Severe Malaria: To Exchange or Not?
June 15, 1998
Severe Malaria: To Exchange or Not?
ABSTRACT & COMMENTARY
Synopsis: The mortality rate in children with high level parasitemia due to Plasmodium falciparum who were treated with chemotherapy but without exchange transfusion was only 1.8%.
Source: Mordmuller B, Kremsner PG. Hyperparasitemia and blood exchange transfusion for treatment of children wiht falciparum malaria. Clin Infect Dis 1998;26:850-852.
Current recommendations for the management of severe malaria with high levels of Plasmodium falciparum parasitemia include the use of exchange transfusion. Mordmuller and Kremsner, working at the Albert Schweitzer Hospital in Lambarene, Gabon, treated 113 consecutive children with greater than 10% parasitized erythrocytes with chemotherapy alone. Although some received transfusions (38 patients received a mean of 200 mL blood) for severe anemia, none underwent exchange.
The children were treated with either quinine alone or quinine with clindamycin. Twelve patients received diazepam because of seizure activity, and 12 were treated for hypoglycemia. Only two (1.8%) of the children died, although seven responders were lost to subsequent follow-up. Recrudescent parasitemia was observed in nine initial responders. The responders included a child with 81% parasitemia.
COMMENT BY STAN DERESINSKI, MD, FACP
Although no randomized clinical trial data are available, multiple authors have recommended exchange transfusion for severe P. falciparum malaria. For instance, as pointed out in an accompanying editorial comment, it is stated in a 1996 review that: "Exchange transfusion should be performed if there are adequate facilities, the patient is seriously ill, and the parasitemia exceeds 15%. Exchange should still be considered with parasitemia in the range of 5 to 15%, if there are other signs of poor prognosis." (White NJ. The treatment of malaria. N Engl J Med 1996;335:800-806). Poor prognostic signs include hypoglycemia, respiratory distress, repeated seizures, and coma.
The low mortality rate reported in the paper reviewed here do not appear to provide much room for improvement in survival as a result of the addition to chemotherapy of exchange transfusion, a procedure that is not risk-free. A number of authors have previously questioned the rationale for exchange, given that the major trigger of end organ damage in P. falciparum malaria is believed to be the schizonts sequestered within capillaries as a result of their adherence to endothelial cells at this location. Thus, the large number of circulating ring forms of the parasite that may potentially be removed by exchange are not the main problem. Instead, the less accessible schizonts are.
This report throws into question current recommendations for exchange transfusion in patients with severe malaria due to P. falciparum. If the low mortality rate reported here without exchange has become the new standard, any randomized trial of exchange would have to enroll an enormous, probably infeasible, number of patients in order to have sufficient power to have a chance of demonstrating an improved outcome.
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