Mathew J S, Ewing S A, Panciera R J, Woods J P
Department of Infectious Diseases and Physiology, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078-2006, USA.
Vet Parasitol. 1998 Dec 15;80(1):1-14. doi: 10.1016/s0304-4017(98)00189-7.
Experimental transmission of Hepatozoon americanum to dogs was attempted with four ixodid ticks, viz., Rhipicephalus sanguineus, Amblyomma americanum, Amblyomma maculatum and Dermacentor variabilis. Ticks that dogs ingested included some that were laboratory-reared and experimentally fed as nymphs on a dog with naturally occurring hepatozoonosis; other ticks were collected as replete or partially engorged larvae, nymphs and adults from dogs that had hepatozoonosis and natural infestations of ticks. Whole ticks used to expose susceptible dogs orally were partially dissected to help release oocysts. Among eight dogs exposed, only the three that were fed A. maculatum adults experimentally acquisition fed as nymphs became infected. Dogs developed elevated body temperature and other evidence of clinical disease starting 4 weeks after exposure. 'Cysts' typical of H. americanum were found in skeletal muscle when samples were first examined 5 weeks after dogs ingested ticks, and parasites were also observed in peripheral blood smears at approximately the same time. Our study demonstrates that A. maculatum nymphs can acquire H. americanum by feeding on a parasitemic dog and that transstadial transmission of the protozoan occurs, with dogs acquiring infection when they ingest newly molted adult ticks.
尝试用四种硬蜱，即血红扇头蜱、美洲钝缘蜱、斑点钝缘蜱和变异革蜱，将美洲肝簇虫实验性传播给犬。犬摄入的蜱包括一些实验室饲养的，并作为若虫在患自然发生的肝簇虫病的犬身上进行实验性取食的蜱；其他蜱是从患肝簇虫病且有蜱自然寄生的犬身上采集的饱血或部分饱血的幼虫、若虫和成虫。用于经口感染易感犬的整只蜱被部分解剖以帮助释放卵囊。在八只被感染的犬中，只有三只喂食了作为若虫进行过实验性取食的斑点钝缘蜱成虫的犬被感染。犬在接触后4周开始出现体温升高和其他临床疾病迹象。在犬摄入蜱5周后首次检查样本时，在骨骼肌中发现了典型的美洲肝簇虫“囊肿”，并且大约在同一时间在外周血涂片中也观察到了寄生虫。我们的研究表明，斑点钝缘蜱若虫通过取食患寄生虫血症的犬可感染美洲肝簇虫，并且原生动物会发生经变态期传播，犬在摄入新蜕皮的成年蜱时会被感染。
