Genesis Laboratories, Inc., Wellington, Colorado, United States of America.
Ecological Systems Laboratory, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, United States of America.
PLoS Negl Trop Dis. 2020 Feb 18;14(2):e0008011. doi: 10.1371/journal.pntd.0008011. eCollection 2020 Feb.
Visceral leishmaniasis (VL) is a deadly disease transmitted by the sand fly Phlebotomus argentipes on the Indian subcontinent, with a promising means of vector control being orally treating cattle with fipronil-based drugs. While prior research investigating the dynamic relationship between timing of fipronil-based control schemes and the seasonality of sand flies provides insights into potential of treatment on a large scale, ecological uncertainties remain. We investigated how uncertainties associated with sand fly ecology might affect our ability to assess efficacy of fipronil-based control schemes. To do this, we used a previously-described, individual-based, stochastic sand fly model to quantify how uncertainties associated with 1) the percentage of female sand flies taking blood meals from cattle, and 2) the percentage of female sand flies ovipositing in organic matter containing feces from treated cattle might impact the efficacy of fipronil-based sand fly control schemes.
Assuming no prior knowledge of sand fly blood meal and oviposition sites, the probabilities of achieving effective sand fly population reduction with treatments performed 3, 6 and 12 times per year were ≈5-22%, ≈27-36%, and ≈46-54%, respectively. Assuming ≥50% of sand flies feed on cattle, probabilities of achieving efficacious control increased to ≈8-31%, ≈15-42%, and ≈52-65%. Assuming also that ≥50% of sand flies oviposit in cattle feces, the above probabilities increased further to ≈14-53%, ≈31-81%, and ≈89-97%.
Our assessments of the efficacy of fipronil-based cattle treatments in controlling sand fly populations depend on our assumptions regarding key aspects of sand fly ecology. Assessments are most sensitive to assumptions concerning the percentage of sand flies ovipositing in feces of treated cattle, thus emphasizing the importance of identifying sand fly oviposition sites. Our results place the evaluation of fipronil-based cattle treatment within a broader ecological context, which could aid in the planning and execution of a largescale field trial.
内脏利什曼病（VL）是一种由印度次大陆上的沙蝇 Phlebotomus argentipes 传播的致命疾病，用含有氟虫腈的药物对牛进行口服治疗是一种很有前途的病媒控制手段。虽然先前的研究调查了氟虫腈控制方案的时间与沙蝇季节性之间的动态关系，为大规模治疗提供了一些见解，但仍存在生态不确定性。我们研究了沙蝇生态学的不确定性如何影响我们评估氟虫腈控制方案效果的能力。为此，我们使用了以前描述的、基于个体的、随机沙蝇模型来量化与 1）从牛身上吸血的雌性沙蝇比例，以及 2）在含有来自处理过的牛的粪便的有机物中产卵的雌性沙蝇比例相关的不确定性如何影响氟虫腈沙蝇控制方案的效果。
假设对沙蝇的吸血和产卵地点没有先验知识，每年进行 3、6 和 12 次处理实现有效沙蝇种群减少的概率分别约为 5-22%、27-36%和 46-54%。假设≥50%的沙蝇以牛为食，实现有效控制的概率增加到约 8-31%、15-42%和 52-65%。还假设≥50%的沙蝇在牛的粪便中产卵，上述概率进一步增加到约 14-53%、31-81%和 89-97%。
我们对基于氟虫腈的牛处理控制沙蝇种群效果的评估取决于我们对沙蝇生态学关键方面的假设。评估对假设沙蝇在处理过的牛的粪便中产卵的百分比最为敏感，因此强调了确定沙蝇产卵地点的重要性。我们的研究结果将基于氟虫腈的牛处理的评估置于更广泛的生态背景下，这有助于规划和执行大规模现场试验。
