1. the Burden of Malaria in Africa
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Chapter 1: The burden of malaria in Africa 1. The burden of malaria in Africa About 90% of all malaria deaths in the world Jamahiriya, Morocco, and Tunisia. In these today occur in Africa south of the Sahara. countries the disease was caused This is because the majority of infections in predominantly by Plasmodium vivax and Africa are caused by Plasmodium falciparum, transmitted by mosquitoes that were much Roll Back the most dangerous of the four human easier to control than those in Africa south Malaria target malaria parasites. It is also because the most of the Sahara. Surveillance efforts continue effective malaria vector – the mosquito in most of these countries in order to prevent Anopheles gambiae – is the most widespread both a reintroduction of malaria parasites to The global target in Africa and the most difficult to control. An local mosquito populations, and the of Roll Back Malaria estimated one million people in Africa die introduction of other mosquito species that is to halve from malaria each year and most of these are could transmit malaria more efficiently (a malaria-associated children under 5 years old (1). particular risk in southern Egypt). The malaria morbidity and situation in these countries is not considered mortality by 2010 Malaria affects the lives of almost all further in this report. compared with levels people living in the area of Africa defined by in year 2000. the southern fringes of the Sahara Desert Malaria is endemic in some of the offshore in the north, and a latitude of about 28° islands to the west of mainland Africa – Sao in the south. Most people at risk of the Tome and Principe and São Tiago Island of disease live in areas of relatively stable Cape Verde. In the east, malaria is endemic in malaria transmission – infection is common Madagascar, in the Comoro islands (both the and occurs with sufficient frequency that Islamic Federal Republic of the Comoros and some level of immunity develops. A smaller the French Territorial Collectivity of Mayotte), 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 Distribution of endemic malaria 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 Endemic malaria particularly dangerous. Ninety percent of all Malaria marginal/ epidemic prone 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 Source: reference 2 countries, Algeria, Egypt, Libyan Arab Figure 1.1 17 The Africa Malaria Report–2003 and on Pemba and Zanzibar, but has been eliminated from the island of Reunion. In Malaria kills children in Mauritius, malaria has been well controlled since the 1950s, but occasional outbreaks of three different ways vivax malaria occur, the last in association with a cyclone in 1982. Since that year there has been a steady decrease in cases Chronic, and risk is now extremely low. Seychelles Infection in Acute febrile repeated has been free of malaria since 1930, pregnancy illness infection and malaria vectors are believed to no longer exist there. Cerebral malaria Low birth weight Severe 1.1 Respiratory distress Preterm delivery anaemia Burden of malaria on Hypoglycaemia health in Africa Mortality There are three principal ways in which Death malaria can contribute to death in young children (Figure 1.2). First, an overwhelming Figure 1.2 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. Most of the malaria burden is Third, low birth weight – frequently the consequence of malaria infection in from deaths in young children pregnant women – is the major risk factor for death in the first month of life (3). In addition, repeated malaria Rest of the world Africa 1000 infections make young children more susceptible to other common childhood 800 illnesses, such as diarrhoea and respiratory infections, and thus contribute indirectly 600 to mortality (4). 400 The consensus view of recent studies and reviews is that malaria causes at least 20% of Deaths (thousands) 200 all deaths in children under 5 years of age in Africa (Figures 1.3 and 1.4). Although 0 respiratory disease caused by a variety of 0–4 5–14 15+ infectious agents results in a similar Age (years) proportion of deaths, P. falciparum is the most important single infectious agent causing death among young children. Although adults also become infected with malaria, Morbidity and long-term disability the illness is usually less severe thanks to their acquired immunity. Infections in young children Children who survive malaria may suffer long-term consequences of the infection. are serious and may kill if not treated promptly. Repeated episodes of fever and illness reduce appetite and restrict play, social Source: WHO Global Burden of Disease project, estimates for 2000, interaction, and educational opportunities, reference 17 thereby contributing to poor development. An estimated 2% of children who recover Figure 1.3 18 Chapter 1: The burden of malaria in Africa from malaria infections affecting the brain (cerebral malaria) suffer from learning impairments and disabilities due to brain damage, including epilepsy and spasticity (5). Under-five all cause mortality 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 Per 1000 children under-five malaria (see country profiles for details). With high case-fatality rates due to late 19–79 80–126 presentation, inadequate management, 127–165 and unavailability or stock-outs of effective 166–211 drugs, malaria is also a major contributor 212–316 to deaths among hospital inpatients No data (Figure 1.5). This high burden may in fact be partly a Source: UNICEF, State of the World's Children, 2003 result of misdiagnoses, since many facilities lack laboratory capacity and it is often difficult clinically to distinguish malaria from Figure 1.4 other infectious diseases. Nonetheless, malaria is responsible for a high proportion of public health expenditure on curative treatment, and Malaria burden on health facilities substantial reductions in malaria incidence Under-five All ages would free up available health resources and facilities and health workers’ time, to tackle 50 % of outpatient visits due to malaria other health problems. 40 30 20 10 1.3 0 Western Africa Central/Eastern Africa Southern Africa Burden of malaria on the poor % of hospital admissions due to malaria Poor people are at increased risk both of 50 becoming infected with malaria and of 40 becoming infected more frequently. Child 30 mortality rates are known to be higher in 20 10 poorer households and malaria is responsible 0 for a substantial proportion of these deaths. Western Africa Central/Eastern Africa Southern Africa In a demographic surveillance system in rural areas of the United Republic of Tanzania, 50 % of hospital deaths due to malaria under-5 mortality following acute fever 40 (much of which would be expected 30 to be due to malaria) was 39% higher in the 20 poorest socioeconomic group than in 10 0 the richest (6). Western Africa Central/Eastern Africa Southern Africa A survey in Zambia also found a substantially higher prevalence of malaria Source: AFRO routine Health Information System data. Averages 1998–2001. infection among the poorest population Error bars give the standard errors. Figure 1.5 19 The Africa Malaria Report – 2003 Parasite prevalence is higher in poor children 80 The prevalence of malaria infection 60 was higher in under-fives from 40 poorer families in 10 districts % under-fives infected % under-fives 20 suveyed in Zambia. 0 Poorest Second Middle Fourth Richest Wealth quintile Source: reference 7 Figure 1.6 groups (7) (Figure 1.6). Poor families live in weakness – are nonspecific and may well be dwellings that offer little protection against due to other common infections. mosquitoes and are less able to afford Reporting from facilities to districts and insecticide-treated nets. Poor people are also from districts to the ministry of health varies less likely to be able to pay either for in its completeness and timeliness from effective malaria treatment or for country to country and often does not transportation to a health facility capable of include nongovernment facilities. Thus, treating the disease. routine reports of the number of malaria Both direct and indirect costs associated cases and deaths have limited value for with a malaria episode represent a substantial comparisons of the malaria burden between burden on the poorer households. A study in countries. Demographic and health surveys northern Ghana found that, while the cost of (DHS) and other sources (9) indicate that less malaria care was just 1% of the income than 40% of malaria morbidity and mortality of the rich, it was 34% of the income of is seen in formal health facilities – a small poor households (8).