Control of urban malaria transmitted by Anopheles stephensi in Ethiopia: development of context sensitive vector control interventions for use in houses

Project Details

Description

Rapid urbanisation presents new risks for transmission of vector-borne diseases such as malaria and dengue in towns and cities worldwide. Africa has the highest rate of increase in urbanisation of any continent and the UN estimates that 58% of the population will live in urban areas by 2050 [1]. Anopheles stephensi is an urban-adapted Asian malaria vector which is invasive to and spreading across the Horn of Africa, having been identified Djibouti in 2012 [2] and Ethiopia and Sudan in 2016 [3]. The potential impact of the proliferation of this vector on malaria morbidity and mortality in towns and cities in the region is significant [4]. There is growing appreciation of the importance of the built environment in determining malaria risk [5, 6]. Evidence from Asia shows that An. stephensi is zoophilic, endophilic and endophagic [7, 8], suggesting that the home will be a place of risk for malaria transmission in the Horn of Africa. We urgently need new tools for control of An. stephensi in and around homes. Evidence from other parts of Africa suggests that house modifications including screening, eave tubes and insecticide-treated eave ribbons may be effective [9-12] but these have not been evaluated locally. It is important to make sure that any new interventions are locally appropriate, taking into account both local vector behaviour and potential for community adoption. Indeed, the WHO Integrated Vector Management (IVM) approach [13] encourages vector control programmes to find and use more local evidence, engaging and collaborating with households and communities to ensure that interventions are sustainable, locally adapted and effective.

Aims and Objectives
This research aims to identify and develop locally adapted vector control approaches for the control of An. stephensi in homes in Ethiopia:
1. Explore perceptions and practices relating to malaria transmission in and around the home, and the acceptability of novel vector control interventions focusing on the home.
2. Determine how characteristics of the built environment influence mosquito density in and around homes, and impact on the effectiveness of potential vector control approaches.
3. Evaluate the entomological efficacy of a (to be determined) vector control tool to protect people at home.

Methods
Objective 1: Identify perceptions and practices relating to malaria transmission in and around the home, and acceptability of novel control interventions focusing on the home
Qualitative methods will be used to identify and reflect upon perceptions, practices, challenges and opportunities which can exacerbate or reduce malaria transmission in and around the home. Activities will include participant observation, in-depth interviews, group discussions, transect walks, participatory mapping and photovoice sessions [14]. The qualitative study will be conducted in settlements with different housing characteristics including informal, vernacular (chikka or stone houses) and 'modern' (e.g. condominiums) housing.
Objective 2: Determine how characteristics of the built environment influence mosquito density in and around homes, and impact on the effectiveness of potential vector control approaches.
A household survey will quantify qualitative findings from Objective 1 on characteristics of the built environment and around household practices related to malaria transmission and control. The survey will collect information on socio-demographic characteristics (e.g. occupation, asset ownership, household size) and the built environment characteristics (e.g. land tenure, house construction, use of indoor and outdoor space, access to and use of water, and interactions with livestock). The survey will also determine how information on malaria is received, how transmission and symptoms are understood, what is known about the vector͛'s biology and behaviour, attitudes towards responsibility for malaria prevention, preventative practices and health-seeking behaviours.
In the same location we will also conduct entomological surveillance of immature and adult An. stephensi using a range of sampling methods including aspirator and double net mini traps [15] to determine biting and resting behaviours in and around houses. Statistical analysis will be performed to determine how characteristics of the built environment and household knowledge, attitudes and practices influence presence and abundance of An. stephensi.
Objective 3: Evaluate the efficacy of a potential vector control tool against entomological outcomes
Based on the findings from Objective 1 and 2, we will be able to identify vector control interventions that may be most efficacious against An. stephensi in and around the home. Potential interventions to reduce transmission risk in houses include house modifications (e.g. screening [10-12, 16]) or spatial repellents (e.g. emanators, eave ribbons [17]). We will evaluate the impact of the chosen intervention on entomological outcomes such as house entry of An. stephensi. Studies will be conducted in experimental houses or in the community. Participatory workshops will be held with community members after the trial to share trial results and determine acceptability and feasibility for local adoption.
StatusActive
Effective start/end date3/11/21 → …

IWETO expertise domain

  • B680-public-health