Ensuring quality and access for malaria diagnosis: how can it be achieved?

To study the diagnosis and outcomes in people admitted to hospital with a diagnosis of severe malaria in areas with differing intensities of malaria transmission. Prospective observational study of children and adults over the course a year. 10 hospitals in north east Tanzania. 17,313 patients were admitted to hospital; of these 4474 (2851 children aged under 5 years) fulfilled criteria for severe disease. Details of the treatment given and outcome. Altitudes of residence (a proxy for transmission intensity) measured with a global positioning system. Blood film microscopy showed that 2062 (46.1%) of people treated for malaria had Plasmodium falciparum (slide positive). The proportion of slide positive cases fell with increasing age and increasing altitude of residence. Among 1086 patients aged > or = 5 years who lived above 600 metres, only 338 (31.1%) were slide positive, while in children < 5 years living in areas of intense transmission (< 600 metres) most (958/1392, 68.8%) were slide positive. Among 2375 people who were slide negative, 1571 (66.1%) were not treated with antibiotics and of those, 120 (7.6%) died. The case fatality in slide negative patients was higher (292/2412, 12.1%) than for slide positive patients (142/2062, 6.9%) (P < 0.001). Respiratory distress and altered consciousness were the strongest predictors of mortality in slide positive and slide negative patients and in adults as well as children. In Tanzania, malaria is commonly overdiagnosed in people presenting with severe febrile illness, especially in those living in areas with low to moderate transmission and in adults. This is associated with a failure to treat alternative causes of severe infection. Diagnosis needs to be improved and syndromic treatment considered. Routine hospital data may overestimate mortality from malaria by over twofold.

Many attempts have been made to quantify Africa's malaria burden but none has addressed how urbanization will affect disease transmission and outcome, and therefore mortality and morbidity estimates. In 2003, 39% of Africa's 850 million people lived in urban settings; by 2030, 54% of Africans are expected to do so. We present the results of a series of entomological, parasitological and behavioural meta-analyses of studies that have investigated the effect of urbanization on malaria in Africa. We describe the effect of urbanization on both the impact of malaria transmission and the concomitant improvements in access to preventative and curative measures. Using these data, we have recalculated estimates of populations at risk of malaria and the resulting mortality. We find there were 1,068,505 malaria deaths in Africa in 2000 - a modest 6.7% reduction over previous iterations. The public-health implications of these findings and revised estimates are discussed.

Effective and affordable treatment is recommended for all cases of malaria within 24 h of the onset of illness. Most cases of "malaria" (ie, fever) are self-diagnosed and most treatments, and deaths, occur at home. The most ethical and cost-effective policy is to ensure that newer drug combinations are only used for true cases of malaria. Although it is cost effective to improve the accuracy of malaria diagnosis, simple, accurate, and inexpensive methods are not widely available, particularly in poor communities where they are most needed. In a recent study in Uganda, Karin Kallander and colleagues emphasise the difficulty in making a presumptive diagnosis of malaria, and highlight the urgent need for improved diagnostic tools that can be used at community and primary-care level, especially in poorer populations (Acta Trop 2004; 90: 211-14). WHERE NEXT? Health systems need strengthening at referral and community level, so that rapid accurate diagnosis and effective treatment is available for those who are least able to withstand the consequences of illness. Indirect evidence strongly suggests that misdiagnosis of malaria contributes to a vicious cycle of increasing ill-health and deepening poverty. Much better direct evidence is needed about why and how misdiagnosis affects the poor and vulnerable.