Impact of national malaria control scale-up programmes in Africa: magnitude and attribution of effects

Abstract

Background: Since 2005, malaria control scale-up has progressed in many African countries. Controlled studies of insecticide-treated mosquito nets (ITNs), indoor residual spraying (IRS), intermittent preventive treatment during pregnancy (IPTp) and malaria case management suggested that when incorporated into national programmes a dramatic health impact, likely more than a 20% decrease in all-cause childhood mortality, was possible. To assess the extent to which national malaria programmes are achieving impact the authors reviewed African country programme data available through 2009.

Methods: National survey data, published literature, and organization or country reports produced during 2000-2009 were reviewed to assess available malaria financing, intervention delivery, household or target population coverage, and reported health benefits including infection, illness, severe anaemia, and death.

Results: By the end of 2009, reports were available for ITN household ownership (n = 34) and IPTp use (n = 27) in malaria-endemic countries in Africa, with at least two estimates (pre-2005 and post-2005 intervals). Information linking IRS and case management coverage to impact were more limited. There was generally at least a three-fold increase in household ITN ownership across these countries between pre-2005 (median of 2.4% of households with at least one ITN) and post-2005 (median of 32.5% of households with at least one ITN). Ten countries had temporal data to assess programme impact, and all reported progress on at least one impact indicator (typically on mortality); in under-five year mortality rates most observed a decline of more than 20%. The causal relationship between malaria programme scale-up and reduced child illness and mortality rates is supported by biologic plausibility including mortality declines consistent with experience from intervention efficacy trials, consistency of findings across multiple countries and different epidemiologic settings, and temporal congruity where morbidity and mortality declines have been documented in the 18 to 36 months following intervention scale-up.

Conclusions: Several factors potentially have contributed to recent health improvement in African countries, but there is substantial evidence that achieving high malaria control intervention coverage, especially with ITNs and targeted IRS, has been the leading contributor to reduced child mortality. The documented impact provides the evidence required to support a global commitment to the expansion and long-term investment in malaria control to sustain and increase the health impact that malaria control is producing in Africa.

Figure 1

Malaria programme scale-up: relationship between coverage and expected burden reduction. Note: Programme scale-up showing gradual incremental coverage increases (in red) versus rapid and accelerated coverage increases (in blue); the expected concomitant burden reduction suggests that the rapid and accelerated approach leads to an increased burden reduction and added benefit (in gray) from accelerated scale-up. This graphic assumes a direct relationship between population-based intervention coverage and programme impact; it also suggests a time lag between achieving high coverage and having the population experience the intervention benefit (perhaps across a malaria transmission season).

Figure 2

Percent coverage in rural areas of countries where households own at least one insecticide-treated net (ITN): pre-2005 coverage level (blue) and post-2005 increase in coverage levels (red) from national survey data. Source: Demographic and Health Surveys (MACRO, http://www.measuredhs.com); Multiple Indicator Cluster Surveys (UNICEF, http://www.childinfo.org); and Malaria Indicator Surveys (RBM, http://www.rollbackmalaria.org).

Figure 3

Percent coverage in rural areas of the countries using prevention in pregnant women--either repeated use of intermittent preventive treatment during pregnancy (IPTp) or ITN use. * These estimates were not specified as two or more doses of sulphadoxine-pyrimethamine received at antenatal clinic visit. ~These estimates reflect pregnant women sleeping under an ITN the night before the survey; all others are IPTp received among women giving birth in the past two years. Source: Demographic and Health Surveys (MACRO, http://www.measuredhs.com), Multiple Indicator Cluster Surveys (UNICEF, http://www.childinfo.org), and Malaria Indicator Surveys (RBM, http://www.rollbackmalaria.org).

Figure 4

Geographic distribution in Africa of household ownership of at least one insecticide-treated net (ITN) from national surveys in the intervals of 1999-2004 and 2005-2009. Source: Demographic and Health Surveys (MACRO, http://www.measuredhs.com), Multiple Indicator Cluster Surveys (UNICEF, http://www.childinfo.org), and Malaria Indicator Surveys (RBM, http://www.rollbackmalaria.org).

Figure 5

Percentage point increases in core malaria interventions in 10 countries reporting substantial improvement with malaria intervention scale-up. Source: Demographic and Health Surveys (MACRO, http://www.measuredhs.com), Multiple Indicator Cluster Surveys (UNICEF, http://www.childinfo.org), Malaria Indicator Surveys (RBM, http://www.rollbackmalaria.org), and country reports.

Figure 6

Percent changes in key malaria indicators in countries with substantial malaria control programme scale-up. Source: Impact of national malaria control scale-up programs in Africa: magnitude and attribution of effects. Report for the Malaria Control and Evaluation Partnership in Africa (MACEPA)/PATH, Seattle, USA citing the following articles: Zambia [38], Zanzibar [34], Rwanda and Ethiopia [48].

Figure 7

Malaria intervention coverage rates from national surveys (2001-2008), and parasitaemia and anaemia rates from Malaria Indicator Surveys (2006 and 2008) in Zambia. Note: National survey data is available for 2001-2002, 2004, 2006, 2007, and 2008; interim annual estimates are linear extrapolations between known data points. HH: households; IPTp: intermittent preventive treatment in pregnancy; IRS: indoor residual spraying; ITN: insecticide-treated net; anaemia = Hb <8 gm/dl.

Figure 8

Malaria intervention coverage rates per national surveys (2001-2008) and infant and child mortality rates (DHS 2001-2002 and 2007) in Zambia. Note: National survey data is available for 2001-2002, 2004, 2006, 2007, and 2008; interim annual estimates are linear extrapolations between known data points. IPTp: intermittent preventive treatment in pregnancy; IRS: indoor residual spraying; ITN: insecticide-treated net.

Figure 9

Changes in intervention coverage, malaria morbidity and mortality, and other child health intervention coverage in Zambia between 2001 and 2008. Source: Demographic and Health Surveys (DHS) in 2001-2 and 2007; Malaria Indicator Surveys (MIS) in 2006 and 2008.

Figure 10

Rates of all-cause under-five mortality on Bioko Island, Equatorial Guinea: pre- and post-malaria control interventions (IRS, ITNs, case management). Source: Data taken directly from Table four in Kleinschmidt et al [41]. Malaria interventions included indoor residual spraying (IRS) and malaria case management with diagnosis and artemisinin-based combination therapy; increased household ownership of insecticide-treated mosquito nets (ITNs) was added in 2007.