Korean J Parasitol.  2017 Oct;55(5):481-489. 10.3347/kjp.2017.55.5.481.

Hematological Changes Associated with Theileria orientalis Infection in Korean Indigenous Cattle

Affiliations
  • 1National Institute of Animal Science, Rural Development Administration, Wanju 55365, Korea.
  • 2College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea.
  • 3College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea.
  • 4Laboratory of Veterinary Internal Medicine, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea.
  • 5College of Ecology and Environmental Science, Kyungpook National University, Sangju 37224, Korea.
  • 6College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea.
  • 7College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea.
  • 8College of Veterinary Medicine, Chonbuk National University, Iksan 54596, Korea. jpark@jbnu.ac.kr

Abstract

Tick-borne pathogens can cause serious problems in grazing cattle. However, little information is available on tick-mediated diseases in cattle grazing on mountains. Thus, this study aimed to understand the potential problems related to tick-borne diseases in grazing cattle through the investigation of prevalent tick-transmitted infections, and their associated hematological changes, in terms of season and grazing type in Korean indigenous cattle (=Hanwoo). Hanwoo cattle from 3 regions of the Republic of Korea (=Korea) were either maintained indoors or placed on grassy mountains from spring to fall of 2014 and 2015. Cattle that grazed in mountainous areas showed a greater prevalence of tick-borne infections with an increased Theileria orientalis infection rate (54.7%) compared to that in non-grazing cattle (16.3%) (P < 0.001). Accordingly, the red blood cell (RBC) count and hematocrit (HCT) values of grazing cattle were significantly lower than those of non-grazing cattle throughout the season (P < 0.05). Moreover, RBC, hemoglobin (Hb), and HCT of T. orientalis-positive group were significantly lower than those of T. orientalis-negative group (P < 0.05). T. orientalis is a widespread tick-borne pathogen in Korea. Grazing of cattle in mountainous areas is closely associated with an increase in T. orientalis infection (RR=3.4, P < 0.001), and with consequent decreases in RBC count and HCT. Thus, these findings suggest that the Hanwoo cattle in mountainous areas of Korea are at a high risk of infection by T. orientalis, which can lead to hematological alterations. This study highlights the necessity of preventive strategies that target T. orientalis infection.

Keyword

Theileria orientalis; grazing; Hanwoo cattle; RBC profile; tick-borne pathogen
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