SHEEP DISEASES

Actinobacillus species are Gram-negative bacteria responsible for several quite distinct disease conditions of animals. The natural habitat of the organisms is primarily the upper respiratory tract and oral cavity. A. lignieresii is the cause of actinomycosis (wooden tongue) in cattle: a sporadic, insidiously-developing granulomatous infection. In sharp contrast is A. pleuropneumoniae which is responsible for a rapidly spreading often fatal pneumonia, common among intensively reared pigs. Detailed investigation of this organism has provided a much clearer picture of the bacterial factors involved in causing disease. A. equuli similarly causes a potent septicaemia in the neonatal foal; growing apparently unrestricted once infection occurs. Other members of the genus induce characteristic pathogenesis in their preferred host, with one, A. actinomycetemcomitans, being a cause of human periodontal disease. This article reviews recent understanding of the taxonomy and bacteriology of the...

Rift Valley fever virus (RVFV) infects humans and livestock, causing haemorrhaging andabortions in animals. Three major RVF epizootics have occurred in South Africa since the1950s and the outbreak in 2010 had a mortality rate of 10.7% in humans. Accurate and earlydetection is therefore essential for management of this zoonotic disease. Enzyme-linkedimmunosorbent assays (ELISAs) have been developed for the detection of either IgM or IgGantibodies to RVFV in animal sera. In this study, data are presented on the validation of adouble-antigen ELISA for the simultaneous detection of both classes of antibodies to RVFV ina single test. ELISA plates were coated with a recombinant nucleoprotein. The nucleoprotein,conjugated to horseradish peroxidase, was used as the detecting reagent. A total of 534 serafrom sheep and cattle were used in the validation. The sheep sera were collected during a RVFpathogenesis study at the Agricultural Research Council (ARC) – Onderstepoort VeterinaryInstitute ...

Intra-uterine growth retardation (IUGR), caused by maternal undernutrition or placental insufficiency, is usually associated with disproportionately large reductions in the growth of some fetal organs and tissues (thymus, liver, spleen, thyroid) and impaired cellular development of other tissues (small intestine, secondary wool follicles, skeletal muscle). Growth of other tissues, most notably brain, is relatively unimpaired. In our restudy of postnatal consequences of IUGR in the offspring of prolific ewes, growth-retarded newborn lambs tended to be hypoglycaemic and showed sluggish postnatal engagement of the growth hormone (GH)-insulin-like growth factor (IGF) system. When artificially reared in an optimum environment, low birth weight lambs grew at rates similar to those of normal lambs. However, low birth weight lambs were fatter at any given weight, apparently related to their high energy intakes, especially soon after birth, had low maintenance energy requirements, and limite...

The socio-economic impact of cystic echinococcosis (CE), caused by Echinococcus granulosus, is reviewed with special reference to the following topics: consequences in man and livestock, costs and benefits of control programmes and economic procedures for evaluating control programmes. Examples of some important costs and benefits are given. Many consequences in man and livestock are difficult to evaluate from an economic point of view, because some basic data are difficult to obtain in many countries. However, the socio-economic evaluation of the consequences of CE and of the present and future control actions proves indispensable to best use available resources and possibly tailor control stategies.

This experiment was carried out on 8 ha of Panicum maximum cv. Tanzania pastures, with rotational grazing consisting of 7 days of occupation and 21 days of rest. Four treatments were evaluated: cattle grazing alone (BOV), sheep grazing alone (OVI), cattle and sheep grazing simultaneously (SIM) and cattle grazing followed by sheep (alternate - ALT). Twenty heifers and 30 male Santa Inês lambs were used. Fecal egg count (FEC) and fecal cultures were carried out. Blood was also collected to examine red and white cell series, total plasma protein (TPP), albumin and hemoglobin. FEC and estimated nematode pathogenicity index in sheep were lower in the SIM treatment. The Haemonchus spp. proportion was higher in isolated grazing systems. For sheep, mixed grazing was shown to reduce endoparasite infection, and SIM was better than ALT. For cattle, no difference between grazing systems was seen. Therefore, simultaneous grazing (sheep and cattle) may be a tool for reducing the need for anthelmi...

This project was conducted to investigate the comparative efficiency of competitive ELISA (cELISA), standard Agar Gel Immunodiffusion Test (AGID) and Precipitinogen Inhibition Test (PIT) for the diagnosis of Peste des Petits Ruminants (PPR) in Pakistan. To deal with this, serum samples from 198 sheep and 82 goats were collected from three different government livestock farms and all the samples were run simultaneously with the three serological tests. The samples found positive for PPR antibodies through cELISA, AGID and PIT were 96 (34.2%), 60 (21.4%) and 72 (25.7%), respectively. Kappa statistics were applied to evaluate the concordance between the laboratory-based test (cELISA) and field-based tests (AGID and PIT). Kappa statistics scores for cELISA versus AGID and PIT were 0.6343 (95% Confidence Interval CI 0.5231–0.7456) and 0.7134 (95% Confidence Interval CI 0.5987–0.8281), respectively, which indicate a “substantial” agreement between cELISA and AGID and “significant” agreement between cELISA and PIT. AGID and PIT revealed relative diagnostic sensitivities with cELISA of 59.3% and 69.7% and relative diagnostic specificities of 98.3% and 97.2%, respectively. The data suggested that for mass screening and control of PPR, these serological tests proved practical in the absence of cELISA since they have high relative diagnostic specificities and a satisfactory relative diagnostic sensitivities.

Peste des petits ruminants (PPR) is a contagious and economically important disease affecting production of small ruminants (i.e., sheep and goats). Taking into consideration the lessons learnt from the Global Rinderpest Eradication Programme (GREP), PPR is now targeted by the international veterinary community as the next animal disease to be eradicated. To support the African continental programme for the control of PPR, the Pan African Veterinary Vaccine Centre of the African Union (AU-PANVAC) is developing diagnostics tools. Here, we describe the development of a blocking enzyme-linked immunosorbent assay (bELISA) that allows testing of a large number of samples for specific detection of antibodies directed against PPR virus in sheep and goat sera. The PPR bELISA uses an anti-haemagglutinin (H) monoclonal antibody (MAb) as a competitor antibody, and tests results are interpreted using the percentage of inhibition (PI) of MAb binding generated by the serum sample. PI values below...

The identification of coagulase-negative staphylococci (CNS) causing ovine infections remains problematic, although these bacteria are considered the main etiologic agents of subclinical mastitis in sheep and goats. In this study, 226 CNS isolates were collected from 2201 milking sarda sheep belonging to 15 flocks with high somatic cell count scores. All isolates were subjected to identification with the API Staph ID test, and then to the amplification of staphylococcal 16S rRNA and gap genes by PCR assays. The gap gene was subjected to restriction fragment length polymorphism analysis with the restriction endonuclease AluI, whereas the 16S rRNA gene was subjected to ribosomal fingerprinting with the restriction endonucleases RsaI, PstI and AluI. When PCR–RFLP patterns of CNS isolates were different from those of their reference strains, gap gene amplicons were sequenced for definitive identification. The API Staph ID test, in alternative to the genotypic identification method, produced considerably different results in terms of species identified within each group. Using the PCR–RFLP assay, most of the isolates clustered together with the Staphylococcus epidermidis type strain (131, corresponding to 57.9%), followed by S. caprae (34, corresponding to 15%) and S. chromogenes (30, corresponding to 13.2%). In conclusion, the PCR–RFLP assay of 16S rRNA and gap genes is a more reliable and reproducible method than the API Staph ID test for the identification of CNS causing sheep mastitis.

The socio-economic impact of cystic echinococcosis (CE), caused by Echinococcus granulosus, is reviewed with special reference to the following topics: consequences in man and livestock, costs and benefits of control programmes and economic procedures for evaluating control programmes. Examples of some important costs and benefits are given. Many consequences in man and livestock are difficult to evaluate from an economic point of view, because some basic data are difficult to obtain in many countries. However, the socio-economic evaluation of the consequences of CE and of the present and future control actions proves indispensable to best use available resources and possibly tailor control stategies.

The objectives of this epidemiological study on cystic echinococcosis (CE) in Morocco (2001-2004) were to update the prevalence of CE in different animal species living in the most important areas of the country and to collect protoscoleces and germinal layers for genetic research purposes. The post mortem inspection concerned 2948 sheep, 2337 goats, 618 cattle, 482 camels and 455 equines (325 horses, 60 mules and 70 donkeys) in five different regions: the Rif (Mediterranean coast and high mountains of the Rif), the Loukkos (Atlantic northwest plain), the center (Rabat and Casablanca regions), the Middle Atlas mountains and the south (arid and semi desert areas). The global CE infection prevalence rates obtained were 22.98% in cattle, 10.58% in sheep, 12.03% in camels, 17.80% in equines and 1.88% in goats. The infection rates were especially high in the Middle Atlas in cattle (48.72%) and in the Loukkos in cattle and sheep (37.61 and 31.65%, respectively). The majority of infected c...

The aim of this study was to compare the efficacy of triclabendazole (TCBZ) and nitroxynil against a TCBZ-resistant Fasciola hepatica strain in a naturally infected sheep flock. The efficacies were measured by the faecal egg count reduction test. The level of F. hepatica antigens was tested in faeces; and haematological indices such as total proteins (TP), albumin, hepatic enzymes and total IgG were also studied. The results confirmed the resistance of F. hepatica against TCBZ in the flock with an efficacy during the first month post-treatment between 59.4% and 73.8%. In the nitroxynil group, the efficacy during the same period ranged between 81.3% and 86%, likely because the efficacy of this drug against 7- to 9-week-old immature stages is only 50–90%. Anemia was showed in all groups and white blood cells were always higher than the reference range. The values of TP and albumin were within normal range in most of the sheep, and an increase in hepatic enzymes confirmed the liver damage. Regarding total IgG, some negative correlations were found with egg excretion, and in relation to the level of antigens in faeces, these ones decreased immediately after treatment. We conclude that nitroxynil could be an alternative in case of TCBZ resistance.

The faecal egg count reduction (FECR) in faeces is the most widely used method to assess the efficacy of anthelmintics against gastrointestinal strongyles. Several methods are used and they yield different efficacy values. They give important weight to those animals which excrete the majority of eggs, before or after treatment. We propose using individual animal FECR tests that give equal weight to every tested host. The first method is based on a before and after treatment without untreated controls, whereas the second one takes into account the use of non-treated control hosts. Confidence interval at P=0.95 were established on bootstrap resamples for both individual-based methods. The individual-based FECR presented lower values than the average-based FECR in most cases. The individual FECR provided reliable evaluation when egg counts were over 300 eggs/g and when at least 10 animals were tested.