Detection of Brucella abortus antigens by immunoperoxidase histochemical staining of lochia smears.

An immunoperoxidase histochemical staining technique for the detection of Brucella abortus organisms in lochia of brucellosis-infected cows was described. In comparison with the standard culture technique, the former method resulted in 36% false positive and 2.3% false negative reactions, which represents a sensitivity of 82% and a specificity of 94%. False positive reactions are presumably the result of organisms which succumbed during transit. The feasibility of the test in the confirmation of brucellosis is discussed.

Bovine brucellosis in the Highveld veterinary region: a preliminary report on the seroprevalence of brucellosis amongst adult beef cows in the region.

A preliminary survey to determine the seroprevalence of bovine brucellosis amongst adult beef cows in the Highveld veterinary region was conducted. Based on complement fixation tests, about 48.2% of seropositive beef herds and 4.47% of seropositive individual animals could be expected in the region. Since heifer calves on some farms apparently receive their doses of strain 19 vaccine later than the prescribed age of 4 to 8 months, more vaccination reactions than would normally occur, could be expected. The above figures should therefore be considered an over-estimation.

Bovine trichomoniasis in the north western Cape Province, western Transvaal and the Orange Free State.

In bulls (n = 2,437) examined by preputial sheath washes, 7.1% were found to be positive for trichomoniasis. The incidence varied from one area to the other, as well as between breeds.

Bovine brucellosis in the Highveld region: incidence in dairy herds.

Bulk tank milk samples which were collected twice with an interval of 2 months from 2103 herds were tested for brucellosis by employing the brucella ring test. Farmers involved were all supplying industrial milk to the National Co-operative Dairies. A questionnaire was circulated to these farmers in which they were asked to indicate how heifer calf vaccination with strain 19 vaccine was practised on their properties. Of the herds tested, 18.1% could be regarded as infected. This figure varied from 8.9% in the Potchefstroom area to 30.9% in the northern districts of the Hoopstad area. An important cause of this rate of infection should be sought in improper calfhood vaccination. At least 9% of the respondents did not practice heifer calf vaccination whilst another 8.1% only commenced with vaccination during 1985 or later. About 12.4% of farmers commenced heifer calf vaccination prior to 1970.

Aerobic metabolism of trehalose in the taxonomy of coagulase negative staphylococci.

Comparative assays demonstrated that the probability of error was 12.1% when testing the aerobic fermentation of trehalose by coagulase negative staphylococci when this carbohydrate was added to the medium prior to sterilization whereas the error was only 2.7% in media if filtered trehalose was added subsequent to steam sterilization of the medium.

Bovine brucellosis in the Highveld Region. 1. Effect of delay in transit on rose bengal test results.

Although the incidence of false negative rose bengal plate test (RBPT) results on sera which were delayed in transit for one to 17 days was greater than 0.65%, up to 7.2% of such reactions occurred in one infected herd. Since no correlation between the incidence of false negative RBPT results and delay in sera in transit could be found, it was postulated that this type of reaction should be attributed to animals in the early incubation stage of the disease or to individual variation in the rate of response to the RBPT; a problem which should resolve itself during consecutive tests. Blood samples taken from herds to be sold at sales or public auctions, however, should all be tested by the complement fixation test. No correlation between the serum agglutination test and complement fixation test results were noted except where serum agglutination test titres exceeded 134 IU ml-1.

The use of reduced-dose Brucella abortus strain 19 vaccine in the control of bovine brucellosis.

Adult animals from a known negative and an infected herd were vaccinated with reduced-dose Brucella abortus strain 19 vaccine. Since some of these animals developed elevated post-vaccinal blood titres, it is suggested that, when adult vaccination is decided on, such herds should be bled and tested about 4 months after vaccination and thereafter at 2 month intervals. Reactions with complement fixation titres of 392 IU ml-1 or higher on the first test should be taken as positive. During the 2nd and 3rd tests, positive reactions should be taken as less than 98 IU ml-1 and 49 IU ml-1, respectively. After vaccination, an overkill of up to 5%, due to vaccination reactions could be expected. Positive cases might occur up to 9 months after vaccinating an infected herd. On farms selected for adult vaccination suitable calving facilities in isolation, largely facilitate eradication. Lochia samples for the early diagnosis of brucellosis should be collected. Adult vaccination with a reduced dose S 19 vaccine, should be practised on selected, problem herds only, where the owner is fully aware of the consequences of this procedure.

Some features of coagulase positive staphylococci from bovine milk. II. Comparison of conventional techniques and the API Staph system.

A total of 150 isolates of Staphylococcus aureus were subjected to the tests on the API Staph system. Of these, 50 were also tested by conventional methods, using the same tests as those found on the API Staph strips. Applying the principles of numerical taxonomy, the relationship between these isolates was 82% and more. Tests for the metabolism of sucrose and N-acetyl-glucosamine and for the production of argenine dihydrolysate and urease appear to be superfluous in the identification of S. aureus in this system.

Examination of lochia as an aid to the early diagnosis of bovine brucellosis.

The standard technique for diagnosing bovine brucellosis is the serological examination of blood samples. As affected females may excrete large numbers of the Brucella organism in the lochia, the bacteriological and smear examination of such material appeared to be a suitable alternative for early diagnosis. Of the lochia samples collected from 210 cows and heifers within 12-24 h after parturition or abortion, 10.9% were bacteriologically positive. Only 70% of these could be diagnosed correctly as positive by microscopic examination. This technique also resulted in 3.3% false negative and 1.4% false positive diagnoses. Results of the serological examinations of blood, collected simultaneously with the lochia samples, correlated fairly well with those obtained microscopically. Culture of lochia samples on a suitable medium appears to be the method of choice, when dealing with the early diagnosis of bovine brucellosis.

Ovine brucellosis: repeated vaccination with Rev 1 vaccine and the prevalence of the disease in the Winburg district.

The effect of repeated vaccination of ram lambs with Brucella melitensis Rev 1 vaccine was studied in relation to complement fixation titres. The presence of Brucella organisms in semen and changes in neutrophil densities of the semen were also studied. A survey of the incidence of ovine brucellosis in the Winburg district on the basis of a clinical examination of rams and the complement fixation test is also reported on. Repeated vaccination of ram lambs with Rev 1 vaccine resulted in high complement fixation titres for Brucella abortus in all cases and slight Brucella ovis titres in some cases. Neither Brucella organisms, nor increased numbers of neutrophils could be found in semen samples collected from the experimental animals. The incidence of ovine brucellosis in commercial and stud flocks in the Winburg district was in the order of 2%. As a fairly high incidence of brucellosis occurred in 2 stud Döhne merino flocks where ram lambs are vaccinated with Rev 1 at weaning, the administration thereof in this breed should take place at an earlier age. A second dosage at weaning should not have any disadvantageous effects. In order to protect newly vaccinated ram lambs from contracting brucellosis from older, infected cases, the separation of age groups is essential. The incidence of clinically detectable testicular lesions in rams from the Winburg district was in the order of 2%.

Some features of coagulase positive staphylococci from bovine milk. 1. Carbohydrate metabolism: comparison of conventional techniques and the API 50 CH system.

When conventional techniques were applied to 84 isolates of Staphylococcus aureus from milk samples, it was found that they were all catalase and phosphatase positive and oxidase negative. They all fermented glucose within 24 h and mannitol within 24-48 h when inoculated into Hugh & Leifson's medium, enriched with 1% horse serum. When they were subjected to the carbohydrates of the API 50 CH system, all metabolized glucose aerobically, but only 85-89% of the isolates could utilize mannitol aerobically. Because of the difference in the utilization of mannitol observed, the value of the API 50 CH classification in the taxonomy of S. aureus becomes questionable. This system could be used as a handy tool, however, when selecting carbohydrates to be used in taxonomical studies.

Suspected facial eczema in sheep in the central Orange Free State.

Facial eczema is known to occur in the Humansdorp district of the Cape Province. During June 1982-January 1984, 5 outbreaks of hepatogenous photosensitivity occurred in sheep in central districts of the Orange Free State. In one of these outbreaks a diagnosis of suspected facial eczema was made histologically.

Epididymitis of rams in the central and southern districts of the Orange Free State.

Scrotal palpation, microscopical examination of semen smears and the application of bacteriological techniques, revealed the incidence of Actinobacillus seminis and Brucella ovis infection of rams in the central and southern districts of the Orange Free State to be 2,9% and 4,3%, respectively. More Dorper than Merino rams were affected. Although clinically detectable epididymitis was found in 5,9% of rams examined, infection with A. seminis and B. ovis, as measured by the presence of neutrophils in semen and positive semen cultures, could only be demonstrated in a small minority of affected cases. These organisms were found more regularly in clinically negative rams excreting neutrophils in their semen. Possible reasons for the high incidence of sheep brucellosis in rams in the particular area as well as the higher incidence of infection in Dorper rams are discussed.

Blood selenium levels of sheep in some districts of the Northern Orange Free State: the Bultfontein area.

Blood selenium levels of apparantly healthy, adult sheep from the Bultfontein area, as determined by neutron activation, varied between 0,165 and 0,500 micrograms/ml. Due to the absence of anaemia, a symptom which could be taken as one of the earliest signs of chronic selenosis, these values suggest the intake of high but non-toxic amounts of selenium.

Electron microscopic observations on the luminal surface of teat cup liners of milking machines used under South African conditions.

An investigation undertaken with the aid of scanning electron microscopy (SEM) on new and used teat cup liners revealed the generally poor quality of luminal surfaces. Even those of the brand-new distributor controls showed significant faults in the evenness and continuity of the liner surface. A hundred and 500 milkings apparently tend to aggravate faults like cracks, pores, grooves and pits, because of the general brittleness of some of the teat cup liners. The poor quality of the liners investigated raises various questions about the method of distribution of teat cup liners and serious concern about the role they play in predisposing bovine udders to mastitogenic infections, spreading mastitis, affecting the production and quality of milk, increasing the cost of milk production and reducing profits of dairy farming.

The application of numerical taxonomy in the classification of staphylococci from bovine milk.

One-hundred-and-two isolates of staphylococci from bovine milk were each subjected to a battery of 19 different tests. With the application of numerical taxonomy these isolates could be classified into 1 genus and 3 different species. Although the majority of the coagulase negative organisms were grouped as 1 species, the biochemical differences within this group indicated that they should belong to at least 2 species. About 50% of these isolates could be designated Staphylococcus epidermidis. Possibly because of the small number of tests, a finer division into different species could not be made.

Blood selenium of sheep in some districts of the Northern Orange Free State: a preliminary report.

Blood selenium concentrations of clinically healthy sheep were determined using a neutron activation technique. Although the number of samples were relatively small, the selenium concentration in the blood of sheep in the Kroonstad district appeared to be fairly normal. In the Bethlehem and Fouriesburg districts on the other hand, the blood selenium levels indicated the possible appearance of selenium responsive diseases.

The usefulness of the API 20 E classification system in the identification of Actinobacillus actinomycetem comitans, Actinobacillus seminis and Pasteurella haemolytica.

The prepuces of lambs aged 6--8 months and semen of 2 adult rams were found to be infected with gram negative, non-motile, non-haemolytic, pleomorphic bacilli. These organisms were compared with those of known strains of actinobacillus actinomycetem comitans. Actinobacillus seminis and Pasteurella haemolytica, using the API 20 E classification system. Applying the principles of numerical taxonomy, the majority of suspected strains of A. seminis could be classified as A. actinomycetem comitans and 3 examples as Histophilus ovis. Although some of the suspected strains of A. seminis could be classified as P. haemolytica, obvious differences between the genera Actinobacillus and Pasteurella were evident.