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“The only thing necessary for these diseases to the triumph is for good people and governments to do nothing.”

    

AFRICA MALARIA REPORT 2003

http://www.rbm.who.int/amd2003/amr2003/amr_toc.htm

  FORWARD

In October 1998, together with the President of the World Bank and the Administrator of the United Nations Development Programme, we launched Roll Back Malaria as a catalyst for a renewed global commitment to tackle a disease that has been ignored by the world for far too long - a single disease that puts a brake on development, particularly in Africa.

This report from UNICEF and WHO suggests that, in 2003, malaria remains the single biggest cause of death of young children in Africa and one of the most important threats to the health of pregnant women and their newborns. However, there are clear signs that the movement to Roll Back Malaria is having an impact. The combined strategies suggested in 1998 for reducing the burden of malaria (insecticide-treated nets, prompt access to treatment, and prevention of malaria in pregnancy) are now widely accepted; their application on a large scale throughout Africa is under way.

Although coverage of individual interventions, such as insecticide-treated nets, is still far too low, the good news is that there is a clear trend towards increasing coverage, and other encouraging moves - a change in government taxation policies

on nets and netting materials, for example, and the development of Africa-based industrial production of nets - that will help sustain this trend.

Parasite resistance to previously effective low-cost drugs is an enormous and growing problem, but governments are now fully engaged in this challenge, monitoring the development of resistance and energetically pursuing the most promising options for more effective treatment.

The financial resources for fighting malaria are increasing. The establishment of the Global Fund to Fight AIDS, Tuberculosis and Malaria is providing significant new grants to help countries accelerate implementation of their plans to Roll Back Malaria. In addition, funds made available to improve health under debt-relief initiatives are being used to finance malaria interventions in some countries.

Our two organizations remain firmly committed to working together, with our other partners and with Africa, to achieve the ambitious goals for Roll Back Malaria set in Abuja on 25 April 2000 and agreed to by African heads of state. We intend that this report should be the first of a regular series, tracking progress towards achievement of these goals and of the Millennium Development Goal for malaria.

Carol Bellamy
Executive Director
United Nations Children's Fund

Dr Gro Harlem Brundtland
Director-General
World Health Organization

  EXECUTIVE SUMMARY

This report - the first of its kind - takes stock of the malaria situation and of continuing efforts to tackle the disease in Africa; it is based on a review of the best information available to WHO and UNICEF, from sample surveys and routine reports, at the end of 2002.

Malaria continues to be a major impediment to health in Africa south of the Sahara, where it frequently takes its greatest toll on very young children and pregnant women. Because malaria is such a common disease and well known to the people it affects most, and because many of those who become sick with malaria do not visit health care facilities, assessing the size of the problem, and how it is changing over time, is an enormous challenge.

New analyses confirm that malaria is a principal cause of at least one-fifth of all young child deaths in Africa. The latest available data on outpatient visits and on hospital admissions and deaths due to malaria confirm that this disease makes substantial demands on Africa's fragile health infrastructure. In endemic countries, as many as one-third of all clinic visits and at least a quarter of all hospital admissions are for malaria. In some countries, these data suggest that illness due to malaria has increased over the past decade; in others, the size of the problem has remained constant. No country in Africa south of the Sahara for which data are available shows a substantial decline.

Additional information on trends in malaria mortality is available for an increasing number of countries with "demographic surveillance systems". These sources indicate that the number of children dying of malaria rose substantially in eastern and southern Africa during the first half of the past decade compared with the 1980s. In west Africa over the same period there was little change in the overall malaria mortality rate in children.

In summary, the burden of sickness and death due to malaria remained high in Africa south of the Sahara during the 1990s and increased in most countries in the eastern and southern part of the continent. Monitoring systems cannot yet reliably track changes in indicators of the burden of malaria, particularly malaria mortality, on a yearly basis.

The high burden of malaria in Africa, and the increasing burden in some parts of the continent during the 1990s, is not an indication that the intensified efforts to control the disease over the past few years have had no impact. The full impact on malaria sickness and death of the recent efforts to accelerate malaria control described in this report will be measurable only some years after high coverage of interventions is achieved. It is possible that the start of intensified control efforts coincided with increasing malaria mortality, meaning that - without them - the situation might have been substantially worse than is now reported. The strengthening of malaria surveillance and monitoring needs to be given priority in parallel with efforts to control malaria.

The 2000 Summit on Roll Back Malaria, held in Abuja, endorsed a "shortlist" of relatively inexpensive malaria control interventions already available and known to be effective. Partners in the Roll Back Malaria effort, which include governments of malaria-endemic countries, donor governments, international organizations, the private sector, and civil society bodies, have supported the introduction of these interventions.

Insecticide-treated nets (ITNs) are a low-cost and highly effective way of reducing the incidence of malaria in people who sleep under them, and they have been conclusively shown in a series of trials to substantially reduce child mortality in malaria-endemic areas of Africa. By preventing malaria, ITNs reduce the need for treatment and the pressure on health services, which is particularly important in view of the increase in drug-resistant falciparum malaria parasites. Although accurate data from the 1980s are not generally available for comparison, it is certain that there are now more children sleeping under nets and a greater use of ITNs in Africa than ever before. Recent survey data showed that approximately 15% of young children slept under a net, but that only about 2% used nets that were treated with insecticide. Untreated nets provide some protection against malaria, but their full protective benefits can be realized only if they are regularly retreated with insecticide.

The price of nets has fallen substantially as a result of greater demand, increased competition between producers, and reductions in taxes and tariffs and other obstacles to trade that many African countries instituted after the Abuja Summit. In many countries, both nets and the insecticide to treat them can now be purchased in small shops and markets and even on street corners; only a few years ago they would have been available only in a few specialist shops in capital cities. At least five large factories in Africa are now producing nets. Almost all malaria-endemic African countries now have active programmes under way to encourage ITN use, and most of these support a variety of different mechanisms to increase net coverage. Nevertheless, the commercial price of nets and insecticide - though falling - still puts this life-saving technology beyond the reach of the poorest income groups of the population. Major efforts are now being made in at least five African countries to provide subsidized ITNs to the most vulnerable groups - young children and pregnant women. New technological developments promise nets that will retain insecticidal activity for many years, and novel ways of encouraging regular net treatment with insecticide should make it possible to increase the proportion of nets that are effectively treated.

Treated nets and other means of reducing mosquito bites will not totally prevent malaria. People who become ill with the disease need prompt and effective treatment to prevent the development of severe manifestations and death. Since the 1980s, parasite resistance to chloroquine, the most commonly available antimalarial drug, has emerged as a major challenge. In most countries in eastern, central, and southern Africa, chloroquine has lost its clinical effectiveness as a malaria treatment. A similar evolution is taking place, though some years later, in west Africa, and there is indirect, but compelling, evidence that this is giving rise to increasing mortality. Unfortunately, resistance to the most common replacement drug, sulfadoxine-pyrimethamine, has also emerged, especially in eastern and southern Africa.

Over the past few years, 13 countries in Africa have changed their national policies to require the use of more effective antimalarial treatments. Where current monotherapies are failing, WHO recommends artemisinin-based combination therapy (ACT), which is highly efficacious and promises to delay the emergence of resistance. So far however, its use is constrained by high costs and limited operational experience in Africa. To date, four African countries have adopted ACTs as first-line treatment.

Improved management of malaria cases may be undertaken as part of a general strengthening of public health services, for example as part of the strategy for Integrated Management of Childhood Illness (IMCI). However, in many malaria-endemic countries the first treatment for malaria is often purchased from a shop. Data from representative sample surveys indicate that almost half of all children under 5 years of age with fever are treated with an antimalarial drug. Although this is encouraging, some of these treatments may have been with failing drugs or been given too late or in the wrong dosage. Recent studies indicate that home treatment, supported by public information and pre-packaging (as an aid, to ensure that patients take the full treatment course at the right time), can help to reduce malaria mortality in children. Many countries now concentrate on making effective malaria treatment available close to the home, through support to community initiatives and engagement of drug sellers and the pharmaceutical industry. Realizing the full potential of effective treatment as a tool for reducing mortality will require a systems approach, ensuring that effective drugs are affordable (which will often require subsidization) and that they are supported by appropriate education of formal and informal providers as well as mothers, and by quality assurance and regulation.

The impact of malaria on pregnant women and their newborns can be substantially reduced by the recently recommended use of "intermittent preventive treatment" (IPT). This strategy provides at least two treatment doses of an effective antimalarial at routine antenatal clinics to all pregnant women living in areas at risk of endemic falciparum malaria in Africa (irrespective of whether they are actually infected with malaria or not). About two-thirds of pregnant women in Africa south of the Sahara attend clinics for antenatal care, and incorporating IPT for malaria into their routine care should be straightforward. Now an integral part of the "Making Pregnancy Safer" strategy, IPT has been adopted as policy by six countries to replace chemoprophylaxis; most other countries in the region are reviewing their policies in the light of the new recommendation. The beneficial effects of IPT will probably be additive to the proven benefits of ITN use by pregnant women. A comprehensive approach to the prevention and management of malaria during pregnancy therefore calls for a combination of IPT, support for ITN use, and prompt access to effective treatment. Five countries in eastern and southern Africa have recently formed a coalition to reduce the impact of malaria in pregnancy through this combined approach.

Areas on the northern and southern fringes of the malaria-endemic belt of Africa, as well as highland areas in many countries, are at risk of epidemic malaria. Unlike the endemic disease, epidemic malaria typically affects people of all ages and can have high case-fatality. Roll Back Malaria has been supporting efforts to improve the early recognition of, and effective and timely response to, malaria epidemics. Indoor residual spraying can play an important role in malaria vector control, especially in the control of epidemics. Malaria early warning systems have been established in southern Africa to improve outbreak detection and response and are being developed in other epidemic-prone parts of Africa. Fifteen epidemic-prone countries have developed a preparedness plan of action; data on the timeliness and effectiveness of epidemic response in these countries are presented in this report.

Tackling malaria effectively requires substantial resources. At the Abuja Summit it was estimated that at least US$ 1 billion is needed from a combination of increased domestic spending and international assistance; the report provides information on resource flows. Since the launch of Roll Back Malaria in 1998, international spending on malaria has more than doubled to approximately US$ 200 million per year. Further untapped resources for malaria control may become available through debt relief initiatives. Government spending on all health care is low in most African countries - typically less than US$ 15 per person per year - and the costs of malaria control are high: artemisinin-based combination drugs to treat resistant malaria are likely to cost US$ 1-3 per treatment for the drug alone, and ITNs cost around US$ 5. Most of the costs of preventing and treating malaria in Africa today are in fact borne by people themselves. For example, people buy nets, insecticide sprays, and coils, and spend a considerable amount of money on malaria treatment, which may contribute to poverty. Increasing the efficiency of domestic "out of pocket" spending is a priority, and this can be achieved through government support for the most effective interventions and the appropriate regulation to ensure that only safe, effective malaria interventions are sold and that the public is fully informed about their use and effectiveness.

The recently established Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM) is a major new source of grant funding for tackling malaria in Africa. Twenty-five countries and one multi-country group have submitted successful proposals to the GFATM. Almost all of these proposals build on the national malaria control plans developed by these countries with the support of the Roll Back Malaria Partnership during the period 1999-2001. The countries have been awarded a total of US$ 256 million for an initial two years to scale up malaria control activities. Depending on success, it is expected that additional funds will be made available for a total period of five years.

  INTRODUCTION

This report has been drafted in response to a seemingly very simple question: "What do we know about malaria in Africa today?" In the past, the answer to this question would have been, "It depends on whom you ask." Although most experts would have agreed on the fundamental facts, including the relative importance of the disease, its geographical distribution, and the key strategies for prevention and treatment, opinions would have begun to diverge at the next level of detail - dictated by personal experience in the absence of routinely collected and authoritative information on the global malaria situation.

Accurate statistics on malaria in Africa have been difficult to collect and report because of the enormity of the disease problem, the weakness of health information systems, and the fact that treatment of most malaria cases, as well as many deaths from the disease, occurs outside the formal health system. Following the period of international indifference to malaria, there was also little international agreement on what information was needed for monitoring malaria control and how it should be collected. This situation is changing, and there is now a strong consensus on priority indicators and the best way of collecting representative information.

During the 1950s and 1960s, the malaria eradication campaign successfully eliminated or controlled the disease in countries with temperate climates and in some countries where malaria transmission was low or moderate. However, the emergence of drug and insecticide resistance, coupled with concerns about the feasibility and sustainability of tackling malaria in areas with weak infrastructure and high transmission, brought an end to the eradication era, as well as to the bulk of international funding for malaria control and investment in malaria research. Despite international indifference in subsequent years, progress continued to be made in understanding the problem of malaria and strategies for its control. By the early 1990s the international community began to appreciate that the malaria burden was unacceptably high and worsening, particularly in Africa, and that real reductions in malaria mortality and morbidity were possible with existing but under-used tools and strategies.

In 1992, malaria control was re-established as a global health priority by a Conference of Ministers of Health held in Amsterdam. Scientific interest in the disease and its control, political commitment to reducing the burden of malaria, and the financial resources for malaria research and control began to increase rapidly. The project for Accelerated Implementation of Malaria Control (1997-1998) represented an unprecedented contribution to the fight against malaria in Africa south of the Sahara, in terms of both technical support and funds. The funding provided for the project over the two years was estimated to have been more than 12 times the contributions made by WHO during the previous decade.

By the year 2000 a sequence of critical milestones had been achieved and an ambitious global commitment had been realized:

  • 1991-1998: malaria control expertise and capacity were expanded and strengthened, particularly in Africa, especially through the project for Accelerated Implementation of Malaria Control (1997-1998);
  • 1997: new research collaborations, notably the Multilateral Initiative on Malaria (http://mim.nih.gov/), were formed.
  • 1998: the Roll Back Malaria Partnership (www.rbm.who.int/) was launched and consensus on the core technical strategies for tacking malaria established.
  • 2000: the United Nations declared 2001-2010 the Decade to Roll Back Malaria in developing countries, particularly in Africa (United Nations General Assembly, Resolution 55/284).
  • 2000: malaria figured prominently in the United Nations' Millennium Development Goals (General Assembly official records: 27th Special Session: Supplement 3. Document A/S-27/19/Rev.1).
  • 2000: African heads of state met in a historic summit in Abuja, Nigeria, to express their personal commitment to tackling malaria and to establish targets for implementing the technical strategies to Roll Back Malaria.
  • 2001: resources for controlling malaria were significantly boosted with the establishment of the Global Fund to Fight AIDS, Tuberculosis and Malaria.

With the renewed international commitment to fighting malaria, the need for regular and reliable information on the global malaria situation is greater than it has ever been. The general indifference of the past has given way to an urgent demand for information that can be used to define and analyse the malaria situation and measure progress towards the goals established by the international community and by national control programmes. The World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) are committed to meeting this demand.

This report is an initial effort to collect, analyse, and present information on the malaria situation. The report focuses on Africa and specifically on those African countries with the highest burden of the disease. These countries bear more than 90% of the global malaria burden. Emphasis is also given to the technical strategies for malaria control established by the Roll Back Malaria Partnership and the targets set at the Abuja Summit. In addition, with due regard to the importance of understanding the resource requirements of malaria control, a chapter on resource mobilization and financing is included.

The data contained in this report have been drawn from a variety of sources in order to provide the most complete picture of the malaria situation in Africa. The UNICEF Multiple Indicator Cluster Surveys and the and Health Surveys, in particular, are national surveys that represent a major advance in collection of baseline data to provide benchmarks against which progress can be measured. It is fully expected that the recent consensus on core data needs, well coordinated efforts to collect data, and progress in solving methodological and other data collection problems will together fulfil the new demands for malaria information.

The goal of Roll Back Malaria is to halve the burden of malaria by 2010. The following targets for specific intervention strategies were established at the Abuja Malaria Summit, April 2000

RBM strategy

Abuja target (by 2005)

Prompt access to effective treatment

·  60% of those suffering with malaria should have access to and be able to use correct, affordable, and appropriate treatment within 24 hours of the onset of symptoms

Insecticide-treated nets (ITNs)

·  60% of those at risk for malaria, particularly children under 5 years of age and pregnant women, will benefit from a suitable combination of personal and community protective measures, such as ITNs

Prevention and control of malaria in pregnant women

·  60% of pregnant women at risk of malaria will be covered with suitable combinations of personal and community protective measures, such as ITNs

·  60% of pregnant women at risk of malaria will have access to intermittent preventive treatmenta

Malaria epidemic and emergency response

·  60% of epidemics are detected within 2 weeks of onset

·  60% of epidemics are responded to within 2 weeks of detection

a: The original Abuja declaration included the recommendation for chemoprophylaxis as well, but present WHO and RBM policy strongly recommends IPT - and not chemoprophylaxis - for prevention of malaria during pregnancy.

 

On the left is a normal, healthy, red blood cell with a smooth surface. The flexible and deformable disc shape allows it to flow easily through narrow blood capilliaries.

On the right is a similar red blood cell infected for one day with Plasmodium falciparum parasites. It has many knob-like protrusions.

The cell's rapid transformation to a more rigid spherical shape impedes flow through narrow blood capillaries. Additionally the protrusions act like Velcro, causing the infected blood cell to bind to specific receptors such as those on the lining of blood vessels. These adhesions in the brain and the placenta are part of the cause of cerebral and placental malaria.

·  Picture from scanning electron microscope: Lirong Shi, Michael Delannoy, David Sullivan, Johns Hopkins Bloomberg School of Public Health, Malaria Research Institute

 

 

 

     

1. THE BURDEN OF MALARIA IN AFRICA

About 90% of all malaria deaths in the world today occur in Africa south of the Sahara. This is because the majority of infections in Africa are caused by Plasmodium falciparum, the most dangerous of the four human malaria parasites. It is also because the most effective malaria vector - the mosquito Anopheles gambiae - is the most widespread in Africa and the most difficult to control. An estimated one million people in Africa die from malaria each year and most of these are children under 5 years old (1).

Malaria affects the lives of almost all people living in the area of Africa defined by the southern fringes of the Sahara Desert in the north, and a latitude of about 28° in the south. Most people at risk of the disease live in areas of relatively stable malaria transmission - infection is common and occurs with sufficient frequency that some level of immunity develops. A smaller proportion of people live in areas where risk of malaria is more seasonal and less predictable, because of either altitude or rainfall patterns. People living in the peripheral areas north or south of the main endemic area (Figure 1.1) or bordering highland areas are vulnerable to highly seasonal transmission and to malaria epidemics.

In areas of stable malaria transmission, very young children and pregnant women are the population groups at highest risk for malaria morbidity and mortality. Most children experience their first malaria infections during the first year or two of life, when they have not yet acquired adequate clinical immunity - which makes these early years particularly dangerous. Ninety percent of all malaria deaths in Africa occur in young children. Adult women in areas of stable transmission have a high level of immunity, but this is impaired especially in the first pregnancy, with the result that risk of infection increases.

Malaria has been well controlled or eliminated in the five northernmost African countries, Algeria, Egypt, Libyan Arab Jamahiriya, Morocco, and Tunisia. In these countries the disease was caused predominantly by Plasmodium vivax and transmitted by mosquitoes that were much easier to control than those in Africa south of the Sahara. Surveillance efforts continue in most of these countries in order to prevent both a reintroduction of malaria parasites to local mosquito populations, and the introduction of other mosquito species that could transmit malaria more efficiently (a particular risk in southern Egypt). The malaria situation in these countries is not considered further in this report.

Malaria is endemic in some of the offshore islands to the west of mainland Africa - Sao Tome and Principe and Săo Tiago Island of Cape Verde. In the east, malaria is endemic in Madagascar, in the Comoro islands (both the Islamic Federal Republic of the Comoros and the French Territorial Collectivity of Mayotte), and on Pemba and Zanzibar, but has been eliminated from the island of Reunion. In Mauritius, malaria has been well controlled since the 1950s, but occasional outbreaks of vivax malaria occur, the last in association with a cyclone in 1982. Since that year there has been a steady decrease in cases and risk is now extremely low. Seychelles has been free of malaria since 1930, and malaria vectors are believed to no longer exist there.                        

1.1 Burden of malaria on health in Africa

Mortality

There are three principal ways in which malaria can contribute to death in young children (Figure 1.2). First, an overwhelming acute infection, which frequently presents as seizures or coma (cerebral malaria), may kill a child directly and quickly. Second, repeated malaria infections contribute to the development of severe anaemia, which substantially increases the risk of death. Third, low birth weight - frequently the consequence of malaria infection in pregnant women - is the major risk factor for death in the first month of life (3). In addition, repeated malaria infections make young children more susceptible to other common childhood illnesses, such as diarrhoea and respiratory infections, and thus contribute indirectly to mortality (4).

The consensus view of recent studies and reviews is that malaria causes at least 20% of all deaths in children under 5 years of age in Africa (Figures 1.3 and 1.4). Although respiratory disease caused by a variety of infectious agents results in a similar proportion of deaths, P. falciparum is the most important single infectious agent causing death among young children.

Morbidity and long-term disability

Children who survive malaria may suffer long-term consequences of the infection. Repeated episodes of fever and illness reduce appetite and restrict play, social interaction, and educational opportunities, thereby contributing to poor development. An estimated 2% of children who recover from malaria infections affecting the brain (cerebral malaria) suffer from learning impairments and disabilities due to brain damage, including epilepsy and spasticity (5).

1.2 Burden of malaria on African health systems

In all malaria-endemic countries in Africa, 25-40% (average 30%) of all outpatient clinic visits are for malaria (with most diagnosis made clinically). In these same countries, between 20% and 50% of all hospital admissions are a consequence of malaria (see country profiles for details).

With high case-fatality rates due to late presentation, inadequate management, and unavailability or stock-outs of effective drugs, malaria is also a major contributor to deaths among hospital inpatients (Figure 1.5).

This high burden may in fact be partly a result of misdiagnoses, since many facilities lack laboratory capacity and it is often difficult clinically to distinguish malaria from other infectious diseases. Nonetheless, malaria is responsible for a high proportion of public health expenditure on curative treatment, and substantial reductions in malaria incidence would free up available health resources and facilities and health workers' time, to tackle other health problems.

1.3 Burden of malaria on the poor

Poor people are at increased risk both of becoming infected with malaria and of becoming infected more frequently. Child mortality rates are known to be higher in poorer households and malaria is responsible for a substantial proportion of these deaths. In a demographic surveillance system in rural areas of the United Republic of Tanzania, under-5 mortality following acute fever (much of which would be expected to be due to malaria) was 39% higher in the poorest socioeconomic group than in the richest (6).

A survey in Zambia also found a substantially higher prevalence of malaria infection among the poorest population groups (7) (Figure 1.6). Poor families live in dwellings that offer little protection against mosquitoes and are less able to afford insecticide-treated nets. Poor people are also less likely to be able to pay either for effective malaria treatment or for transportation to a health facility capable of treating the disease.

Both direct and indirect costs associated with a malaria episode represent a substantial burden on the poorer households. A study in northern Ghana found that, while the cost of malaria care was just 1% of the income of the rich, it was 34% of the income of poor households (8).

1.4 Recent trends in the burden of malaria

Routine case detection and reporting

Data from health facilities are potentially useful for monitoring time trends in the number of malaria cases and deaths but have severe limitations (Figure 1.7). In Africa, most cases of malaria are diagnosed on the basis of clinical symptoms and treatment is presumptive, rather than based on laboratory confirmation. Moreover, malaria parasitaemia is common among clinic attendees in many endemic areas, so that a positive laboratory result does not necessarily mean that the patient is ill with malaria. The main clinical symptoms of malaria - fever and general weakness - are nonspecific and may well be due to other common infections.

Reporting from facilities to districts and from districts to the ministry of health varies in its completeness and timeliness from country to country and often does not include nongovernment facilities. Thus, routine reports of the number of malaria cases and deaths have limited value for comparisons of the malaria burden between countries. Demographic and health surveys (DHS) and other sources (9) indicate that less than 40% of malaria morbidity and mortality is seen in formal health facilities - a small fraction of the total burden. However, routinely collected data are often the only information available over a prolonged period and over a wide geographical area. While these data are of use for local programme planning, major investment in improving both the quality of health information systems and access to health services would be required before their utility for monitoring changes in malaria disease trends could be assessed.

At present, the most reliable data available on trends in malaria deaths in children under 5 years of age is obtained from demographic surveillance systems (DSS), which measure deaths and possible causes prospectively over time in populations of known size and composition. The number of DSS sites is increasing: 24 sites in 13 African countries are collaborating under the INDEPTH network (International Network of field sites with continuous Demographic Evaluation of Populations and Their Health) (10). Most of these sites are in eastern and southern Africa; there are a few sites in the west of the continent but none in central Africa.

Recently, data from 1982-1998 were analysed across 28 DSS sites, adjusting for the specificity and sensitivity of verbal autopsies that were used to attribute deaths to malaria (11). Malaria mortality in under-5s almost doubled in eastern and southern Africa over the period 1990-1998 compared with 1982-1989. It is known that the prevalence of malaria infections caused by chloroquine-resistant parasites increased substantially from the late 1980s in these same areas (Figure 1.8). Thus, although the methodology cannot prove cause and effect, it is very likely that some of this increase in child mortality was related to some extent to the spread of chloroquine-resistant malaria. In west Africa the mortality rate remained the same; here too, however, malaria became proportionally more important (11). Analysis of mortality data being collected from INDEPTH using standardized verbal autopsy questionnaires since 2000 should soon provide further insight into more recent disease trends.

Throughout Africa south of the Sahara, the decrease in all-cause under-5 mortality that was apparent during the 1970s and 1980s levelled off in the 1990s (Figure 1.9), perhaps partially as a result of increased malaria mortality. Some of the important factors that may have contributed to the increasing malaria burden in these African settings include:

  • drug resistance (12)
  • more frequent exposure of non-immune populations
  • emergence of HIV/AIDS (13, 14)
  • climate and environmental change (15)
  • breakdown of control programmes (16).

1.5 Future prospects

From the time trends shown, it appears that RBM is acting against a background of increasing malaria burden. With the typical 2-3-year delay in national-level data becoming available, it is still too early to evaluate the extent to which RBM has achieved a levelling-off or reversal of the rising trend in the malaria burden. The very low level of coverage with ITNs and untreated nets documented in 2000 and 2001 falls far below the coverage levels in the ITN trials that demonstrated substantial health benefits. It should therefore come as no surprise that significant reductions in child mortality have yet to be observed. The impact of treatment coverage levels is more difficult to estimate, given both a lack of information on promptness and dosage, and varying levels of drug effectiveness. Coverage levels approaching the Abuja target of 60% will probably be required before the full effect of ITNs and effective treatment on child health will become apparent.

References

1. The World Health Report 2002: reducing risks, promoting healthy life. Geneva, World Health Organization, 2002.

2. MARA/ARMA collaboration (Mapping Malaria Risk in Africa), July 2002. www.mara.org.za.

3. Steketee RW et al. The burden of malaria in pregnancy in malaria-endemic areas. American Journal of Tropical Medicine and Hygiene, 2001, 64(1,2 S):28-35.

4. Molineaux L. Malaria and mortality: some epidemiological considerations. Annals of Tropical Medicine and Parasitology, 1997, 91(7):811-825.

5. Murphy SC, Breman JG. Gaps in the childhood malaria burden in Africa: cerebral malaria, neurological sequelae, anemia, respiratory distress, hypoglycemia, and complications of pregnancy. American Journal of Tropical Medicine and Hygiene, 2001, 64(1,2 S):57-67.

6. Mwageni E et al. Household wealth ranking and risks of malaria mortality in rural Tanzania. In: Third MIM Pan-African Conference on Malaria, Arusha, Tanzania, 17-22 November 2002. Bethesda, MD, Multilateral Initiative on Malaria: abstract 12.

7. Report on the Zambia Roll Back Malaria baseline study undertaken in 10 sentinel districts, July to August 2001. Zambia, RBM National Secretariat, 2001.

8. Akazili J. Costs to households of seeking malaria care in the Kassena-Nankana District of Northern Ghana. In: Third MIM Pan-African Conference on Malaria, Arusha, Tanzania, 17-22 November 2002. Bethesda, MD, Multilateral Initiative on Malaria: abstract 473.

9. Breman JG. The ears of the hippopotamus: manifestations, determinants, and estimates of the malaria burden. American Journal of Tropical Medicine and Hygiene, 2001, 64(1,2 S):1-11.

10. Population and health in developing countries. Vol. 1. Population, health and survival at INDEPTH sites. Ottawa, International Development Research Centre, 2002.

11. Korenromp EL et al. Measuring trends in childhood malaria mortality in Africa: a new assessment of progress toward targets based on verbal autopsy. [Lancet Infectious Diseases, conditionally accepted, March 2003].

12. Trape J-F. The public health impact of chloroquine resistance in Africa. American Journal of Tropical Medicine and Hygiene, 2001, 64(1,2 S):12-17.

13. Grimwade K et al. HIV-infection in adults increases rates of severe and fatal falciparum malaria in regions of unstable transmission. In: XIVth International AIDS conference 2002, Barcelona, Spain: abstract ThPeC7604.

14. Nwanyanwu OC et al. Malaria and human immunodeficiency virus infection among male employees of a sugar estate in Malawi. Transactions of the Royal Society of Tropical Medicine and Hygiene, 1997, 91(5):567-569.

15. Mouchet J et al. Evolution of malaria in Africa for the past 40 years: impact of climatic and human factors. Journal of the American Mosquito Control Association, 1998, 14(2):121-130.

16. Sharp B et al. Malaria control by residual insecticide spraying in Chingola and Chililabombwe, Copperbelt Province, Zambia. Tropical Medicine and International Health, 2002, 7(9):732-736.

17. The World Health Report 2001. Mental health: new understanding, new hope. Geneva, World Health Organization, 2001.

 

2. INSECTICIDE-TREATED NETS

Before the development of insecticide-treated nets (ITNs) as a new technology in the mid-1980s, people in many countries were already using nets, mainly to protect themselves against biting insects and for cultural reasons (1-3). It was only recently appreciated that a net treated with insecticide offers much greater protection against malaria: not only does the net act as a barrier to prevent mosquitoes biting, but also the insecticide repels, inhibits, or kills any mosquitoes attracted to feed. Thus ITNs provide protection both to individuals sleeping under them and to other community members. The effect is so significant that use of ITNs is considered to be one of the most effective prevention measures for malaria.

2.1 Evidence

Randomized controlled trials in African settings of different transmission intensities have shown that ITNs can reduce the number of under-5 deaths by around one-fifth (5), saving about 6 lives for every 1000 children aged 1-59 months protected each year (Figure 2.1). The incidence of clinical episodes of Plasmodium falciparum infection is reduced by 50% on average. When used by pregnant women, ITNs are also efficacious in reducing maternal anaemia, placental infection, and low birth weight (6).

This may even be an underestimate of the efficacy of ITNs because the impact of reduced mosquito burden extends to households and communities without nets, which reduces the apparent difference between study areas with nets and study areas without nets. The protection afforded to non-users in the vicinity is difficult to quantify, but it appears to extend over several hundred metres. From observed reductions in parasite prevalences, it has recently been estimated that, in the long term, widespread use of ITNs - if regularly retreated - will massively reduce malaria transmission (7), but this effect will become fully apparent only after the usual 2-year duration of a trial.

The ITN trials achieved their impact with close to 100% of households possessing nets and 50-75% of under-5s sleeping under them, a level of use similar to the Abuja target of 60%. Where lower coverage and use rates are achieved, the impact on mortality will be less.

Subsequent programmes have demonstrated the effectiveness of ITNs under field conditions. In a large-scale social marketing programme in two rural districts in the south of the United Republic of Tanzania with high perennial malaria transmission, ITN coverage of infants rose from less than 10% at baseline to more than 50% 3 years later. ITN use was associated with a 27% increase in survival of children aged 1 month to 4 years and a 63% reduction of anaemia in this same age group (evaluated by case-control design) (8).

In the Gambia, the National Impregnated Bednet Programme achieved an 83% net treatment rate and reported 77% of under-5s and 78% of women of childbearing age sleeping under ITNs (9). Overall under-5 mortality fell by 25%, and case-control studies suggested that there were 59% fewer episodes of uncomplicated malaria in ITN users (10, 11).

2.2 Progress: ITN strategy plans

Eighteen of the 40 malaria-endemic countries in Africa with country strategy plans for rolling back malaria have developed strategic plans which include increasing access to ITNs. Twenty-five African countries have successfully applied for funding in the second round of Global Fund applications.

2.3 Progress: taxes and tariffs

The cost of ITNs is a barrier to their widespread use. As one element in reducing prices, the Abuja Declaration committed governments to "reduce or waive taxes and tariffs for nets and materials, insecticides, antimalarial drugs and other recommended goods and services that are needed for malaria control strategies". Eighteen countries have now reduced or eliminated taxes and tariffs (Figure 2.2). Time-limited changes in tax or tariff regimes can be introduced through informal agreements between health and finance ministries, but more permanent arrangements normally require national legislation.

Most countries apply the "Harmonized Commodity Description and Coding System" to classify products introduced by the World Customs Office (12). Under this system, each product is assigned a six-digit code for the purposes of levying tariffs and collecting trade statistics. Nets are currently classified as textiles and customs offices can be reluctant to give exemption for the whole range of products covered by the code. Some countries also subscribe to regional agreements on tariffs and taxation rates, which can influence the adoption of policy change. For example, the West African Economic and Monetary Union requires all of its eight member states to adhere to the Common External Tariff Resolution, which stipulates fixed rates for import duty of 20% and for value-added tax (VAT) of 18%. Clearly, changes in national policy would be greatly facilitated by changes to international agreements.

2.4 Progress: long-lasting insecticidal nets

In response to low re-treatment rates of conventional insecticide-treated nets, especially in Africa, WHO prompted industry to develop long-lasting insecticidal nets (LLINs) - ready-to-use, factory-pretreated nets that require no further treatment during their expected lifespan of 4-5 years. This technology obviates the need for re-treatment (unlike conventional ITNs, LLINs resist washing) and reduces both human exposure (at any given time, most of the insecticide is hidden and not bioavailable) and the risk of environmental contamination.

Using the most recent fibre technologies, LLINs are regarded as a major breakthrough in malaria prevention. One LLIN is already commercially available and is recommended by WHO. At a current price of around US$ 5 per net, LLINs are already more cost-effective than conventionally treated nets. Efforts are being made to scale up production capacity to meet demand, which is already high. The RBM partnership is facilitating technology transfer and stimulating local production of LLINs in Africa (13).

2.5 Progress: coverage

In nine countries surveyed between 1997 and 2001, a median 13% of households possess one or more nets (range 1.1-54%). A median 1.3% (range 0.2-4.9%) of households surveyed in three countries own at least one ITN (14). The proportion of under-5s sleeping under nets is also low - about 15% across 28 countries surveyed. Even fewer children (less than 2%) sleep under ITNs. Only two countries, the Gambia and Sao Tome and Principe, reported ITN use rates of more than 10% (Figure 2.3).

While current rates of coverage are generally low, the availability and use of nets have increased appreciably over the past 10 years, particularly in countries where nets were not normally used. In the United Republic of Tanzania, for example, nets were rare in the 1980s, especially in rural areas, but ownership has increased to 63% in towns and to 29% in rural areas (14). Such trends are encouraging and highlight the progress that is being made.

2.6 Challenges: increasing coverage

Most African households in malaria risk areas do not possess any net, whether treated with insecticide or not. To achieve adequate coverage most countries will require many more nets; to cover all Africans at risk (16), an estimated total of 260 million nets would be needed.

Increasing ITN availability will require large-scale expansion of supply and distribution. Barriers to increasing the supply and distribution of nets and insecticides include taxes and tariffs, regulatory issues, and inadequate distribution systems. Barriers to increasing the demand for nets and insecticides relate to the price, to their affordability for households, and to promotion and marketing.

There is also scope to increase the use of ITNs by providing insecticide treatment for any untreated nets already in houses. Based on the comparative coverage with untreated and treated nets, this could double the percentage of households with ITNs.

Low insecticide re-treatment rates are another challenge. Insecticide for net treatment is still an unfamiliar commodity in Africa. Moreover, people's motivation for using nets is often to reduce mosquito nuisance, not to repel or kill malaria-transmitting mosquitoes. The increasing availability of attractive branded formulations in Africa should stimulate demand for insecticides, and the development of LLINs is another potential solution to the problem of low re-treatment rates.

2.7 Challenges: overcoming disparities in net coverage

A major barrier to net ownership is poverty. The most common reason cited for not possessing a net is lack of money: the price of a net represents a large proportion of the income of a poor household.

2.8 Scaling up

Net possession and use have to increase considerably if the gap between the number of under-5s who would benefit from a net and those who currently sleep under one is to be reduced. The challenge is to find the balance between covering the costs of increasing ITN coverage and stimulating the growth of commercial markets, while ensuring that the poorest and most vulnerable are protected (23).

In most malaria-endemic African countries the public sector does not have the financial or logistic capacity to extend net use to the scale required. Most countries spend only US$ 4 per capita a year on health - the equivalent of the average cost of an untreated net. The Abuja target for expanding ITN use in Africa will therefore require synergy between public and private sector activities.

In providing an enabling environment for scaling-up actions, governments need to focus on the following priorities:

  • Creating demand for ITNs through health information channels and mass media.
  • Providing sustained subsidies targeted to the most vulnerable groups, preferably through a system that uses public channels (e.g. at antenatal clinics) for delivery of subsidies but commercial distribution channels for delivery of the goods.
  • Stimulating and facilitating the development of commercial markets, through tax and tariff reduction and by streamlining the regulation of new insecticide products. Competition between manufacturers and distributors must be promoted to ensure that nets are available to the general population at the lowest possible price.
  • Monitoring insecticide resistance.
  • Possibly, market priming (i.e. the temporary procurement and distribution of ITNs, aimed at strengthening commercial distribution channels) in areas where the demand for nets is too low for manufacturers to make an economical return.

To overcome the challenge of low re-treatment rates, there should be a stronger role for subsidy of insecticide distribution through publicly funded channels. This is the system followed in the world's largest and longest-sustained ITN programmes, namely those in China and Viet Nam (23).



References

1. MacCormack CP, Snow RW. Gambian cultural preferences in the use of insecticide-impregnated bed nets. Journal of Tropical Medicine and Hygiene, 1986, 89(6):295-302.

2. Robert V, Carnevale P. Influence of deltamethrin treatment of bed nets on malaria transmission in the Kou valley, Burkina Faso. Bulletin of the World Health Organization, 1991, 69(6):735-740.

3. Aikins MK, Pickering H, Greenwood BM. Attitudes to malaria, traditional practices and bednets (mosquito nets) as vector control measures: a comparative study in five west African countries. Journal of Tropical Medicine and Hygiene, 1994, 97(2):81-86.

4. The African summit on Roll Back Malaria. Abuja, Nigeria, 25 April 2000. Geneva, World Health Organization, 2000 (document WHO/CDS/RBM/2000.17).

5. Lengeler C. Insecticide-treated bednets and curtains for preventing malaria (Cochrane Review). In: The Cochrane Library, Issue 4. Oxford, Update Software, 2001.

6. Garner P, Gulmezoglu AM. Prevention versus treatment for malaria in pregnant women. In: The Cochrane Library, Issue 2. Oxford, Update Software, 2000.

7. Smith T et al. Effects of insecticide-treated mosquito nets on malaria transmission. In: Third European Congress on Tropical Medicine and International Health, Lisbon, Portugal, 8-11 September 2002.

8. Armstrong Schellenberg JRM et al. Effect of large-scale social marketing of insecticide-treated nets on child survival in rural Tanzania. Lancet, 2001, 357:1241-1247.

9. Cham MK et al. Implementing a nationwide insecticide-impregnated bednet programme in The Gambia. Health Policy Plan, 1996, 11(3):292-298.

10. D'Alessandro U et al. The Gambian National Impregnated Bed Net Programme: evaluation of effectiveness by means of case-control studies. Transactions of the Royal Society of Tropical Medicine and Hygiene, 1997, 91(6):638-642.

11. D'Alessandro U et al. Mortality and morbidity from malaria in Gambian children after introduction of an impregnated bednet programme. Lancet, 1995, 345(8948):479-483.

12. Harmonized Commodity Description And Coding System. http://www.com-law.net/findlaw/customs/hs.htm.

13. Guillet P et al. Long-lasting treated mosquito nets: a breakthrough in malaria prevention. Bulletin of the World Health Organization, 2001, 79(10):998.

14. Demographic and Health Surveys (DHS). Calverton, MD, ORC Macro. http://www.measuredhs.com.

15. Progress Report Regional Procurement Centre, Pretoria, South Africa. New York. United Nations Children's Fund, 2002.

16. MARA/ARMA collaboration (Mapping Malaria Risk in Africa), July 2002. www.mara.org.za.

17. Mission Report on Mass Mosquito Net Impregnation Campaign, Eritrea, 2002. Brazzaville, WHO Regional Office for Africa (document WHO/AFRO/CDS/VBC/2002).

18. Chimumbwa J. A community-based programme in Zambia. 1999. Luapula Community-based malaria prevention and control programme. Presentation at Second International Conference on Insecticide Treated Nets, Dar es Salaam, United Republic of Tanzania, 11-14 October 1999.

19. Guyatt HL, Ochola SA, Snow RW. Too poor to pay: charging for insecticide-treated bednets in highland Kenya. Tropical Medicine and International Health, 2002, 7(10):846-850.

20. Onwujekwe O et al. Hypothetical and actual willingness to pay for insecticide-treated nets in five Nigerian communities. Tropical Medicine and International Health, 2001, 6(7):545-553.

21. Simon JL et al. How will the reduction of tariffs and taxes on insecticide-treated bednets affect household purchases? Bulletin of the World Health Organization, 2002, 80(11):892-899.

22. Hanson K et al. Equity and ITNs in Tanzania: evidence from a social marketing project. Third MIM Pan-African Malaria Conference 2002, Arusha, Tanzania: abstract no.446.

23. Global Partnership to Roll Back Malaria. Scaling-up insecticide-treated netting programmes in Africa. A strategic framework for coordinated national action. Geneva, World Health Organization, 2002 (document WHO/CDS/RBM/2002.43.)

24. Phillips-Howard PA et al. The efficacy of permethrin-treated bednets on child mortality and morbidity in western Kenya. American Journal of Tropical Medicine and Hygiene, 2003 (in press).

3. PROMPT AND EFFECTIVE TREATMENT

Prompt and effective treatment of malaria is a critical element of malaria control (1). In Africa south of the Sahara, where most malaria is due to Plasmodium falciparum and potentially fatal, early and effective treatment could save many lives. It is vital that sufferers, especially children aged under 5 years, start treatment within 24 hours of the onset of symptoms, to prevent progression - often rapid - to severe malaria and death (2).

A strong health system would provide for reliable diagnosis as the basis for optimal treatment. However, in most malaria-endemic areas, access to curative and diagnostic services is limited and drugs are purchased through the private, informal sector (3, 4). Moreover, diagnosis is complicated by the lack of a specific clinical presentation, frequent occurrence of several diseases simultaneously, and - in areas of intense transmission - asymptomatic malaria infections. In high-transmission malaria-endemic areas, WHO therefore recommends that, as part of the strategy of Integrated Management of Childhood Illnesses (IMCI), all under-5s with fever be presumptively treated with antimalarials (5). Community-level interventions to strengthen home management of children with fever are gaining importance as part of efforts to improve access to prompt treatment, particularly in isolated rural areas.

3.1 Evidence

The global consensus that access to prompt, effective treatment should be a key element of the RBM strategy is based on the widespread recognition that untreated falciparum malaria contributes both directly and indirectly to the death of non-immune individuals, sometimes within hours of the onset of symptoms (2). Prompt, effective treatment of malaria and appropriate management of clinical complications will be life-saving.

Uncontrolled studies in Madagascar (7) and the United Republic of Tanzania (8) revealed significant reductions in mortality when research teams provided prompt access to antimalarial treatment. However, these studies took place in circumstances where the obstacles to access that characterize most health systems in endemic countries had been eliminated.

Randomized, controlled trials of treatment of febrile illness with reduction of mortality as the end-point are fraught with methodological and ethical problems and have produced conflicting results. In a widely quoted community-randomized trial in an area of low, seasonal malaria transmission in Ethiopia, under-5 mortality was reduced by 40% as a result of teaching mothers to provide prompt chloroquine treatment for fevers at home (9) (Figure 3.1). However, a general improvement in child care may have contributed to this high level of impact.