Background and Aim: Previous studies recorded the prevalence of gastrointestinal nematodes (GIN) in Limpopo Province. However, the studies did not address the seasonal patterns of infection and did not cover all districts of Limpopo Province, namely; Capricorn, Sekhukhune, Waterberg, Mopani, and Vhembe. It is, therefore, important to provide up to date information on the prevalence and seasonal occurrence data of GIN in all districts of Limpopo province. The present study was conducted to determine the occurrence of anthelmintic resistance (AR) and document the prevalence of GIN infecting sheep in five districts of Limpopo Province, South Africa. Materials and Methods: Forty animals in each district were used for fecal egg count reduction test (FECRT) to determine AR against ivermectin (0.2 mg/kg), levamisole (LEV) (5 mg/kg), and albendazole (7.5 mg/kg). Egg hatch test (EHT) was used to determine AR against thiabendazole (TBZ) and micro-agar larval development test (MALDT) was used for both TBZ and LEV. Naturally, infected sheep (n=780) were sampled for prevalence across five districts of Limpopo. FAMACHA© eye-color score estimations were also performed for each study animal. Results: FECRT showed occurrence of AR in most of the districts and a few with suspected resistance. EHT results showed AR development against TBZ for all districts, while the MALDT showed no AR against LEV in all districts, but detected AR against TBZ in Sekhukhune, Capricorn, and Waterberg. Haemonchus contortus was the most resistant species. A high nematode prevalence (88-100%) and 1210-1861 eggs per gram (EPG) was observed in all districts during the hot wet season, decreasing to 75-80% (453-1202 EPG) during the cold dry season. The sheep revealed a FAMACHA© mean score of 3, indicating mild anemia during the hot wet season except for Vhembe district that revealed a FAMACHA© mean score of 4 during the hot wet season, indicating anemia. Conclusion: AR recorded in Limpopo Province may be due to under-dosing caused by lack of weighing equipment and high treatment frequencies due to lack of proper training on anthelmintic use. The detection of AR in Limpopo is an important finding because it will help in outlining effective management systems against GIN.

For decades anthelmintics have been used as the primary control measure for worm infections in livestock. However, there has been continuous development of anthelmintic resistance (AR) by the parasitic worms infecting livestock. This chapter reviews AR in livestock with a special focus on treatment and control, modes of action of different anthelmintic classes, risk factors leading to development of AR, conventional and molecular tools used to detect AR, FAMACHA© and holistic control strategy to control anthelmintic resistance.

Anthelmintic treatment is the most common way of controlling nematode infections in ruminants even though several countries have reported anthelmintic resistance (AR), resulting in limitation for sustainable small ruminant production. The aim of the present study was to evaluate the knowledge of resource poor sheep farmers in Limpopo province on the use of anthelmintics. A questionnaire survey regarding helminthosis control practices was administered to farmers of small ruminant flocks in five districts of Limpopo province, South Africa, namely Capricorn, Sekhukhune, Waterberg, Vhembe and Mopani. A total of 77 resource poor farmers who owned 40 -100 sheep were interviewed between June and August of 2017 using a structured questionnaire with a combination of qualitative and quantitative, open-ended questions. None of the farmers weighed their sheep before dosing them instead visual appraisal of individual weight was the most common means of estimating the anthelmintic dose.Farmers that owned sheep for more than 10 years were better informed than their inexperienced counterparts in terms of identifying symptoms of gastrointestinal parasites infection and knowledge of infection mode (p<0.05) although no significant difference was found to exist between the three groups of farmers with regard to the usage and correct application of anthelmintics (p˃0.05). Majority of the respondents (57%) were aware of gastrointestinal nematodes (GI) that infect sheep although only 34% knew how animals become infected. The results from the present study also revealed that 57% of the respondents can identify the clinical symptoms of gastrointestinal nematodes infection. Although 67.5% of farmers mentioned that they never dose their sheep, 32.5% use anthelmintics at varying times in a year. The above information is an indication of risks associated with occurrence of anthelmintic resistance in the study areas. In vivo and in vitro AR studies should be conducted in flocks with high treatment frequencies to establish the degree of resistance if there's any using faecal egg count reduction tests. Furthermore, there is a need to give training to resource-poor farmers of small stock on proper application of anthelmintic treatment and to educate them on how to prevent development of AR.