Lennon Shirley Evelyn, Miranda Adolfo, Henao Juliana, Vallejo Andres F, Perez Julianh, Alvarez Alvaro, Arévalo-Herrera Myriam, Herrera Sócrates
Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.
Centro Nacional de Epidemiología (CNE), Guatemala City, Guatemala.
Malar J. 2016 Aug 30;15(1):441. doi: 10.1186/s12936-016-1500-6.
Even though malaria incidence has decreased substantially in Guatemala since 2000, Guatemala remains one of the countries with the highest malaria transmission in Mesoamerica. Guatemala is committed to eliminating malaria as part of the initiative 'Elimination of Malaria in Mesoamerica and the Island of Hispaniola' (EMMIE); however, it is still in the control phase. During the past decade, the government strengthened malaria control activities including mass distribution of long-lasting insecticide-impregnated bed nets, early diagnosis and prompt treatment. This study aimed to determine the prevalence of malaria, including gametocytes, in three areas of Guatemala using active case detection (ACD) and quantitative polymerase chain reaction (qPCR).
Cross-sectional surveys were conducted in three departments with varying transmission intensities: Escuintla, Alta Verapaz and Zacapa. Blood samples from 706 volunteers were screened for malaria using microscopy and qPCR which was also used to determine the prevalence of gametocytes among infected individuals. Results were collected and analysed using REDCap and R Project, respectively.
Malaria was diagnosed by microscopy in only 2.8 % (4/141) of the volunteers from Escuintla. By contrast, qPCR detected a prevalence of 7.1 % (10/141) in the same volunteers, 8.4 % (36/429) in Alta Verapaz, and 5.9 % (8/136) in Zacapa. Overall, 7.6 % (54/706) of the screened individuals were positive, with an average parasitaemia level of 40.2 parasites/μL (range 1-1133 parasites/μL) and 27.8 % carried mature gametocytes. Fifty-seven percent (31/54) of qPCR positive volunteers were asymptomatic and out of the 42.6 % of symptomatic individuals, only one had a positive microscopy result.
This study found a considerable number of asymptomatic P. vivax infections that were mostly submicroscopic, of which, approximately one-quarter harboured mature gametocytes. This pattern is likely to contribute to maintaining transmission across the region. Robust surveillance systems, molecular diagnostic tests and tailored malaria detection activities for each endemic site may prove to be imperative in accelerating malaria elimination in Guatemala and possibly across all of Mesoamerica.
尽管自2000年以来危地马拉的疟疾发病率大幅下降，但危地马拉仍是中美洲疟疾传播率最高的国家之一。危地马拉致力于作为“中美洲和伊斯帕尼奥拉岛消除疟疾”（EMMIE）倡议的一部分消除疟疾；然而，该国仍处于控制阶段。在过去十年中，政府加强了疟疾控制活动，包括大规模分发长效杀虫剂浸渍蚊帐、早期诊断和及时治疗。本研究旨在通过主动病例检测（ACD）和定量聚合酶链反应（qPCR）确定危地马拉三个地区疟疾（包括配子体）的流行情况。
在三个传播强度不同的省份进行横断面调查：埃斯昆特拉、上韦拉帕斯和萨卡帕。对706名志愿者的血样进行显微镜检查和qPCR筛查以检测疟疾，qPCR还用于确定感染个体中配子体的流行情况。结果分别使用REDCap和R项目进行收集和分析。
在埃斯昆特拉的志愿者中，仅2.8%（4/141）通过显微镜检查诊断出疟疾。相比之下，qPCR检测到同一批志愿者中的流行率为7.1%（10/141），在上韦拉帕斯为8.4%（36/429），在萨卡帕为5.9%（8/136）。总体而言，7.6%（54/706）的筛查个体呈阳性，平均寄生虫血症水平为40.2个寄生虫/微升（范围为1 - 1133个寄生虫/微升），27.8%携带成熟配子体。qPCR阳性的志愿者中有57%（31/54）无症状，在42.6%有症状的个体中，只有一人显微镜检查结果呈阳性。
本研究发现大量无症状间日疟原虫感染大多为亚显微镜下感染，其中约四分之一携带成熟配子体。这种模式可能有助于维持该地区的传播。强大的监测系统、分子诊断测试以及针对每个流行地区量身定制的疟疾检测活动可能对于加速危地马拉乃至整个中美洲的疟疾消除至关重要。
