Longitudinal studies of naturally acquired Brucella abortus infection in sheep.

Naturally acquired Brucella abortus infections were studied during consecutive pregnancies in eight sheep and in their lambs over a period of 40 months to evaluate epizootiologic aspects of natural infection in sheep. Brucella abortus was isolated from the ewes following 16 of 26 natural terminations of pregnancy: from 5 of 6 ewes in the first year, from six of eight ewes in the second year, from two of six ewes in the third year, and from three of six ewes in the fourth year. Vaginal swab samples and milk samples were the most consistent source of the brucella organisms. Brucella abortus was isolated from three ewes when standard tube test seroagglutination titers were less than 1:100. In contrast, results of supplemental tests (card, 2-mercaptoethanol, complement-fixation, and Rivanol) remained positive during the study. During the 40 months, B abortus was isolated from 4 of 4 aborted fetuses, 2 of 5 stillborn lambs, 10 of 37 living lambs, and as an indicator of continuing infection, from 6 of 12 lambs born during the fourth year. Although B abortus has a definite host preference for cattle, this study demonstrated that under appropriate management conditions, sheep may be naturally infected and may remain infected for more than 40 months. Epizootiologic evaluation of all factors, including husbandry practices and exposure potential, should be utilized in determining the need to test other species that may have been exposed to cattle infected with B abortus.     

Intranuclear cisternal and vesicular structures in canine circumanal gland carcinoma cells

Intranuclear cisternal and vesicular structures, bound by a single membrane, were observed for the first time in some glandular "bird's eye" cells of canine circummanal gland carcinomas. The role of these intranuclear structures is not clear. It is suggested that they may be involved in cellular adaptation to an environment of nutrient deficiency, as a result of cell overcrowding.     

Structure of the sheep epidermis.

The stratum corneum measured on fresh frozen sections was found to be considerably thicker than previously reported. It was uniformly permeated with sebum, which also formed an intact film over the skin surface and it could readily be divided into two zones. The living epidermis was approximately half as thick as the stratum corneum.     

The blood volumes and erythrokinetics of Ndama and Zebu cattle experimentally infected with Trypanosoma brucei.

The responses of susceptible Ndama and Zebu cattle to experimental infection with Trypanosoma brucei were compared using haematological, parasitological and radioisotopic methods. Animals of both breeds became anaemic, but this was more severe in the Zebu cattle, one of which died. Although the prepatent period was the same in animals of both breeds, the levels of the first and subsequent peaks of parasitaemia were higher in the Zebu. The anaemia was due to an accelerated rate of red cell break-down which was more marked in the Zebu cattle. Haemodilution was not a feature. There was no evidence of dyshaemopoiesis but iron reutilisation from degraded erythrocytes was impaired. The greater resistance of the Ndama to T brucei infection could not be attributed to the capacity of this breed to mount a more effective erythropoietic response than the Zebu.     

Detection of the K99 antigen of Escherichia coli in calf faeces by enzyme-linked immunosorbent assay (ELISA)

Summary An enzyme-linked immunosorbent assay (ELISA) is presented for the detection of the K99 antigen of Escherichia coli in calf faeces. False-positive reactions were not observed with K99-negative strains and with several viral antigens. Only bovine coronavirus caused slight positive reactions which could be eliminated by a blocking test. As compared with the conventional procedure for the detection of the K99 antigen, ELISA seemed to be at least as sensitive and had the advantage that samples could be stored at -20° C before testing. In addition many samples could be handled at the same time and the results became available quickly. By carrying out the assay as a blocking test, specific antibody against K99 in serum or colostrum could be detected and titrated.     

Prevalence of antibodies to equine viruses in the Netherlands

Summary The prevalence of antibodies to various viruses was investigated in a series of serum samples collected from horses in the Netherlands between 1963 and 1966 and from 1972 onwards. Neutralizing antibodies to equine rhinopneumonitis virus, equine arteritis virus and to equine rhinovirus types 1 and 2 were detected in respectively 76%, 14%, 66% and 59% of the equine serum samples tested. The observed incidence of serum samples positive to equine adenovirus in the complement fixation test was 39%. Precipitating antibodies to equine infectious anaemia virus were detected only in serum samples from two horses imported from abroad. Haemagglutination inhibiting antibodies to Myxovirus influenzae A / equi-1, M. Influenzae A / equi-2, and Reovirus types 1, 2, and 3 were present in respectively 82%, 50%, 10%, 33% and 3.6% of the serum samples tested. The most frequently observed incidence of antibodies to the various equine respiratory viruses occurred in the groups of horses having repeatedly contact with other horses.