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Received Jan 16, 2018; Revised Mar 19, 2018; Accepted Apr 22, 2018
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Neospora caninum is an obligate intracellular protozoan which can infect a variety of mammals and birds [1]. During the whole life cycle of N. caninum, canids are the exclusive definitive hosts and shed environmentally resistant oocysts [2]. Many ruminants like sheep, goats, and dairy cattle commonly act as the primary intermediate hosts and are subjected to abortion, stillbirths, and neonatal mortalities [3, 4]. Both vertical transmission from infected mother to foetus and horizontal transmission from food or water contaminated with oocysts can result in the infection of N. caninum [5]. Though no N. caninum has been found from human tissue till now, antibodies to N. caninum have been detected in human serum [6], suggesting a zoonotic potential of the parasite.
The N. caninum seroprevalence has been reported in sheep and goats worldwide [7–9]. In China’s Tibetan areas, the prevalence and infection of N. caninum have been reported in black yaks [10, 11] and white yaks [12]. However, there is no information about the infection of N. caninum in Tibetan sheep in China. Tibetan sheep is one of China’s three major varieties of sheep, mainly inhabiting in the Qinghai-Tibet Plateau [13]. Tibetan sheep produce high quality pelage, provide nutritive and delicious meat, and are economically important for the local Tibetans. Thus, the objective of this study was to determine the seroprevalence and assess rick factors of N. caninum infection in Tibetan sheep in China.
2. Materials and Methods
2.1. The Study Sites
In the present study, serum samples were collected from Tibetan sheep in Gansu province (32°31′′~42°57′′ N, 92°13′′~108°46′′ E), northwest China, and Nyingchi prefecture (26°52′′~30°40′′ N, 92°09′′~98°47′′ E) in southeast Tibet, southwest China. The average elevation of the surveyed areas is more than 3000 meters above sea level and has a plateau continental climate.
2.2. Serum Samples
Serum samples were collected from Tibetan sheep via the caudal vein by local veterinary practitioners. A total of 2187 serum samples were collected from farmed Tibetan sheep from Luqu, Maqu, and Tianzhu in...