Biotechnology Research Institute, KALRO, Kikuyu, Kenya.
East African Science and Technology Commission (EASTECO)\East African Community, Kigali, Rwanda.
PLoS One. 2023 Feb 2;18(2):e0281180. doi: 10.1371/journal.pone.0281180. eCollection 2023.
Trypanocidal resistance is a major cause of treatment failure. This study evaluated the sensitivity of Trypanosoma evansi field isolates collected from Marsabit and Isiolo counties, Kenya. A total of 2,750 camels were screened using parasitological tests for trypanosomes. Of the screened camels, 113 tested positive from which 40 T. evansi isolates were tested using the single dose mice sensitivity test. Five treatment groups each comprising of 6 mice were inoculated intraperitoneally with 1x105 trypanosomes of each isolate and treated 24 hours later with isometamidium chloride at 1 mg/kg, homidium chloride at 1mg/kg, diminazene aceturate at 20 mg/kg and quinapyramine sulphate & chloride at 1 mg/kg. The fifth group was left untreated (positive control). The mice were monitored daily for 60 days. A survey on camel owners' practices that influence development of resistance to trypanocidal drugs was then conducted. Results indicated presence of drug resistance in all the 7 study sites that had infected camels. Seven of the isolates tested were resistant to diminazene aceturate whereas, 28, 33 and 34 were resistant to isometamidium chloride, quinapyramine sulphate & chloride and homidium chloride, respectively. Seven (17.5%) isolates of the 40 tested were sensitive to all 4 drugs, whereas, 7.5%, 10%,55% and 10% were resistant to 1,2,3 and 4 drugs, respectively. The prevalence of multiple drug resistance was 75%. Survey data indicated that camel management practices influenced the prevalence and degree of drug resistance. In conclusion, the multiple drug resistance observed in the two counties may not be an indication of total trypanocidal drug failure. Judicious treatment of confirmed trypanosomiasis cases with correct dosage would still be effective in controlling the disease since the observed resistance was at the population and not clonal level. However, integrated control of the disease and the vectors using available alternative methods is recommended to reduce drug use.
抗锥虫性是治疗失败的主要原因。本研究评估了从肯尼亚马萨比特和伊西奥洛县采集的野伊氏锥虫田间分离株的敏感性。总共对 2750 头骆驼进行了锥虫的寄生虫学检测。在所筛选的骆驼中，有 113 头呈阳性，其中 40 株野伊氏锥虫分离株用单剂量小鼠敏感性试验进行了检测。将每组 6 只的 5 个治疗组分别用 1x105 个每个分离株的锥虫接种腹腔，并在 24 小时后用异咪脒氯酸盐 1mg/kg、双羟萘酸氯苯脒 1mg/kg、二脒那嗪乙酰脲 20mg/kg 和硫酸喹那普丁盐&盐酸盐 1mg/kg 进行治疗。第五组不治疗（阳性对照）。每天监测小鼠 60 天。然后对影响抗锥虫药物耐药性发展的骆驼主人的做法进行了调查。结果表明，在所有有感染骆驼的 7 个研究地点都存在耐药性。测试的 7 个分离株对二脒那嗪乙酰脲耐药，而 28、33 和 34 个分离株分别对异咪脒氯酸盐、硫酸喹那普丁盐&盐酸盐和双羟萘酸氯苯脒耐药。在 40 个测试的分离株中，有 7 个（17.5%）对所有 4 种药物敏感，而 7.5%、10%、55%和 10%分别对 1、2、3 和 4 种药物耐药。多药耐药的患病率为 75%。调查数据表明，骆驼管理实践影响了耐药性的流行程度。总之，在这两个县观察到的多药耐药性可能并不表明总锥虫药物治疗失败。用正确剂量对确诊的锥虫病病例进行明智的治疗仍将有效控制疾病，因为观察到的耐药性是在群体水平而不是克隆水平。然而，建议使用现有的替代方法对疾病和媒介进行综合控制，以减少药物的使用。
