Impact of Insecticide Resistance on Vector Control

Study Overview
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Brief Summary
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The purpose of the study is to determine whether long lasting insecticidal nets and indoor residual insecticide spraying, alone or in combination, are effective for controlling insecticide resistant anopheles mosquitoes for malaria prevention.

Detailed Description
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The study will assess the impact that insecticide resistance has on the effectiveness of malaria vector control tools LLIN and IRS. This is done by a cluster randomised trials of universal coverage LLINs versus universal coverage LLINs in combination with IRS, with levels of baseline insecticide resistance in the main vector balanced between the two study arms. In each cluster resistance to the insecticide used on LLINs is monitored, and malaria incidence is estimated from cluster specific cohorts of children followed up over the duration of the study. Resistance impact will be assessed from the ratio of incidence rates in clusters with high compared to those with low resistance and from a continuous measure of resistance expressed as percentage loss of mosquito mortality when exposed to insecticide in standardised WHO tests. Resistance mechanisms will be studied in subsets of study clusters.

Official Title
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Impact of Insecticide Resistance in Anopheles Arabiensis on the Effectiveness of Malaria Vector Control in Sudan

Conditions
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Malaria, Falciparum

Intervention / Treatment
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* Other: Indoor residual insecticide spraying (IRS)
* Device: Long Lasting Insecticidal Nets (LLIN)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Children older than 6 months and younger than 10 years in approximately 100 randomly selected households in all 140 study clusters selected in the four study areas Exclusion Criteria: Children living in households within 1 km from the edge of a neighbouring cluster (the buffer zone)

Ages Eligible for Study
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Minimum Age: 6 Months
Maximum Age: 10 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Universal coverage of Long Lasting Insecticidal Nets (LLIN)<br>Distribution of long lasting insecticidal nets to all community members in the study arm allowing for at least one net per 2 persons | Device: Long Lasting Insecticidal Nets (LLIN)<br>* Provision of LLIN to all community members in the clusters allocated to the study arm. LLIN protect individuals from bites by malaria vector mosquitoes by providing a physical barrier and insecticidal and repellent effect.<br>* Other names: Permanet2.0;|
| Experimental: LLIN Plus Indoor Residual Spraying<br>Distribution of long lasting insecticidal nets to all community members in the study arm allowing for at least one net per 2 persons plus indoor residual spraying with insecticide of interior walls of all houses twice yearly. | Other: Indoor residual insecticide spraying (IRS)<br>* Application of insecticide to interior walls of domiciliary structures to kill malaria vector mosquitoes which rest on walls after taking human blood meal<br>* Other names: Deltamethrin;Device: Long Lasting Insecticidal Nets (LLIN)<br>* Provision of LLIN to all community members in the clusters allocated to the study arm. LLIN protect individuals from bites by malaria vector mosquitoes by providing a physical barrier and insecticidal and repellent effect.<br>* Other names: Permanet2.0;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Malaria Incidence | Infection with malarial parasites determined by rapid diagnostic tests/microscopy in cohort members who report or have fever (>37.5C) | 3 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of P.falciparum Infection | Infection with plasmodial parasites (falciparum and/or vivax) in randomly selected members of the study cohort in each study cluster during the peak of the malaria transmission season by rapid diagnostic test | 3 years | 
| Entomological Innoculation rate | Anopheles arabiensis mosquitoes collected in sentinel clusters by light trap, window trap, clay pot and pyrethrum sheet collection and determination of sporozoite, human blood index, feeding and resting behaviour. | Average for months Sept, Oct, Nov for years 2011, 2012, 2013 | 
| Frequency of insecticide resistance associated genotypes (kdr) in anopheles arabiensis | Molecular analysis of mosquito specimens caught in subset of clusters by pyrethrum spray collection. | Yearly average 2011, 2012, 2013, 2014 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Mosquito Control, Insecticide Resistance