Quinine in severe falciparum malaria: evidence of declining efficacy in Thailand.

Between 1981 and 1992, 196 Thai adults with severe falciparum malaria were treated with a quinine loading dose regimen. Nineteen patients died (10%) and 6 developed late hypoglycaemia. There was no serious cardiovascular or nervous system toxicity. Although there was no evidence of high grade resistance, and no change in the mortality rate, in recent years an increasing proportion of patients had a delayed clinical and parasitological response to treatment. Since 1988, 78% (29/37) of patients with cerebral malaria were unconscious for > 72 h compared with 41% (11/27) between 1981 and 1987 (P = 0.002). In the past 2 years parasite clearance times have exceeded 96 h in 33% (26/78) of patients compared with 14% (15/102) previously (P = 0.006). Quinine remains an effective treatment for severe multi-drug resistant falciparum malaria in this area, but there is now evidence of a decline in the immediate therapeutic response, and its efficacy will need close monitoring as resistance increases further.