The Rising Incidence of Serious Chloroquine Overdose in Harare, Zimbabwe: Emergency Department Surveillance in the Developing World

INTRODUCTION Between 200 and 400 million cases of malaria occur in the world each year. Due to the prevalence of malaria and the scarcity of healthcare services, the governments of many developing countries make chloroquine freely available to their citizens at local shops without prescription. Doses of as little as 3 g of chloroquine (i.e., 20 tablets of 150 mg) have been fatall-'. Chloroquine has a direct negative inotropic effect on cardiac muscle, slows intraventricular conduction and is a vasodilator. With substantial overdose, patients may experience cardiovascular collapse, arrhythmias, convulsions, coma and respiratory distress'r', Previously reported mortality rates for substantial chloroquine overdose vary widely 10 of 11 (91%) died in one group of severely poisoned patients treated without epinephrine and diazepam; only one of 11 (9%) died in a similar group treated with epinephrine and diazepam'. In two other studies, mortality rates of 21% (6 of 29) and 21% (10 of 47) have been reported':", From 1980-1989, chloroquine overdose constituted 5% of the therapeutic drug overdoses at six referral hospitals in urban Zimbabwe", The Zimbabwean Government laboratory performs analyses of clinical specimens from suspicious overdoses being investigated by the police for any evidence of murder. In reviewing government laboratory records we found that since 1986 the Zimbabwean Government laboratory has reported a marked increase in the number of positive chloroquine analyses performed (from 8 in 1986 to 100 in 1994). It was unclear if this increase was due to a rising incidence of chloroquine poisoning, a higher detection rate, or both.