Boosted by increased international funding and greater political commitment, several countries in Africa with high-burden malaria have achieved in recent years high coverage of their at-risk populations with effective mosquito control interventions and access to artemisin-based combination therapy (ACT)
. Despite these efforts morbidity and mortality caused by malaria remains high in 67 of the 99 countries in which malaria is endemic
In highly endemic countries, such as Angola, the current main focus of interventions is to reduce the disease burden to a level at which it is no longer a public health problem. Angola is estimated to have 3.4 million cases of malaria annually, mainly caused by Plasmodium falciparum[3, 4]. Malaria transmission in Angola occurs all year round, but is highest in northern provinces while the southern provinces have highly seasonal or epidemic malaria
. Here, malaria is thought to be responsible for 35% of mortality in children under the age of five, 25% of maternal mortality, and 60% of hospital admissions for children under five
National guidelines currently in place for malaria control include indoor residual spraying (IRS) in selected urban districts (covering over 100,000 households and 4% of the population at risk); free distribution of long-lasting insecticidal nets (LLINs) at neonatal consultations, and free ACT at public health facilities, with over four million doses delivered in 2007–08, enough to treat almost 70% of the reported cases
. These efforts in the last few years have led to a reduction of about 60 percent in the number of deaths caused by the disease in the country
. Furthermore, based on the results of national malaria indicator surveys, between 2006 and 2011 the prevalence of P. falciparum infection in children under five declined from 21% to 13%
Despite the progress achieved, there are still major challenges related to the control and eventual elimination of malaria, particularly in endemic foci. Recently, a sub-national malaria survey was conducted in a meso-endemic area in Northern Angola (Dande municipality, Bengo province)
. The results of this study revealed that children were at a significantly increased risk of Plasmodium spp. infections (18.3% versus 9.3%) and parasitaemia (309.0 versus 194.4 parasites/μL) compared to female adults. It also revealed significant differences in endemicity between the communes (the lowest administrative level) included in the analysis.
The existence of unidentified hyper-endemic communities within meso-endemic areas constitutes an important challenge in the control or elimination of malaria
. Modern spatial analysis methods provide tools for the identification and quantification of the population at risk of parasite infections in endemic communities
[8, 9]. In the case of malaria, these tools have been used to model and develop malaria infection maps at different spatial scales
[10–24]. These include continental and national spatial models of malaria infection constructed using data from a sample of the population with interpolation to areas where infection data are absent. At the highest scale, researchers have used a global model of malaria and spatially predicted malaria parasite rates for children aged 2–10 years
[10, 25]. More recently, malaria indicator survey (MIS) data from Angola for 2007 were used to produce a national level predictive risk map for the country
. However, large uncertainties surround these efforts particularly at small-spatial scales at which most malaria control programmes operate.
A recent mathematical modelling study has shown that targeting hotspots within areas of lower endemicity with LLINs and IRS could help achieve malaria elimination, while untargeted interventions with the same resources would lead to more modest reductions in malaria parasite prevalence
. Therefore, for current global and national malaria models to be useful spatial decision support tools for targeted malaria surveillance and intervention delivery, they need to provide sufficient detail (i.e. at the appropriate decision-making spatial resolution) to identify areas where malaria endemicity is at its highest. One way of determining the need for higher resolution malaria mapping is to empirically evaluate the performance of larger-scale models to that of local, sub-national models at identifying communities that require targeted malaria interventions.
The study aimed to quantify the role of individual-level factors and physical environment in the small-scale geographical variation of malaria, generate a predictive prevalence map for children aged <15 years and compare this map with previous continental and national mapping efforts to observe the need for local spatial prediction studies. It also aimed to provide a high-resolution cartographic resource that can help identify malaria hot-spots to enable the national malaria control programme to plan and implement targeted malaria interventions within each commune of Dande municipality, Angola.