Efficacy of Three Novel Bi-treated Long Lasting Insecticidal Nets

Efficacy of Three Different Bi-treated Long Lasting Insecticidal Nets and Deployment Strategy for Control of Malaria Transmitted by Pyrethroid Resistant Vectors: A Randomised Controlled Trial

Kilimanjaro Christian Medical Centre, Tanzania, National Institute for Medical Research, Tanzania, University of Ottawa

The massive scale-up of Long Lasting Insecticidal Nets (LLIN) has led to a major reduction in malaria burden (up to 50%) in many sub-Saharan African countries. This progress is threatened by the wide scale selection of insecticide resistant malaria vectors. New types of LLIN combining a mixture of two insecticides or an insecticide and a synergist have been developed to control resistant mosquitoes. The efficacy of three bi-treated LLIN are compared to a standard LLIN in a four-arm, single blinded, cluster-randomized trial in Misungwi district, Tanzania. The arms are; 1/ Royal Guard, a net combining pyriproxyfen (PPF), which is known to disrupt female reproduction and fertility of eggs, and the pyrethroid alpha-cypermethrin, 2/Interceptor G2, LLIN incorporating a mixture of two adulticides with different modes of action; chlorfenapyr and a pyrethroid (alpha-cypermethrin), and 3/ Olyset Plus an LLIN which incorporates a synergist, piperonyl butoxide (PBO), to enhance the potency of pyrethroid insecticides, and 4/ The control arm: Interceptor treated a standard LLIN treated with alpha-cypermethrin. The primary outcome of the trial will be cross-sectional community prevalence of malaria infection (by RDT) in children aged 6 months to 14 years at 12 and 24 months post-intervention.

Royal Guard® (Disease Control Technologies, LLC) is a Long Lasting Insecticidal Net made of polyethylene incorporating a mixture of 225 mg/m2 pyriproxyfen and 261mg/m2 alpha-cypermethrin. This LLIN will be distributed to all the households in 21 clusters on a 1 LLIN per two household residents basis.

Interceptor® G2 (BASF corporation) is a LLIN made of polyester coated with a wash-resistant formulation of 200 mg/m2 chlorfenapyr and 100 mg/m2 alpha-cypermethrin. This LLIN will be distributed to all the households in 21 clusters on a 1 LLIN per two household residents basis.

Olyset® Plus (Sumitomo Chemicals) is a LLIN combining Piperonyl butoxide (400mg/m2) and the repellent pyrethroid permethrin (800 mg/m2) incorporated into the polyethylene fibres. This LLIN will be distributed to all the households in 21 clusters on a 1 LLIN per two household residents basis.

Interceptor® (BASF Corporation) is a single pyrethroid-treated LLIN with alpha-cypermethrin (coated onto filaments) at a target dose of 200 mg/m2 of polyester fabric. This LLIN will be distributed to all the households in 21 clusters on a 1 LLIN per two household residents basis.

Malaria prevalence will be assessed using Malaria Rapid Diagnostic test (CareStart Malaria histidine-rich protein 2 (HRP2)/plasmodium lactate dehydrogenase (pLDH) Combo, DiaSys, UK)

Anopheles density per house per night will be assess every quarter in 8 houses per cluster using light trap. Anopheles density and sporozoite rate will be used to estimate the entomological inoculation rate (EIR)

A sub-samples of Anopheles collected indoor will be tested for Plasmodium falciparum circumsporozoite protein using an ELISA test. Sporozoite rate will be used to estimate the EIR with Anopheles density.

30 LLINs will be collected at yearly interval and Insecticide content in g/kg assessed with High-performance liquid chromatography (HPLC)

30 LLINs will be sampled every 6 months and tested in cone bio assay or tunnel test using resistant Anopheles and susceptible Kisumu Anopheles to assess for bio efficacy. 24, 48 and 72 hours mortality post exposure will be recorded.

The proportion of study participant declaring sleeping under a LLIN the previous night will be assessed during household survey every 6 months using a questionnaire.

Malaria prevalence will be assessed using Malaria Rapid Diagnostic test (CareStart Malaria histidine-rich protein 2 (HRP2)/plasmodium lactate dehydrogenase (pLDH) Combo, DiaSys, UK)

Malaria prevalence will be assessed using Malaria Rapid Diagnostic test (CareStart Malaria histidine-rich protein 2 (HRP2)/plasmodium lactate dehydrogenase (pLDH) Combo, DiaSys, UK)

Malaria prevalence will be assessed using Malaria Rapid Diagnostic test (CareStart Malaria histidine-rich protein 2 (HRP2)/plasmodium lactate dehydrogenase (pLDH) Combo, DiaSys, UK)

Malaria prevalence will be assessed using Malaria Rapid Diagnostic test (CareStart Malaria histidine-rich protein 2 (HRP2)/plasmodium lactate dehydrogenase (pLDH) Combo, DiaSys, UK)

Cost of each intervention will be gathered and used to calculate cost per malaria case averted and cost per DALY averted

Twice a year insecticide resistance will be assessed in wild Anopheles. 24 hours mortality will be recorded in Anopheles exposed to different concentrations of insecticides in CDC bottle assay or WHO test

P450 genes involved in pyrethroid insecticide resistance will be monitored in the 4 arms once a year using reverse-transcription quantitative polymerase chain reaction (PCR)

A sub sample of mosquitoes collected in the 4 arms will be tested for the Vgsc mutation involved in pyrethroid resistance using Taq Man PCR.

Inclusion Criteria: At least one child between 6 months to 14 years old having permanent residence in selected household Having an adult caregiver willing to provide written consent for the household and clinical survey Exclusion Criteria: Dwelling not found or vacant during the survey No adult caregiver capable to give informed consent Children severely ill

all IPD that underlie results in each publication will be shared and accessible in the LSHTM repository.

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https://www.who.int/docs/default-source/malaria/mpac-documentation/mpac-oct2017-updated-recommendations-pbo-nets-session2.pdf?sfvrsn=7ed12eb0_2

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