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

量化撒哈拉以南非洲恶性疟原虫地方性预消灭环境中间日疟原虫和斯氏按蚊的双重威胁

• 批准号: 10726003
• 负责人: Wendy PrudhommeOMeara
• 金额: $ 22.83万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10726003
• 关键词: Acceleration; Address; Africa; Africa South of the Sahara; African; Aftercare; Anopheles Genus; Antigens; Antimalarials; Area; Blood typing procedure; Case Management; Case Study; Classification; Clinical; Collaborations; Country; County; Coupled; Culicidae; Detection; Diagnostic; Documentation; Ecology; Erythrocytes; Ethiopia; Exclusion; Foundations; Future; Genetic; Goals; Health; Health care facility; Home; Horns; Household; Human; Individual; Infection; Invaded; Kenya; Larva; Learning; Liver; Malaria; Measures; Modeling; Molecular; Morbidity - disease rate; Parasites; Patients; Phase; Plasmodium falciparum; Plasmodium vivax; Population; Prevalence; Relapse; Reporting; Reproducibility; Rest; Risk Factors; Testing; Time; Universities; Work; blood group; disorder control; emerging pathogen; evidence base; fighting; high risk; infection rate; infectious disease model; mortality; multidisciplinary; neglect; patient screening; programs; transmission process; treatment strategy; vector

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.

项目摘要/摘要：30行 尽管疟原虫每年引起超过700万个疟疾病例，但通常是 由于没有报告的病例 并且假设主要达菲（Duffy-Duffy）阴性人群对维瓦克斯（Vivax）感染无力。 但是，有越来越多的证据表明，在SSA中确实存在疟原虫，并且达菲阴性个体 可以被感染，尽管其速度低于其Duffy阳性对应物。此外，最近 Anopheles Stephensi的文档，是拟南芥和恶性疟原虫的高能力载体 非洲角增加了这种新兴载体可能会增强型维瓦克斯的传播的可能性 向南传播到SSA。随着肯尼亚在与疟疾作斗争中接近淘气前阶段， 面对侵入性an的双重威胁。 Stephensi矢量和大部分的未知负担 被忽视的Vivax物种。虽然模型已经阐明了AN的潜在扩展。斯蒂芬西进入 SSA，这些预测及其对日疟原虫传播的潜在影响仍有待确认或 量化。在这里，我们专注于肯尼亚北部半干旱地区Turkana，我们最近记录了 全年的P. Vivax首次低水平。图尔卡纳县接壤埃塞俄比亚，那里的Vivax是地方性的 和一个。 Stephensi的存在最近已得到证实。在肯尼亚的边界，几乎没有 可获得有关疟原虫患病率，临床负担或与达菲血型的关系的信息。 此外，斯蒂芬西的监视尚未在图尔卡纳安装，尽管事实是 具有最高的AN风险。斯蒂芬西入侵。首先，我们建议测量Vivax的临床负担 以及通过被动病例检测与达菲血型的关系。通过与精选健康合作 全县的设施筛查和测试寻求疟疾治疗的患者，我们可以测量 可疑的疟疾病例中的Vivax患病率，并比较不同的达菲血液中感染率 组。其次，通过对经过治疗的患者进行随访，我们将量化腹地疟原虫的速率 恶性疟原虫寄生虫清除后，由于休眠的催眠症的存在，感染复发，A 在恶性疟原虫和维瓦克斯菌是共同流行的许多领域中，现象已得到充分证明。 这将使我们能够估算肝脏阶段的基础静音储层。第三，我们会的 通过收集和分类蚊子的种类，识别可能参与体内疟原虫传播的载体 和/或幼虫，来自维瓦克斯病例病例的家中，尤其强调检测。斯蒂芬西。证据 从这项研究中，将为理解Vivax可能的条件提供基础 从图尔卡纳（Turkana 肯尼亚和SSA的其他领域的控制策略。斯蒂芬西可能有一个 影响的增加。