A LARGE-SCALE FIELD TRIAL WITH DICHLORVOS AS A RESIDUAL FUMIGANT INSECTICIDE IN NORTHERN NIGERIA.

An extended field trial with dichlorvos was carried out in the Kankiya District of Northern Nigeria during 1963. Two types of dispenser were used-the dichlorvos-impregnated-montan-wax type and the liquid-dichlorvos type. The objective of the trial was to see if dichlorvos would interrupt the transmission of malaria under local conditions when used at a dosage of one dispenser per 15 m(3) of living space. On the basis of epidemiological findings-both parasitological and entomological-it was found that, owing to excessive ventilation in the huts treated, an adequate concentration of dichlorvos was not maintained, and transmission continued uninterrupted.