Asymptomatic Plasmodium infections significantly drive malaria transmission and impact control and elimination strategies, but are largely uncharacterized. We investigated the prevalence and risk factors of asymptomatic malaria infections to inform malaria control strategies in Ghana. Five cross-sectional surveys were conducted at the end of the peak transmission season (August–September) on 4892 school children aged between 6 and 14 years in two distinct ecological settings in Ghana between 2013 and 2017. The study sites were Begoro (forest ecology) and Cape Coast (coastal ecology). The children were screened for malaria parasites by microscopic examination of Giemsa-stained thin and thick blood films. Hemoglobin levels were measured using the Hemocue HB analyzer. In addition, height was measured and the height-for-age z-scores estimated from the reference population defined by WHO to determine children who were stunted. Proportions of categorical and means of continuous variables were compared using Chi-square test and Student’s t-test respectively, and multivariable logistic regression was done to assess risk factors associated with asymptomatic infections. The overall prevalence of asymptomatic malaria in the school children was higher in Begoro compared to Cape Coast (27% (95% CI: 17, 24%) vs. 24% (95% CI: 17, 24%), p value = 0.04). The study recorded three species of Plasmodium (Plasmodia falciparum, malariae, and ovale) in both sites. Plasmodium falciparum was the predominant species, accounting for about 85% of infections in both study sites. The asymptomatic school children were more likely to be anaemic (OR = 2.01, p value< 0.001) and stunted in growth (OR = 1.46, p value< 0.001). Males carried more asymptomatic infection than females (OR = 1.18, p value = 0.015). School children aged 12–14 years had more asymptomatic infections than those aged 6–8 years (OR = 1.28, p value = 0.005). There is a considerable burden of asymptomatic malaria in the two regions of Ghana, which is associated with males, older children, anaemia, and stunted growth in children, and may have implications for malaria control and elimination strategies in Ghana.

中文翻译：

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学童无症状疟疾流行率和风险因素：对加纳两个生态区学童的重复横断面调查

无症状疟原虫感染显着推动疟疾传播并影响控制和消除策略，但在很大程度上没有特征。我们调查了无症状疟疾感染的流行率和危险因素，以告知加纳的疟疾控制策略。2013 年至 2017 年，在传播高峰季节（8 月至 9 月）结束时，对加纳两个不同生态环境中的 4892 名 6 至 14 岁学童进行了五次横断面调查。研究地点是 Begoro（森林生态学）和海岸角（海岸生态）。通过对吉姆萨染色的薄和厚血片进行显微镜检查，对这些儿童进行了疟原虫筛查。使用 Hemocue HB 分析仪测量血红蛋白水平。此外，测量身高，并根据世界卫生组织定义的参考人群估计年龄别身高 z 分数，以确定发育迟缓的儿童。分别使用卡方检验和学生 t 检验比较连续变量的分类和平均值的比例，并进行多变量逻辑回归以评估与无症状感染相关的风险因素。Begoro 的学童无症状疟疾总体流行率高于海岸角（27%（95% CI：17, 24%）与 24%（95% CI：17, 24%），p 值 = 0.04） ）。该研究在两个地点都记录了三种疟原虫（恶性疟原虫、疟疾和卵形疟原虫）。恶性疟原虫是主要物种，占两个研究地点感染的约 85%。无症状学童更可能是贫血（OR = 2.01，p 值< 0.001）和发育迟缓（OR = 1.46，p 值< 0.001）。男性比女性携带更多的无症状感染（OR = 1.18，p 值 = 0.015）。12-14 岁的学龄儿童比 6-8 岁的学生有更多的无症状感染（OR = 1.28，p 值 = 0.005）。加纳的两个地区存在相当大的无症状疟疾负担，这与男性、年龄较大的儿童、贫血和儿童发育迟缓有关，可能对加纳的疟疾控制和消除战略产生影响。12-14 岁的学龄儿童比 6-8 岁的学生有更多的无症状感染（OR = 1.28，p 值 = 0.005）。加纳的两个地区存在相当大的无症状疟疾负担，这与男性、年龄较大的儿童、贫血和儿童发育迟缓有关，可能对加纳的疟疾控制和消除战略产生影响。12-14 岁的学龄儿童比 6-8 岁的学生有更多的无症状感染（OR = 1.28，p 值 = 0.005）。加纳的两个地区存在相当大的无症状疟疾负担，这与男性、年龄较大的儿童、贫血和儿童发育迟缓有关，可能对加纳的疟疾控制和消除战略产生影响。