Malaria

Summary

Malaria is defined as an acute febrile illness with parasitaemia (presence of parasites in the blood), although this may not be detectable, depending upon local capability for parasitologic confirmation. Four species of protozoal plasmodia: Plasmodium falciparum; P. vivax; P. ovale; and P. malariae can cause human malaria, transmitted by the female Anopheles mosquito when biting for a blood meal. The clinical features of uncomplicated malaria, i.e. fever, diarrhoea, headache, generalized aching and vomiting are non-specific and describe the symptoms of a variety of febrile illnesses prevalent in malaria-endemic areas.

Overview

Over 40% of the world's population from more than 90 countries lives with the risk of malaria. The World Health Organization (WHO) estimates that there are over 300 million clinical cases of malaria each year, resulting in the deaths of over 1 million people, 90% of whom are children under 5 years in sub-Saharan Africa. An estimated 3 million children are admitted to hospital with malaria each year in endemic regions of sub-Saharan Africa, although this represents only a minority of clinical cases, as more than 80% of patients have no contact with formal health services. Many deaths from malaria occur at home, making the establishment of reliable health statistics difficult.

In endemic areas, almost every child is infected with the malaria parasite but most carry it asymptomatically. Approximately 1–2% of clinical infections result in severe disease, which is characterized by the presence of life-threatening complications, operationally defined as any malaria syndrome associated with high mortality (>5%) despite appropriate hospital treatment (Newton & Krishna, 1998).