Byaruhanga C, Collins N E, Knobel D, Kabasa W, Oosthuizen M C
Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; National Agricultural Research Organisation, P.O. Box 259, Entebbe, Uganda.
Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
Vet Parasitol Reg Stud Reports. 2015 Dec;1-2:21-30. doi: 10.1016/j.vprsr.2015.11.001. Epub 2016 Jan 30.
We conducted a study to investigate tick species diversity, seroprevalence of antibodies to Anaplasma marginale and Theileria parva, and the risk factors for these infections among cattle under a transhumant production system in Karamoja Region, Uganda, from November 2013 through January 2014. Twenty herds were randomly selected from 20 purposively-selected superherds. Semi-structured interviews and piling for annual proportion of tick-borne disease (TBD) cases in different age groups, with pastoralist groups, clinical examinations and field observations were employed to obtain information related to the epidemiology of TBDs. Ticks were collected and identified from whole body inspections of at least seven systematically selected cattle in each herd. Concurrently, serum was collected from 397 cattle. Antibodies to A. marginale were detected by MSP-5 competitive inhibition enzyme-linked immunosorbent assay, and to T. parva by indirect fluorescent antibody test. Clinical examinations and informant interviews showed that TBDs affected all age groups of cattle. Tick species that have not been reported in recent studies from other parts of Uganda were collected, namely Amblyomma lepidum, Hyalomma truncatum, Amblyomma gemma, and Rhipicephalus pulchellus. Out of the 10,923 ticks collected, Rhipicephalus appendiculatus (54.4%) was the most abundant species followed by Rhipicephalus (Boophilus) decoloratus (17.7%), Amblyomma variegatum (12%) and A. lepidum (11.6%). Two-thirds of the sampled cattle had moderate (37.3%, 11-50 ticks) to abundant (28.6%, >50 ticks) numbers of ticks. Seroprevalence of A. marginale was high (86.6%, 95% confidence interval [CI] 80.8%-91.8%), while that of T. parva was low (14.6%, 95% CI 7.1%-22.4%). Cattle of 5-12months (18.3%, Odds ratio [OR]=4.1) and 13-24months (30.3%, OR=8.0) were more likely to be seropositive for T. parva than those >24months. For A. marginale, cattle of 13-24months (92.4%, OR=2.7) and >24months (89.7%, OR=2.0) were more likely to be seropositive than those 5-12months. There was a significant difference (p<0.001, OR=6.5) in the proportion of T. parva seropositive animals between Moroto (24.5%) and Kotido districts (4.8%), but not for A. marginale. In conclusion, the low seroprevalence for T. parva, possibly due to limited exposure in calves, may suggest a high likelihood of ECF in cattle. High seroprevalence for A. marginale suggests that a high proportion of cattle were exposed to infection. The findings provide knowledge of epidemiology of TBDs in Karamoja cattle and support for strategic control and improvement of cattle productivity.
2013年11月至2014年1月，我们在乌干达卡拉莫贾地区的一个游牧生产系统中开展了一项研究，以调查蜱种多样性、牛边缘无形体和小泰勒虫抗体血清阳性率以及这些感染的风险因素。从20个有目的地选择的超级畜群中随机选取20个畜群。采用半结构化访谈和不同年龄组蜱传疾病（TBD）病例年比例的堆积法，与牧民群体、临床检查和实地观察相结合，以获取与TBDs流行病学相关的信息。从每个畜群中至少7头系统选取的牛的全身检查中收集并鉴定蜱。同时，从397头牛中采集血清。通过MSP-5竞争抑制酶联免疫吸附试验检测牛边缘无形体抗体，通过间接荧光抗体试验检测小泰勒虫抗体。临床检查和信息提供者访谈表明，TBDs影响所有年龄组的牛。采集到了乌干达其他地区近期研究中未报道的蜱种，即鳞纹硬蜱、截形璃眼蜱、宝石硬蜱和美丽扇头蜱。在采集的10923只蜱中，血红扇头蜱（54.4%）是数量最多的蜱种，其次是无色扇头蜱（17.7%）、变异革蜱（12%）和鳞纹硬蜱（11.6%）。三分之二的采样牛身上有中等数量（37.3%，11 - 50只蜱）到大量（28.6%，>50只蜱）的蜱。牛边缘无形体的血清阳性率很高（86.6%，95%置信区间[CI] 80.8% - 91.8%），而小泰勒虫的血清阳性率较低（14.6%，95% CI 7.1% - 22.4%）。5 - 12个月大的牛（18.3%，比值比[OR]=4.1）和13 - 24个月大的牛（30.3%，OR=8.0）比24个月以上的牛更有可能小泰勒虫血清呈阳性。对于牛边缘无形体，13 - 24个月大的牛（92.4%，OR=2.7）和24个月以上的牛（89.7%，OR=2.0）比5 - 12个月大的牛更有可能血清呈阳性。在莫罗托（24.5%）和科蒂多区（4.8%）之间，小泰勒虫血清阳性动物的比例存在显著差异（p<0.001，OR=6.5），但牛边缘无形体没有差异。总之，小泰勒虫血清阳性率低，可能是由于犊牛接触有限，这可能表明牛患东非蜱传热的可能性很高。牛边缘无形体的高血清阳性率表明很大比例的牛接触过感染。这些发现提供了卡拉莫贾牛群中TBDs流行病学的知识，并为TBDs的战略控制和牛生产力的提高提供了支持。
