The impact of weekly fever-screening and treatment and monthly RDT testing and treatment on the infectious reservoir of malaria in Burkina Faso: results from a cluster-randomised trial

The majority of malaria infections in endemic countries are asymptomatic
and a source of onward transmission to mosquitoes. Malaria transmission
and disease burden could be reduced by improving early detection and
treatment of these infections with active screening
approaches. In an 18-month cluster-randomized study in Sapone,
Burkina Faso, households were enrolled and randomised to 1 of 3 arms: arm
1 - control; arm 2 - active weekly screening for febrile individuals and
treatment if rapid diagnostic test (RDT) positive; or arm 3 – active
weekly fever-screening (as arm 2) plus monthly RDT-testing regardless of
symptoms. The primary outcome was parasite prevalence by qPCR in the
end-of-study cross-sectional survey. Secondary outcomes included parasite
and gametocyte prevalence and density in all three end-of-season
cross-sectional surveys, incidence of infection, and the transmissibility
of infections to mosquitoes. A total of 906 individuals were enrolled
during 2 phases. In Phase 1, 412 individuals were enrolled between August
9 and 17, 2018, and in Phase 2, 494 individuals were enrolled between
January 10 and 31, 2019. In the end-of-study cross-sectional survey,
malaria parasite prevalence by qPCR was statistically significantly lower
in arm 3 (29·26% 79/270), but not in arm 2 (45·66% 121/265), when compared
to arm 1 (48·72% 133/273) (RR = 0·65, 95%CI = 0·52 to 0·81, P=0·0001).
Total parasite and gametocyte prevalence and density were also
significantly lower in arm 3 in all surveys. The largest differences were
seen at the end of the dry season, with gametocyte prevalence 78·38 % and
transmission potential 98·20% lower in arm 3 vs arm 1. Active
monthly RDT testing and treatment can reduce parasite carriage and the
infectious reservoir of malaria to <2% when used during the dry
season. This insight may inform approaches for malaria control and
elimination.

在疟疾流行国家，大多数感染为无症状感染，且是向蚊子传播的传染源。疟疾传播及疾病负担可通过主动筛查方法提高对这类感染的早期检测和治疗来降低。在布基纳法索萨蓬开展的一项为期18个月的整群随机研究（cluster-randomized study）中，研究人员招募家庭并将其随机分配至3个组中的1组：1组为对照组；2组为每周主动筛查发热个体，若快速诊断试验（RDT）阳性则进行治疗；3组为每周主动发热筛查（与2组相同），另加每月无论有无症状均进行RDT检测。主要结局指标为研究结束时横断面调查中通过定量聚合酶链反应（qPCR）检测的寄生虫流行率。次要结局指标包括所有三次季末横断面调查中的寄生虫及配子体（gametocyte）流行率和密度、感染发生率，以及感染向蚊子的传播性。共分两阶段招募906人。第一阶段于2018年8月9日至17日招募412人，第二阶段于2019年1月10日至31日招募494人。研究结束时的横断面调查显示，与1组（48.72%，133/273）相比，3组通过qPCR检测的疟疾寄生虫流行率在统计学上显著降低（29.26%，79/270），而2组（45.66%，121/265）则无显著差异（相对风险（RR）=0.65，95%置信区间（CI）=0.52至0.81，P=0.0001）。在所有调查中，3组的总寄生虫及配子体流行率和密度也显著降低。差异最显著的是在旱季结束时，3组的配子体流行率较1组低78.38%，传播潜力低98.20%。旱季采用每月主动RDT检测及治疗，可将疟疾寄生虫携带率及感染库降至<2%。这一发现可为疟疾控制及消除策略提供参考。