Chaubey Rahul, Shukla Ashish, Kushwaha Anurag Kumar, Singh Shakti Kumar, Singh Om Prakash, Kumar Rajiv, Lawyer Phillip, Rowton Edgar, Petersen Christine A, Bernhardt Scott A, Sundar Shyam
Kala-Azar Medical Research Center (KAMRC), Muzaffarpur, Bihar, India.
Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Parasit Vectors. 2024 Dec 5;17(1):503. doi: 10.1186/s13071-024-06579-w.
Visceral leishmaniasis (VL), known as Kala-azar on the Indian subcontinent, is a parasitic disease caused by the flagellated protozoa Leishmania donovani and can be fatal if left untreated. The sand fly Phlebotomus argentipes is the only proven vector of VL in the Southeast Asia region, and VL control in this region has relied on the use of synthetic insecticides for indoor residual spraying (IRS). The use of DDT in VL control programmes has led to the development of resistance to this insecticide in sand flies, resulting in DDT being replaced with the insecticide alpha-cypermethrin. However, alpha-cypermethrin has a similar mode of action as DDT and, therefore, the risk of resistance development in sand flies increases under the pressure of regular exposure to this insecticide. In the present study we assessed the susceptibility status of wild-caught sand flies and F1 progeny using the CDC bottle bioassay.
Sand flies were collected from 10 villages in Muzaffarpur District, Bihar, India. Eight of these villages are receiving continuous IRS with alpha-cypermethrin, one village had discontinued IRS with alpha-cypermethrin and one village had never received IRS with alpha-cypermethrin. The collected sand flies were exposed to a pre-determined diagnostic dose for a specific time duration (3 µg/ml for 40 min), and knockdown and mortality at 24 h post-exposure were recorded.
Knockdown ranged from 91.19% to 99.47% for wild-caught sand flies and from 91.70% to 98.89% for their F1 progeny. At 24 h post-exposure, mortality ranged from 89.34% to 98.93% for wild-caught sand flies and from 90.16% to 98.33% for F1 progeny.
The results of this study showed that P. argentipes is potentially developing resistance, signalling the need for continuous monitoring and vigilance to sustain the validation of elimination once achieved.
内脏利什曼病（VL），在印度次大陆被称为黑热病，是一种由有鞭毛的原生动物杜氏利什曼原虫引起的寄生虫病，若不治疗可能会致命。白蛉是东南亚地区唯一经证实的VL传播媒介，该地区的VL防控一直依赖于使用合成杀虫剂进行室内滞留喷洒（IRS）。在VL防控项目中使用滴滴涕导致白蛉对这种杀虫剂产生了抗性，结果滴滴涕被杀虫剂α-氯氰菊酯所取代。然而，α-氯氰菊酯与滴滴涕的作用方式相似，因此，在定期接触这种杀虫剂的压力下，白蛉产生抗性的风险增加。在本研究中，我们使用疾控中心瓶式生物测定法评估了野生捕获的白蛉及其F1代的易感性状况。
从印度比哈尔邦穆扎法尔布尔区的10个村庄收集白蛉。其中8个村庄正在接受α-氯氰菊酯的持续室内滞留喷洒，1个村庄已停止使用α-氯氰菊酯进行室内滞留喷洒，1个村庄从未接受过α-氯氰菊酯的室内滞留喷洒。将收集到的白蛉暴露于预先确定的诊断剂量下特定时间（3μg/ml，持续40分钟），并记录暴露后24小时的击倒率和死亡率。
野生捕获的白蛉的击倒率在91.19%至99.47%之间，其F1代的击倒率在91.70%至98.89%之间。暴露后24小时，野生捕获的白蛉的死亡率在89.34%至98.93%之间，F1代的死亡率在90.16%至98.33%之间。
本研究结果表明，白蛉可能正在产生抗性，这表明需要持续监测并保持警惕，以维持一旦实现消除后的验证工作。
