Owusu Ewurama D A, Buabeng Vincent, Dadzie Samuel, Brown Charles A, Grobusch Martin P, Mens Petra
Department of Infectious Diseases, Division of Internal Medicine, Academic Medical Centre, Centre of Tropical Medicine and Travel Medicine, University of Amsterdam, Amsterdam, The Netherlands.
Department of Medical Laboratory Sciences, School of Biomedical and Allied Health Sciences, College of Health Sciences, University of Ghana, Accra, Ghana.
Malar J. 2016 Jan 22;15:38. doi: 10.1186/s12936-015-1066-8.
Malaria control efforts in Ghana have reduced the countrywide average malaria prevalence from 71% in 2000 to about 51% in 2012; however, its main focus is on symptomatic malaria. If further progress is to be made, parasite reservoirs in asymptomatic carriers need to be moved into focus. This study profiles asymptomatic Plasmodium spp. parasitaemia amongst residents of mountainous Kwahu-Mpraeso in the Eastern region of Ghana.
A cross-sectional study of 360 residents was carried out from October to December 2013. This included recording demographics, malaria testing of asymptomatic residents, and gathering of their malaria history. Assessment of malaria transmission was done with molecular identification of vectors, determination of sporozoite rate, insecticide resistance status and biting pattern. Univariate and multivariate analysis were used to establish risk determinants.
In Mpraeso, in the Kwahu highland of Eastern Region, children were at higher risk of asymptomatic parasitaemia, thereby contributing to the parasite reservoir and hence sustained malaria transmission. As well, findings suggested Hb AC genotype influenced susceptibility to asymptomatic malaria with 8.03-fold increase in odds (univariate) and 11.92-fold higher odds (multivariate) than the normal Hb AA. The mosquito vector predominant in the area was Anopheles gambiae sensu stricto of the homozygous pyrethroid resistant form (RR); with biting mainly occurring indoors.
For an effective malaria control in this area, interventions should be formulated and implemented to target asymptomatic parasite reservoirs; especially in children and people with Hb AC. The dominant vector species An. gambiae s.s. and its feeding patterns of biting indoors should also be considered.
加纳的疟疾防控工作已使全国平均疟疾患病率从2000年的71%降至2012年的约51%；然而，其主要重点是有症状的疟疾。若要取得进一步进展，无症状携带者中的寄生虫储存库需要成为关注焦点。本研究描述了加纳东部山区夸胡-姆普拉埃索居民中无症状疟原虫血症的情况。
2013年10月至12月对360名居民进行了横断面研究。这包括记录人口统计学信息、对无症状居民进行疟疾检测以及收集他们的疟疾病史。通过对媒介进行分子鉴定、确定子孢子率、杀虫剂抗性状况和叮咬模式来评估疟疾传播情况。采用单变量和多变量分析来确定风险决定因素。
在东部地区夸胡高地的姆普拉埃索，儿童患无症状寄生虫血症的风险更高，从而形成了寄生虫储存库，进而导致疟疾持续传播。此外，研究结果表明，Hb AC基因型影响对无症状疟疾的易感性，其比值比单变量分析中比正常Hb AA高8.03倍，多变量分析中高11.92倍。该地区主要的蚊媒是纯合拟除虫菊酯抗性形式（RR）的冈比亚按蚊；叮咬主要发生在室内。
为有效控制该地区的疟疾，应制定并实施针对无症状寄生虫储存库的干预措施；特别是针对儿童和Hb AC基因型的人群。还应考虑主要的媒介物种冈比亚按蚊及其室内叮咬的觅食模式。
