EPIDEMIOLOGICAL STUDY AND EVALUATION OF ANTHELMINTIC ACTIVITY OF INDIGENOUS PLANTS ON GASTROINTESTINAL NEMATODES OF SHEEP IN HYDERABAD DISTRICT

Abstract

The epidemiology of gastrointestinal nematodes of sheep was investigated in farms of small farmers in Hyderabad district during the year of 2004-05. Faecal egg counts, packed cell volume, herbage larval counts, adult worm counts and inhibited/arrested development larvae from permanently grazing sheep were monitored. On the basis of the coproculture and necropsy, seven species of gastrointestinal nematodes were identified i.e. Haemonchus contortus, Trichostrongylus spp, Ostertagia circumcincta, Strongyloides papillosus, Trichuris ovis, Oesphagostomum columbianum and Chabertia ovina. The overall prevalence rate of infection was 42.1 and 44.75 per cent on the basis of coprological examination and necropsy respectively. The results revealed that faecal egg counts (FEC), larval pasture counts, total worm counts (TWC) and packed cell volume (PCV) of sheep were significantly (P<0.01) influenced by seasonal variation (months). The FEC and TWC of sheep reached to the highest level during the rainy summer season (September) i.e.1913.4 and 920.8 respectively, while it declined to lower level during the dry season (February) i.e. 826.19 and 625.25. The arrested development larvae (L4) of H.contortus, O.circumcincta, Trichostrongylus spp. and Oe.columbianum were observed to occur from November to April and reached the peak in February i.e.511.4; whereas, L4 of S. papillosus, T. ovis and C. ovina did not show prone to arrest. The numbers of infective larvae (L3) on the pasture reached the peak of infectivity in August (1885) and declined to lower level in January (790). The PCV values of sheep were monitored during entire course of the study. There was highly decreased on PCV values of sheep during summer season (August) i.e. 24.88 percent and remained fluctuated during other seasons of the year. The drastic drop in PCV values were coincided with increased of FEC of sheep. During the year of 2005-06, the anthelmintic activity of Fumaria parviflora L. (Fumariaceae) whole plant, Adhatoda vasica (Acanthaceae) whole plant, Nigella sativa L. ( Ranunculaceae ) seeds, and Azadirachta indica L. ( Meliaceae) seeds were screened through the egg hatch and larval development assays in vitro. The results revealed that the aqueous and ethanolic extracts of F. parviflora A. vasica, N. sativa and A. indica at the concentrations of 3.12, 6.3, 12.5, 25.0, and 50.0 mg/ml exhibited ovicidal and larvicidal (P<0.05) against egg and larvae of gastrointestinal nematodes of sheep. All plant extracts showed dose-dependent (P<0.05). The inhibition rate of plant extracts on eggs and larvae was ranged between 9.3 - 96.0 percent. In the year of 2006-07, the field trials were conducted to evaluate the anthelmintic activity of F. parviflora, A. vasica, N. sativa and A. indica extracts against gastrointestinal nematodes of sheep using the faecal egg counts reduction test (FECRT) in vivo. In each plant treatment trial, the experimental animals (n=50) were divided into five groups (n=10) at random using age, weight, sex and level of helminth infections as the blocking factors and subjected to different treatment with single dose of plant extracts and/or commercial anthelmintic as follow: 1st, 2nd, and 3rd groups received single doses of 50 mg/kg,100 mg/kg and 200mg/kg respectively of respective plant extracts, while 4th group acted as a positive control group which was given a single dose of levamisole 7.5mg/kg (ICI® Pakistan) and 5th group served as negative control group and received no treatment. The results revealed a gradual reduction in FEC of experimental animals treated with different doses of different plant extracts and commercial anthelmintic drugs, and the difference was significant (P<0.05) on day 14 post treatment from day 0. The FEC decreased (P<0.05) significantly from day 3 onward to day 14 post treatment. F. parviflora extract exhibited the highest effect (P<0.05) in FEC reduction of experimental animals i.e. 77.6 and 70.5 percent for ethanolic and aqueous extracts respectively at the dose of 200mg/kg on the day 14 post-treatment. The effect of plant extracts on the haematological values also was discussed. The results of the study suggest that combination of strategic use of anthelmintic drugs and medicinal plant extracts could be useful for the control of gastrointestinal nematode infections in sheep.