Quantifying the dual threat of Plasmodium vivax and Anopheles stephensi in a P. falciparum endemic pre-elimination setting in sub-Saharan Africa

项目摘要/摘要：30行 尽管间日疟原虫每年导致700多万疟疾病例，但它通常是 由于没有报告病例，被排除在撒哈拉以南非洲疟疾控制方案编制之外 以及假设以达菲阴性为主的人群对间日疟原虫感染是免疫的。 然而，越来越多的证据表明，间日疟原虫确实存在于SSA中，而且达菲阴性个体 可以被感染，尽管感染率低于达菲阳性患者。此外，最近 间日疟原虫和恶性疟原虫的高效媒介斯氏按蚊在 非洲之角提出了间日疟原虫传播可能会被这种新兴媒介加强的可能性，因为它 向南扩散到SSA。随着肯尼亚在防治疟疾方面接近消灭前阶段，它 正面临着入侵AN的双重威胁。斯氏载体和一种未知的大负担 被忽视的间日疟原虫物种。虽然模型已经揭示了AN的潜在传播。斯捷芬西进入 SSA，这些预测及其对间日疟原虫传播的潜在影响仍有待证实或 量化的。在这里，我们关注图尔卡纳，这是肯尼亚北部的一个半干旱地区，我们最近在那里记录了 首次出现全年低水平的间日疟原虫。图尔卡纳县与埃塞俄比亚接壤，间日疟原虫在埃塞俄比亚流行 还有一个。斯蒂芬斯的存在最近已得到证实。在边境另一边的肯尼亚，几乎没有 关于间日疟原虫流行率、临床负担或其与达菲血型的关系的信息。 此外，An.图尔卡纳没有进行斯捷芬塞人的监视，尽管据预测 有最高的风险。史坦芬斯入侵。首先，我们建议衡量间日疟原虫的临床负担。 以及通过被动病例检测与达菲血型的关系。通过使用精选健康 整个县都有筛查和检测寻求治疗疟疾的患者的设施，我们可以测量 间日疟疑似病例间日疟原虫感染率及不同Duffy血感染率比较 组。其次，通过对接受治疗的患者进行随访，我们将量化间日疟原虫感染的速度。 恶性疟原虫清除后，由于休眠催眠体的存在，感染复发。 在恶性疟原虫和间日疟原虫共同流行的许多地区都有很好的记录。 这将使我们能够估计肝期间日疟原虫感染的潜在沉默宿主。第三，我们将 通过收集和分类蚊子种类来识别可能参与间日疟原虫传播的媒介 和/或来自间日疟原虫家庭的幼虫，特别强调检测。斯特芬西。证据 这项研究将为理解间日疟原虫潜在地 从图尔卡纳传播到肯尼亚，并将有广泛的应用，告知疟疾监测和 在肯尼亚以及间日疟原虫和间日疟原虫横跨SSA的其他地区的控制策略。斯特芬西可能有一种 影响越来越大。

Project Summary/Abstract: 30 lines Although Plasmodium vivax causes more than 7 million malaria cases each year, it has typically been excluded from malaria control programming in sub-Saharan Africa (SSA) due to the absence of reported cases and the assumption that the predominantly Duffy-negative population is invulnerable to P. vivax infection. However, there is growing evidence that P. vivax is indeed present in SSA and that Duffy-negative individuals can be infected, albeit at lower rates than their Duffy-positive counterparts. In addition, the recent documentation of Anopheles stephensi, a highly competent vector for both P. vivax and P. falciparum, in the Horn of Africa raises the possibility that P. vivax transmission may be enhanced by this emerging vector as it spreads southward into SSA. As Kenya approaches pre-elimination phase in its fight against malaria, it is facing the dual threat of the invasive An. stephensi vector and an unknown burden of the largely neglected P. vivax species. While models have shed some light on the potential spread of An. stephensi into SSA, these predictions and their potential impact on P. vivax transmission remain to be confirmed or quantified. Here, we focus on Turkana, a semi-arid region of northern Kenya where we recently documented low levels of year-round P. vivax for the first time. Turkana county borders Ethiopia, where P. vivax is endemic and An. stephensi presence has recently been confirmed. Across the border in Kenya, there is little to no information available on P. vivax prevalence, clinical burden, or its relationship with Duffy blood groups. Furthermore, An. stephensi surveillance has not been mounted in Turkana, despite the fact that it is predicted to have the highest risk of An. stephensi invasion. First, we propose to measure the clinical burden of P. vivax and its relationship with Duffy blood groups through passive case detection. By working with select health facilities across the county to screen and test patients seeking malaria treatment, we can measure the prevalence of P. vivax in suspected malaria cases and compare the rate of infections in different Duffy blood groups. Second, by conducting follow-ups with treated patients, we will quantify the rate at which P. vivax infections relapse due to dormant hypnozoite presence following the clearance of P. falciparum parasites, a phenomenon that has been well documented in many areas where P. falciparum and P. vivax are co-endemic. This will allow us to estimate the underlying silent reservoir of liver-stage P. vivax infection. Third, we will identify vectors likely involved in P. vivax transmission by collecting and classifying the species of mosquitoes and/or larvae from the homes of P. vivax cases, with particular emphasis on detecting An. stephensi. Evidence from this study will provide the foundation for understanding the conditions in which P. vivax could potentially spread from Turkana across Kenya and would have broad application, informing malaria surveillance and control strategies in Kenya and other areas across SSA where P. vivax and An. stephensi may have an increasing impact.