Anaemia of Plasmodiumfalciparum malaria RODNEY E. PHILLIPS GEOFFREY PASVOL Malaria remains a disease of major health and economic importance in many parts of the world. Unfortunately, estimates of mortality and morbidity caused by the disease are incomplete, largely because of the difficulty in attributing death or illness to malaria in a population where multiple pathology is common, and where a large proportion may harbour malarial parasites and yet remain asymptomatic. As a result, estimates that there are over 250 million clinical cases of malaria worldwide each year, and that over 1 million children die of the disease each year in Africa may well be inaccurate. Mortality from malaria is largely due to Plasmodium [alciparum and therefore the anaemia caused by this parasite will dominate the discussion . THE IMPORTANCE OF THE ANAEMIA OF MALARIA The clinical manifestations of malaria vary from a mild flu-like illness to unrousable coma. In cerebral malaria, which is often heralded by convulsions, there is a rapid deterioration in conscious level, leading to coma. Such a clinical presentation is reasonably characteristic, although it can be mimicked by meningoencephalitis, drug overdose and head injury. However, other manifestations of severe malaria, such as anaemia, are less drainatic, and, while severe anaemia may be recognized clinically, it is not often ascribed to malaria. In many cases, by the time the patient has developed anaemia the peripheral parasitaemia may be scanty, and in some cases absent. Moreover. the clinical picture may be complicated when cardiac failure supervenes. For example we have observed a number of children in Africa, who have died shortly after admission to hospital, in whom a clinical diagnosis of 'pneumonia' has been made but in whom haemoglobin estimation and a blood film have indicated that malarial anaemia leading to cardiac failure was a far more likely cause of death. These anecdotal observations require confirmation but emphasise the potential for misdiagnosis of malarial anaemia. Mortality There is little formal documentation of the lethal potential of acute malarial Bailliere 's Clinical Haematology-« Vol. 5,No. 2. April 1992 ISBN (}-702(}-1627--6


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anaemia. In this context it is probably useful to quote figures from the Garki project in northern Nigeria where antimalarial measures, which consisted of mass drug administration, spraying with insecticide and the use of larvicide, resulted in an infant mortality rate of 55 per 1000 per year in the protected villages as compared with a rate of 135 per 1000 per year in the unprotected villages (a reduction of about 60%). In the 1-4 year age group, the mortality rate was also reduced by 60% (from 154 to 61 per 1000 per year) (Molineaux and Gramiccia, 1980). Whilst these figures are dramatic, they unfortunately do not indicate the reduction due to the prevention of malarial anaemia. Anaemia in malarial areas is often multifactorial, with the different causes interacting in a vicious cycle of nutritional deficiencies, including those of iron and folate, infections such as pneumonia and gastroenteritis, and inherited red cell disorders. A severe attack of malaria may itself prove fatal and anaemia may be the principal cause of death. Statistics from Nigeria (Bruce-Chwatt, 1952) and the Gambia (Greenwood et al, 1987) emphasize the importance of malaria as a cause of childhood mortality, but neither specify the relative role of malarial anaemia. Malaria as a cause of death was found in 9.9% of all autopsies in children under 15 years old between 1933 and 1950 in Lagos, Nigeria (Bruce-Chwatt, 1952). In Uganda, 16% of deaths in infants were attributed to malarial anaemia (Davies, 1948). Severe falciparum malaria in patients of all ages is frequently accompanied by a life-threatening fall in haematocrit which necessitates treatment with transfusion (Phillips et al, 1986; Warrell et al, 1990). In children, the cause of death during an attack of malaria is often unclear, although anaemia is almost invariably present (Molyneux et al, 1989). Although falciparum malaria is recognized as an important cause of death in endemic areas, the contribution of anaemia to malaria mortality has not as yet been fully assessed. Morbidity Morbidity caused by malarial anaemia is considerable. In the Gambia many children aged 1-4 years had anaemia which was primarily associated with malaria parasitaemia (McGregor et al, 1966; Greenwood et al, 1987). The association of asexual parasitaemia, a fall in haemoglobin (Hb) coincident with the rainy season, and the lower Hb levels observed in children with splenic enlargement, implicate malaria as an important cause of anaemia in this part of the world. In our continuing study of severe malaria in children at Kilifi on the coast of Kenya, 109 (25%) of the 452 paediatric patients admitted to the ward with the primary diagnosis of falciparum malaria had an Hb of less than 50 gil. Only 52 (12%) patients had case-definition cerebral malaria (unrousable coma with peripheral parasitaemia in which other causes of coma have been excluded). Thus in east Africa there were twice as many admissions with malarial anaemia compared with cerebral malaria. In contrast, in a study of 650 children with severe malaria in west Africa in the Gambia, 66% had cerebral malaria and the rest had severe malarial anaemia (Hb

Anaemia of Plasmodium falciparum malaria.

The pathophysiology of the anaemia of falciparum malaria is both complex and multifactorial, and results in a condition which is a major cause of mort...
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