Haemonchosis: A Challenging Parasitic Infection of Sheep and Goats

SIMPLE SUMMARY: The paper reviews the challenges regarding haemonchosis, a common parasitic infection of sheep and goats, caused by Haemonchus parasites. The disease affects the health and welfare of sheep and goats and reduces their productivity, and thus, currently, there are various concerns regarding the disease. These refer to (a) the varying prevalence of the infection around the world as influenced by differing climatic conditions and environmental factors, (b) the increased resistance of the causative parasites to the available antiparasitic drugs, (c) the difficulties present regarding the accurate diagnosis of the disease and (d) the effective control of the infection. ABSTRACT: The paper reviews the challenges about haemonchosis—a significant and common parasitic infection of small ruminants. Haemonchus contortus is a highly pathogenic parasite that localises in the abomasum of affected animals and exerts its pathogenicity by blood-sucking activity, adversely affecting the health and productivity of animals. The first challenge is the uneven distribution of the infection globally, this being more prevalent in tropical and subtropical and warm temperate and summer rainfall regions than in cool and cold temperate and arid regions; hence, this leads in differences in the approaches required for its control. Another challenge is the widespread presence of Haemonchus strains resistant to the various anthelmintics available: Benzimidazoles, imidazothiazoles, macrocyclic lactones, closantel and monepantel, which makes the control of the infection difficult. The third challenge refers to the difficulty of diagnosing the disease, given that field evidence can provide suspicion about the infection, which needs to be subsequently confirmed by laboratory tests through parasitological or molecular techniques. The final challenge relates to the difficulties in the control of the infection and the necessity to use pharmaceutical products cautiously and with a planned approach, to avoid further development of anthelmintic resistance, also given that use of a recently licenced vaccine is not widespread. In conclusion, at the moment, we should be concerned, but not worried, about this infection, and apply correctly the appropriate health management plans.