Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/21362
Title: Some epidemiological aspects of gastrointestinal strongyles "nematodes strongyloidea" of sheep in the sub-tropical zone, of Pakistan
Authors: Qayyum, Mazhar
Keywords: Animal Sciences
Issue Date: 1996
Publisher: Quaid i Azam University
Abstract: An epidemiological study of gastrointestinal nematode parasites o f 1000 sheep was carried out at different abattoirs of sub-tropical (Barani or rainfed) region of northern Punj ab, Pakistan. The overall prevalence of nematodes infection was recorded to be 92 per cent. The following nematode parasites were recovered and their incidence is given in parentheses: Haemonchus contortus (83.6 per cent), Tri chostrongylus colubriformis (72.7 per cent), Oesophagostomum columbianum (69.6 per cent) , Trichostrongylus axei (69. 2 per cent), Ostertagia trifurcata (42.6 per cent), Trichuris ovis (39.6 per cent) , Strongyloides papillosus (32.4 per cent), Trichuris globulosa (10 .2 per cent), Nematodirus spathiger (9.3 per cent) , Bunostomum trigonocephalum (7 .2 per cent) and Oesophagostomum venulosum (6.5 per cent). Peak mean values of pepsinogen level were recorded from March-April (700-800 mu tyrosine) and from July to October with peak 1380 mu tyrosine occurring in September. The highest overall egg per gram of faeces was observed from August to November (2700-6500 epg). Larval inhibition at early fourth-stage (L4 ) of Trichostrongylus axei, Ostertagia spp. and Haemonchus contortus were also recorded in the abomasal mucosa during hot dry summer season (May-June). Sheep having less than one year of age were heavily infected as compared to 1 - 2 and > 3 years of age groups . The, overall infection was highest in sub-humid climate, followed by semi-arid and arid climates. Heavy infection of Haemonchus contortus was noted during July to September. Similarly, pastures were found heavily contaminated with infective larval stages (L3 ) in July to Octobe~ Trichostrongylus axei and Trichostrongylus colubriformis were also recovered throughout the year and their respective peaks of occurrence was recorded in April and September , respectively. Although Oesophagostomum columbianum was recovered throughout the year with minor fluctuations in different months. Similarly, In Ostertagia spp. the rate of recovery of this genus rose slowly t o a peak in March while remained at low level upto June. Nematodirus spa thiger was recovered In 18 lambs only and no significant seasonal t rends was noted. The faecal egg count was not found to be a reliable measure of the size of the trichostrongyle worms burden. Observations of egg out - put showed that periparurient rise occurred in 92 per cent ewes during the lambing season. Lactating suckled ewes (LSE) acquired high worms burden than that of nons uckled lactating ewes (NLSE) and barren ewes (BE). The development of Trichostrongylus colubriformis eggs into infective larvae was completed throughout the year under wide range of weather conditions. Low temperature has marked effect on the development of the free-living stages as no development occurred below> 10 DC. While the infective larvae of this specie were highly resistant to desiccation . As far as Haemonchus contortus was concerned from March to October the majority of the eggs developed into thirdstage infective larvae, but their proportion was varied depending upon moisture content of the faeces. At 10DC only S per cent eggs developed as compared to 2SDC. At 40DC majority of the eggs died due to desiccation . The present study has provided some excellent understandings of the epidemiology of gastrointestinal trichostrongylosis of sheep in sUb-tropical areas of Pakistan, and might help in designing control measures in future.
URI: http://hdl.handle.net/123456789/21362
Appears in Collections:Ph.D

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