Evidence of asymptomatic submicroscopic malaria in low transmission areas in Belaga district, Kapit division, Sarawak, Malaysia
Evidence of asymptomatic submicroscopic malaria in low transmission areas in Belaga district, Kapit division, Sarawak, Malaysia
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DOI：
10.1186/s12936-019-2786-y
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发表时间：
2019-05-02
期刊：
影响因子：
3
通讯作者：
Alias, Nor Wahida
中科院分区：
文献类型：
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作者：
Jiram, Adela Ida;Ooi, Choo Huck;Alias, Nor Wahida
背景马来西亚已宣布其消除疟疾的目标，目标是到 2020 年实现零本地传播。然而，要实现消除疟疾，需要针对人类感染者，包括无症状感染者。由于明显缺乏临床表现且寄生虫水平往往不明显，因此诊断无症状疟疾并不那么简单。疟疾的准确诊断对于提供疟疾负担的实际估计和防止误导性干预措施非常重要。低水平的寄生虫血症充当沉默的传播库，因此对易感蚊媒仍然具有传染性。因此，本研究的目的是调查砂拉越贝拉加区无症状亚显微疟疾（SMM）的患病率。方法2013年，从8个看起来健康的长屋居民中总共获得了1744个干血点（DBS）。随后，根据先前发现的亚显微病例的最高数量，2014 年从 2 个地区的居民采集了 251 份静脉血样本。从本研究中所有参与者的血液中制备薄血膜和厚血膜。对所有样本进行显微镜检查，并对2013年和2014年采集的样本分别进行巢式和巢式多重PCR。结果所有吉姆萨染色血涂片均未检出疟原虫。然而，在 1744 个样本中，有 29 个（1.7%）经 PCR 检测呈间日疟原虫阳性。此外，在 251 个样本中，PCR 检测到的最常见的单一感染是恶性疟原虫 50 (20%)，其次是间日疟原虫 39 (16%)、诺氏疟原虫 9 (4%)，以及混合感染 20 (8%)。临床健康。 Belaga区的SMM不仅由间日疟原虫引起，还由恶性疟原虫和诺氏疟原虫引起。为了补充项目管理者的努力，需要在全国范围内加强对 SMM 的监测，以估计 SMM 的程度，从而需要采取措施阻止新的疟疾传播。
BackgroundMalaysia has declared its aim to eliminate malaria with a goal of achieving zero local transmission by the year 2020. However, targeting the human reservoir of infection, including those with asymptomatic infection is required toachieve malaria elimination. Diagnosing asymptomatic malaria is not as straightforward due to the obvious lack of clinical manifestations and often subpatent level of parasites. Accurate diagnosis of malaria is important for providing realistic estimates of malaria burden and preventing misinformed interventions. Low levels of parasitaemia acts as silent reservoir of transmission thus remains infectious to susceptible mosquito vectors. Hence, the aim of this study is to investigate the prevalence of asymptomatic submicroscopic malaria (SMM) in the District of Belaga, Sarawak.MethodsIn 2013, a total of 1744 dried blood spots (DBS) were obtained from residents of 8 longhouses who appeared healthy. Subsequently, 251 venous blood samples were collected from residents of 2 localities in 2014 based on the highest number of submicroscopic cases from prior findings. Thin and thick blood films were prepared from blood obtained from all participants in this study. Microscopic examination were carried out on all samples and a nested and nested multiplex PCR were performed on samples collected in 2013 and 2014 respectively.ResultsNo malaria parasites were detected in all the Giemsa-stained blood films. However, of the 1744 samples, 29 (1.7%) were positive for Plasmodium vivax by PCR. Additionally, of the 251 samples, the most prevalent mono-infection detected by PCR was Plasmodium falciparum 50 (20%), followed by P. vivax 39 (16%), P. knowlesi 9 (4%), and mixed infections 20 (8%).ConclusionsThis research findings conclude evidence of Plasmodium by PCR, among samples previously undetectable by routine blood film microscopic examination, in local ethnic minority who are clinically healthy. SMM in Belaga district is attributed not only to P. vivax, but also to P. falciparum and P. knowlesi. In complementing efforts of programme managers, there is a need to increase surveillance for SMM nationwide to estimate the degree of SMM that warrant measures to block new transmission of malaria.