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Studies of parasitic helminths of sheep and goats in Ghana.

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    • "In general, the combined effects of these factors are responsible for the seasonal fluctuations in the availability of L3 on pasture, and subsequently in the prevalence of worm burdens in the hosts. This seasonal variation of parasite population dynamics has been described in a number of studies in many African countries (Assoku, 1981; Vercruysse, 1983; Van Wyk, 1985; Fakae, 1990; Fritsche et al., 1993; Maingi et al., 1993; Pandey et al., 1994; Tilahun, 1995; Tembely et al., 1997; Nginyi et al., 2001; Debela, 2002). In general, rapid translation of eggs through to L3 occurs throughout most of the rainy seasons, and grazing animals acquire the highest infections during these times. "
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    ABSTRACT: A two-year epidemiology study of helminths of small ruminants involved the collection of viscera from 655 sheep and 632 goats from 4 abattoirs in eastern Ethiopia. A further more detailed epidemiology study of gastro-intestinal nematode infections used the Haramaya University (HU) flock of 60 Black Head Ogaden sheep. The parasitological data included numbers of nematode eggs per gram of faeces (EPG), faecal culture L3 larvae, packed red cell volume (PCV), adult worm and early L4 counts, and FAMACHA eye-colour score estimates, along with animal performance (body weight change). There were 13 species of nematodes and 4 species of flukes present in the sheep and goats, with Haemonchus contortus being the most prevalent (65–80%), followed by Trichostrongylus spp. The nematode infection levels of both sheep and goats followed the bi-modal annual rainfall pattern, with the highest worm burdens occurring during the two rain seasons (peaks in May and September). There were significant differences in worm burdens between the 4 geographic locations for both sheep and goats. Similar seasonal but not geographical variations occurred in the prevalence of flukes. There were significant correlations between EPG and PCV, EPG and FAMACHA scores, and PCV and FAMACHA scores. Moreover, H. contortus showed an increased propensity for arrested development during the dry seasons. Faecal egg count reduction tests (FECRT) conducted on the HU flocks, and flocks in surrounding small-holder communities, evaluated the efficacy of commonly used anthelmintics, including albendazole (ABZ), tetramisole (TET), a combination (ABZ + TET) and ivermectin (IVM). Initially, high levels of resistance to all of the anthelmintics were found in the HU goat flock but not in the sheep. In an attempt to restore the anthelmintic efficacy a new management system was applied to the HU goat flock, including: eliminating the existing parasite infections in the goats, exclusion from the traditional goat pastures, and initiation of communal grazing of the goats with the HU sheep and animals of the local small-holder farmers. Subsequent FECRTs revealed high levels of efficacy of all three drugs in the goat and sheep flocks, demonstrating that anthelmintic efficacy can be restored by exploiting refugia. Individual FECRTs were also conducted on 8 sheep and goat flocks owned by neighbouring small-holder farmers, who received breeding stock from the HU. In each FECRT, 50 local breed sheep and goats, 6–9 months old, were divided into 5 treatment groups: ABZ, TET, ABZ + TET, IVM and untreated control. There was no evidence of anthelmintic resistance in the nematodes, indicating that dilution of resistant parasites, which are likely to be imported with introduced breeding goats, and the low selection pressure imposed by the small-holder farmers, had prevented anthelmintic resistance from emerging.
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    • "The survey recorded six nematode species in goats of the region, all of which have commonly been reported in goats and sheep of different climatic areas of the world by several workers (Grant, 1981; Specht, 1982; Chermette, 1983; Rose et al., 1984). However, Trichostrongylus, Ostertagia, Cooperia and Strongyloides, which have been reported as commonly occurring in goats from several parts of the world (Assoku, 1981; Grant, 1981; Chermette, 1983; Islam, 1984) and also from other regions of India (Bali, 1976; Dhar et al., 1982), were not encountered in the present study. This is to be expected since these worms occur primarily in temperate regions (Grant, 1981; Soulsby, 1982). "
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    ABSTRACT: Twelve hundred and twenty-eight goats (Capra hircus L.) from a sub-tropical and humid zone of India were examined for gastrointestinal nematodes. The species encountered in the region were: Haemonchus contortus, Bunostomum trigonocephalum, Oesophagostomum columbianum, Trichuris globulosa, O. aspersum, and T. ovis. The overall infection rate was 86.8%. Among various species found, H. contortus emerged as the most prevalent, although B. trigonocephalum and O. columbianum were also significantly in evidence. The seasonal fluctuation in infection was assessed by monitoring the faecal egg count of 1638 goats slaughtered during the 1-year period. The maximum values for the prevalence and overall mean eggs g-1 of faeces (EPG) were observed after the heavy rainfall season and remained at a relatively high level from July to December. H. contortus and O. columbianum appear to be of major importance as parasites in the goats of this climatic zone; the role of climatic factors in their prevalence is discussed.
    Veterinary Parasitology 10/1989; 33(2):135-42. DOI:10.1016/0304-4017(89)90061-7 · 2.55 Impact Factor
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    ABSTRACT: In 1986, following the discovery that Oesophagostomum eggs are excreted by people living in northern Ghana and Togo, Polderman and Gigase concluded that Oesophagostomum worms are able to complete their life cycle in humans, and that the helminth causes considerable disease in this area. There have been many cases of clinical oesophagostomiasis reported in the literature over the last century, but diagnosis has usually been based on a pathology specimen and clinical details have been sparse. We therefore amassed a cohort of 156 patients presenting to Nalerigu hospital in northern Ghana, and identified two distinct clinical presentations of the disease, Dapaong tumour and multinodular disease.
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