf, twin or stillbirth. In conclusion, the success of first and following inseminations depended on parity, breed, season of insemination, last calf status, daily milk yield at insemination date, serial insemination number and days in milk at insemination date.     

Effect of maternal immunity on the immune response to oral vaccination against rabies in young foxes.

OBJECTIVE: To determine effect of maternal antibodies on immune response to oral vaccination against rabies in young foxes. ANIMALS: 250 cubs from 48 vixens. PROCEDURE: Sera were obtained from cubs of 36 vaccinated (maternally vaccinated [MV+]) and 12 nonvaccinated (MV-) vixens between 23 and 71 days of age and tested for neutralizing antibodies. Seventy-one MV+ cubs and 33 MV-cubs were vaccinated orally with modified-live virus vaccine SAD B19. Geometric mean titer (GMT) was determined in these cubs approximately 21, 39, and 57 days after vaccination. In a subsequent experiment, 10 vaccinated MV+ cubs, 6 vaccinated MV- cubs, and 6 control cubs were challenge inoculated with virulent rabies virus approximately 100 days after vaccination. RESULTS: Serum GMT of nonvaccinated MV cubs (0.23 U/ml) was significantly greater than that of non-vaccinated MV- cubs (0.15 U/ml). The GMT of vaccinated MV+ cubs 21, 39, and 57 days after vaccination were 2.85, 2.11, and 0.79 U/ml, respectively, and were significantly less than those of vaccinated MV- cubs (12.19, 6.76, and 4.02 U/ml, respectively). All challenge-inoculated cubs with GMT < 0.5 U/ml succumbed to rabies. CONCLUSION AND CLINICAL RELEVANCE: Partially impaired immune response in cubs < 8 weeks old from vaccinated vixens causes insufficient protection against rabies. Inhibition of the immune response persists longer than the period during which maternal antibodies are detectable. Thus, oral vaccination campaigns for young foxes in areas where vaccination has been performed need to be reconsidered.     

Failure of a recombinant Babesia bovis antigen to protect cattle against heterologous strain challenge

Groups of cattle were inoculated subcutaneously with (i) a recombinant DNA-derived Babesia bovis protein (KaBbl-GZ) fused to beta-galactosidase and combined with adjuvants, or (ii) native beta-galactosidase (GZ) plus adjuvant, or (iii) adjuvant only or (iv) a live, attenuated B bovis vaccine. KaBbl-GZ was produced in the lambda gt11-amp3 system as a 5-10 kD babesial polypeptide linked to GZ. KaBbl has previously been shown to be an immunodominant antigen of B bovis, localised at the apex of the parasite, and present in a range of B bovis strains. High levels of GZ antibodies were observed in KaBbl-GZ and GZ inoculated cattle, but specific KaBbl antibodies could not be detected by ELISA. Five months after primary inoculation, all cattle were blood challenged with a virulent heterologous B bovis strain. Despite four inoculations with KaBbl-GZ, significant protection against the challenge was not observed.     

Hepatic lipidosis in pregnant cows on a dairy farm

Summary

A syndrome very similar to hepatic lipidosis is described in dairy cows during the dry period.

After being sent to pasture the animals did not eat well for undetermined reasons. The disease phenomena were mainly observed in animals carrying twins. At post mortem examination severe falty infiltration was found in the 3 animals made available for post mortem examination. Increase of the energy supply to the dry cows by addition of maize silage to the ration prevented new cases.     

Chemotherapy of Theileria parva lawrencei infections in cattle with halofuginone

Halofuginone lactate, given once orally at a dosage rate of 1,2 mg/kg body mass on the 1st, 3rd or 5th days of fever, resulted in the recovery of only 1 out of 5 splenectomized cattle. Three splenectomized animals, treated on the 1st as well as the 4th day of fever, recovered and were then carriers. Six untreated controls all died. The potential value of a chemotherapeutic agent for Theileria parva lawrencei infections in South Africa is discussed.