Prognostic significance of rises in parasitaemia during treatment of falciparum malaria.

Transient rises in parasitaemia occur commonly during the treatment of falciparum malaria but their prognostic significance has not been well defined. Twelve-hourly parasite counts from 133 malaria patients who were ultimately cured were therefore compared with counts from 97 therapeutic failures to determine if increase in parasitaemia was a useful early indicator of poor treatment response. Parasitaemia in both groups frequently rose during the initial 12 h of therapy (41% of all patients), but rising counts thereafter were rarer in treatment successes (P < 0.01). The relative risk of treatment failure was 3.8 if the count was higher at 24 h than 12 h, rose to 7.8 for increases at 48-60 h, and was 13.7 and 19.4 for counts above admission levels at 48 h and 60 h. These data suggest a way to identify patients at high risk of treatment failure.