Effect of different methods of administration of ivermectin on its efficacy against the shedding of gastrointestinal nematode eggs by gazelles

Seven different methods of administering ivermectin to gazelles were compared: subcutaneous injection, direct oral administration, administration in individual feeds, administration in a herd feed, direct oral administration of a second ivermectin formulation, administration in individual water supplies, and administration in the herd's water supply. The first five treatments were effective, as monitored by faecal egg count reduction tests, and administration in individual feeds or in a herd feed avoided the need to capture the animals, with the attendant risk of mortality. Of the factors associated with the recipients (species, sex, age and inbreeding coefficient) age was the only significant factor for the efficacy of the treatment. Oral or subcutaneous, individual or collective, and direct or indirect administrations were equally satisfactory for the treatment of all the parasite groups studied. Only when parasitic problems were due to Nematodirus species did direct administration to individual animals appear to be preferable.     

Dermatophilus congolensis Infection in Goats in Tanzania

When goats in Eastern Tanzania were screened for skin diseases, Dermatophilus congolensis was isolated from the skin lesions in 8 of 484 animals examined. In one severely affected case, the disease was also characterized by histological studies (Gram stain, Giemsa stain and routine HE studies) and electron microscopy. The histological picture was characterized by hyperkeratosis, parakeratosis, acanthosis, folliculitis and an inflammatory cellular reaction involving the epidermis. Gram stain and Giemsa stain revealed longitudinal and transverse branching filaments in the deeper layers of the epidermis. Ultrastructural studies demonstrated D. congolensis in various morphological forms, ranging from filamentous to tuber-shaped structures, mixed with numerous coccoid bodies of variable size. In some instances, the organisms were geometrically arranged in parallel rows of beading and were present in and among the degenerated epithelial cells. Several host cells showed degenerative changes. Ticks present on the goats were Amblyomma variegatum, Rhipicephalus evertsi, Rhipicephalus pravus and Boophilus sp. The clinical signs, pathological lesions, diagnosis, epidemiology and pathogenesis of the disease are discussed.     

Present and future of veterinary viral vaccinology: a review

This review deals briefly with some key developments in veterinary vaccinology, lists the types of vaccines that are used for vaccinations commonly performed in food animals as well as in companion animals, and indicates that the practising veterinarian can select the best vaccine by comparing the results of efficacy studies. Diva (Differentiating Infected from Vaccinated Animals; also termed marker) vaccines and companion diagnostic tests have been developed that can be used for progammes aimed to control or eradicate virus infections. Vaccine-induced herd immunity, which can be measured relatively easily when diva vaccines are used, is a crucial issue in such programmes. Current vaccine research follows many routes towards novel vaccines, which can be divided into non-replicating ('killed') and replicating ('live') vaccines. Promising trends are the development of DNA vaccination, vector vaccines, and attenuation of DNA and RNA viruses by DNA technology. The lack of (in vitro) correlates of vaccine protection markedly hampers progress in vaccine research. Various characteristics of an 'ideal' vaccine are listed, such as multivalency and the induction of lifelong immunity after one non-invasive administration in animals with maternal immunity. Future research should be aimed at developing vaccines that approach the ideal as closely as possible and which are directed against diseases not yet controlled by vaccination and against newly emerging diseases.     

An Abattoir Survey on the Frequency of Fatty Liver Syndrome in Dairy Cows from the Suburbs of Tehran

One hundred and six Holstein and Holstein x native cows were inspected before and after slaughter, and liver samples were taken. The fat content of all the liver samples was estimated by an extraction method (Soxhlet). The livers of 29 cows (27%) were classified as fatty. Seventeen of the animals were newly calved, 47 were non-pregnant, 33 were pregnant and 9 were dry, the median values for the fat content of their livers being 60.6, 34.4, 34.7 and 33.8 mg/g, respectively. The median concentration of liver fat in the first group was significantly different from that in each of the other groups (p < 0.01).     

One-step RT-PCR for the Detection of Infectious Bursal Disease Virus in Clinical Samples

A single-tube, non-interrupted, one-step RT-PCR has been standardized to amplify the hypervariable region of the VP2 gene sequence of infectious bursal disease virus (IBDV). The technique standardized on purified viral RNA was successfully applied to the detection of the virus directly in clinical samples. The amplified products were confirmed to be IBDV specific by their size in ethidium bromide-stained agarose gel, nested PCR and restriction enzyme digestion. Digestion of the amplicons with StyI restriction enzyme also differentiated classical virus from six very virulent field isolates. The sensitivity of the one-step RT-PCR was found to be 0.2 pg of viral RNA.     

Can epidemiology and economics make a meaningful contribution to national animal-disease control?

The general role of veterinary epidemiology and economics to national animal-disease control throughout the world is considered for the four main groupings of animal diseases: zoonotic, food-borne, endemic and epidemic diseases. This is done by considering how veterinary epidemiology and economics has contributed to priority setting (which diseases come first?), decision-making (for a given disease, which strategy is best?), and disease control implementation (how can optimal delivery and adoption of selected interventions best be achieved?). Within each of these categories, progress made and future opportunities are discussed. In addition, a review is made of how veterinary epidemiology and economics has been institutionalised. We conclude that veterinary epidemiology and economics holds a unique role in the development of national policies and strategies for improved animal health world-wide. However, we consider that we must capitalise more on the unique comparative advantage of the partnership between veterinarians and agricultural economists. We believe that much remains to be done to improve the "institutionalisation" of veterinary epidemiology and economics, and the adoption and impact of the products of our unique partnership, particularly in countries of the developing world.