Latif A A, Hove T, Kanhai G K, Masaka S
Midrand University, Faculty of Science, Halfway House, South Africa.
Onderstepoort J Vet Res. 2001 Sep;68(3):203-8.
The Theileria parva carrier-state in cattle on commercial farms on Zimbabwe was investigated using parasitological and serological methods. The proportion of cattle showing Theileria piroplasms on two farms, which had recent histories of disease outbreaks, were 64% (n = 106, total of heifers and weaned calves examined) and 71.5% (n = 60) while the proportion of T. parva antibodies for the same animals were 59% and 98.5%, respectively. On four farms where no cases of the disease occurred for over 10 years, the average proportion of animals showing piroplasms and antibodies were 55.4% (range 32-82, n = 223) and 73% (range 47-91, n = 223), respectively. However, on another three farms which had no history of theileriosis outbreaks these proportions were very low, being 11.4% (0-24, n = 157) for piroplasms and 12.2% (5-23, n = 157) for antibodies. The mean infection rate in unfed Rhipicephalus appendiculatus adults collected from farms with a high prevalence of cattle which were carriers of Theileria piroplasms during the tick activity season was 29% (range 12-60%) with 9.3 (range 2-18.7) mean infected acini per infected tick. The infectivity of different tick batches to susceptible cattle produced a wide spectrum of theileriosis reactions. Laboratory controlled experiments were carried out to study the persistence of T. parva (Boleni) piroplasms in cattle immunized with this strain as well as its infectivity for ticks and its subsequent transmissibility to cattle. Examination of the salivary glands of 15 batches of ticks collected from six immunized cattle on three different occasions over 18 months showed that none were infected with Theileria parasites. However, the infectivity of other ticks in the same batches to susceptible animals was demonstrated 6, 10 and 18 months after cattle had been immunized with Boleni stabilate.
利用寄生虫学和血清学方法，对津巴布韦商业农场牛群中的泰勒虫携带状态进行了调查。在两个近期有疾病暴发史的农场中，出现泰勒虫梨形虫的牛的比例分别为64%（n = 106，检查的小母牛和断奶小牛总数）和71.5%（n = 60），而同一批动物中泰勒虫抗体的比例分别为59%和98.5%。在四个10多年未发生该病病例的农场中，出现梨形虫和抗体的动物的平均比例分别为55.4%（范围32 - 82，n = 223）和73%（范围47 - 91，n = 223）。然而，在另外三个无泰勒虫病暴发史的农场中，这些比例非常低，梨形虫为11.4%（0 - 24，n = 157），抗体为12.2%（5 - 23，n = 157）。在蜱虫活动季节，从泰勒虫梨形虫携带率高的农场采集的未进食的肩突硬蜱成虫的平均感染率为29%（范围12 - 60%），每只感染蜱的平均感染腺泡数为9.3（范围2 - 18.7）。不同批次蜱对易感牛的感染性产生了广泛的泰勒虫病反应。进行了实验室对照实验，以研究博莱尼株免疫牛体内泰勒虫（博莱尼）梨形虫的持续性、其对蜱的感染性以及随后向牛的传播性。在18个月内分三次从六头免疫牛身上采集了15批次蜱，检查其唾液腺，结果显示无一感染泰勒虫寄生虫。然而，在用博莱尼稳定株免疫牛6、10和18个月后，同一批次的其他蜱对易感动物的感染性得到了证实。
