Vector-Borne Pathogens with Veterinary and Public Health Significance in Melophagus ovinus (Sheep Ked) from the Qinghai-Tibet Plateau

Abstract

Melophagus ovinus (sheep ked) is a hematophagous ectoparasite that mainly parasitizes sheep. In addition to causing inflammation, wool loss, and skin damage to the animal hosts, M. ovinus also serves as a vector for a variety of pathogens and is highly likely to participate in the life and transmission cycle of pathogenic organisms. Herein, we investigated the presence and molecular characterization of vector-borne pathogens in M. ovinus from Qinghai-Tibet Plateau, China. A total of 92 M. ovinus pools collected from the Qinghai province of China were screened for the presence of selected vector-borne pathogens. The overall positive rate of A. ovis, A. bovis, A. phagocytophilum, and T. ovis in M. ovinus was 39.1%, 17.4%, 9.8%, and 89.1%, respectively. All of the samples were negative for Border disease virus (BDV), other Anaplasma species, Babesia spp., Rickettsia spp., and Borrelia spp. Co-infection of different Anaplasma species and T. ovis occurred in 51.2% of all samples with T. ovis. The positive rates of A. ovis, A. bovis, and A. phagocytophilum in different regions and altitudes of the sampling sites were significantly different. Sequence and phylogenetic analysis of target genes confirmed their identity with corresponding pathogens. Our results elucidate the occurrence and molecular characterization of Anaplasma spp. and Theileria spp. in M. ovinus, which could act as potential zoonotic reservoirs. To the best of our knowledge, this is the first report of the detection of A. bovis and A. phagocytophilum DNA in M. ovinus. This study gives the first extensive molecular survey of vector-borne pathogens with veterinary and public health significance in M. ovinus from the Qinghai-Tibet Plateau, China.

Ehrlichia chaffeensis and Four Anaplasma Species With Veterinary and Public Health Significance Identified in Tibetan Sheep (Ovis aries) and Yaks (Bos grunniens) in Qinghai, China

“…In addition, we carried out the comparative analysis and phylogenetic analysis of the msp4 gene sequence of A. ovis ( 25 ). The results showed that the A. ovis strains isolated from Tibetan sheep were identical to those isolated in M. ovinus in our previous study ( 31 ). Whereas, the A. ovis isolated from Dermacentor nuttalli in Qinghai by Han et al ( 23 ) belongs to genotypes III, which is in the same clade as those obtained from sheep in Italy ( Figure 4 ) ( 25 ).…”

“…An explanation for higher infection rates of A. ovis in this area could be the bites of ticks and other arthropods. Ticks and M. ovinus were found in Tibetan sheep in Maqin and Dari, and data on that M. ovinus carried A. ovis has been reported in our previous study (31). In addition, we carried out the comparative analysis and phylogenetic analysis of the msp4 gene sequence of A. ovis (25).…”

“…The genus Anaplasma are widely distributed in domestic animals, wild animals, ticks, and other vectors (23,(30)(31)(32). This study found relatively high A. ovis infection rates of 76.2, 94.1, and 81.3% in Tibetan sheep in three sampling sites, Maqin, Dari, and Qumalai, respectively, which is higher than in sheep in Xinjiang (40.5%) (16) and Gansu (5.7%) (33), and Tibetan sheep in northeast Qinghai (58%) (34).…”

Anaplasma phagocytophilum and Anaplasma ovis–Emerging Pathogens in the German Sheep Population

“…The pathogen is considered to be transmitted by ticks of the genera Dermacentor , Rhipicephalus , and Hyalomma [ 24 ], but recent data about their vector competence are lacking. Lately, A. ovis was also found in sheep keds ( Melophagus ovinus) [ 25 , 26 ]. The main clinical signs in sheep are severe anemia, extreme weakness, anorexia and weight loss, but these signs mainly occur under poor health conditions [ 18 , 27 , 28 ].…”

Seroprevalence and Risk Factors of Anaplasma spp. in German Small Ruminant Flocks

“…Different tick species belonging to the genera Dermacentor, Rhipicephalus and Hyalomma are considered to transmit A. ovis [13,14]. In recent years, A. ovis was also found in sheep keds (Melophagus ovinus) but their vector competence remains doubtful [15,16].…”