Experience with mass drug administration as a supplementary attack measure in areas of vivax malaria.

Mass drug administration was introduced in Syria to supplement DDT spraying after the main malaria vector Anopheles sacharovi had developed considerable resistance to the insecticide. Mass administration of weekly doses of chloroquine and pyrimethamine was carried out in the Ghab area from August to October, the coverage obtained being over 80% for most of the time. The number of cases with positive blood films declined rapidly from August onwards. Entomological observations showed that the house-resting density decreased shortly after the second round of DDT spraying but soon regained its previous level. Some relapsing cases were detected in 1969 but none were found in 1970, and it is considered that the possibility of relapses should not deter authorities from using mass drug administration in emergency situations.