A longitudinal study of factors associated with positivity for Theileria orientalis ikeda genotype in suspected cattle, Virginia, USA

IF 1.6 Q3 PARASITOLOGY

Veterinary parasitology, regional studies and reports Pub Date : 2026-10-01 Epub Date: 2026-09-23 DOI:10.1016/j.vprsr.2026.101595

Jan A. Russek, Stephanie Michelle Todd, Amanda Carbonello, Kevin K. Lahmers, Cristobal Verdugo

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Abstract

Theileria orientalis ikeda genotype (T. orientalis ikeda) is a tickborne hemoparasite that causes anemia in cattle. Its primary competent vector is Haemaphysalis longicornis. T. orientalis ikeda was first described in the USA in the state of Virginia in 2017. Given its recent emergence, the epidemiology and factors associated with its detection in Virginia remain incompletely understood. Therefore, an analysis of longitudinal diagnostic data (2019–2025) was performed, to identify factors associated with T. orientalis ikeda positivity in cattle. Blood samples, from veterinarian-screened suspected cattle were submitted to the Virginia Tech Animal Laboratory Services (ViTALS) at the Virginia-Maryland College of Veterinary Medicine (VMCVM) for qPCR diagnosis. Submission information was used to create predictor variables: breed, sampling year, season, county, veterinary-clinic, age, risk area (low, medium, high), and sex. A generalized linear model was used to identify associated factors.

A total of 1824 samples, with complete data (out of 2186), were analyzed. 74.0% (95% CI, 71.9% - 76.0%) of suspected cattle were T. orientalis ikeda positive. Age, sampling year, risk area and season, were associated with positive results. Animals >1 year old had 3.1 times higher odds of being positive than younger animals. The collection year had an OR of 1.6 per year. Animals sampled from high- and medium-risk counties had an OR of 3.7 and 2.3, respectively (reference: low-risk counties). Spring (OR = 0.5) and winter (OR = 0.5) were negatively associated compared to fall.

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美国维吉尼亚州疑似牛中东方红弧菌基因型阳性相关因素的纵向研究

东方红僵菌（T. orientalis ikeda）是一种引起牛贫血的蜱传血液寄生虫。其主要主管媒介是长角血蜱。2017年，人们在美国弗吉尼亚州首次发现了池田东方瓢虫。鉴于它最近才出现，在弗吉尼亚州发现的流行病学和相关因素仍然不完全清楚。因此，我们对纵向诊断数据（2019-2025）进行了分析，以确定与牛中类东方绦虫阳性相关的因素。兽医筛选的疑似牛的血液样本提交给弗吉尼亚-马里兰兽医学院（VMCVM）的弗吉尼亚理工大学动物实验室服务中心（ViTALS）进行qPCR诊断。提交信息用于创建预测变量：品种、采样年份、季节、县、兽医诊所、年龄、风险区域（低、中、高）和性别。采用广义线性模型识别相关因素。共分析样本1824份，数据完整（共2186份）。74.0% （95% CI, 71.9% ~ 76.0%）疑似牛呈池田针叶绦虫阳性。年龄、采样年份、危险区和季节与阳性结果相关。一岁的动物比年幼的动物有3.1倍的阳性几率。收集年份的OR为1.6 /年。从高风险县和中等风险县取样的动物的OR分别为3.7和2.3（参考：低风险县）。春季（OR = 0.5）和冬季（OR = 0.5）与秋季相比呈负相关。

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来源期刊

Veterinary parasitology, regional studies and reports Multiple-

CiteScore

2.90

自引率

7.10%

发文量

126

审稿时长

97 days

期刊介绍： Veterinary Parasitology: Regional Studies and Reports focuses on aspects of veterinary parasitology that are of regional concern, which is especially important in this era of climate change and the rapid and often unconstrained travel of people and animals. Relative to regions, this journal will accept papers of the highest quality dealing with all aspects of disease prevention, pathology, treatment, epidemiology, and control of parasites within the field of veterinary medicine. Also, case reports will be considered as they add to information related to local disease and its control; such papers must be concise and represent appropriate medical intervention. Papers on veterinary parasitology from wildlife species are acceptable, but only if they relate to the practice of veterinary medicine. Studies on vector-borne bacterial and viral agents are suitable, but only if the paper deals with vector transmission of these organisms to domesticated animals. Studies dealing with parasite control by means of natural products, both in vivo and in vitro, are more suited for one of the many journals that now specialize in papers of this type. However, due to the regional nature of much of this research, submissions may be considered based upon a case being made by the author(s) to the Editor. Circumstances relating to animal experimentation must meet the International Guiding Principles for Biomedical Research Involving Animals as issued by the Council for International Organizations of Medical Sciences (obtainable from: Executive Secretary C.I.O.M.S., c/o W.H.O., Via Appia, CH-1211 Geneva 27, Switzerland).