Blackwater Fever is caused by rapid breakdown of red blood cells (acute intravascular haemolysis), with resulting kidney failure as the breakdown products block the vessels serving the kidney filtration units (see KIDNEYS).

The complication is frequently fatal, being associated with JAUNDICE, fever, vomiting and severe ANAEMIA. In an extreme case the patient's urine appears black. Tender enlarged liver and spleen are usually present. The disease is triggered by quinine usage at less than recommended dosage in the presence of P. falciparum infection, especially in the non-immune individual. Now that quinine is rarely used for prevention of this infection (it is reserved for treatment), Blackwater fever has become very unusual. Treatment is as for severe complicated P. falciparum infection with renal impairment; dialysis and blood transfusion are usually indicated. When inadequately treated, the mortality rate may be over 40 per cent but, with satisfactory intensive therapy, this should be reduced substantially.