The in vivo response of Plasmodium falciparum to the WHO single test dose (10 mg/kg body weight) of chloroquine base was examined in Ethiopia at four localities where malaria was meso- or hyperendemic. Parasitemias cleared by the 3rd day after chloroquine administration in all of the 150 test subjects. No recrudescences were detected during the 6-day or 11-day follow-up periods. The value of the in vivo test was severely limited by the inability to quarantine subjects and follow them for the 28-day period recommended by the World Health Organization.
Mailing address: U.S. Naval Medical Research Unit No. 5, APO New York 09319.