Risk factors associated with occurrence of anthelmintic resistance in sheep of resource-poor farmers in Limpopo province, South Africa

Abstract

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.

Detection of resistance against anti-helminths drugs in gastrointestinal nematodes of calves using fecal egg count reduction test FECRT

“…This resistance is inherited, selected, and resistant generations pass resistance genes on to their offspring, with the constant and notable expansion of helminths resistance AR by parasitic worms of the ruminants over the years. The resistance of worms has also been verified in several previous studies and for all classes of anthelmintic available globally, namely benzimidazoles, imidazothiazoles, and Macrocyclic lactones (36)(37)(38)(39).…”

Resistencia antihelmíntica en granjas ovinas del valle cálido del Alto Magdalena - Tolima

“…El aumento de forma paulatina del grado de resistencia no ha sido esclarecido; sin embargo, en el análisis descriptivo se hace evidente el comportamiento disímil de la resistencia en los predios, lo cual puede deberse a estrategias de manejo individual (Márquez, 2014;Mphahlele et al, 2019). En este estudio se encontró que la resistencia fue mayor en granjas con alta frecuencia de aplicación de antihelmínticos en comparación con aquellas donde se tratan a los animales 1-2 veces en el año; diferencias que pueden deberse a que las altas frecuencias de desparasitación incrementan la presión selectiva para los parásitos resistentes, ya que sobreviven al tratamiento y al reproducirse permiten un aumento en la proporción de parásitos resistentes (Cabaret et al, 2009).…”

“…La producción ovina es considerada de baja rentabilidad (Hernández-Cortázar et al, 2014; Morris, 2017; Díaz- Sánchez et al, 2018), siendo el parasitismo gastrointestinal una de las principales causas que afectan la rentabilidad, dado que genera grandes pérdidas por la disminución en la producción, morbilidad y mortalidad de los animales (Miller et Una de las estrategias de control más comunes en los casos de helmintiasis ovina es el uso de fármacos que en algunos rebaños también son empleados como profilácticos (Medina et al, 2014;Selemon, 2018). A pesar de que los antihelmínticos generan un control efectivo de los parásitos gastrointestinales, el uso inadecuado e indiscriminado de estos fármacos ocasiona un aumento de nematodos resistentes a ellos (Mphahlele et al, 2019), entre otras razones por el prolongado uso del mismo principio activo y por la subdosificación (Márquez, 2014;Mphahlele et al, 2019). Esto hace que aumente la frecuencia de presentación de individuos resistentes generando la pérdida de eficacia antihelmíntica y aumentando las tasas de morbimortalidad de los animales.…”

Anthelmintic Resistance Status in Gastrointestinal Nematodes of Seven Different Breeds of Sheep in intensive management

“…An urgent solution is required for the widespread issue of anthelmintic resistance to the primary medications used to treat helminth infections, particularly in ruminants [8]. The intensive use of anthelmintics to control gastrointestinal nematodes has become an essential issue in many countries, especially related to the problem of resistance [9][10][11][12][13]. A number of countries, including Spain [14], China [15], India [16], New Zealand [17], and Brazil [18], have reported cases of anthelmintic resistance.…”