Graduate School of Veterinary Medicine, Rakuno Gakuen University, 582 Bunkyodai Midorimachi, Ebetsu, Hokkaido, 069-8501, Japan.
Research Center for Tropical Diseases and Vector Control, Department of Veterinary Pharmacy, Clinical and Comparative Medicine, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda; Rakuno Gakuen University, 582 Bunkyodai Midorimachi, Ebetsu, Hokkaido 069-8501, Japan.
Ticks Tick Borne Dis. 2020 Jul;11(4):101438. doi: 10.1016/j.ttbdis.2020.101438. Epub 2020 Apr 9.
Chemical tick control is a major means of preventing East Coast fever (ECF), especially in sub-Saharan Africa. However, in southwestern Uganda, improper tick control practices have led to severe acaricide resistance. The objectives of this study were to determine the risk factors associated with tick infestation in dairy cattle and Theileria parva infection, and to generate evidence for the prioritization of effective countermeasures for tick control. A cross-sectional study was conducted in 30 farms in Mbarara District, and information on tick control practices and tick infestation were collected. Tick samples were collected from 13 farms to test tick acaricide efficacy. A total of 420 blood samples from calves to adults of exotic- and cross-breed dairy cattle were collected, and T. parva diagnosis via polymerase chain reaction was performed. All the 13 tick populations tested were resistant to deltamethrin (synthetic pyrethroid). Resistance to single-formulation organophosphate-chlorfenvinphos was 39 % (5/13); co-formulations (chlorpyrifos + cypermethrin), 69 % (9/13); and amitraz (amidine), 85 % (11/13). The overall prevalence of T. parva infection at the individual-level was 45.2 % (190/420, 95 % confidence interval (CI): 40.4-50.1), and that at the farm-level was 83 % (25/30, 95 %CI: 65-94). A good quality cattle crush was a preventive factor for tick infestation (odds ratio (OR): 0.32, 95 %CI: 0.15-0.63, p = 0.001). Well-managed acaricide storage (OR: 0.36, 95 %CI: 0.17-0.76, p = 0.008), and a good quality measuring cylinder for acaricide were preventive factors (OR: 0.32, 95 %CI: 0.11-0.93, p = 0.036) for T. parva infection. The risk factors for T. parva infection were a longer period of acaricide use of the same brand (OR: 1.06, 95 %CI: 1.01-1.10, p = 0.012), and a higher frequency (twice a week) of acaricide use rather than once a week (OR: 11.70, 95 %CI: 1.95-70.13, p = 0.007). These risk factors should be given high intervention priority in order to effectively control ticks and prevent T. parva infections in dairy farms. Teaching proper practices to dairy farmers and to technical staff should be used to overcome the severe challenge of acaricide resistance in Mbarara District.
化学蜱控制是预防东海岸热（ECF）的主要手段，特别是在撒哈拉以南非洲。然而，在乌干达西南部，不当的蜱控制措施导致了严重的杀蜱剂耐药性。本研究的目的是确定与奶牛蜱感染和感染相关的风险因素，并为蜱控制的有效对策提供优先排序的证据。在姆巴拉拉区的 30 个农场进行了横断面研究，并收集了蜱控制措施和蜱感染的信息。从 13 个农场采集蜱样本以测试蜱杀蜱剂功效。共采集了 420 份来自外来和杂交奶牛的小牛至成年牛的血液样本，并通过聚合酶链反应进行了 T. parva 诊断。所有 13 个测试的蜱种群均对溴氰菊酯（合成拟除虫菊酯）具有抗性。对单一制剂有机磷-氯菊酯的抗性为 39%（5/13）；共制剂（氯菊酯+氯氰菊酯）为 69%（9/13）；和甲脒为 85%（11/13）。个体层面 T. parva 感染的总体患病率为 45.2%（190/420，95%置信区间（CI）：40.4-50.1），而农场层面为 83%（25/30，95%CI：65-94）。良好的牛畜栏是预防蜱感染的因素（比值比（OR）：0.32，95%CI：0.15-0.63，p=0.001）。良好管理的杀蜱剂储存（OR：0.36，95%CI：0.17-0.76，p=0.008）和质量良好的杀蜱剂测量筒是预防 T. parva 感染的因素（OR：0.32，95%CI：0.11-0.93，p=0.036）。T. parva 感染的风险因素是使用相同品牌的杀蜱剂的时间较长（OR：1.06，95%CI：1.01-1.10，p=0.012），以及使用杀蜱剂的频率更高（每周两次）而不是每周一次（OR：11.70，95%CI：1.95-70.13，p=0.007）。在奶牛场中，为了有效控制蜱虫并预防 T. parva 感染，应高度重视这些风险因素。向奶牛农民和技术人员传授正确的做法，以克服姆巴拉拉地区杀蜱剂耐药性的严重挑战。
