REVIEW Use of medicinal plants to control Haemonchus contortus infection in small ruminants

Haemonchus contortus is singly the most important of all the gastrointestinal nematodes that constrain the survival and productivity of sheep and goats owned by rural poor farmers in the developing world. This haematophagus parasite is infamous throughout the humid tropics/subtropics, being responsible for acute disease outbreaks with high levels of mortalities, particularly in young animals. Costs associated with control of this parasite in India, have been estimated to be US$ 103 million. H. contortus is also prominent amongst the reports of anthelmintic resistance that has emerged in all countries of the world that produce small ruminants. This emergence of multiple anthelmintic resistances has provided a spur for research on alternative forms of control. Recent surveys in developing countries have identified many plants that are intended and have the potential to be used as anthelmintics. This paper reviews the use of some medicinal plants as anthelmintics against H. contortus infection in small ruminants.


Introduction
nematodes.H. contortus has been documented to be resistant to all three broad spectrum families of Infections by gastrointestinal helminth parasites anthelmintics viz.benzimidazole, lmidazothiazole and of livestock are among the common and economically ivermectin (Prichard, 1990;Singh et al., 2002) and important diseases of grazing livestock (Perry et al., against drugs with narrow spectrum of activity such as 2002).Gastrointestinal parasites are world wide salicylanilides (Rolfe et al., 1990;Singh et al., 1996; problem, manifested by reduced weight, lowered meat Swarnkar et al., 1999).The emergence of resistance to and milk production (Githigia et al., 2005).
anthelmintic drugs which is now a world wide Furthermore, competition for the nutrients and tissue phenomenon (Jackson and Coop, 2000) and the damage during feeding and migration could cause increased awareness of consumers about drug severe clinical signs such as anorexia, anaemia, residues that potentially enter the food chain have diarrhoea and oedema associated with poor stimulated investigation into alter native to performance and mortality particularly in young, aged commercially available anthelmintics such as and immunosuppressed animals (Eysker and Pleoger, medicinal plants. 2003).One exception to this is the highly pathogenic For centuries, medicinal plants have been used nematode parasite of ruminants, Haemonchus to combat parasitism and in many parts of the world are contortus, which is capable of causing acute disease still used for this purpose.The use of medicinal plants and high mortality in all classes of livestock (Allonby for the prevention and treatment of gastro-intestinal and Urquhart, 1975).Consequently, there is an urgent parasitism has its origin in ethnoveterinary medicine and ever present need to control infections caused by (Athansidou et al., 2007).In ethnoveterinary medicine, H. contortus in ruminants.
Control is generally achieved by use of synthetic there seems to be a range of plants or plant extract suitable anthelmintics in combination with grazing for treating almost every parasitic disease of livestock.management.The frequent use of these anthelmintics Anthelmintic activity of medicinal plants with over many years has inevitably led to the development particular reference to Haemonchus contortus infection. of drug resistance to each class in parasitic Azadirachta indica (Neem) by 87.11% as compared to 68.10% by ethyl acetate extract at 50mg/ml.The ethanol extract inhibited egg The neem is known for its medicinal properties hatching by 99.77% at 3.12mg/ml.These results and has been recommended for use against gastrosuggest that A. indica extracts may be useful in the intestinal nematodes and related problems in many control of gastro-intestinal nematodes of small parts of the world (Biswas et al., 2002;Subapriya and ruminants. Nagini, 2005).In 1992, the National Research Council Butea frondosa (Palas) (NRC) of the United States considers the neem tree to be, "one of the most promising of all plants, that it may Butea frondosa, popularly known as 'palas', is eventually benefit every person on this planet.Native to commonly distributed throughout India.Fruits and India, the Neem tree is widely planted and naturalized seeds of B. frondosa are reported to have anthelmintic evergreen tree found throughout Asia.Preliminary property and largely used in treatment of round worms studies showed that feeding Neem foliage is safe, eco- (Kirthikar and Basu, 1975).Active principle of seed is friendly, cheap and palatable to sheep.Ad libitum an alkaloid-palasonin.In various in vivo and in vitro feeding of fresh Neem leaves produced 82% reduction studies, palasonin had been attributed to possess in worm eggs of animals (Chandrawathani et al., 2000) anthelmintic activity against adult Toxocara canis in and a further trial on a limited number of sheep showed dog, Ascardia galli in poultry and H. contortus in that neem produced a significant reduction in worm ruminants (Kumar et al., 1995;Jangde et al., 2001).The burdens (Chandrawathani et al., 2002).
anthelmintic activity of palasonin was due to ability to In another study, Chandrawathani et al. (2006) inhibit glucose uptake and depiction of the glycogen evaluated the anthelmintic effect of Neem (A. indica) on content of worms, thus causing inhibition of energy nematode parasites of sheep.Twelve Santa Ines cross metabolism (Kumar et al., 1995).bred sheep from a government farm were randomly Swarnkar et al. (2008b) have reported that seed selected and equally divided into control (n = 6) and extracts of B. frondosa have potent embryonicidal treated groups (n =6).Faecal egg counts (FEC) using (Chloroform and ether extract @ 1.25mg/ml), ovicidal the modified McMaster technique and the FAMACHA (alcoholic extract @ 1.25mg/ml) and larvicidal (aqueous score for assessing clinical anaemia were carried out extract @20mg/ml) activity against exogenous stages daily and recorded for 6 weeks.At the end of the study, of H. contortus.The in vitro assay used in the study all the animals were slaughtered and the total worm measures the effect of extracts directly on physiocount (TWC) was done.The results of FEC showed logical process viz.embryonic development, egg that there was no significant difference between the hatching and mortality and results suggest that control and treated group (p = 0.081).However, worm possibly isolated bioactive compound from B. frondosa burden estimations showed that the number of seeds could be a promising alternative to conventional parasites was significantly higher in the control group anthelmintic for the treatment of gastrointestinal compared to the treated group (p < 0.05).This result nematodes in the future.indicated that feeding neem had an effect on worm Allium sativum (Garlick), Zingiber officinale numbers in sheep.Most significantly, it is apparent that (Ginger), Curcurbita mexicana (Kaddu) and Ficus the highly pathogenic parasite, H. contortus appears religiosa (Pippal) particularly sensitive to the intake of fresh neem leaves by the animal.Iqbal et al. (2001a)  discards all injurious parasites in the intestine contortus eggs and larvae.The ethanol extract was (Nadkarni, 1976).found to be more effective inhibiting larval development Crude powder (CP) and crude aqueous extract anthocynidin, leteoforol etc) of sorghum or due to the (CAE) of dried ginger (1-3 g/kg) were administered to interactions of these tannins with the external surface sheep naturally infected with mixed species of of larvae of nematodes.gastrointestinal nematodes.Both CP and CAE Vernonia amygdalina (bitter leaf) and Annona exhibited a dose-and a time-dependent anthelmintic senegalensis (Custard tree) effect with respective maximum reduction of 25.6% Vernonia amygdalina and Annona senegalensis, and 66.6% in eggs per gram (EPG) of faeces on day 10 two plants used by local/smallholder livestock farmers of post-treatment.This study shows that ginger in Nigeria as anthelmintic were screened for in vitro possesses in vivo anthelmintic activity in sheep thus anthelmintic activity using H. contortus eggs.The justifying the age-old traditional use of this plant in extract of V. amygdalina did not show any significant helminth infestation (Iqbal et al., 2006) effects of plants has shown an exponential growth.For The first two groups were treated with crude aqueous some plant products, like condensed tannins, extract of C. sativum at 0.45 and 0.9 g/kg dose levels, evidences have accumulated indicating that plants the third group with albendazole at 3.8 mg/kg and the whose AH properties have been to some extent last group was left untreated.Efficacy was tested by scientifically validated, might represent a valuable faecal egg count reduction (FECR) and total worm solution within the "basket of options" to achieve a more count reduction (TWCR).On day 2 post treatment, sustainable control of gastro-intestinal nematodes with significant FECR was detected in groups treated with a reduced reliance on chemical anthelmintics (Krecek higher dose of C. sativum (p < 0.05) and albendazole (p & Waller, 2006).A holisitic approach supported by the < 0.001).On days 7 and 14 post treatment, significant participation of specialists from a large range of FECR was not detected for both doses of C. sativum (p scientific fields is highly desirable to help small farmers > 0.05).Significant (p < 0.05) TWCR was detected only to contain nematode parasite infections in sheep and for higher dose of C. sativum compared to the goats by relying on natural resources.untreated group.Reduction in male worms was higher than female worms.
The aqueous extract of C. sativum was also w/w in fecal culture when whole ground plant material investigated for in vivo anthelmintic activity in sheep was used. A. senegalensis showed promising anthelinfected with H. contortus.Both extract types of C. mintic activity especially with use of ground whole plant sativum inhibited hatching of eggs completely at a materials as used by some farmers (Alawa et al., concentration less than 0.5 mg/ml.The hydro-alcoholic 2003).extract showed better in vitro activity against adult Conclusion parasites than the aqueous one.For the in vivo study, Since the last decade, the number of studies 24 sheep artificially infected with H. contortus were dedicated to the scientific validation of the antiparasitic randomly divided into four groups of six animals each.