Genetic Diversity of Bovine Hemoprotozoa in South Korea

Abstract

Tick-borne pathogens cause economically significant diseases in cattle. Theileria spp. are parasitic protozoa and the causative agent of bovine theileriosis. Here we report the distribution and risk factors of bovine Theileria using blood samples taken between 2018 and 2019. Of 737 tested cattle, nine animals (1.2%) were positive for Theileria orientalis infection by 18S rRNA gene amplification. Further analysis of the infected samples using the T. orientalis major piroplasm surface protein (MPSP) gene revealed five different genotypes circulating in the population: Types 1, 2, 3, 7, and N3. To the best of our knowledge, this is the first research to describe the existence of the T. orientalis MPSP genotype N3 in South Korea. Although the prevalence of bovine T. orientalis was low, our study offers data on the geographical distribution and prevalence of bovine Theileria spp. in South Korea. Further studies are warranted to determine the correlation of clinical symptoms with parasite MPSP genotypes. Our data provide epidemiological information to help control bovine theileriosis in South Korea.

Latitude and seasons influence the prevalence of Theileria orientalis and affect the hematology of non-grazed dairy cows in Korea

“…The prevalence of T. orientalis in Korea was significantly higher during the warm period (43.0%) than during the cold period (13.5%). This finding is partly consistent with that of an earlier study in which T. orientalis was detected only during the summer [ 10 ]. This is because invertebrate ectotherm vectors, such as ticks and insects, have better survival rates in warmer environments than in cooler environments [ 3 ].…”

“…The 20.0% prevalence of this T. orientalis infection recorded in this study was higher than that in previous regional studies in the country. For example, an earlier study reported that Holstein cattle in a farm in Jeolla Province, Korea, had a T. orientalis infection rate of 13.2% during the non-grazing period [ 25 ], whereas a more recent study in Gyeongsang province revealed a T. orientalis infection rate of 4.2% among indoor-raised Holstein cattle [ 10 ]. The high prevalence of T. orientalis is considered a potential threat to the dairy cattle industry in Korea, as it has been observed to cause significant losses in other dairy industries [ 17 ].…”

“…Theileria orientalis is a tick-borne parasite (TBP) that impairs the health and production of farm animals, especially cattle [5]. It is mainly transmitted by the Asian long-horned tick Haemaphysalis longicornis, which is widely distributed in many certain regions, such as Asian countries [6][7][8][9][10], Australia [11], and New Zealand [12], and has also been recently reported in the USA [13]. Since T. orientalis proliferates as piroplasms within red blood cells (RBCs), its main pathological effect is hemolytic anemia [14].…”

“…Korea is a temperate Asian region facing the risk of notable shifts in climatic conditions [19,20], placing it at a high risk of dynamic VBD outbreaks. This has led to numerous studies in Korea assessing the prevalence of TBDs in livestock and wild animals, indicating that various TBPs, particularly T. orientalis, are prevalent in certain regions of Korea [10,[21][22][23]. The influence of climatic factors, such as latitude and season, on the health of livestock, particularly dairy cattle infected with T. orientalis, has not been extensively studied across Korea.…”

A clinical case of bovine anemia due to Theileria orientalis group in a non-grazed dairy cow in the upper part of South Korea

“…ehrlichiosis, paralleled to theileriosis which has 69.4% to 96.0% prevalence in three different regions of South Korea [5], while babesiosis was not detected based on a recent study [6]. Recent reports on hematological changes in BATOG in South Korea, in relation to the genotypes [4], season [1], management and breed [5], suggests that outbreaks in the country are mainly asymptomatic or subclinical cases only [5].…”