Severe malaria 11/8/04. By Caroline Cross Severe malaria, the life-threatening form of the disease, is always caused by Plasmodium falciparum.

It can develop from uncomplicated malaria in a few hours, especially if the malaria has not been properly treated or is caused by a drug-resistant parasite. People who develop severe malaria tend to be those with low levels of immunity to malaria, which usually means those who have not been exposed to repeated episodes of the disease. Groups most at risk include young African children, adults from areas such as South-east Asia and South America - where the transmission of malaria is less intense than in much of Africa - and Western tourists visiting any malarious region.

African children with severe malaria suffer from four main complications: coma (cerebral malaria), severe breathing difficulties (respiratory distress), dangerously low blood sugar (hypoglycaemia) and dangerously low blood haemoglobin (severe anaemia). Even with good hospital treatment, up to 20 per cent of these children will die.

Severe malaria in adults is similar to that in African children in some ways but different in others. Adults can also go into coma (cerebral malaria), and develop hypoglycaemia or severe anaemia. In contrast to children, adults can also develop as major common complications sudden loss of kidney function (acute renal failure) and severe breathing difficulties different from the respiratory distress of children but equally serious (pulmonary oedema). Of all hospitalised adults with severe malaria, up to 20 per cent die.