Therapeutic Efficacy of Closantel Against Different Gastrointestinal Parasites in Sheep

Overall and general health status of the small ruminants will be affected by the gastrointestinal parasitic infection in a flock. India has a population of 120 million goats and 62.5 million sheep, besides other livestock [1]. Worldwide essential information on the epidemiological studies of the parasitic diseases in the different geographical regions is essential to monitor the control of these diseases [2]. The severe economic loss because of parasitic infections in sheep might be due to mortality, enhanced susceptibility to other diseases and loss from the cost of the drugs. Among the different endoparasitic infections, haemonchosis and fascioliasis cause severe economic losses in sheep due to anaemia and liver damage respectively [3,4]. The expected annual cost due to parasitic diseases in sheep and cattle has been estimated as ten billions of dollars worldwide [5].  Due to an excessive and frequent utilization of the anthelmintics results in anthelmintic resistance in nematode populations and there is an obvious need for the development of the improved methods to control parasitic diseases. In India, several studies have been conducted to determine the prevalence of gastrointestinal parasites in small ruminants at different parts of the country [6,7]. Literature availability was very limited on the therapeutic effect of closantel in the management of gastrointestinal parasitic infection in sheep in India [8]. Hence, the present study was planned with an aim to record the therapeutic efficacy of closantel against different gastrointestinal parasitic infection in sheep in YSR Kadapa district of Andhra Pradesh.

The present study was conducted from September 2015 to April 2016 in YSR district of Andhra Pradesh, India. In this study, thirty sheep (age between 6 months to 14 months, weighing from 15 to 26 kg) were selected randomly from the three different flocks which had the previous history of diarrhoea. Sheep were treated with oral administration of closantel at 10 mg/kg body weight. Faecal samples were collected from the individual sheep and processed for the different types of parasitic ova. Identification of the different types of parasitic ova was done by morphological confirmation of ova and by copra-culture. Samples were collected before therapy and 1^st, 7^th, 14^th and 21^st day of post treatment. Analysis of the faecal samples was done by the direct smear, flotation technique and eggs per gram (EPG) was done by McMaster slide technique [9]. Efficacy of the closantel was estimated by the standard formula that is reduction in faecal egg counts (%)=100 × (arithmetic mean number of eggs per gram of faeces in the before treatment)-(arithmetic mean number of eggs per gram of faeces after treatment)/(arithmetic mean number of eggs per gram of faeces in the before treatment.

Therapeutic response to the closantel at different intervals in sheep was mentioned in Table 1 and the percentage efficacy was mentioned in Table 2. By the 7^th day of therapy, uneventful reduction in the EPG was noticed in the treated group. Reduction in the intensity of parasitic ova was 25.5%, 90.6%, 98.2% and 99.5% by the 1^st day, 7^th day, 14^th day and 21^st day of post treatment. After twenty fours of therapy, 25.5% reduction in the parasitic ova was noticed in sheep and it was highest against the Haemonchus contortus (37.8%), Oesophagostomum spp. (36.6%), Trichuris spp. (36.2%) parasites. 90.6% of the reduction in EPG levels was noticed after the seven days of therapy and it was highest against Oesophagostomum spp. (95.1%) and Haemonchus contortus (93.3%) parasites. Hundred percent of the reduction in EPG levels noticed against the Strongyloides spp., Trichuris spp. and Fasciola gigantic by the twenty first day of post therapy.

Table 1: Parasitic intensity before and after the therapy with closantel (EPG).

Table 2: Efficacy of closantel against the different parasites (%).

Different types of parasitic infections including haemoprotozoans, trematodes, cestodes and nematodes cause severe economic loss to the farmers [10]. Gastrointestinal parasitism leads to lowered protein levels by the loss of protein into the gut and increased gastrointestinal tissue protein metabolism finally had the effect on meat quality. In the present study sheep with the history of diarrhoea was selected to obtain the different types of parasitic ova because, helminths considered as one of the most common causes of diarrhoea in small ruminants in India [11]. Chemotherapy is the best way to treat helminths infection, but due to the indiscriminative use of the drugs, resistance to drugs has developed and it is a major constraint for nematode control throughout the world [12]. Closantel is a salicylanilide molecule it can affect the both nematodes and trematodes. But, development of the resistance varies according to the geographical location and utilization of different dewormers in the field [13]. It is essential to record the more prevalent gastrointestinal parasites in the different geographical locations to select a therapeutic protocol [14]. Closantel will be useful to prevent economic loss caused by parasitic infections in sheep in the present geographical region.

Present communication reports about the efficacy of closantel against common gastro intestinal parasites in sheep in YSR Kadapa district of Andhra Pradesh. The study concludes that the closantel can be used for control and prevention of parasitic infections in sheep.

The authors declare no conflict of interests in relation to this work.

The authors are thankful to the sheep herd owners for their cooperation and the authorities of Sri Venkateswara Veterinary University for providing the facilities to carry out the work.