Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya.
Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, United Kingdom.
J Infect Dis. 2019 Feb 23;219(6):936-944. doi: 10.1093/infdis/jiy591.
Plasmodium falciparum infections lead to febrile illness unless the host has sufficient immunity, in which case infection may cause no immediate symptoms (ie, "asymptomatic parasitemia"). Previous studies are conflicting on the role of asymptomatic parasitemia in determining the risk of developing febrile malaria.
We monitored 2513 children (living in Kilifi, Kenyan Coast) by blood smears in 17 cross-sectional surveys to identify asymptomatic parasitemia and used active surveillance over 11325 child-years of follow-up to detect febrile malaria. We evaluated the interaction between transmission intensity, age, and asymptomatic parasitemia in determining the risk of developing febrile malaria.
In the moderate and high transmission intensity settings, asymptomatic parasitemia was associated with a reduced risk of febrile malaria in older children (> 3 years), while in the lower transmission setting, asymptomatic parasitemia was associated with an increased risk of febrile malaria in children of all ages. Additionally, the risk associated with asymptomatic parasitemia was limited to the first 90 days of follow-up.
Asymptomatic parasitemia is modified by transmission intensity and age, altering the risk of developing febrile episodes and suggesting that host immunity plays a prominent role in mediating this process.
恶性疟原虫感染会导致发热性疾病，除非宿主有足够的免疫力，否则感染可能没有立即出现症状（即“无症状疟原虫血症”）。先前的研究对无症状疟原虫血症在确定发热性疟疾发病风险中的作用存在争议。
我们通过 17 项横断面研究中的血涂片监测了 2513 名儿童（生活在肯尼亚沿海基利菲），以确定无症状疟原虫血症，并通过 11325 儿童年的随访进行主动监测，以检测发热性疟疾。我们评估了传播强度、年龄和无症状疟原虫血症之间的相互作用，以确定发热性疟疾发病的风险。
在中高传播强度环境中，无症状疟原虫血症与年龄较大的儿童（>3 岁）发热性疟疾发病风险降低有关，而在低传播强度环境中，无症状疟原虫血症与所有年龄段儿童发热性疟疾发病风险增加有关。此外，无症状疟原虫血症相关的风险仅限于随访的前 90 天。
无症状疟原虫血症受传播强度和年龄的影响，改变了发热发作的风险，并表明宿主免疫在介导这一过程中起着重要作用。
