Evaluation of the effectiveness of topical repellent distributed by village health volunteer networks against Plasmodium spp. infection in Myanmar: A stepped-wedge cluster randomised trial

Abstract

Background The World Health Organization has yet to endorse deployment of topical repellents for malaria prevention as part of public health campaigns. We aimed to quantify the effectiveness of repellent distributed by the village health volunteer (VHV) network in the Greater Mekong Subregion (GMS) in reducing malaria in order to advance regional malaria elimination. Methods and findings Between April 2015 and June 2016, a 15-month stepped-wedge cluster randomised trial was conducted in 116 villages in Myanmar (stepped monthly in blocks) to test the effectiveness of 12% N,N-diethylbenzamide w/w cream distributed by VHVs, on Plasmodium spp. infection. The median age of participants was 18 years, approximately half were female, and the majority were either village residents (46%) or forest dwellers (40%). No adverse events were reported during the study. Generalised linear mixed modelling estimated the effect of repellent on infection detected by rapid diagnostic test (RDT) (primary outcome) and polymerase chain reaction (PCR) (secondary outcome). Overall Plasmodium infection detected by RDT was low (0.16%; 50/32,194), but infection detected by PCR was higher

Community-based molecular and serological surveillance of subclinical malaria in Myanmar

“…From this sub-sample, 13,157 samples were suitable for molecular diagnosis by qPCR, and 971 were excluded due to insufficient sample (Table 1 ). As reported previously [ 19 ], the prevalence of Plasmodium spp. infections detected by RDT was 0.16% (50/32,194; 13 P. falciparum mono-infection [0.04%], 34 P. vivax mono-infection [0.11%] and 3 mixed species infections [0.01%], 29 symptomatic), and in the sub-sample of participants consenting to additional sampling, RDT-positive Plasmodium spp.…”

“…One hundred and fourteen VHVs (48% male, median age 26 years (25th and 75th percentiles 21–33) in 102/114 VHV respondents) were trained to undertake malaria diagnosis by RDT and collection of dried blood spot samples in their villages. From April 2015 until June 2016, trained VHVs performed 32,194 RDTs in 114 villages of Southeast Myanmar, as previously described [ 19 ]. In a sub-population of consenting participants, VHVs collected 14,938 dried blood spot samples, 810 of which were missing key demographic data ( n = 692) or were compromised due to improper storage ( n = 118) and were excluded from all further molecular and serological analyses.…”

“…Details of the study design and sample collection have previously been reported [ 18 , 19 ] and are detailed in the Supplementary Methodology (Additional File 1 ). Briefly, from April 2015 to June 2016, residents of 114 villages across three south-eastern states/regions (Kayin, Kayah and Bago East) in Myanmar were invited to take part in an open stepped-wedge cluster-randomised control trial designed to estimate the effectiveness of topical insect repellent distributed by VHV on Plasmodium spp.…”

“…P. falciparum or P. vivax (or both) infection was determined by SD bioline Pf/Pv combo RDT according to the manufacturer’s instructions and by quantitative PCR (qPCR) as previously described [ 19 ] and detailed in Additional File 1 and 2 . A positive P. falciparum result included any qPCR-detectable infection where P. falciparum was detected, including mixed infections, and likewise for P. vivax.…”

“…Consequently, the repellent was provided in plain unbranded tubes, and the investigators registered the trial after completion of fieldwork (but prior to the commencement of data analysis) to minimise public disclosure. The study protocol has been published previously [ 18 ], and the study is reported according to the CONSORT guidelines of reporting a stepped-wedge cluster randomised trial [ 19 ].…”