AFRICA MALARIA REPORT 2003
Contents

Some 110 million Africans live in areas at risk for epidemic malaria (Figure 5.1). The increasing frequency of epidemics in both low-risk areas and areas of moderate transmission make imperative the institution of special responses to epidemics, in addition to regular malaria control activities. The impact of epidemics can be greatly reduced by timely detection or, ideally, prediction and prevention. Timely response may include the deployment of additional drug stocks, use of different drugs, and vector control.

5.1 Magnitude of the problem

Devastating malaria epidemics have recently been reported from Botswana, Mozambique, South Africa, Swaziland and Zimbabwe (Figure 5.2) and have been attributed mainly to heavy rainfall following a drought. Epidemics also affected several Sahelian countries in the 1990s.

In East Africa and the Great Lakes region, Burundi, Ethiopia, Kenya, Uganda, and the United Republic of Tanzania, are subject to frequent and recurrent malaria epidemics that often affect large numbers of people (Table 5.1). Anomalies of rainfall and/or temperature are thought to be the most important causes of the epidemics here.

Although the extent of suffering caused by malaria epidemics is not adequately documented, it is generally believed that morbidity, mortality, and the overall economic impact of these epidemics are enormous. For example, the number of deaths during the malaria epidemic that hit Ethiopia in 1958 was estimated at more than 150 000 out of 3 million clinical cases (a case-fatality rate of 5%) (1). Adults account for a relatively large proportion of epidemic cases and deaths.

On the basis of the following assumptions (4) it is estimated that there are 110 000 deaths from epidemics each year:

• 110 million Africans are at epidemic risk
• Epidemics occur on average every 5 years (cyclical) (5)
• Assuming 0.5 malaria episodes per person during epidemics:
  • 0.1 episodes per person at risk per year
  • 11 million malaria episodes in epidemics each year
• Up to 5% of malaria episodes are severe, with case-fatality rate for severe episodes in epidemics possibly up to 20%:
  • possible 110 000 malaria deaths from epidemics each year.

5.2 Prevention and control of epidemics

The main functions of a malaria control programme in combating epidemics are illustrated in Figure 5.3 and described in greater detail in several WHO documents (1).

The burden of an epidemic will be much less if the number of cases is contained by early detection and rapid response (1) (Figure 5.4).

Antimalarial treatment during epidemics

It may be necessary to formulate drug policies for treatment during epidemics, because malaria epidemics usually involve non-immune patients who have lower spontaneous parasite clearance than partially immune patients from endemic areas. It is essential that treatments selected for use in these situations are highly effective. The trend is toward artemisinin-based combinations (ACT) which have the added advantage of reducing gametocyte carriage. Some countries, e.g. Burundi, Ethiopia, and Mozambique, have already adopted special drug policies for epidemics.

5.3 Progress and challenges

Identification of risk areas

Table 5.2 shows 15 of the 25 African countries which have identified their areas of risk and have prepared plans to respond to epidemics.

Actual detection and response

It is difficult to say with certainty whether countries are close to the Abuja target of 60% adequate detection and response. Evaluation is hampered by the diverse nature of epidemics and associated definition issues.

In evaluations of control programmes, timely detection has been found to be a bigger challenge than adequate and timely response once an epidemic has been identified (7). (Table 5.3) However, there is indication that response, especially with measures like indoor residual spraying, is often too slow (more than 2 weeks after detection of the epidemic) as well.

Integrated Disease Surveillance

A recently initiated programme on Integrated Disease Surveillance and Response, promoted by WHO/AFRO, is helping epidemiologists to select and use accurate indicators - initially on a monthly basis. In defined epidemic-prone districts, the second step is to collect weekly malaria morbidity and mortality data in order to detect any unusual increase occurring within 2 weeks and to take immediate action. This programme has considerable potential for rapidly improving the capacity for early detection of epidemics of malaria and other diseases; its implementation is making good progress across the continent (Table 5.4).

Complex emergencies

A large proportion of malaria deaths in Africa occur among populations affected by conflicts. Population displacement, malnutrition, and breakdown of health systems characterize these conflicts, making victims highly vulnerable to disease. Given the large numbers of cases occurring within short periods of time, and the consequent heavy burden on the health system, malaria epidemics in complex emergencies might be considered as "man-made epidemics".

International organizations are the main providers of relief assistance - in the first instance, emergency shelters, clean water, and food - to displaced populations, then basic health care.

A main requirement in complex emergencies is coordination of the activities of different NGOs to streamline the technical approaches for malaria-specific interventions (cost-effective drugs, ITNs, and residual spraying) and to ensure that existing resources are used cost-effectively, within a context of basic health care.

Other activities supported by WHO and other RBM partners include:

• producing and distributing an emergencies handbook;
• operational research into emergency management, including suitable drug regimens;
• increasing capacity on the ground, including training;
• stimulating the development of tools, such as insecticide-impregnated sheet shelters and blankets.

5.4 Strategies for the future

A key challenge for district and national health managers is to improve the use of data routinely generated at the peripheral level, using Integrated Disease Surveillance where appropriate. In areas affected by epidemics related to anomalies in seasonal rainfall and temperature, joint MoH/meteorological services teams should be set up to promote the use of local epidemic predictions. Similar coordination mechanisms may need to be established among appropriate government services in areas that are affected by epidemics linked to, for instance, migration or agricultural practices.

Control options are as important as prediction and early detection; they must be well defined and agreed upon in advance by the MoH and partners of malaria control programmes as part of a preparedness plan of action allowing for rapid and cost-effective deployment. Treatment options may need to include new and more effective drugs or drug combinations (such as ACT) to be supplied free of charge to all malaria patients in the early stage of an epidemic. As regards efficient vector control approaches, the controversy surrounding the choice of insecticides for IRS needs to be resolved. Logistic support capacity should be strengthened in countries considering the use of IRS for early response or prevention. In epidemic-prone areas, all strategies to increase the coverage with ITNs to a level that reduces transmission are relevant to epidemic prevention.

Broad agreement on the choice of efficient prevention and control options will contribute to securing funds from RBM partners in advance of the epidemic season, particularly for the establishment of essential emergency stocks. In this context, collaboration in epidemic risk assessment and response with other epidemic-prone countries by managing subregional/cross-border surveillance systems and emergency stocks is vital. The participation of NGOs in national and international partnerships is particularly important, because these groups can rapidly deploy assistance at field level.

References

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

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

4. Worrall E. The burden of malaria epidemics and cost-effectiveness in epidemic situations. In: Third MIM Pan-African Conference on Malaria, Arusha, Tanzania, 17-22 November 2002, pre-MIM meeting/workshop, "The intolerable burden of malaria: what's new, what's needed". Bethesda, MD, Multilateral Initiative on Malaria: Annex II, p. 367, number 12.

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