First description of the endogenous life cycle of Hypoderma sinense affecting yaks and cattle in China

Abstract

Larvae belonging to five species of Hypoderma spp. (Diptera, Oestridae) cause myiasis in wild and domestic ruminants that is characterized by migrations within deep tissues. In China hypodermosis is one of the most important arthropod diseases affecting ruminants and, moreover, represents a significant zoonosis, with numerous reports of Hypoderma spp. affecting farmers. Recently, a sixth species, Hypoderma sinense Pleske, has been rediscovered but the endogenous migration pathway within the host body is completely unknown and it represents a major constraint for the control of larval infection. In December 2003 a total of 165 larval stages of Hypoderma spp. were collected from different anatomical sites of 40 yaks slaughtered at an abattoir in the province of Gansu, China. The morphological characters and size of the recovered larvae were used to infer migratory routes and 45 specimens were also subjected to a polymerase chain reaction (PCR) assay of cox1 mtDNA and amplicons sequenced. All the larvae molecularly processed were identified as H. sinense and sequence identity was confirmed by a PCR-restriction fragment length polymorphism (PCR-RFLP) tool carried out using BfaI and HinfI endonucleases. The finding of H. sinense larvae only in the oesophagus or both in oesophagus and subcutaneous tissue of 12 and 15 animals, respectively, indicates that H. sinense larvae migrate through the oesophagus similarly to Hypoderma lineatum (De Villers). The description of the endogenous life cycle of H. sinense will help to determine the timing of specific treatment programmes to guarantee the improvement of animal welfare and health, thus resulting in an increase in livestock production in China.

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

“…It has been reported that the 1st instar larvae of H. lineatum and H. sinense parasitized in the esophagus and those of H. bovis in the epidural fat of the spinal canal [2, 4, 15, 21]. However, as observed in our previous study [13], a large proportion of 1st instar larvae were found not only in the esophagus but also in the rumen.…”

“…Unfortunately, species identification was not conducted in this study. Although morphological identification for the species of 1st instar larvae is impossible [15], DNA identification of species would help to understand the migration patterns of H. bovis, H. lineatum and H. sinense in yaks.…”

“…One was Yushu county with an average elevation of 4,000 m, and the other was Haiyan county with an average elevation of 3,000 m. Every month from April 2008 to March 2009, five one-year-old yaks were selected from the herd grazed in the counties and autopsied to check for Hypoderma larvae in visceral organs, such as esophagus, rumen, jejunum, colon, diaphragm, spinal canal and in the skin of back. The larvae collected were fixed in 10% formalin and counted, and their instar larval stage was determined as previously described [10, 15]. …”

“…Hypodermosis is a serious disease affecting livestock throughout the world, and two species of Hypoderma , H. bovis and H. lineatum , mainly affect cattle [10]. However, in yaks, a third species, H. sinense , is also commonly found [12, 15]. The overall prevalence of Hypoderma larval infection in yak is around 70–95%, reaching 100% in some areas [24].…”

Haematobia irritans parasitism of F1 yak × beef cattle (Bos grunniens × Bos taurus) hybrids

“…An awareness of the risk for parasitism of F1 yak × beef hybrids by horn flies is important for practising veterinarians, entomologists and agricultural producers in Europe and North America in order that appropriate monitoring protocols and preventative treatment strategies can be developed, and decisions on interventions made during peak parasitism periods (Oyarzún et al, 2008;Swiger & Payne, 2016). Initial assessments such as that reported in this study, like the initial reports by Otranto et al (2006) for Hypoderma species (Diptera: Oestridae) in yaks and cattle in China, have similar medical and veterinary applications that are also relevant to the traditional regions of production of yaks and their associated hybrids in Asia (Saravanan et al, 2008;Barsila et al, 2014;Angell et al, 2018).…”