Sustained protection against mortality and morbidity from malaria in rural Gambian children by chemoprophylaxis given by village health workers

The impact of home-based management of malaria on clinical outcomes in sub-Saharan African populations: a systematic review and meta-analysis

BACKGROUND

Malaria remains a significant cause of morbidity and mortality globally and continues to disproportionately afflict the African population. We aimed to evaluate the effect of home management of malaria intervention on health outcomes.

METHODS

In our systematic review and meta-analysis, six databases (Pubmed, Cochrane CENTRAL, EMBASE, CAB Abstracts and Global Health, CINAHL Complete, and BIOSIS) were searched for studies of home management of malaria from inception until November 15, 2023. We included before-after studies, observational studies, and randomised controlled trials of home management intervention delivered in community settings. The primary outcomes were malaria mortality and all-cause mortality. The risk of bias in individual observational studies was assessed using the ROBINS-I tool, whilst randomised controlled trials were judged using a revised Cochrane risk of bias tool and cluster-randomised controlled trials were evaluated using an adapted Cochrane risk of bias tool for cluster-randomised trials. We computed risk ratios with accompanying 95% confidence intervals for health-related outcomes reported in the studies and subsequently pooled the results by using a random-effects model (DerSimonian-Laird method).

RESULTS

We identified 1203 citations through database and hand searches, from which 56 articles from 47 studies encompassing 234,002 participants were included in the systematic review. All studies were conducted in people living in sub-Saharan Africa and were rated to have a low or moderate risk of bias. Pooled analyses showed that mortality rates due to malaria (RR = 0.40, 95% CI = 0.29-0.54, P = 0.00001, I2 = 0%) and all-cause mortality rates (RR = 0.62, 95% CI = 0.53-0.72, P = 0.00001, I2 = 0%) were significantly lower among participants receiving home management intervention compared to the control group. However, in children under 5 years of age, there was no significant difference in mortality rates before and after implementation of home management of malaria. In terms of secondary outcomes, home management of malaria was associated with a reduction in the risk of febrile episodes (RR = 1.27, 95% CI = 1.09-1.47, P = 0.002, I2 = 97%) and higher effective rates of antimalarial treatments (RR = 2.72, 95% CI = 1.90-3.88, P < 0.00001, I2 = 96%) compared to standard care. Home malaria management combined with intermittent preventive treatment showed a significantly lower incidence risk of malaria than home management intervention that exclusively provided treatment to individuals with febrile illness suggestive of malaria. The risks for adverse events were found to be similar for home management intervention using different antimalarial drugs. Cost-effectiveness findings depicted that home malaria management merited special preferential scale-up.

CONCLUSIONS

Home management of malaria intervention was associated with significant reductions in malaria mortality and all-cause mortality. The intervention could help decrease health and economic burden attributable to malaria. Further clinical studies are warranted to enable more meaningful interpretations with regard to wide-scale implementation of the intervention, settings of differing transmission intensity, and new antimalarial drugs.

Village health workers as health diplomats: negotiating health and study participation in a malaria elimination trial in The Gambia

Background

Although many success stories exist of Village Health Workers (VHWs) improving primary health care, critiques remain about the medicalisation of their roles in disease-specific interventions. VHWs are placed at the bottom of the health system hierarchy as cheap and low-skilled volunteers, irrespective of their highly valued social and political status within communities. In this paper, we shed light on the political role VHWs play and investigate how this shapes their social and medical roles, including their influence on community participation.

Method

The study was carried out within the context of a malaria elimination trial implemented in rural villages in the North Bank of The Gambia between 2016 and 2018. The trial aimed to reduce malaria prevalence by treating malaria index cases and their potentially asymptomatic compound members, in which VHWs took an active role advocating their community and the intervention, mobilising the population, and distributing antimalarial drugs. Mixed-methods research was used to collect and analyse data through qualitative interviews, group discussions, observations, and quantitative surveys.

Results and discussion

We explored the emic logic of participation in a malaria elimination trial and found that VHWs played a pivotal role in representing their community and negotiating with the Medical Research Council to bring benefits (e.g. biomedical care service) to the community. We highlight this representative role of VHWs as ‘health diplomats’, valued and appreciated by community members, and potentially increasing community participation in the trial. We argue that VHWs aspire to be politically present and be part of the key decision-makers in the community through their health diplomat role.

Conclusion

It is thus likely that in the context of rural Gambia, supporting VHWs beyond medical roles, in their social and political roles, would contribute to the improved performance of VHWs and to enhanced community participation in activities the community perceive as beneficial.

Asymptomatic malaria infection prevailing risks for human health and malaria elimination

There has been a consistent rise in malaria cases in the last few years. The existing malaria control measures are challenged by insecticide resistance in the mosquito vector, drug résistance in parasite populations, and asymptomatic malaria (ASM) in healthy individuals. The absence of apparent malaria symptoms and the presence of low parasitemia makes ASM a hidden reservoir for malaria transmission and an impediment in malaria elimination efforts. This review focuses on ASM in malaria-endemic countries and the past and present research trends from those geographical locations. The harmful impacts of asymptomatic malaria on human health and its contribution to disease transmission are highlighted. We discuss certain crucial genetic changes in the parasite and host immune response necessary for maintaining low parasitemia leading to long-term parasite survival in the host. Since the chronic health effects and the potential roles for disease transmission of ASM remain mostly unknown to significant populations, we offer proposals for developing general awareness. We also suggest advanced technology-based diagnostic methods, and treatment strategies to eliminate ASM.

Integrated community case management of childhood illness in low- and middle-income countries

BACKGROUND

The leading causes of mortality globally in children younger than five years of age (under-fives), and particularly in the regions of sub-Saharan Africa (SSA) and Southern Asia, in 2018 were infectious diseases, including pneumonia (15%), diarrhoea (8%), malaria (5%) and newborn sepsis (7%) (UNICEF 2019). Nutrition-related factors contributed to 45% of under-five deaths (UNICEF 2019). World Health Organization (WHO) and United Nations Children's Fund (UNICEF), in collaboration with other development partners, have developed an approach - now known as integrated community case management (iCCM) - to bring treatment services for children 'closer to home'. The iCCM approach provides integrated case management services for two or more illnesses - including diarrhoea, pneumonia, malaria, severe acute malnutrition or neonatal sepsis - among under-fives at community level (i.e. outside of healthcare facilities) by lay health workers where there is limited access to health facility-based case management services (WHO/UNICEF 2012).

OBJECTIVES

To assess the effects of the integrated community case management (iCCM) strategy on coverage of appropriate treatment for childhood illness by an appropriate provider, quality of care, case load or severity of illness at health facilities, mortality, adverse events and coverage of careseeking for children younger than five years of age in low- and middle-income countries.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and CINAHL on 7 November 2019, Virtual Health Library on 8 November 2019, and Popline on 5 December 2018, three other databases on 22 March 2019 and two trial registers on 8 November 2019. We performed reference checking, and citation searching, and contacted study authors to identify additional studies.

SELECTION CRITERIA

Randomized controlled trials (RCTs), cluster-RCTs, controlled before-after studies (CBAs), interrupted time series (ITS) studies and repeated measures studies comparing generic WHO/UNICEF iCCM (or local adaptation thereof) for at least two iCCM diseases with usual facility services (facility treatment services) with or without single disease community case management (CCM). We included studies reporting on coverage of appropriate treatment for childhood illness by an appropriate provider, quality of care, case load or severity of illness at health facilities, mortality, adverse events and coverage of careseeking for under-fives in low- and middle-income countries.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened abstracts, screened full texts and extracted data using a standardised data collection form adapted from the EPOC Good Practice Data Collection Form. We resolved any disagreements through discussion or, if required, we consulted a third review author not involved in the original screening. We contacted study authors for clarification or additional details when necessary. We reported risk ratios (RR) for dichotomous outcomes and hazard ratios (HR) for time to event outcomes, with 95% confidence intervals (CI), adjusted for clustering, where possible. We used estimates of effect from the primary analysis reported by the investigators, where possible. We analysed the effects of randomized trials and other study types separately. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included seven studies, of which three were cluster RCTs and four were CBAs. Six of the seven studies were in SSA and one study was in Southern Asia. The iCCM components and inputs were fairly consistent across the seven studies with notable variation for the training and deployment component (e.g. on payment of iCCM providers) and the system component (e.g. on improving information systems). When compared to usual facility services, we are uncertain of the effect of iCCM on coverage of appropriate treatment from an appropriate provider for any iCCM illness (RR 0.96, 95% CI 0.77 to 1.19; 2 CBA studies, 5898 children; very low-certainty evidence). iCCM may have little to no effect on neonatal mortality (HR 1.01, 95% 0.73 to 1.28; 2 trials, 65,209 children; low-certainty evidence). We are uncertain of the effect of iCCM on infant mortality (HR 1.02, 95% CI 0.83 to 1.26; 2 trials, 60,480 children; very low-certainty evidence) and under-five mortality (HR 1.18, 95% CI 1.01 to 1.37; 1 trial, 4729 children; very low-certainty evidence). iCCM probably increases coverage of careseeking to an appropriate provider for any iCCM illness by 68% (RR 1.68, 95% CI 1.24 to 2.27; 2 trials, 9853 children; moderate-certainty evidence). None of the studies reported quality of care, severity of illness or adverse events for this comparison. When compared to usual facility services plus CCM for malaria, we are uncertain of the effect of iCCM on coverage of appropriate treatment from an appropriate provider for any iCCM illness (very low-certainty evidence) and iCCM may have little or no effect on careseeking to an appropriate provider for any iCCM illness (RR 1.06, 95% CI 0.97 to 1.17; 1 trial, 811 children; low-certainty evidence). None of the studies reported quality of care, case load or severity of illness at health facilities, mortality or adverse events for this comparison.

AUTHORS' CONCLUSIONS

iCCM probably increases coverage of careseeking to an appropriate provider for any iCCM illness. However, the evidence presented here underscores the importance of moving beyond training and deployment to valuing iCCM providers, strengthening health systems and engaging community systems.

Motivation of Community Health Workers in Diagnosing, Treating, and Referring Sick Young Children in a Multicountry Study

Background. Community health workers (CHWs) are an important element of care provision for a wide range of conditions, but their turnover rate is high. Many studies have been conducted on health workers’ motivation, focusing on formal sector staff but not CHWs. Although CHWs are easy to recruit, motivating and retaining them for service delivery is difficult. This article investigates factors influencing CHW motivation and retention in health service delivery.

Methods. Quantitative and qualitative data were collected to identify the key factors favoring motivation and retention of CHWs as well as those deterring them. We interviewed 47, 25, and 134 CHWs in Burkina Faso, Nigeria, and Uganda, respectively, using a structured questionnaire. Focus group discussions (FGDs) were also conducted with CHWs, community participants, and facility health workers.

Results. Except for Burkina Faso, most CHWs were female. Average age was between 38 and 41 years, and most came from agricultural communities. The majority (52%–80%) judged they had a high to very high level of satisfaction, but most CHWs (approximately 75%) in Burkina Faso and Uganda indicated that they would be prepared to leave the job, citing income as a major reason. Community recognition and opportunities for training and supervision were major incentives in all countries, but the volume of unremunerated work, at a time when both malaria-positive cases and farming needs were at their peak, was challenging.

Conclusions. Most CHWs understood the volunteer nature of their position but desired community recognition and modest financial remuneration.

Clinical Trials Registration. ISRCTN13858170.

Effects of community health volunteers on infectious diseases of children under five in Volta Region, Ghana: study protocol for a cluster randomized controlled trial

Background

In many low- and middle-income countries, community health volunteers (CHVs) are employed as a key element of the public health system in rural areas with poor accessibility. However, few studies have assessed the effectiveness of CHVs in improving child health in sub-Saharan Africa through randomized controlled trials. The present study aims to measure the impact of health promotion and case management implemented by CHVs on the health of under-5 children in Ghana.

Methods/Design

This study presents the protocol of a cluster-randomized controlled trial assessing the impacts of CHVs, in which the community was used as the randomization unit. A phase-in design will be adopted, and the intervention arm will be implemented in the intervention arm during the first phase and in the control arm during the second phase. The key intervention is the deployment of CHVs, who provide health education, provide oral rehydration solutions and zinc tablets to children with diarrhea, and diagnose malaria using a thermometer and a rapid diagnostic test kit during home visits. The primary endpoints of the study are the prevalence of diarrhea and fever/malaria in children under 5 years of age, as well as the proportion of affected children receiving case management for diarrhea and malaria. The first and second rounds of household surveys to collect data will be conducted in the first phase, and the final round will be conducted during the second phase.

Discussion

With growing attention paid to the roles of CHVs as an essential part of the community health system in low-income countries, this study will contribute valuable information to the body of knowledge on the effects of CHVs.

Trial registration

ISRCTN49236178. (June 16th, 2015)

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3991-z) contains supplementary material, which is available to authorized users.

"Asymptomatic" Malaria: A Chronic and Debilitating Infection That Should Be Treated

Roland Gosling and colleagues argue that "asymptomatic" malaria infections have significant health and societal consequences, and propose that they should be renamed "chronic" malaria infections.

Health & Demographic Surveillance System Profile: Farafenni Health and Demographic Surveillance System in The Gambia

The Farafenni Health and Demographic Surveillance System (Farafenni HDSS) is located 170 km from the coast in a rural area of The Gambia, north of the River Gambia. It was set up in 1981 by the UK Medical Research Council Laboratories to generate demographic and health information required for the evaluation of a village-based, primary health care programme in 40 villages. Regular updates of demographic events and residency status have subsequently been conducted every 4 months. The surveillance area was extended in 2002 to include Farafenni Town and surrounding villages to support randomized, controlled trials. With over three decades of prospective surveillance, and through specific scientific investigations, the platform (population ≈ 50,000) has generated data on: morbidity and mortality due to malaria in children and during pregnancy; non-communicable disease among adults; reproductive health; and levels and trends in childhood and maternal mortality. Other information routinely collected includes causes of death through verbal autopsy, and household socioeconomic indicators. The current portfolio of the platform includes tracking Millennium Development Goal 4 (MDG4) attainments in rural Gambia and cause-of-death determination.

A review of generalist and specialist community health workers for delivering adolescent health services in sub-Saharan Africa

BACKGROUND

The health of adolescents is increasingly seen as an important international priority because the world's one point eight billion young people (aged 10 to 24 years) accounts for 15.5% of the global burden of disease and are disproportionately located in low- and middle-income countries (LMICs). Furthermore, an estimated 70% of premature adult deaths are attributable to unhealthy behaviors often initiated in adolescence (such as smoking, obesity, and physical inactivity). In order for health services to reach adolescents in LMICs, innovative service delivery models need to be explored and tested. This paper reviews the literature on generalist and specialist community health workers (CHWs) to assess their potential for strengthening the delivery of adolescent health services.

METHODS

We reviewed the literature on CHWs using Medline (PubMed), EBSCO Global Health, and Global Health Archive. Search terms (n = 19) were sourced from various review articles and combined with subject heading 'sub-Saharan Africa' to identify English language abstracts of original research articles on generalist and specialist CHWs.

RESULTS

A total of 106 articles, from 1985 to 2012, and representing 24 African countries, matched our search criteria. A single study in sub-Saharan Africa used CHWs to deliver adolescent health services with promising results. Though few comprehensive evaluations of large-scale CHW programs exist, we found mixed evidence to support the use of either generalist or specialist CHW models for delivering adolescent health services.

CONCLUSIONS

This review found that innovative service delivery approaches, such as those potentially offered by CHWs, for adolescents in sub-Saharan Africa are lacking, CHW programs have proliferated despite the absence of high quality evaluations, rigorous studies to establish the comparative effectiveness of generalist versus specialist CHW programs are needed, and further investigation of the role of CHWs in providing adolescent health services in sub-Saharan Africa is warranted.

Quantifying the indirect effects of key child survival interventions for pneumonia, diarrhoea, and measles

To date many studies have measured the effect of key child survival interventions on the main cause of mortality while anecdotally reporting effects on all-cause mortality. We conducted a systematic literature review and abstracted cause-specific and all-cause mortality data from included studies. We then estimated the effect of the intervention on the disease of primary interest and calculated the additional deaths prevented (i.e. the indirect effect). We calculated that insecticide-treated nets have been shown to result in a 12% reduction [95% confidence interval (CI) 0·0-23] among non-malaria deaths. We found pneumonia case management to reduce non-pneumonia mortality by 20% (95% CI 8-22). For measles vaccine, seven of the 10 studies reporting an effect on all-cause mortality demonstrated an additional benefit of vaccine on all-cause mortality. These interventions may have benefits on causes of death beyond the specific cause of death they are targeted to prevent and this should be considered when evaluating the effects of implementation of interventions.

Intermittent preventive treatment for malaria in children living in areas with seasonal transmission

BACKGROUND

In malaria endemic areas, pre-school children are at high risk of severe and repeated malaria illness. One possible public health strategy, known as Intermittent Preventive Treatment in children (IPTc), is to treat all children for malaria at regular intervals during the transmission season, regardless of whether they are infected or not.

OBJECTIVES

To evaluate the effects of IPTc to prevent malaria in preschool children living in endemic areas with seasonal malaria transmission.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register (July 2011), CENTRAL (The Cochrane Library 2011, Issue 6), MEDLINE (1966 to July 2011), EMBASE (1974 to July 2011), LILACS (1982 to July 2011), mRCT (July 2011), and reference lists of identified trials. We also contacted researchers working in the field for unpublished and ongoing trials.

SELECTION CRITERIA

Individually randomized and cluster-randomized controlled trials of full therapeutic dose of antimalarial or antimalarial drug combinations given at regular intervals compared with placebo or no preventive treatment in children aged six years or less living in an area with seasonal malaria transmission.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed eligibility, extracted data and assessed the risk of bias in the trials. Data were meta-analysed and measures of effects (ie rate ratio, risk ratio and mean difference) are presented with 95% confidence intervals (CIs). The quality of evidence was assessed using the GRADE methods.

MAIN RESULTS

Seven trials (12,589 participants), including one cluster-randomized trial, met the inclusion criteria. All were conducted in West Africa, and six of seven trials were restricted to children aged less than 5 years.IPTc prevents approximately three quarters of all clinical malaria episodes (rate ratio 0.26; 95% CI 0.17 to 0.38; 9321 participants, six trials, high quality evidence), and a similar proportion of severe malaria episodes (rate ratio 0.27, 95% CI 0.10 to 0.76; 5964 participants, two trials, high quality evidence). These effects remain present even where insecticide treated net (ITN) usage is high (two trials, 5964 participants, high quality evidence).IPTc probably produces a small reduction in all-cause mortality consistent with the effect on severe malaria, but the trials were underpowered to reach statistical significance (risk ratio 0.66, 95% CI 0.31 to 1.39, moderate quality evidence).The effect on anaemia varied between studies, but the risk of moderately severe anaemia is probably lower with IPTc (risk ratio 0.71, 95% CI 0.52 to 0.98; 8805 participants, five trials, moderate quality evidence).Serious drug-related adverse events, if they occur, are probably rare, with none reported in the six trials (9533 participants, six trials, moderate quality evidence). Amodiaquine plus sulphadoxine-pyrimethamine is the most studied drug combination for seasonal chemoprevention. Although effective, it causes increased vomiting in this age-group (risk ratio 2.78, 95% CI 2.31 to 3.35; two trials, 3544 participants, high quality evidence).When antimalarial IPTc was stopped, no rebound increase in malaria was observed in the three trials which continued follow-up for one season after IPTc.

AUTHORS' CONCLUSIONS

In areas with seasonal malaria transmission, giving antimalarial drugs to preschool children (age < 6 years) as IPTc during the malaria transmission season markedly reduces episodes of clinical malaria, including severe malaria. This benefit occurs even in areas where insecticide treated net usage is high.

Thirty years after Alma-Ata: a systematic review of the impact of community health workers delivering curative interventions against malaria, pneumonia and diarrhoea on child mortality and morbidity in sub-Saharan Africa

BACKGROUND

Over thirty years have passed since the Alma-Ata Declaration on primary health care in 1978. Many governments in the first decade following the declaration responded by developing national programmes of community health workers (CHWs), but evaluations of these often demonstrated poor outcomes. As many CHW programmes have responded to the HIV/AIDS pandemic, international interest in them has returned and their role in the response to other diseases should be examined carefully so that lessons can be applied to their new roles. Over half of the deaths in African children under five years of age are due to malaria, diarrhoea and pneumonia - a situation which could be addressed through the use of cheap and effective interventions delivered by CHWs. However, to date there is very little evidence from randomised controlled trials of the impacts of CHW programmes on child mortality in Africa. Evidence from non-randomised controlled studies has not previously been reviewed systematically.

METHODS

We searched databases of published and unpublished studies for RCTs and non-randomised studies evaluating CHW programmes delivering curative treatments, with or without preventive components, for malaria, diarrhoea or pneumonia, in children in sub-Saharan Africa from 1987 to 2007. The impact of these programmes on morbidity or mortality in children under six years of age was reviewed. A descriptive analysis of interventional and contextual factors associated with these impacts was attempted.

RESULTS

The review identified seven studies evaluating CHWs, delivering a range of interventions. Limited descriptive data on programmes, contexts or process outcomes for these CHW programmes were available. CHWs in national programmes achieved large mortality reductions of 63% and 36% respectively, when insecticide-treated nets and anti-malarial chemoprophylaxis were delivered, in addition to curative interventions.

CONCLUSIONS

CHW programmes could potentially achieve large gains in child survival in sub-Saharan Africa if these programmes were implemented at scale. Large-scale rigorous studies, including RCTs, are urgently needed to provide policymakers with more evidence on the effects of CHWs delivering these interventions.

Two strategies for the delivery of IPTc in an area of seasonal malaria transmission in the Gambia: a randomised controlled trial

BACKGROUND

The Expanded Programme on Immunisation (EPI) provides an effective way of delivering intermittent preventive treatment for malaria (IPT) to infants. However, it is uncertain how IPT can be delivered most effectively to older children. Therefore, we have compared two approaches to the delivery of IPT to Gambian children: distribution by village health workers (VHWs) or through reproductive and child health (RCH) trekking teams. In rural areas, RCH trekking teams provide most of the health care to children under the age of 5 years in the Infant Welfare Clinic, and provide antenatal care for pregnant women.

METHODS AND FINDINGS

During the 2006 malaria transmission season, the catchment populations of 26 RCH trekking clinics in The Gambia, each with 400-500 children 6 years of age and under, were randomly allocated to receive IPT from an RCH trekking team or from a VHW. Treatment with a single dose of sulfadoxine pyrimethamine (SP) plus three doses of amodiaquine (AQ) were given at monthly intervals during the malaria transmission season. Morbidity from malaria was monitored passively throughout the malaria transmission season in all children, and a random sample of study children from each cluster was examined at the end of the malaria transmission season. The primary study endpoint was the incidence of malaria. Secondary endpoints included coverage of IPTc, mean haemoglobin (Hb) concentration, and the prevalence of asexual malaria parasitaemia at the end of malaria transmission period. Financial and economic costs associated with the two delivery strategies were collected and incremental cost and effects were compared. A nested case-control study was used to estimate efficacy of IPT treatment courses. Treatment with SP plus AQ was safe and well tolerated. There were 49 cases of malaria with parasitaemia above 5,000/µl in the areas where IPT was delivered through RCH clinics and 21 cases in the areas where IPT was delivered by VHWs, (incidence rates 2.8 and 1.2 per 1,000 child months, respectively, rate difference 1.6 [95% confidence interval (CI) -0.24 to 3.5]). Delivery through VHWs achieved a substantially higher coverage level of three courses of IPT than delivery by RCH trekking teams (74% versus 48%, a difference of 27% [95% CI 16%-38%]). For both methods of delivery, coverage was unrelated to indices of wealth, with similar coverage being achieved in the poorest and wealthiest groups. The prevalence of anaemia was low in both arms of the trial at the end of the transmission season. Efficacy of IPTc against malaria during the month after each treatment course was 87% (95% CI 54%-96%). Delivery of IPTc by VHWs was less costly in both economic and financial terms than delivery through RCH trekking teams, resulting in incremental savings of US$872 and US$1,244 respectively. The annual economic cost of delivering at least the first dose of each course of IPTc was US$3.47 and US$1.63 per child using trekking team and VHWs respectively.

CONCLUSIONS

In this setting in The Gambia, delivery of IPTc to children 6 years of age and under by VHWs is more effective and less costly than delivery through RCH trekking clinics.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00376155. Please see later in the article for the Editors' Summary.

Intermittent preventive treatment for malaria in infants: a decision-support tool for sub-Saharan Africa

OBJECTIVE

To develop a decision-support tool to help policy-makers in sub-Saharan Africa assess whether intermittent preventive treatment in infants (IPTi) would be effective for local malaria control.

METHODS

An algorithm for predicting the effect of IPTi was developed using two approaches. First, study data on the age patterns of clinical cases of Plasmodium falciparum malaria, hospital admissions for infection with malaria parasites and malaria-associated death for different levels of malaria transmission intensity and seasonality were used to estimate the percentage of cases of these outcomes that would occur in children aged <10 years targeted by IPTi. Second, a previously developed stochastic mathematical model of IPTi was used to predict the number of cases likely to be averted by implementing IPTi under different epidemiological conditions. The decision-support tool uses the data from these two approaches that are most relevant to the context specified by the user.

FINDINGS

Findings from the two approaches indicated that the percentage of cases targeted by IPTi increases with the severity of the malaria outcome and with transmission intensity. The decision-support tool, available on the Internet, provides estimates of the percentage of malaria-associated deaths, hospitalizations and clinical cases that will be targeted by IPTi in a specified context and of the number of these outcomes that could be averted.

CONCLUSION

The effectiveness of IPTi varies with malaria transmission intensity and seasonality. Deciding where to implement IPTi must take into account the local epidemiology of malaria. The Internet-based decision-support tool described here predicts the likely effectiveness of IPTi under a wide range of epidemiological conditions.

Efficacy and safety of intermittent preventive treatment with sulfadoxine-pyrimethamine for malaria in African infants: a pooled analysis of six randomised, placebo-controlled trials

BACKGROUND

Intermittent preventive treatment (IPT) is a promising strategy for malaria control in infants. We undertook a pooled analysis of the safety and efficacy of IPT in infants (IPTi) with sulfadoxine-pyrimethamine in Africa.

METHODS

We pooled data from six double-blind, randomised, placebo-controlled trials (undertaken one each in Tanzania, Mozambique, and Gabon, and three in Ghana) that assessed the efficacy of IPTi with sulfadoxine-pyrimethamine. In all trials, IPTi or placebo was given to infants at the time of routine vaccinations delivered by WHO's Expanded Program on Immunization. Data from the trials for incidence of clinical malaria, risk of anaemia (packed-cell volume <25% or haemoglobin <80 g/L), and incidence of hospital admissions and adverse events in infants up to 12 months of age were reanalysed by use of standard outcome definitions and time periods. Analysis was by modified intention to treat, including all infants who received at least one dose of IPTi or placebo.

FINDINGS

The six trials provided data for 7930 infants (IPTi, n=3958; placebo, n=3972). IPTi had a protective efficacy of 30.3% (95% CI 19.8-39.4, p<0.0001) against clinical malaria, 21.3% (8.2-32.5, p=0.002) against the risk of anaemia, 38.1% (12.5-56.2, p=0.007) against hospital admissions associated with malaria parasitaemia, and 22.9% (10.0-34.0, p=0.001) against all-cause hospital admissions. There were 56 deaths in the IPTi group compared with 53 in the placebo group (rate ratio 1.05, 95% CI 0.72-1.54, p=0.79). One death, judged as possibly related to IPTi because it occurred 19 days after a treatment dose, was subsequently attributed to probable sepsis. Four of 676 non-fatal hospital admissions in the IPTi group were deemed related to study treatment compared with five of 860 in the placebo group. None of three serious dermatological adverse events in the IPTi group were judged related to study treatment compared with one of 13 in the placebo group.

INTERPRETATION

IPTi with sulfadoxine-pyrimethamine was safe and efficacious across a range of malaria transmission settings, suggesting that this intervention is a useful contribution to malaria control.

FUNDING

Bill & Melinda Gates Foundation.

Home management of malaria with artemether-lumefantrine compared with standard care in urban Ugandan children: a randomised controlled trial

BACKGROUND

Home management of malaria-the presumptive treatment of febrile children with antimalarial drugs-is advocated to ensure prompt effective treatment of the disease. We assessed the effect of home delivery of artemether-lumefantrine on the incidence of antimalarial treatment and on clinical outcomes in children from an urban setting with fairly low malaria transmission.

METHODS

In Kampala, Uganda, 437 children aged between 1 and 6 years from 325 households were randomly assigned by a computer-generated sequence to receive home delivery of prepackaged artemether-lumefantrine for presumptive treatment of febrile illnesses (n=225) or current standard of care (n=212). Randomisation was done by household after a pilot period of 1 month. After randomisation, study participants were followed up for an additional 12 months and information on their health and treatment of illnesses was obtained by use of monthly questionnaires and household diaries, which were completed by the participants' carers. The primary outcome was treatment incidence density per person-year. Analysis of the primary outcome was done on the modified intention-to-treat population, which included all participants apart from those excluded before data collection. This trial is registered with ClinicalTrials.gov, number NCT00115921.

FINDINGS

Eight participants in the home management group and four in the standard care group were excluded before data collection; therefore, the primary analysis was done in 217 and 208 participants, respectively. The home management group received nearly twice the number of antimalarial treatments as the standard care group (4.66 per person-year vs 2.53 per person-year; incidence rate ratio [IRR] 1.72, 95% CI 1.43-2.06, p<0.0001), and nearly five times the number given to children with microscopically confirmed malaria in a comparable cohort of children (4.66 per person-year vs 1.03 per person-year, IRR 5.19, 95% CI 4.24-6.35, p<0.0001). Clinical data were available for 189 children in the home management group and 176 in the control group at study end; the main reasons for exclusion were movement out of the study area or loss to follow-up. The proportion of participants with parasitaemia at final assessment in the intervention group was lower than in the control group (four [2%] vs 17 [10%], p=0.006), but there were no other differences in standard malariometric indices, including anaemia. Serious adverse events were captured retrospectively. One child died in each group (home management-severe pneumonia and possible septicaemia; standard care-presumed respiratory failure).

INTERPRETATION

Although home management of malaria led to prompt treatment of fever, there was little effect on clinical outcomes. The substantial over-treatment suggests that artemether-lumefantrine provided in the home might not be appropriate for large urban areas or settings with fairly low malaria transmission.

FUNDING

Gates Malaria Partnership.

Changes in malaria indices between 1999 and 2007 in The Gambia: a retrospective analysis

BACKGROUND

Malaria is a major cause of morbidity and mortality in Africa. International effort and funding for control has been stepped up, with substantial increases from 2003 in the delivery of malaria interventions to pregnant women and children younger than 5 years in The Gambia. We investigated the changes in malaria indices in this country, and the causes and public-health significance of these changes.

METHODS

We undertook a retrospective analysis of original records to establish numbers and proportions of malaria inpatients, deaths, and blood-slide examinations at one hospital over 9 years (January, 1999-December, 2007), and at four health facilities in three different administrative regions over 7 years (January, 2001-December, 2007). We obtained additional data from single sites for haemoglobin concentrations in paediatric admissions and for age distribution of malaria admissions.

FINDINGS

From 2003 to 2007, at four sites with complete slide examination records, the proportions of malaria-positive slides decreased by 82% (3397/10861 in 2003 to 337/6142 in 2007), 85% (137/1259 to 6/368), 73% (3664/16932 to 666/11333), and 50% (1206/3304 to 336/1853). At three sites with complete admission records, the proportions of malaria admissions fell by 74% (435/2530 to 69/1531), 69% (797/2824 to 89/1032), and 27% (2204/4056 to 496/1251). Proportions of deaths attributed to malaria in two hospitals decreased by 100% (seven of 115 in 2003 to none of 117 in 2007) and 90% (22/122 in 2003 to one of 58 in 2007). Since 2004, mean haemoglobin concentrations for all-cause admissions increased by 12 g/L (85 g/L in 2000-04 to 97 g/L in 2005-07), and mean age of paediatric malaria admissions increased from 3.9 years (95% CI 3.7-4.0) to 5.6 years (5.0-6.2).

INTERPRETATION

A large proportion of the malaria burden has been alleviated in The Gambia. Our results encourage consideration of a policy to eliminate malaria as a public-health problem, while emphasising the importance of accurate and continuous surveillance.

Chemoprophylaxis and intermittent treatment for preventing malaria in children

BACKGROUND

Malaria causes repeated illness in children living in endemic areas. Policies of giving antimalarial drugs at regular intervals (prophylaxis or intermittent treatment) are being considered for preschool children.

OBJECTIVES

To evaluate prophylaxis and intermittent treatment with antimalarial drugs to prevent malaria in young children living in malaria-endemic areas.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (August 2007), CENTRAL (The Cochrane Library 2007, Issue 3), MEDLINE (1966 to August 2007), EMBASE (1974 to August 2007), LILACS (1982 to August 2007), mRCT (February 2007), and reference lists of identified trials. We also contacted researchers.

SELECTION CRITERIA

Individually randomized and cluster-randomized controlled trials comparing antimalarial drugs given at regular intervals (prophylaxis or intermittent treatment) with placebo or no drug in children aged one month to six years or less living in a malaria-endemic area.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed methodological quality. We used relative risk (RR) or weighted mean difference with 95% confidence intervals (CI) for meta-analyses. Where we detected heterogeneity and considered it appropriate to combine the trials, we used the random-effects model (REM).

MAIN RESULTS

Twenty-one trials (19,394 participants), including six cluster-randomized trials, met the inclusion criteria. Prophylaxis or intermittent treatment with antimalarial drugs resulted in fewer clinical malaria episodes (RR 0.53, 95% CI 0.38 to 0.74, REM; 7037 participants, 10 trials), less severe anaemia (RR 0.70, 95% CI 0.52 to 0.94, REM; 5445 participants, 9 trials), and fewer hospital admissions for any cause (RR 0.64, 95% CI 0.49 to 0.82; 3722 participants, 5 trials). We did not detect a difference in the number of deaths from any cause (RR 0.90, 95% CI 0.65 to 1.23; 7369 participants, 10 trials), but the CI do not exclude a potentially important difference. One trial reported three serious adverse events with no statistically significant difference between study groups (1070 participants). Eight trials measured morbidity and mortality six months to two years after stopping regular antimalarial drugs; overall, there was no statistically significant difference, but participant numbers were small.

AUTHORS' CONCLUSIONS

Prophylaxis and intermittent treatment with antimalarial drugs reduce clinical malaria and severe anaemia in preschool children.

Comparison of all-cause and malaria-specific mortality from two West African countries with different malaria transmission patterns

Background

Malaria is a leading cause of death in children below five years of age in sub-Saharan Africa. All-cause and malaria-specific mortality rates for children under-five years old in a mesoendemic malaria area (The Gambia) were compared with those from a hyper/holoendemic area (Burkina Faso).

Methods

Information on observed person-years (PY), deaths and cause of death was extracted from online search, using key words: "Africa, The Gambia, Burkina Faso, malaria, Plasmodium falciparum, mortality, child survival, morbidity". Missing person-years were estimated and all-cause and malaria-specific mortality were calculated as rates per 1,000 PY. Studies were classified as longitudinal/clinical studies or surveys/censuses. Linear regression was used to investigate mortality trends.

Results

Overall, 39 and 18 longitudinal/clinical studies plus 10 and 15 surveys and censuses were identified for The Gambia and Burkina Faso respectively (1960–2004). Model-based estimates for under-five all-cause mortality rates show a decline from 1960 to 2000 in both countries (Burkina Faso: from 71.8 to 39.0), but more markedly in The Gambia (from 104.5 to 28.4). The weighted-average malaria-specific mortality rate per 1000 person-years for Burkina Faso (15.4, 95% CI: 13.0–18.3) was higher than that in The Gambia (9.5, 95% CI: 9.1–10.1). Malaria mortality rates did not decline over time in either country.

Conclusion

Child mortality in both countries declined significantly in the period 1960 to 2004, possibly due to socio-economic development, improved health services and specific intervention projects. However, there was little decline in malaria mortality suggesting that there had been no major impact of malaria control programmes during this period. The difference in malaria mortality rates across countries points to significant differences in national disease control policies and/or disease transmission patterns.

Impact of home-based management of malaria on health outcomes in Africa: a systematic review of the evidence

Background

Home-based management of malaria (HMM) is promoted as a major strategy to improve prompt delivery of effective malaria treatment in Africa. HMM involves presumptively treating febrile children with pre-packaged antimalarial drugs distributed by members of the community. HMM has been implemented in several African countries, and artemisinin-based combination therapies (ACTs) will likely be introduced into these programmes on a wide scale.

Case presentations

The published literature was searched for studies that evaluated the health impact of community- and home-based treatment for malaria in Africa. Criteria for inclusion were: 1) the intervention consisted of antimalarial treatment administered presumptively for febrile illness; 2) the treatment was administered by local community members who had no formal education in health care; 3) measured outcomes included specific health indicators such as malaria morbidity (incidence, severity, parasite rates) and/or mortality; and 4) the study was conducted in Africa. Of 1,069 potentially relevant publications identified, only six studies, carried out over 18 years, were identified as meeting inclusion criteria. Heterogeneity of the evaluations, including variability in study design, precluded meta-analysis.

Discussion and evaluation

All trials evaluated presumptive treatment with chloroquine and were conducted in rural areas, and most were done in settings with seasonal malaria transmission. Conclusions regarding the impact of HMM on morbidity and mortality endpoints were mixed. Two studies showed no health impact, while another showed a decrease in malaria prevalence and incidence, but no impact on mortality. One study in Burkina Faso suggested that HMM decreased the proportion of severe malaria cases, while another study from the same country showed a decrease in the risk of progression to severe malaria. Of the four studies with mortality endpoints only one from Ethiopia showed a positive impact, with a reduction in the under-5 mortality rate of 40.6% (95% CI 29.2 – 50.6).

Conclusion

Currently the evidence base for HMM in Africa, particularly regarding use of ACTs, is narrow and priorities for further research are discussed. To optimize treatment and maximize health benefits, drug regimens and delivery strategies in HMM programmes may need to be tailored to local conditions. Additional research could help guide programme development, policy decision-making, and implementation.

Review: Intermittent preventive treatment--a new approach to the prevention of malaria in children in areas with seasonal malaria transmission

Intermittent preventive treatment, the administration of a full course of an anti-malarial treatment to a population at risk at specified time points regardless of whether or not they are known to be infected, is now a recommended approach to the prevention of malaria in pregnancy and is being explored as a potential way of preventing malaria in infants. However, in many malaria endemic areas, the main burden of malaria is in older children and increasing use of insecticide treated bednets is likely to increase further the proportion of episodes of malaria that occur in older children. Recently, it has been shown in Senegal and in Mali that intermittent preventive treatment given to older children during the malaria transmission season can be remarkably effective in preventing malaria. This approach to malaria control is likely to be most effective in areas with a high level of malaria transmission concentrated in a short period of the year. However, several issues need to be addressed before intermittent preventive treatment in children can be advocated for use in malaria control programmes. These include: (1) determination of whether intermittent preventive treatment adds to the protection afforded by other control measures such as insecticide-treated bednets; (2) whether an effective and sustainable delivery system can be found; (3) choice of drug to be used; (4) optimum timing of drug administration; (5) the requisite interval between treatments. The potential benefits of intermittent preventive treatment in children are substantial; more research is needed to determine if this is a practical approach to malaria control.

Long-term impact of malaria chemoprophylaxis on cognitive abilities and educational attainment: follow-up of a controlled trial

Objectives:

We investigated the long-term impact of early childhood malaria prophylaxis on cognitive and educational outcomes.

Design:

This was a household-based cluster-controlled intervention trial.

Setting:

The study was conducted in 15 villages situated between 32 km to the east and 22 km to the west of the town of Farafenni, the Gambia, on the north bank of the River Gambia.

Participants:

A total of 1,190 children aged 3–59 mo took part in the trial. We traced 579 trial participants (291 in the prophylaxis group and 288 in the placebo group) in 2001, when their median age was 17 y 1 mo (range 14 y 9 mo to 19 y 6 mo).

Interventions:

Participants received malaria chemoprophylaxis (dapsone/pyrimethamine) or placebo for between one and three malaria transmission seasons from 1985 to 1987 during the controlled trial. At the end of the trial, prophylaxis was provided for all children under 5 y of age living in the study villages.

Outcome Measures:

The outcome measures were cognitive abilities, school enrolment, and educational attainment (highest grade reached at school).

Results:

There was no significant overall intervention effect on cognitive abilities, but there was a significant interaction between intervention group and the duration of post-trial prophylaxis (p = 0.034), with cognitive ability somewhat higher in the intervention group among children who received no post-trial prophylaxis (treatment effect = 0.2 standard deviations [SD], 95% confidence interval [CI] −0.03 to 0.5) and among children who received less than 1 y of post-trial prophylaxis (treatment effect = 0.4 SD, 95% CI 0.1 to 0.8). The intervention group had higher educational attainment by 0.52 grades (95% CI = −0.041 to 1.089; p = 0.069). School enrolment was similar in the two groups.

Conclusions:

The results are suggestive of a long-term effect of malaria prophylaxis on cognitive function and educational attainment, but confirmatory studies are needed.

Background: The burden of disease and death from malaria is well documented, but little is known about the impact of malaria on the mental development of children and their ability to learn. Evidence from observational studies suggests episodes of malaria are associated with a negative impact on mental processes such as language, memory, and attention. However, there is very little evidence from trials on whether community-level approaches to malaria prevention can improve mental and educational development in children. In a trial conducted in the Gambia between 1985 and 1987, which was reported in The Lancet (21: 1121–1127), young children were allocated either to receive dapsone/pyrimethamine (a commonly used drug for malaria prevention) or placebo, for up to four years. At the end of the trial, the drug was then offered to all children at the study sites. In a follow-up to the original trial, reported here, the researchers then attempted to trace the original trial participants and look at various measures relating to mental development: memory, attention, reasoning, knowledge, language, and level of schooling reached.

What this trial shows: The investigators found no significant differences in mental development scores (memory, attention, reasoning, knowledge, and language) between children who had received malaria prevention during the trial and those who had not, although scores appeared higher for children who received malaria prevention for the longest period. However, they did see a significant difference in schooling level, with children who received malaria prevention during the trial having achieved just over half a grade higher in school.

Strengths and limitations: The original trial methods ensured that the two participant groups were comparable on relevant demographic, household, and educational factors at the start of the trial. Furthermore, the measures used to compare mental development were appropriate, validated for African populations, and then further adapted in the groups being studied. Although only close to half of the original trial participants could be successfully traced, a sample size calculation shows that the follow-up study probably had enough power to detect important effects. However, a major limitation of the study is that once the main trial was complete, all participants were offered malaria prevention with dapsone/pyrimethamine. This limits the extent to which the follow-up study could have detected prevention effects 14 years later, had they existed. The researchers investigated this by doing separate analyses based on how long children spent in the trial. They found a stronger positive effect of malaria prevention on mental development scores for children who spent longer in the trial (and therefore got post-trial prevention for a shorter period of time). This finding supports, but does not conclusively prove, the hypothesis that malaria prevention enhances mental development.

Contribution to the evidence: This study adds data from a well-controlled clinical trial to the body of evidence suggesting that malaria prevention may have beneficial effects on mental and educational development. Very few previous trials have examined this outcome; these results need to be confirmed in future studies specifically designed to test such hypotheses.

Chemoprophylaxis and intermittent treatment for preventing malaria in children

BACKGROUND

Malaria causes repeated illness in children living in endemic areas. Policies of giving antimalarial drugs at regular intervals (prophylaxis or intermittent treatment) are being considered for preschool children.

OBJECTIVES

To evaluate chemoprophylaxis and intermittent treatment with antimalarial drugs to prevent malaria in young children living in malaria endemic areas.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (April 2005), CENTRAL (The Cochrane Library Issue 1, 2005), MEDLINE (1966 to April 2005), EMBASE (1974 to April 2005), LILACS (1982 to April 2005), and reference lists of identified trials. We also contacted researchers.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing antimalarial drugs given at regular intervals (prophylaxis or intermittent treatment) with placebo or no drug in children aged one month to six years or less living in an area where malaria is endemic.

DATA COLLECTION AND ANALYSIS

We independently extracted data and assessed methodological quality. We used relative risk (RR) or weighted mean difference with 95% confidence intervals (CI) for meta-analyses. Where we detected heterogeneity and considered it appropriate to combine the trials, we used the random-effects model (REM).

MAIN RESULTS

Nineteen trials (14,393 participants) met the inclusion criteria. Children receiving antimalarial drugs as prophylaxis or intermittent treatment had fewer clinical malaria episodes (RR 0.52, 95% CI 0.35 to 0.77, REM; 4051 participants, 8 trials), and severe anaemia was less common (RR 0.54, 95% CI 0.42 to 0.68; 2727 participants, 8 trials). We did not detect a difference in the number of deaths from any cause (RR 0.82, 95% CI 0.65 to 1.04; 7929 participants, 9 trials), but the confidence intervals do not exclude a potentially important difference. None of the trials reported serious adverse events. Three trials measured morbidity and mortality six months to two years after stopping regular antimalarial drugs; overall, there was no statistically significant difference, but participant numbers were small.

AUTHORS' CONCLUSIONS

Prophylaxis and intermittent treatment with antimalarial drugs reduce clinical malaria and severe anaemia in preschool children. There is insufficient evidence to detect an effect on mortality.

Impact of malaria control on childhood anaemia in Africa -- a quantitative review

OBJECTIVE

To review the impact of malaria control on haemoglobin (Hb) distributions and anaemia prevalences in children under 5 in malaria-endemic Africa.

METHODS

Literature review of community-based studies of insecticide-treated bednets, antimalarial chemoprophylaxis and insecticide residual spraying that reported the impact on childhood anaemia. Anaemia outcomes were standardized by conversion of packed cell volumes into Hb values assuming a fixed threefold difference, and by estimation of anaemia prevalences from mean Hb values by applying normal distributions. Determinants of impact were assessed in multivariate analysis.

RESULTS

Across 29 studies, malaria control increased Hb among children by, on average, 0.76 g/dl [95% confidence interval (CI): 0.61-0.91], from a mean baseline level of 10.5 g/dl, after a mean of 1-2 years of intervention. This response corresponded to a relative risk for Hb < 11 g/dl of 0.73 (95% CI: 0.64-0.81) and for Hb < 8 g/dl of 0.40 (95% CI: 0.25-0.55). The anaemia response was positively correlated with the impact on parasitaemia (P = 0.005, P = 0.008 and P = 0.01 for the three outcome measures), but no relationship with the type or duration of malaria intervention was apparent. Impact on the prevalence of Hb < 11 g/dl was larger in sites with a higher baseline parasite prevalence. Although no age pattern in impact was apparent across the studies, some individual trials found larger impacts on anaemia in children aged 6-35 months than in older children.

CONCLUSION

In malaria-endemic Africa, malaria control reduces childhood anaemia. Childhood anaemia may be a useful indicator of the burden of malaria and of the progress in malaria control.

Mosquito bed nets: implementation in rural villages in Zambia and the effect on subclinical parasitaemia and haemoglobin

Malaria continues to be an increasing health concern in many endemic areas where it remains a major contributor to childhood morbidity and mortality. Chemoprophylaxis and treatment are increasingly compromised by drug resistance. Vaccination for malaria is not yet available outside clinical trials. In clinical trials bed nets have been shown to be effective in reducing malarial morbidity and mortality. Their efficacy outside of the clinical trial setting has been less well documented. We describe our experience with the introduction of bed nets in a remote rural Zambian village and document the effect on malarial parasitaemia, spleen rates and haemoglobin. Children were evaluated at the end of the rainy seasons in April 1998 and April 1999. Insecticide impregnated nets were made available for purchase to the village in July 1998. Rates of parasitaemia and anaemia were significantly reduced.

Intermittent treatment for malaria and anaemia control at time of routine vaccinations in Tanzanian infants: a randomised, placebo-controlled trial

BACKGROUND

Clinical malaria and severe anaemia are major causes of paediatric hospital admission and death in many malaria-endemic settings. In the absence of an effective and affordable vaccine, control programmes continue to rely on case management while attempting the large-scale deployment of insecticide-treated nets. We did a randomised, placebo-controlled trial to assess the efficacy and safety of intermittent sulphadoxine-pyrimethamine treatment on the rate of malaria and severe anaemia in infants in a rural area of Tanzania.

METHODS

We randomly assigned 701 children living in Ifakara, southern Tanzania, sulphadoxine-pyrimethamine or placebo at 2, 3, and 9 months of age. All children received iron supplementation between 2 and 6 months of age. The intervention was given alongside routine vaccinations delivered through WHO's Expanded Program on Immunisation (EPI). The primary outcome measures were first or only episode of clinical malaria, and severe anaemia in the period from recruitment to 1 year of age. Morbidity monitoring through a hospital-based passive case-detection system was complemented by cross-sectional surveys at 12 and 18 months of age. Results were expressed in terms of protective efficacy (100 [1-hazard ratio]%) and analysis was by intention to treat.

FINDINGS

40 children dropped out (16 died, 11 migrated, 12 parents withdrew consent, and one for other reasons). Intermittent sulphadoxine-pyrimethamine treatment was well tolerated and no drug-attributable adverse events were recorded. During the first year of life, the rate of clinical malaria (events per person-year at risk) was 0.15 in the sulphadoxine-pyrimethamine group versus 0.36 in the placebo group (protective efficacy 59% [95% CI 41-72]), and the rate of severe anaemia was 0.06 in the sulphadoxine-pyrimethamine group versus 0.11 in the placebo group (50% [8-73]). Serological responses to EPI vaccines were not affected by the intervention.

INTERPRETATION

This new approach to malaria control reduced the rate of clinical malaria and severe anaemia by delivering an available and affordable drug through the existing EPI system. Data are urgently needed to assess the potential cost-effectiveness of intermittent treatment in areas with different patterns of malaria endemicity.

Micronutrient and iron supplementation and effective antimalarial treatment synergistically improve childhood anaemia

The control of childhood anaemia in malaria holoendemic areas is a major public health challenge for which an optimal strategy remains to be determined. Malaria prevention may compromise the development of partial immunity. Regular micronutrient supplementation has been suggested as an alternative but its effectiveness remains unsettled. We therefore conducted a randomised placebo-controlled intervention trial with 207 Tanzanian children aged 5 months to 3 years on the efficacy of supervised supplementation of low-dose micronutrients including iron (Poly Vi-Sol with iron) three times per week, with an average attendance of >/= 90%. The mean haemoglobin (Hb) level increased by 8 g/l more in children on supplement (95% CI 3-12) during the 5-month study. All age groups benefited from the intervention including severely anaemic subjects. The mean erythrocyte cell volume (MCV) increased but Hb in children >/= 24 months improved independently of MCV and no relation was found with hookworm infection. The data therefore suggest that micronutrients other than iron also contributed to Hb improvement. In the supplement group of children who had received sulfadoxine-pyrimethamine (SP) treatment, the mean Hb level increased synergistically by 22 g/l (95% CI 13-30) compared to 7 g/l (95% CI 3-10) in those without such treatment. Supplementation did not affect malaria incidence. In conclusion, micronutrient supplementation improves childhood anaemia in malaria holoendemic areas and this effect is synergistically enhanced by temporary clearance of parasitaemia.

Teaching mothers to provide home treatment of malaria in Tigray, Ethiopia: a randomised trial

BACKGROUND

No satisfactory strategy for reducing high child mortality from malaria has yet been established in tropical Africa. We compared the effect on under-5 mortality of teaching mothers to promptly provide antimalarials to their sick children at home, with the present community health worker approach.

METHODS

Of 37 tabias (cluster of villages) in two districts with hyperendemic to holoendemic malaria, tabias reported to have the highest malaria morbidity were selected. A census was done which included a maternity history to determine under-5 mortality. Tabias (population 70,506) were paired according to under-5 mortality rates. One tabia from each pair was allocated by random number to an intervention group and the other was allocated to the control group. In the intervention tabias, mother coordinators were trained to teach other local mothers to recognise symptoms of malaria in their children and to promptly give chloroquine. In both intervention and control tabias, all births and deaths of under-5s were recorded monthly.

FINDINGS

From January to December 1997, 190 of 6383 (29.8 per 1000) children under-5 died in the intervention tabias compared with 366 of 7294 (50.2 per 1000) in the control tabias. Under-5 mortality was reduced by 40% in the intervention localities (95% CI from 29.2-50.6; paired t test, p<0.003). For every third child who died, a structured verbal autopsy was undertaken to ascribe cause of mortality as consistent with malaria or possible malaria, or not consistent with malaria. Of the 190 verbal autopsies, 13 (19%) of 70 in the intervention tabias were consistent with possible malaria compared with 68 (57%) of 120 in the control tabias.

INTERPRETATION

A major reduction in under-5 mortality can be achieved in holoendemic malaria areas through training local mother coordinators to teach mothers to give under-5 children antimalarial drugs.

Health centre versus home presumptive diagnosis of malaria in southern Ghana: implications for home-based care policy

A study was conducted in 1997 to compare the accuracy of presumptive diagnosis of malaria in children aged 1-9 years performed by caretakers of the children to that of health centre staff in 2 ecological zones in southern Ghana. Similar symptoms were reported in the children at home and at the health centre. In the home setting, symptoms were reported the same day that they occurred, 77.6% of the children with a report of fever were febrile (axillary temperature > or = 37.5 degrees C) and 64.7% of the reports of malaria were parasitologically confirmed. In the health centre, the median duration of symptoms before a child was seen was 3 days (range 1-14 days), 58.5% of the children with a report of fever were febrile and 62.6% of the clinically diagnosed cases were parasitologically confirmed. In the 2 settings almost all the infections were due to Plasmodium falciparum. Parasite density was 3 times higher in the health centre cases compared to the home-diagnosed cases. Early and appropriate treatment of malaria detected in children by caretakers may prevent complications that arise as a result of persistence of symptoms and attainment of high parasitaemic levels.

Decline of mortality in children in rural Gambia: the influence of village-level primary health care

Using data from a longitudinal study conducted in 40 villages by the UK MRC in the North Bank Division of The Gambia beginning in late 1981, we examined infant and child mortality over a 15-year period for a population of about 17 000 people. Comparisons are drawn between villages with and without PHC. The extra facilities in the PHC villages include: a paid Community Health Nurse for about every 5 villages, a Village Health Worker and a trained Traditional Birth Attendant. Maternal and child health services with a vaccination programme are accessible to residents in both PHC and non-PHC villages. The data indicate that there has been a marked improvement in infant and under-five mortality in both sets of villages. Following the establishment of the PHC system in 1983, infant mortality dropped from 134/1000 in 1982-83 to 69/1000 in 1992-94 in the PHC villages and from 155/1000 to 91/1000 in the non-PHC villages over the same period. Between 1982 and 83 and 1992-94, the death rates for children aged 1-4 fell from 42/1000 to 28/1000 in the PHC villages and from 45/1000 to 38/1000 in the non-PHC villages. Since 1994, when supervision of the PHC system has weakened, infant mortality rates in the PHC villages have risen to 89/1000 in 1994-96. The rates in the non-PHC villages fell to 78/1000 for this period. The under-five mortality rates in both sets of villages have converged to 34/1000 for 1994-96. When the PHC programme was well supported in the 1980s, we saw significantly lower mortality rates for the 1-4-year-olds. These differences disappeared when support for PHC was reduced after 1994. The differential effects on infant mortality are less clear cut.

Cost-effectiveness of malaria control in sub-Saharan Africa

BACKGROUND

Information on the cost-effectiveness of malaria control is needed for the WHO Roll Back Malaria campaign, but is sparse. We used mathematical models to calculate cost-effectiveness ratios for the main prevention and treatment interventions in sub-Saharan Africa.

METHODS

We analysed interventions to prevent malaria in childhood (insecticide-treated nets, residual spraying of houses, and chemoprophylaxis) and pregnancy (chloroquine chemoprophylaxis and sulfadoxine-pyrimethamine intermittent treatment), and to improve malaria treatment (improved compliance, improved availability of second-line and third-line drugs, and changes in first-line drug). We developed models that included probabilistic sensitivity analysis to calculate ranges for the cost per disability-adjusted life year (DALY) averted for each intervention in three economic strata. Data were obtained from published and unpublished sources, and consultations with researchers and programme managers.

FINDINGS

In a very-low-income country, for insecticide treatment of existing nets, the cost-effectiveness range was US$4-10 per DALY averted; for provision of nets and insecticide treatment $19-85; for residual spraying (two rounds per year) $32-58; for chemoprophylaxis for children $3-12 (assuming an existing delivery system); for intermittent treatment of pregnant women $4-29; and for improvement in case management $1-8. Although some interventions are inexpensive, achieving high coverage with an intervention to prevent childhood malaria would use a high proportion of current health-care expenditure.

INTERPRETATION

Cost-effective interventions are available. A package of interventions to decrease the bulk of the malaria burden is not, however, affordable in very-low-income countries. Coverage of the most vulnerable groups in Africa will require substantial assistance from external donors.

A community-based programme to provide prompt and adequate treatment of presumptive malaria in children

A community-based programme to ensure prompt and adequate treatment of presumptive episodes of clinical malaria in children has been established in a rural province of Burkina Faso. The implementation strategy was based on training a core group of mothers in every village and supplying community health workers with essential antimalarial drugs specially packed in age-specific bags containing a full course of treatment. Drugs were sold under a cost-recovery scheme. The programme was run in 1994 by the national malaria control centre (CNLP), and in 1995 it was developed to the provincial health team (PHT). Knowledge and awareness of malaria increased with the intervention. Drug consumption by age group was compatible with the distribution of disease, and no major problem of misuse emerged. The actual implementation costs of the intervention were US$ 0.06 per child living in the province. An evaluation of the impact of the intervention on the severity of malaria, using routine data from the health information system and taking as an indicator the proportion of malaria cases which were recorded as severe in health centres, was performed. In 1994, when the intervention was implemented on a provincial scale by CNLP, this proportion was lower than the average of the 4 preceding years (3.7% vs. 4.9%). In 1995, when the programme was implemented by the PHT, the proportion of severe cases was lower in health centres achieving a programme coverage of > or = 50% in their catchment area compared with the others (4.2% vs. 6.1%). Our experience shows that a low-cost, community-based intervention aimed at providing children with prompt and adequate treatment of presumptive episodes of clinical malaria is feasible, and suggests that it may lead to a reduction in the morbidity from severe malaria.

Hyperpigmented dermal macules in children following the administration of Maloprim for malaria chemoprophylaxis

The occurrence of an unexpected side effect following the use of Maloprim (pyrimethamine/dapsone) for malaria chemosuppression in 3-59 months old children in Sierra Leone is reported. As part of a trial of chemoprophylaxis and insecticide-impregnated bed nets, 2000 children received either Maloprim or placebo; 4% of children who received Maloprim fortnightly for more than 3 months developed hyperpigmented macules, whereas none of the children who received placebo did so. Histopathological examination of full thickness skin biopsies showed macrophages containing melanin in the dermal layer. Clustering of cases was noted among siblings, suggesting the possible involvement of genetic factors in the pathogenesis of these skin reactions. One child was accidentally re-exposed to Maloprim after the drug had been withdrawn and he developed a severe reaction. No other serious side effect was noted. Hyperpigmented lesions similar to those reported in this study have been described previously in patients with leprosy treated with dapsone, and the dapsone component of Maloprim is the likely cause of the skin reactions seen in children given this drug for malaria chemoprophylaxis.

Maloprim malaria prophylaxis in children living in a holoendemic village in north-eastern Tanzania

A randomized, double-'blind', placebo-controlled trial of weekly Maloprim (dapsone-pyrimethamine, D-P) for malaria prophylaxis was conducted at Magoda village in north-eastern Tanzania. The effect of D-P on the incidence of clinical malaria, Plasmodium falciparum prevalence and density, splenomegaly, and packed cell volume (PCV) was investigated in a cohort of 249 children (126 receiving D-P and 123 receiving placebo) aged 1-9 years. The case definition of clinical malaria (malaria fever) was measured axillary temperature > or = 37.5 degrees C and/or reported fever, and P. falciparum asexual parasitaemia > or = 5000/microL. Children aged 1-4 years given D-P experienced 1.56 episodes of clinical malaria per year, whereas children on placebo experienced 2.55 episodes (relative rate [RR] = 0.61, 95% confidence interval [CI] 0.47, 0.80). Thus, D-P protective efficacy against clinical malaria, in this age group, was 39% (95% CI 20%, 53%; P = 0.0002). The annual incidence of clinical malaria among children aged 5-9 years was 0.16 episodes in the D-P group and 0.26 episodes in those receiving placebo (RR = 0.58, 95% CI 0.26, 1.28; P = 0.17). Increased malaria transmission and drug resistance, during the course of the trial, resulted in a reduction in the protective efficacy of D-P. Overall, D-P was able to reduce parasite densities and splenomegaly. D-P prophylaxis also resulted in an increase in PCV but this effect diminished towards the end of the trial. D-P exerted a suppressive effect on asexual parasitaemia throughout the trial.

Mortality and morbidity from malaria after stopping malaria chemoprophylaxis

Gambian children who had received malaria chemoprophylaxis for a variable period of time during their first 5 years of life were followed to determine whether they experienced a rebound in mortality or in morbidity from malaria during the period after chemoprophylaxis was stopped. The risk of dying between the ages of 5 years, when chemoprophylaxis was stopped, and 10 years was no higher among children who had received chemoprophylaxis with Maloprim (pyrimethamine plus dapsone) for some period during their first 5 years of life than among children who had received placebo (21 vs. 24 deaths) and the beneficial effect of chemoprophylaxis on mortality observed during the first 5 years of life was sustained. The incidence of clinical attacks of malaria during the year after medication was stopped was significantly higher among children who had previously received Maloprim for several years than among children who had previously received placebo. However, at the end of this year, there was no significant difference in spleen rate, parasite rate or packed cell volume between the 2 groups of children. Thus, stopping chemoprophylaxis after a period of several years increased the risk of clinical malaria but did not result in a rebound in mortality in Gambian children. However, the number of deaths recorded was small, so a modest effect on mortality cannot be excluded.

The epidemiology of malaria in the Wosera area, East Sepik Province, Papua New Guinea, in preparation for vaccine trials. II. Mortality and morbidity

Malaria mortality and morbidity were studied in a rural population of 4000 in the Wosera area, East Sepik Province, Papua New Guinea. Malaria accounted for 4.9% of the 162 deaths investigated by verbal autopsy and for 12.2% of the 49 deaths assessed through medical records. Malaria was the first cause of death in children aged 0.5-4 years. Of the 7795 subjects interviewed and bled during six cross-sectional community-based surveys, children of 1-4 years had the highest malaria-related morbidity. In this age group, point prevalences of fever, fever associated with parasitaemia, and fever plus Plasmodium falciparum (Pf) parasitaemia > or = 10,000 parasites/microliters blood were 5%, 4.1% and 1.5%, respectively. The corresponding figures for adults were 2%, 0.9% and 0.1%, respectively. The calculation of attributable fraction (AF) using a multiple logistic regression model showed that malaria accounted for 0.44 of all fevers in children of 1-4 years and 0.08 of the fevers in adults. Prevalence data derived from the AF estimate were compared with those calculated using different accepted density thresholds. The prevalences which best approximated the results from the logistic regression model were obtained using parasitaemia cut-offs of > or = 1000 Pf parasites/microliter in children aged 1-4 years and adults older than 19 years and of > or = 10,000 parasites/microliter in those aged 5-19 years. Prevalence of fever associated with parasitaemia was highly seasonal, with a peak at the beginning of the wet season. The geographical distribution of malaria morbidity was not uniform. The measurement of malaria-related morbidity, the identification of significant seasonal and local variation as well as the assessment of different methods of defining a clinical episode of Pf malaria are crucial for the design and evaluation of intervention studies, including field trials of antimalarial vaccines.

Attributable fraction estimates and case definitions for malaria in endemic areas

Asymptomatic carriage of malaria parasites occurs frequently in endemic areas and the detection of parasites in a blood film from a febrile individual does not necessarily indicate clinical malaria. In areas of low and moderate endemicity the parasite prevalence in fever cases can be compared with that in community controls to estimate the fraction of cases which are attributable to malaria. In areas of very high transmission such estimates of the attributable fraction may be imprecise because very few individuals are without parasites. Furthermore, non-malarial fevers appear to suppress low levels of parasitaemia resulting in biased estimates of the attributable fraction. Alternative estimation techniques were therefore explored using data collected during 1989-1991 from a highly endemic area of Tanzania, where over 80 per cent of young children are parasitaemic. Logistic regression methods which model fever risk as a continuous function of parasite density give more precise estimates than simple analyses of parasite prevalence and overcome problems of bias caused by the effects of non-malarial fevers. Such models can be used to estimate the probability that any individual episode is malaria-attributable and can be extended to allow for covariates. A case definition for symptomatic malaria that is used widely in endemic areas requires fever together with a parasite density above a specific cutoff. The choice of a cutoff value can be assisted by using the probabilities derived from the logistic model to estimate the sensitivity and specificity of the case definition.

Malaria: how useful are clinical criteria for improving the diagnosis in a highly endemic area?

To assess the validity of clinical criteria, we investigated 2096 outpatients diagnosed as malaria cases by nurses at a rural health subcentre in a highly endemic area of Papua New Guinea. 73% of the children < 10 years old had a positive blood slide for any species of Plasmodium and 32% had > or = 10,000 P. falciparum parasites per microL. For adults the frequencies were 51% and 9%, respectively. Stepwise logistic regression identified spleen size, no cough, temperature, no chest indrawing, and normal stools as significant predictors for a positive blood slide in children; no cough and normal stools predicted a positive blood slide in adults. Fever, no cough, vomiting, and enlarged spleen were significant predictors for a P. falciparum parasitaemia > or = 10,000/microL in children; in adults the only predictor was vomiting. In children the association of no cough and enlarged spleen had the best predictive value for a positive blood slide, and a temperature > or = 38 degrees C had the best predictive value for a P. falciparum parasitaemia > or = 10,000 microL. In adults, no major symptom had a good predictive value for a positive blood slide but vomiting had the best predictive value for a P. falciparum parasitaemia > or = 10,000/microL. When microscopy is not available, these findings can help in areas of high endemicity to determine which patients with a history of fever are most likely to have malaria and, more importantly, for which patients another diagnosis should be strongly considered.

Dynamics of malaria parasitaemia associated with febrile illness in children from a rural area of Madang, Papua New Guinea

Active community and self-reporting surveillance techniques have been used to describe the dynamics of febrile illness and associated malaria infection in children aged 2 to 15 years from a rural area of Madang Province, Papua New Guinea (PNG). Both history of fever and fever in association with parasitaemia appeared to be reliable indicators of malaria morbidity in this endemic area. Parasite density was observed to be a major determinant of mild malarial disease at both the population level and within an individual. Age-specific prevalence of febrile illness correlated with age-specific patterns of parasite density but not of parasite prevalence. Seasonal changes in fever incidence correlated with parasite density. The transition from afebrile to febrile state within an individual was generally associated with an increase in parasite density. Surveillance and self-reported febrile cases (which differ in severity on the basis of the perceived need for treatment) could be distinguished on the basis of parasite density. Thus surveillance techniques divide clinical malaria in rural PNG into 'mild' and 'very mild' forms. The age-specific pattern of decline of prevalence of malaria-associated febrile illness and parasite density is best explained by induction of strain-specific anti-disease immunity upon infection with a given strain of Plasmodium falciparum. The fever threshold in self-reporting febrile cases was seen to decrease with age and can be explained by an age-specific decline in anti-toxic immunity.

Evaluation of C-reactive protein and haptoglobin as malaria episode markers in an area of high transmission in Africa

Field studies of malaria in endemic areas frequently use the presence or levels of parasitaemia, together with the measurement of fever, as the primary criteria with which to identify cases. However, since malaria cases do not always present with measurable fever, and since asymptomatic parasitaemia occurs, additional episode markers might be useful epidemiological tools. We have measured the C-reactive protein and haptoglobin levels in paediatric patients presenting to a village health post in the Kilombero District in Tanzania and in convalescent sera from the same patients, in order to evaluate these acute-phase reactants as alternative markers of Plasmodium falciparum episodes. Among afebrile patients, C-reactive protein levels were highly correlated with parasite density. High C-reactive protein levels are therefore probably indicative of recent clinical malaria episodes in currently afebrile individuals with high parasite densities. An appropriate case definition for malaria in epidemiological studies in endemic areas might therefore be hyperparasitaemia accompanied by either, or both, measurable fever and raised C-reactive protein levels. This would give less biased estimates of the overall burden of malaria morbidity than does a definition which requires measurable fever. Levels of haptoglobin were highly negatively correlated with parasitaemia, but did not appear to be useful episode markers because this correlation was probably not related to acute morbidity. However, haptoglobin can be useful to assess at community level the impact of interventions on parasitaemia.

Classification of clinical falciparum malaria and its use for the evaluation of chemosuppression in children under six years of age in Liberia, west Africa

The possible role of malaria as cause of morbidity was assessed during one year in 262 children aged 6 months to 6 years living in two villages in a rural area of Liberia. The study population was followed by weekly clinics and three-monthly surveys and the children were randomly allocated to receive either chloroquine or placebo every 3 weeks. The morbidity of the children was evaluated by criteria based on the history and the clinical condition into four different stages, in order to describe the probability that an observed clinical event could be attributed to malaria infection, based on the presence of detectable parasites in the blood, the history the previous week, and the clinical status of the child. The level of anaemia, splenomegaly and measured body temperature supported that malaria was the major contributor to the overall morbidity observed. Based on the stage classification of clinical illness, children were classified as having 'possible clinical malaria' or 'probable clinical malaria'. Malaria appeared to be an important cause of febrile episodes during both dry and rainy seasons. During the rainy season more than 60% of the children experienced at least one clinical malaria episode, and during the dry season more than 50% of the children experienced at least one clinical attack of malaria. Children receiving chemosuppression had overall fewer clinical malaria attacks, and the effect of the chemosuppression was most pronounced in the dry season, the odds ratio comparing children receiving regular chemosuppression with children receiving presumptive treatment only was estimated to 0.39 (0.25-0.62).

A malaria control trial using insecticide-treated bed nets and targeted chemoprophylaxis in a rural area of The Gambia, west Africa. 1. A review of the epidemiology and control of malaria in The Gambia, west Africa

Malaria was recognized as an important cause of death among early European visitors to The Gambia, but the infection was first studied systematically in the local population only in the 1950s. Studies undertaken in the village of Keneba at that time showed that nearly all children under the age of 5 years had parasitaemia throughout the year. More recent surveys in rural areas of The Gambia have shown much lower levels of parasitaemia, probably as a result of a decline in rainfall in The Gambia during the past 30 years and because of an increase in the availability of anti-malarial drugs. Nevertheless, community surveys and reviews of hospital statistics show that malaria is still one of the most important causes of death among Gambian children; about 1 in 25 rural Gambian children die from malaria before reaching the age of 5 years. Until recently, malaria control in The Gambia relied upon prompt treatment of clinical attacks, first with quinine and more recently with chloroquine, and upon some limited vector control in the capital, Banjul. However, during the past few years, it has been shown that mortality in rural children can be reduced substantially by means of chemoprophylaxis given by village health workers. Bed nets (mosquito nets) are used widely in The Gambia and epidemiological surveys have shown an association between the use of bed nets and protection against malaria. This observation led to a series of small scale intervention trials.(ABSTRACT TRUNCATED AT 250 WORDS)

A malaria control trial using insecticide-treated bed nets and targeted chemoprophylaxis in a rural area of The Gambia, west Africa. 6. The impact of the interventions on mortality and morbidity from malaria

The effects of insecticide-impregnated bed nets on mortality and morbidity from malaria have been investigated during one malaria transmission season in a group of rural Gambian children aged 6 months to 5 years. Sleeping under impregnated nets was associated with an overall reduction in mortality of about 60% in children aged 1-4 years. Mortality was not reduced further by chemoprophylaxis with Maloprim given weekly by village health workers throughout the rainy season. Episodes of fever associated with malaria parasitaemia were reduced by 45% among children who slept under impregnated nets. The addition of chemoprophylaxis provided substantial additional benefit against clinical attacks of malaria; 158 episodes were recorded among 946 children who slept under impregnated nets but who also received chemoprophylaxis. Chemoprophylaxis reduced the prevalence of splenomegaly and parasitaemia at the end of the malaria transmission season by 63% and 83% respectively. Thus, insecticide-impregnated bed nets provided significant protection in children against overall mortality, mortality attributed to malaria, clinical attacks of malaria, and malaria infection. The addition of chemoprophylaxis provided substantial additional protection against clinical attacks of malaria and malaria infection but not against death.

The cost-effectiveness of chemoprophylaxis with Maloprim administered by primary health care workers in preventing death from malaria amongst rural Gambian children aged less than five years old

In recent trials in The Gambia, mass chemoprophylaxis with Maloprim administered over several years by primary health care workers to children aged 3-59 months has reduced both mortality and morbidity without inducing impairment of natural immunity or significant development of drug resistance. Taking expenditure of both time and money, by both public authorities and village volunteers, into account, the costs and the cost effectiveness of such mass chemoprophylaxis are estimated here. The cost per child protected per season was (1990 US) $2.84; the cost per childhood death averted was $143. Both costs compare favourably with those of permethrin bed net impregnation. So in some circumstances where malaria is holoendemic, control of childhood malaria by chemoprophylaxis may be more economically efficient than provision of impregnated bed nets.

Malaria: drug use and the immune response

Malaria is a controllable disease, yet the resources required - human, technical and financial - are massive, and are currently beyond the vast majority of the 96 countries where the disease is endemic. The control measures most widely applied are vector control through spraying or use of insecticide-impregnated bednets, and chemotherapy. The biological problems to add to the resource issues are well known; increasing resistance of anopheline mosquitoes to the most widely used insecticides, and the progressive development of drug resistance in the parasite populations, especiallyPlasmodium falciparum.