School of Agriculture and Environment, Massey University, Palmerston North, 4442, New Zealand.
School of Veterinary Science, Massey University, Palmerston North, 4442, New Zealand.
J Parasitol. 2021 Sep 1;107(5):710-716. doi: 10.1645/20-177.
This study aimed to investigate whether the infection intensity of Theileria orientalis Ikeda type organisms within Haemaphysalis longicornis larvae and nymph stages fluctuated over 6 mo after feeding as larvae on infected calves in the field. Naïve larvae, hatched from eggs, were fed on infected calves for 5 days while contained within cotton socks glued over the calves' ears. Larvae were first sampled immediately post-feeding and then sampled every 3 wk for 23 wk in total, after molting to nymphs. All larvae and nymphs were tested for T. orientalis Ikeda organisms using quantitative PCR. The qPCR results showed that the infection intensity of Haemaphysalis longicornis larvae and nymphs was not constant over the sampling period, and after initially dropping after molting to nymphs, it then rose with fasting to a maximum at 17 and 23 wk post-feeding. The significant rise in T. orientalis Ikeda organisms observed at 23 wk postfeeding may explain why more severe clinical cases of bovine theileriosis in New Zealand are seen in the spring when nymphs are the predominant instar questing.
本研究旨在探究感染东方巴贝斯虫 Ikeda 型生物体的长角血蜱幼虫和若虫在野外经感染牛血餐 5 天后，其感染强度是否会随时间波动。从卵中孵化出的幼稚幼虫被包裹在粘在牛耳上的棉袜中，经 5 天的时间以感染牛为食。幼虫首次取样是在进食后立即进行，然后在蜕皮后总共 23 周内每 3 周取样一次。使用定量 PCR 对所有幼虫和若虫进行东方巴贝斯虫 Ikeda 生物体检测。qPCR 结果表明，长角血蜱幼虫和若虫的感染强度在采样期间并非恒定不变，在蜕皮后最初下降后，随着禁食时间的延长，其感染强度在 17 周和 23 周时达到最大值。在进食后 23 周时观察到东方巴贝斯虫 Ikeda 生物体的显著增加，这可能解释了为什么在新西兰，春季若虫是主要的觅食期时，更严重的牛巴贝斯虫病临床病例会增多。
