Mapping and enumerating houses and households to support malaria control interventions on Bioko Island

Abstract

Background: Housing mapping and household enumeration are essential for the planning, implementation, targeting, and monitoring of malaria control interventions. In many malaria endemic countries, control efforts are hindered by incomplete or non-existent housing cartography and household enumeration. This paper describes the development of a comprehensive mapping and enumeration system to support the Bioko Island Malaria Control Project (BIMCP). Results: A highly detailed database was developed to include every housing unit on Bioko Island and uniquely enumerate the associated households residing in these houses. First, the island was divided into a virtual, geo-dereferenced grid of 1 × 1 km sequentially numbered map-areas, each of which was in turn subdivided into one hundred, 100 × 100 m sequentially numbered map-sectors. Second, high-resolution satellite imagery was used to sequentially and uniquely identify all housing units within each map-sector. Third, where satellite imagery was not available, global positioning systems (GPS) were used as the basis for uniquely identifying and mapping housing units in a sequential manner. A total of 97,048 housing units were mapped by 2018, 56% of which were concentrated in just 5.2% of Bioko Island's total mapped area. Of these housing units, 70.7% were occupied, thus representing uniquely identified households. Conclusions: The housing unit mapping and household enumeration system developed for Bioko Island enabled the BIMCP to more effectively plan, implement, target, and monitor malaria control interventions. Since 2014, the BIMCP has used the unique household identifiers to monitor all household-level interventions, including indoor residual spraying, long-lasting insecticide-treated nets distribution, and annual malaria indicator surveys. The coding system used to create the unique housing unit and household identifiers is highly intuitive and allows quick location of any house within the grid without a GPS. Its flexibility has permitted the BIMCP to easily take into account the rapid and substantial changes in housing infrastructure. Importantly, by utilizing this coding system, an unprecedented quantity and diversity of detailed, geo-referenced demographic and health data have been assembled that have proved highly relevant for informing decision-making both for malaria control and potentially for the wider public health agenda on Bioko Island.

A Colorimetric Test for the Evaluation of the Insecticide Content of LLINs Used on Bioko Island, Equatorial Guinea

“…Only households located within the 18 sentinel sites that had received LLINs from the BIMCP during the 2007/2008 mass distribution campaign, and through antenatal care (ANC) distributions for the next four years, were eligible for the sampling process. Using the project's household mapping system, households within the sentinel sites indicating ownership of LLINs during the 2011 MIS were randomly selected [17]. A total of 356 LLINs were collected in March 2012, from 235 randomly selected households, each time replacing collected nets with new ones.…”

Improving the performance of spray operators through monitoring and evaluation of insecticide concentrations of pirimiphos-methyl during indoor residual spraying for malaria control on Bioko Island

“…Data on sprayed structures were recorded on sprayer reporting cards, using the BIMCP mapping system to record the household's unique identifier [19]. The sprayer card information was then entered into the Campaign Information Management System (CIMS), an Androidbased application built around the household database and used as a tool for identifying and locating households targeted for interventions and surveying.…”

Measuring the accuracy of gridded human population density surfaces: a case study in Bioko Island, Equatorial Guinea

“…BIMEP health census data This health population census was part of a bed-nets mass distribution campaign in 2018 (13). People present during the campaign were counted and registered to their house mapping code for geographical reference (12). Each house is GPS-located on the island.…”

“…Maps need not be perfect, but they should be suited to the task at hand. Here, we measure the accuracy of published overlapping maps of human population density using a high quality map of one locale as a gold standard (12). We use several metrics to evaluate these maps, including a new goodness-of-fit metric and a new application of accuracy profiles.…”