Copper (Cu) metabolism in domestic herbivores as guide to criteria for predicting the Cu nutritional status of wild ruminants in southern Africa.

In southern Africa game farming has become an effective way of using underutilised resources and a valuable method of preserving and increasing wildlife numbers. However, little is known about the mineral requirements of wild animal species or the assessment of the mineral nutritional status of these species. To establish criteria for estimating the copper (Cu) nutritional status of wildlife, current knowledge about Cu metabolism and criteria for domestic animals has been used. Since the Cu metabolism of ruminants differs substantially from that of non-ruminants, Cu metabolism in domestic species such as cattle and sheep representing wild ruminants, and pigs and horses as non-ruminant species, has been scrutinised to propose criteria for wild bovids in southern Africa. In the adequate range of dietary Cu intakes, literature suggests that hepatic Cu concentrations in ruminants increase linearly with an increase in Cu intake, allowing a relatively reliable measure of sufficiency. In non-ruminants, hepatic Cu concentrations follow a lag phase during which hepatic Cu concentrations remain relatively constant with increasing dietary Cu intakes of more that 25 times their requirements. A consequence is that non-ruminants can tolerate much higher dietary levels of Cu compared to ruminants. It is proposed that at liver Cu concentrations of < 20 mg/kg dry matter (DM), a wild ruminant could benefit from Cu supplementation; liver Cu concentrations of between 20 and 300 mg Cu/kg DM suggest an adequate Cu intake; concentrations of 300 to 500 mg/kg DM indicate a potentially unhealthy accumulation of Cu, while liver Cu concentrations of > 500 mg/kg DM indicate that the animal probably consumed more Cu than required and might be at risk of developing Cu toxicosis.

A literature review and investigation of staphylococcal necrotic dermatitis in sheep.

An outbreak of necrotic dermatitis in sheep was intensively investigated. Initially 19 of 147 Letelle (Merino-type) ewes were identified but closer inspection revealed 57 sheep that had skin lesions, some very slight, and that the majority (46 or 80%) had lesions only above the lips. A small number of them had multiple lesions on the legs or vulvae apart from lip lesions. Seven had only vulvar lesions and 2 only leg lesions. Among the sheep with lip lesions, twice as many had lesions on the right as on the left. Electron micrographs did not reveal any virus particles from the lesions, but all bacterial swabs yielded pure cultures of beta-haemolytic, Gram-positive cocci that were catalase, coagulase and DNase positive. The organism was identified as Staphylococcus aureus. Histopathology was consistent with a dermotoxic insult. A review of available literature indicated that this outbreak was consistent with a diagnosis of ovine necrotic (staphylococcal) dermatitis, supported by data on signalment, lesions, distribution, size, number, epidemiology as well as specific tests. The range of differential diagnoses and possible confusers are discussed.

Oesophageal obstruction in Dorper ewes caused by impaction of a pelleted ration.

Two adult Dorper ewes developed an oesophageal obstruction (choke) by consuming a pelleted ration. The history, clinical signs and method of treatment were recorded in each case. One case was treated surgically via rumenotomy and the other conservatively. Both ewes recovered uneventfully and no recurrence was observed. Reasons for the compaction of the pelleted ration in the oesophagus are discussed.

The effect of a natural maedi-visna virus infection on the productivity of South African sheep.

A cohort study was conducted in order to measure the effect of the chronic indurative lymphocytic mastitis caused by the South African strain of maedi visna virus (MVV) on the pre-weaning growth of lambs born either of naturally infected or uninfected ewes kept under similar conditions. Fifty naturally infected ewes as well as another 40 from a maedi-visna-free source to be used as control animals, were purchased and kept in separate flocks which were managed in a similar way. All the ewes were of the same breed and 3-4 years old. During the adaptation period, and through the mating, pregnancy and lactation periods they were periodically monitored for the presence of MVV serum antibodies. The lambs were weighed at birth and thereafter every 2 weeks until the age of 90 days, when they were weaned. The ewes were then slaughtered, and their udders examined histologically and the number of lymphocytic follicles were counted and assessed. Although the calculated values indicated a correlation between the number of follicles in the udder and the reduction in the growth rate of the lambs, this was not statistically significant. Similarly, despite higher counts of lymphoid follicles in the udders of sero-positive ewes as compared to those that were sero-negative and the lower ewe productivity indexes in infected ewes, no statistically significant differences were found in the indexes of ewes in different follicle categories.

Acute hepatitis B in Edinburgh 1975-92: a retrospective study in a population where human immunodeficiency virus is highly prevalent.

A retrospective study of notified hepatitis B virus (HBV) infection in Edinburgh during 1975-92 identified 525 acute cases. For 343 where a probable transmission route could be determined, 215 were due to shared equipment by injection drug users (IDUs), 29 to homosexual intercourse, 25 to heterosexual or household contact with IDUs, 21 to heterosexual contact with infected non-IDU partners and 53 to various other or multiple routes. Cases were unevenly distributed geographically, particularly those among IDUs. The highest incidence within a post code district was approximately 2.5 times that for all Edinburgh. Annual cases peaked in 1984 then declined to low levels in the early 1990s. This reduction was most marked among IDUs, and may be ascribed both to changed injecting behaviour and decreased susceptibility within this group. The latter factor implies that HBV infections may be an unreliable guide to human immunodeficiency virus (HIV) infection in populations where HBV is highly prevalent.

Hospital and hospice resource use of HIV-positive patients in Edinburgh.

A prospective study of health service and hospice resource utilization (average length of stay or ALOS, discharge rate, bed day use, outpatient consultation) analysed with reference to gender, risk activity, immunological and clinical staging (1987 definition of AIDS) for the financial year 1992-93 was undertaken at the Regional Infectious Disease Unit (RIDU), City Hospital, Edinburgh, Scotland where 72% of 513 patients were infected via injection drug use. Not surprising therefore overall, drug users were the heaviest users of the inpatient facilities (74% of the discharges and 65% of the bed days) although homosexuals had the highest discharge rate (114 per 100 person years) and rate of bed day use (1654 days per 100 person years). Immunodeficiency (CD4 count < 200 cells/ul) and a clinical diagnosis of AIDS were both associated with greater inpatient and outpatient resource use compared to those without immunodeficiency (CD4 count > or = 200 CD4 cells/ul) or AIDS. Gender effects were complex; the ALOS for women was increased for all risk groups whatever the CD4 count whilst there was no consistent trend of more resource use for women by risk group. Drug users were the heaviest overall users of the local hospice (84% of all admissions, 83% of the bed days and a discharge rate of 76.4 per 100 person years), more than double the rates experienced by the other risk groups. Thus both clinical and immunological staging (AIDS or a CD4 count < 200 cells/ul) were associated with increased resource use in HIV infection and estimates of resource use for AIDS need to be increased by around one-third to take into account hospice use. Despite the preponderance of drug users in Edinburgh, comparisons with other centres did not reveal increased resource use.

The cost of health care for HIV-positive patients.

Utilizing a prospective study of health service activity for HIV/AIDS, 2 estimates of hospital costs of care analysed with reference to gender, risk activity, immunological and clinical staging (1987 definition of AIDS) were undertaken. Utilizing combined costs per life year (based on hospital and hospice activity but not primary and community care) the ratio of costs for CD4 < 200 and CD4 > 200 was for most risk groups between 2-5:1 whilst for AIDS: pre-AIDS it was between 3.6-8.3:1 except for homosexuals where it was 12.6:1. A comparison of the standard hospital costs for infectious diseases with the published accounts for clinical AIDS care in Lothian suggests a 3-4-fold underestimate in the costs of providing a comprehensive health care service.

Lothian general practitioners, HIV infection and drug misuse: epidemiology, experience and confidence 1988-1993.

BACKGROUND: Lothian has a high prevalence rate of HIV infection associated particularly with injecting drug use in the mid-1980s. During the late 1980s a number of services were introduced to support general practitioners to care for drug users and people with HIV infection. AIM: To ascertain the practice distribution of patients with HIV infection and drug users, and the experience and confidence of Lothian GPs in a number of HIV and drug related tasks, and to see how these changed over a five year period after the introduction of support services. METHOD: Information about practice distribution of patients with HIV infection and drug users and information about GP experience and confidence was obtained from a survey of individual GPs in 1988. Two practice surveys in 1991 and 1993, using a chosen GP for each practice, gave information about practice distribution of people with HIV infection and drug users, while a second survey of individual GPs in 1993, concentrating on GP experience and confidence, acted as a follow up to the 1988 survey. RESULTS: GPs are in touch with an increasing number of people with symptomatic HIV infection. They are increasingly involved and confident in caring for drug users. Offering support and training to GPs appears to have encouraged their involvement. There are a significant number of people with HIV infection in Lothian who are not known to GPs or to hospital services. A combination of practice and individual GP surveys was found to provide the most reliable information. It is planned to repeat the practice survey in 1995.

HIV in injecting drug users in Edinburgh: prevalence and correlates.

A citywide sample of injecting drug users (IDUs) who had injected in the previous 6 months was recruited in Edinburgh. Interviewers administered a questionnaire enquiring about drug use, sharing of injecting equipment, sexual behavior, and imprisonment. A specimen of saliva was assayed for human immunodeficiency virus (HIV) IgG. HIV antibody prevalence in 346 IDUs recruited between June 1992 and October 1993 was 19.7% (95% confidence limits, 15.5 and 23.9%). Univariate analyses indicated that infection was significantly associated with being 27 to 36 years of age, starting to inject between 1975 and 1980, injecting in 1980-1987 and, particularly, 1982-1984, injecting in more than 7 years since 1979, reusing injecting equipment already used by another IDU in 1980-1987, being imprisoned, using equipment used by a fellow prisoner, and residing in north Edinburgh. Multivariate analysis showed that being 27-36 years of age, injecting in 1982-1984, and being imprisoned were independently related to being HIV positive. The risk of being infected increased with the number of times of imprisonment. A quarter of the sample said that they had used injecting equipment already used by another person in the 6 months before interview, and 70% said that they had ever done so. Of IDUs who started injecting after 1986, 4.5% were HIV positive. These findings suggest that the potential for HIV transmission by contaminated equipment still exists in Edinburgh. This is particularly so in prison, where IDUs do not have access to new needles and syringes.

Physical structure and chemical composition of abomasal phytobezoars of goats and sheep.

The diameters of fibres from phytobezoars varied between 2 and 30 microns, with an average 58% measuring less than < 15 microns, 36% between 15 and 23 microns, and 6% greater than 23 microns. These diameters were very similar to those of the pappus hairs surrounding the seeds of the Karoo bushes Chrysocoma ciliata, Eriocephalus ericoides and Gnidia polycephala (means of 6.06 microns, 16.67 microns and 22.73 microns respectively). The microscopic structure and ultrastructure of these pappus hairs moreover closely resembled the fibres of bezoars but were quite distinct from that of hair or wool. Of particular interest was the presence of annular thickenings as well as terminal hooks on both bezoar fibres and pappus hairs, both of which structures are believed to be involved in the formation of bezoars. This close similarity between the fibres in bezoars and those of pappus hairs in the 3 plant species studied, leads to the conclusion that the bezoars consisted largely of pappus hairs of these and possibly other species. The chemical composition of bezoars found in goats and sheep, resembled that of pappus hairs and stems of the Karoo bushes Eriocephalus ericoides and Gnidia polycephala more closely than that of mohair. Ash, nitrogen, phosphorus and zinc concentrations in both bezoars and plant material were similar, but very different to that of mohair; however, the calcium, magnesium, potassium and manganese levels of bezoars were more similar to mohair than plant matter. This may have been due to a leaching effect.

Experimental reproduction of phytobezoars.

In a series of in virtro experiments (n = 64) using the mature flowers or seeds and pappus hairs of Karoo bushes Chrysocoma ciliata, Dimorphotheca cuneata, Eriocephalus ericoides, Gazania krebsiana and Gnidia polycephala, small phytobezoars were formed from material of E. ericoides, G. krebsiana and G. polycephala either alone or in combinations. The ratio of fibre to liquid used was found to be optimal around 1: 7 and milling of material enhanced bezoar formation. Time and pH did not appear to significantly affect the formation of bezoars. Other factors were either standardised or not studied. In a small in vivo trial, 4 groups of one sheep and one goat each were fed 10% of either C. ciliata, E. ericoides, G. polycephala seeds and pappus hairs, or a mixture of all 3, added to a basal diet of milled lucerne fed for up to 31 d. Small phytobezoars were formed in the goats but not the sheep receiving C. ciliata, and G. polycephala material. It was concluded that phytobezoars could form in goats or sheep eating large quantities of mature flowers or seeds of several Karoo bushes.

[The threat of wide dissemination of anthelmintic resistance by veld ram performance testing units]. / Die gevaar van wye verspreiding van weerstandbiedendheid teen wurmmiddels deur veldramprestasietoetssentra.

A veld ram performance testing unit consists of an association of stud or commercial ram breeders, who compare the performance of selected rams under field conditions on common pastures. The best performers are subsequently auctioned at public sales. To date, at least 10 Merino veld ram clubs have been established in various centres in South Africa. A strain of Haemonchus contortus, which was isolated from the pastures of one of these performance testing units, was found to be resistant to ivermectin, oxfendazole and rafoxanide. Closantel, levamisole and disophenol were more than 99% effective. The wide dispersal of the rams after testing, constitutes a potential danger for dissemination of helminths with resistant genes. Precautionary methods should include careful routine monitoring of drug susceptibility on the communal pastures, on the farms of individual members and thorough deworming of rams before they leave the testing unit. The prevention and control of resistance in such testing units are discussed, but it is emphasised that this is difficult, particularly if the worm strains on the communal grazing have become resistant to some of the anthelmintic groups.

A field strain of Trichostrongylus colubriformis resistant to levamisole and morantel in South Africa.

A strain of Trichostrongylus colubriformis from Nottingham Road, in Natal, was found to be solidly resistant to levamisole and morantel at the recommended dose levels. Untreated control sheep in fact harboured fewer worms at slaughter than either of the 2 treated groups. In contrast, the benzimidazoles and ivermectin were more than 99.9% effective against this worm strain. The possible implications of escalating resistance to anthelmintics in the gastrointestinal nematodes of sheep are discussed.