Field evaluation of anthelmintic resistance in Haemonchus contortus from naturally infected goats of Nagpur, Maharashtra

Introduction

Haemonchus contortus, a barber pole worm, wire worm or stomach worm located in abomasums of small ruminants predominant in tropical as well as subtropical countries (Naeem et al., 2021) [12] . The major impact of this nematode has a blood feeding activity responsible for huge blood loss, wherein each worm sucks about 0.05 ml of blood per a day (Urquhart et al., 1996) [22] . It can cause protein deficiency, anaemia, bottle jaw oedema and gastrointestinal disturbances leading to death. (Fetterer and Rhoads, 1998) [5] . The anthelmintic chemotherapy has been the primary method for controlling this infection. Among the various classes of anthelmintics, benzimidazoles (BZ) a brood spectrum anthelmintic widely used due to their efficacy, ease of administration and cost-effectiveness. Nevertheless, resistance to these compounds has been increasingly reported in sheep and goat populations across different agro-climatic regions (Jackson and Coop, 2000) [8] leading to persistent infections, economic losses and compromised animal health. Small ruminant production in developing regions is largely sustained by marginal and landless farmers, for whom gastrointestinal parasitism, particularly due to the Haemonchus contortus with the repeated, frequent, and often indiscriminate use of BZ compounds has resulted in intense anthelmintic resistance (AR) thereby reducing the therapeutic efficacy of commonly used anthelmintics and posing a significant challenge to sustainable parasite control in small ruminants. (Stuchlikova et al., 2018) [20] . The reports from the goat farmers regarding the reduced efficacy of the anthelmintic make it essential to focus on the study to assess the benzimidazole resistance status for haemonchosis in naturally infected goats from Nagpur district of Maharashtra state.

Materials and Methods

The survey of anthelmintic resistance particularly for albendazole (benzimidazole group) in Kamptee by selecting the animals from organized as well as from unorganized goat farms with a history of treatment of goats with albendazole. The faecal samples from goats were collected per rectal and examined using centrifugal sedimentation and floatation methods. The eggs of nematodes were identified based on their morphological characters and egg micrometry (Soulsby, 1982) [19] . The animals positive for haemonchosis were grouped and used for further studies. in vivo anthelmintic resistance was assessed using the Faecal Egg Count Reduction Test as per W.A.A.V.P. guidelines (Coles et al., 1992) [3] , which estimates drug efficacy by comparing egg counts before and after treatment. Animals under study were treated with commercially available albendazole (ABZ) according to the manufacturer's recommended dose in milligrams per kilogram of body weight orally as a single dose.

Faecal egg counts

Faecal egg counts per gram of sample was carried by modified McMaster method. (Coles et al., 1992) [3] . About 3 g of faeces was homogenized in 42 ml of water, from which 15 ml liquid was centrifuged, supernatant was discarded and saturated sodium chloride solution (NaCl) was added in homogenized pallet to give the same volume as before (15 ml). Both the chambers of a McMaster slide were charged with the sample. The number of the eggs under the two ruled grids (total volume 0.3 ml) were counted at 10 X magnification. The number of eggs counted were multiplied by 50 to give the eggs per gram feces (EPG).

Resistance was confirmed when percent egg reduction after treatment was < 95% and the 95% confidence level was <90%; if only one criterion was met, resistance was suspected. FECR was interpreted by comparing the EPG before and after treatment. The percent efficacy of drug was calculated using the following formula according to Coles et al. (1992) [3] .

where T 1 is pre-treatment egg count and T 2 is post-treatment egg count.

Results and Discussion

The detection of BZ resistance in goats was evaluated on the basis of faecal egg count reduction (FECR) percentage after treatment. In Nagpur taluka, the mean egg count of Haemonchus contortus in goats on 0 th day of treatment was 3810.8±21.30 however on the 14

Discussion

There are several reports on the high prevalence of anthelmintic resistance in organized as well as intensively managed farms in India. In North-West India out of 22 intensively managed farms, 16 farms showed moderate degree and 4 farms showed severe resistance to fenbendazole. (Kumar and Yadav; 1994) [9] . In Hisar in sheep and goat farms belonging to Universities and Government farms showed single and multiple anthelmintic resistance in sheep and goats. (Singh and Yadav; 1997) [18] . Resistance in Haemonchus spp to benzimidazole in Pashmina goats at Mukteshwar was observed due to its prolonged use. (Laha et al. 1999) [10] . In sheep flocks maintained at Central Sheep and Wool Research Institute, Avikanagar, Rajasthan with frequent administration of Benzimidazole upto eight years, had developed resistance. (Swarnakar et al., 2001) [21] . In Maharashtra reduced efficacy of albendazole against Haemonchus contortus and Trichostrongylus colubriformis, with egg count reduction values below the critical 95% threshold, confirming established BZ resistance. (Ghalsasi et al., 2012) [7] . Investigations in small-scale goat rearing units in Kerala revealed reduced efficacy of albendazole, with faecal egg count reduction values around 71% and lower confidence limits below the recommended threshold, indicating established resistance. Sheep farms of Karnataka corroborated fenbendazole resistance, as evidenced by low lower 95% confidence limits in both in vivo and in vitro assays (Rajagopal et al., 2013; Amulya et al., 2016) [15,1] [16,11] . Likewise, partial to moderate resistance in organised sheep farms of Jammu and also from semi-arid regions of Gujarat demonstrated poor efficacy of albendazole, levamisole, and ivermectin, reflecting the emergence of multi-drug resistance in field populations of gastrointestinal nematodes (Gelot et al., 2016; Sharma et al., 2015) [6,17] . Field investigations in goats from central India further confirmed a high prevalence of BZ resistance, with a predominance of resistant genotypes detected through FECRT, EHT, and AS-PCR (Dixit et al., 2017) [4] . The widespread occurrence of benzimidazole resistance in gastrointestinal nematodes of goats reported in Dhenkanal district of Odissa. (Nanda et al., 2017) [13] and from the Chhattisgarh Plain zone varying levels of albendazole resistance during the monsoon period (Nath et al., 2024) [14] . Evidence from different regions of India indicates that benzimidazole (BZ) resistance in Haemonchus contortus is widespread in small ruminants. Similarly in present study the findings revealed the presence of ABZ resistance in organized as well as unorganized goat farms. The results in present study are in agreement with researchers who reported BZ resistance from various parts of the country may be due to indiscriminate, frequent and repeated use of same group of anthelmintic. The present investigation clearly establishes the widespread occurrence of BZ resistance in Haemonchus contortus infecting goats in Nagpur district of Maharashtra. Umred taluka was the only area where susceptibility to albendazole was observed may be due to the least exposure of goats to the parasitic infection, less animal population and good management practices.

Conclusion

The present study conclusively confirms widespread benzimidazole resistance in Haemonchus contortus infecting goats in Nagpur, Maharashtra align with earlier reports and are likely due to indiscriminate and repeated use of anthelmintics. The study underscores the urgent need for adoption of strategic parasite control measures, rational use of anthelmintics, regular monitoring of drug efficacy, and improved farmer awareness to ensure sustainable management of gastrointestinal nematode infections in goats.

Acknowledgement

AcknowledgmentsThe authors are grateful to Associate Dean, Nagpur Veterinary College of Maharashtra Animal and Fishery Sciences University Nagpur, for providing necessary research facilities.

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