Achieving universal testing for malaria

Medical care of populations often treads a fine line between the differing harms of underdiagnosis and overdiagnosis. Underdiagnosis may mean that a disease is advanced by the time it is detected, increasing the risk of death, whereas overdiagnosis leads to healthy people being labelled as sick and treated with drugs that will be of no benefit and may even cause harm. How much underdiagnosis or overdiagnosis can be regarded as “reasonable” is a value judgement and may vary between different stakeholders: consumers, clinicians, or policy makers. It will also vary between diseases and populations and be related to the severity of the illness, the benefits and harms of the treatment, the cost of the treatment, the availability of reliable tests, and the public health effects of the approach taken. Malaria is an interesting case study because the perceived benefits of overdiagnosis (few missed cases), and the potential harms of underdiagnosis (unpredictable progression to severe malaria and death) led to the promotion of substantial overdiagnosis and overtreatment for many years. Up until about 15 years ago, policy makers, including the World Health Organization, promoted a strategy known as “presumptive treatment of malaria” in areas where diagnostic testing (by light microscopy) was unavailable. This strategy recommended that all patients with fever were treated with antimalarials, regardless of the presence or absence of signs of other illnesses, and accepted the substantial overuse of chloroquine because it was cheap and well tolerated. 3 However, the balance has now swung the other way, with policy makers and clinicians increasingly concerned about the clinical, financial, and public health harms associated with overtreatment. The currently recommended firstline antimalarial drugs (artemisinin based combination therapies) are not cheap and malaria prevalence is falling in many countries, raising the relative importance of diagnosing and treating other causes of fever.Consequently, the development of rapid diagnostic tests (RDTs) that can be used in basic healthcare services in remote settings led the WHO to recommend a switch to universal parasitological testing before treatment in 2010. Despite the subsequent rapid scale-up of rapid tests, overtreatment remains a problem. We examine the drivers and examine the potential strategies to overcome these. Why might overtreatment still occur?