An Epidemiological Study of <i>Hypoderma</i> Infection and Control Using Ivermectin in Yaks in Qinghai Province, China

Abstract

The prevalence of Hypoderma spp. in yaks grazed in the east of Qinghai province was investigated in 2008. In this area, the prevalence in young yaks (1- to 3-year-old) was very high at 82.2–98.7%, whilst in adult yaks (4-year-old and older), the prevalence was 42.4–50.6%. The seasonal development and migration pattern of Hypoderma larvae in yak bodies was found to be similar for different locations in this area. The numbers of first, second and third instar larvae detected in yak bodies peaked in October, December and March, respectively. Different doses of ivermectin (125 to 500 µg/kg body weight) almost completely dewormed the larvae from yaks, suggesting that using a quarter of the prescribed dose (500 µg/kg body weight) was effective. In October of each year between 2009 and 2012, ivermectin (125 µg/kg body weight) was administered to a total of 562,995 yaks grazed in four counties in Qinghai province, and the pevalence of Hypoderma larval infection in yaks was reduced to 0.5–1.0%.

Brief Overview of Bovine Hypodermosis in Kazakhstan and Other Central Asian Regions - With a Recommendation to Control This Parasitosis by Government Support

“…Bovine hypodermosis can be successfully controlled and eradicated from an area, in principle [1,2]. This is also shown by recent examples from the Russian Federation [3,38,46] and China [47], where the prevalence had been reduced by government monitored and promoted control measures and several years of the consistent use of appropriate antiparasitic drugs.…”

“…The first-choice compounds for the treatment of Hypoderma-infected cattle and yaks are currently macrocyclic lactones, such as ivermectin [36,37,38], doramectin [39,40], eprinomectin [41], and moxidectin [42,43], which have a nearly 100% efficacy against Hypoderma first-stage larvae. Depending on the formulation of the drug, they are applied either subcutaneously at a dose of 200 µg/kg bodyweight (bwt.)…”

Plasma kinetics, excretion in milk of eprinomectin, and its efficacy against Hypoderma spp. following topical administration in yaks

“…A recent, large‐scale controlled trial showed that ivermectin also successfully controlled Hypoderma spp. in yaks in the Qinghai‐Tibetan Plateau (Li et al ., ). However, owing to the high milk/plasma ratio of ivermectin and high residual levels in milk, ivermectin is not suitable for use in lactating yaks.…”

“…Parasite control is achieved through chemical prevention or therapy, and several anthelmintics, including avermectins and benzimidazoles, have been used in yaks. Among the avermectins (known as endectocides), ivermectin and doramectin have been shown to be highly effective in yaks for the control of the warble fly larvae and gastrointestinal nematodes (Cai et al ., , ; Li et al ., ). However, because of their high lipid solubility, these two endectocides are excreted extensively in the milk for a long period of time and, consequently, are not authorized for use in lactating yak in China.…”