PDF(Pubmed)
Abstract：
BACKGROUND: The Gran Chaco region is a major hotspot of Chagas disease. We implemented a 9-year program aimed at suppressing house infestation with Triatoma infestans and stopping vector-borne transmission to creole and indigenous (Qom) residents across Pampa del Indio municipality (Argentine Chaco). The aim of the present study was to assess the intervention effects on parasite-based transmission indices and the spatial distribution of the parasite, and test whether house-level variations in triatomine infection with Trypanosoma cruzi declined postintervention and were influenced by household ethnicity, persistent infestation linked to pyrethroid resistance and other determinants of bug infection.
METHODS: This longitudinal study assessed house infestation and bug infection with T. cruzi before and after spraying houses with pyrethroids and implemented systematic surveillance-and-response measures across four operational areas over the period 2007-2016. Live triatomines were individually examined for infection by optical microscopy or kinetoplast DNA (kDNA)-PCR and declared to be infected with T. cruzi when assessed positive by either method.
RESULTS: The prevalence of infection with T. cruzi was 19.4% among 6397 T. infestans examined. Infection ranged widely among the study areas (12.5-26.0%), household ethnicity (15.3-26.9%), bug ecotopes (1.8-27.2%) and developmental stages (5.9-27.6%), and decreased from 24.1% (baseline) to 0.9% (endpoint). Using random-intercept multiple logistic regression, the relative odds of bug infection strongly decreased as the intervention period progressed, and increased with baseline domestic infestation and bug stage and in Qom households. The abundance of infected bugs and the proportion of houses with ≥ 1 infected bug remained depressed postintervention and were more informative of area-wide risk status than the prevalence of bug infection. Global spatial analysis revealed sharp changes in the aggregation of bug infection after the attack phase. Baseline domestic infestation and baseline bug infection strongly predicted the future occurrence of bug infection, as did persistent domestic infestation in the area with multiple pyrethroid-resistant foci. Only 19% of houses had a baseline domestic infestation and 56% had ever had ≥ 1 infected bug.
CONCLUSIONS: Persistent bug infection postintervention was closely associated with persistent foci generated by pyrethroid resistance. Postintervention parasite-based indices closely agreed with human serosurveys at the study endpoint, suggesting transmission blockage. The program identified households and population subgroups for targeted interventions and opened new opportunities for risk prioritization and sustainable vector control and disease prevention.
METHODS: This longitudinal study assessed house infestation and bug infection with T. cruzi before and after spraying houses with pyrethroids and implemented systematic surveillance-and-response measures across four operational areas over the period 2007-2016. Live triatomines were individually examined for infection by optical microscopy or kinetoplast DNA (kDNA)-PCR and declared to be infected with T. cruzi when assessed positive by either method.
RESULTS: The prevalence of infection with T. cruzi was 19.4% among 6397 T. infestans examined. Infection ranged widely among the study areas (12.5-26.0%), household ethnicity (15.3-26.9%), bug ecotopes (1.8-27.2%) and developmental stages (5.9-27.6%), and decreased from 24.1% (baseline) to 0.9% (endpoint). Using random-intercept multiple logistic regression, the relative odds of bug infection strongly decreased as the intervention period progressed, and increased with baseline domestic infestation and bug stage and in Qom households. The abundance of infected bugs and the proportion of houses with ≥ 1 infected bug remained depressed postintervention and were more informative of area-wide risk status than the prevalence of bug infection. Global spatial analysis revealed sharp changes in the aggregation of bug infection after the attack phase. Baseline domestic infestation and baseline bug infection strongly predicted the future occurrence of bug infection, as did persistent domestic infestation in the area with multiple pyrethroid-resistant foci. Only 19% of houses had a baseline domestic infestation and 56% had ever had ≥ 1 infected bug.
CONCLUSIONS: Persistent bug infection postintervention was closely associated with persistent foci generated by pyrethroid resistance. Postintervention parasite-based indices closely agreed with human serosurveys at the study endpoint, suggesting transmission blockage. The program identified households and population subgroups for targeted interventions and opened new opportunities for risk prioritization and sustainable vector control and disease prevention.
摘要：
背景：GranChaco地区是查加斯病的主要热点。我们实施了一项为期9年的计划，旨在遏制Triatoma侵染者的房屋侵扰，并阻止媒介传播给PampadelIndio市（阿根廷Chaco）的克里奥尔人和土著（Qom）居民。本研究的目的是评估对基于寄生虫的传播指数和寄生虫的空间分布的干预效果，并测试在干预后，克氏锥虫的triatomine感染的家庭水平变化是否下降，并受到家庭种族的影响，持续的侵染与拟除虫菊酯抗性和其他决定因素有关。
方法：这项纵向研究评估了2007-2016年期间，在喷洒拟除虫菊酯之前和之后，库氏毛虫的房屋感染和虫子感染，并在四个作业区域实施了系统的监测和响应措施。通过光学显微镜或动体DNA（kDNA）-PCR分别检查了活的三叶草的感染情况，并通过两种方法评估为阳性时宣布感染了克氏毛虫。
结果：在所检查的6397例T.infestans中，T.cruzi感染的患病率为19.4％。研究区域的感染范围很广（12.5-26.0％），家庭种族（15.3-26.9％），虫子生态圈(1.8-27.2%)和发育阶段(5.9-27.6%)，从24.1%(基线)降至0.9%(终点)。使用随机截距多元逻辑回归，随着干预期的进展，虫子感染的相对几率急剧下降，并随基线家庭侵扰和病虫阶段以及库姆家庭的增加而增加。受感染的虫子的数量和具有≥1个感染的虫子的房屋比例在干预后仍然受到抑制，并且与虫子感染的患病率相比，该地区的风险状况提供了更多的信息。全局空间分析显示，攻击阶段后，虫子感染的聚集发生了急剧变化。基线家庭感染和基线虫子感染强烈预测未来虫子感染的发生，在具有多个拟除虫菊酯抗性病灶的地区，持续的家庭感染也是如此。只有19％的房屋有基准的家庭感染，而56％的房屋曾经有≥1个感染的虫子。
结论：干预后持续的虫子感染与拟除虫菊酯抗性产生的持续病灶密切相关。在研究终点，基于寄生虫的干预后指数与人类血清调查密切相关，提示传输阻塞。该方案确定了有针对性的干预措施的家庭和人口亚组，并为风险优先排序和可持续的媒介控制和疾病预防开辟了新的机会。
方法：这项纵向研究评估了2007-2016年期间，在喷洒拟除虫菊酯之前和之后，库氏毛虫的房屋感染和虫子感染，并在四个作业区域实施了系统的监测和响应措施。通过光学显微镜或动体DNA（kDNA）-PCR分别检查了活的三叶草的感染情况，并通过两种方法评估为阳性时宣布感染了克氏毛虫。
结果：在所检查的6397例T.infestans中，T.cruzi感染的患病率为19.4％。研究区域的感染范围很广（12.5-26.0％），家庭种族（15.3-26.9％），虫子生态圈(1.8-27.2%)和发育阶段(5.9-27.6%)，从24.1%(基线)降至0.9%(终点)。使用随机截距多元逻辑回归，随着干预期的进展，虫子感染的相对几率急剧下降，并随基线家庭侵扰和病虫阶段以及库姆家庭的增加而增加。受感染的虫子的数量和具有≥1个感染的虫子的房屋比例在干预后仍然受到抑制，并且与虫子感染的患病率相比，该地区的风险状况提供了更多的信息。全局空间分析显示，攻击阶段后，虫子感染的聚集发生了急剧变化。基线家庭感染和基线虫子感染强烈预测未来虫子感染的发生，在具有多个拟除虫菊酯抗性病灶的地区，持续的家庭感染也是如此。只有19％的房屋有基准的家庭感染，而56％的房屋曾经有≥1个感染的虫子。
结论：干预后持续的虫子感染与拟除虫菊酯抗性产生的持续病灶密切相关。在研究终点，基于寄生虫的干预后指数与人类血清调查密切相关，提示传输阻塞。该方案确定了有针对性的干预措施的家庭和人口亚组，并为风险优先排序和可持续的媒介控制和疾病预防开辟了新的机会。
