Educational campaign versus malathion spraying for the control of Aedes aegypti in Colima, Mexico

To evaluate the effect of an educational campaign for reducing the breeding places of Aedes aegypti, the principal vector of dengue; and to compare its effects with the ones obtained by spraying of malathion at ultralow volume.

Randomised community trial.

Colima city, in the State of Colima, Mexico.

Householders of 187 houses, randomly selected from the west sector of the city.

In each house, an entomological survey was done, as well as one for knowledge, attitude and practices (KAP), before the intervention and six months after. The intervention consisted of educational campaign alone (47 houses); malathion spraying at ultra low volume alone (46 houses); both treatments simultaneously (49 houses) and no intervention, or control group (45 houses).

The global average of the positive containers by house (C+/C) was reduced from 0.97 to 0.77. A two way analysis of variance showed that this reduction was more apparent in the houses that received educational campaign (F=8.4, p<0.005) with relation to the ones that received malathion spraying (F=0.38, p>0.5), while the combination of both treatments demonstrated a discrete negative interaction (F=6.52, p<0.05). These effects were independent of climatic changes and level of knowledge about dengue, as the KAP indicator did not show any significant changes in any group (F=1.14, p>0.1).

The results indicated that the educational campaign reduced the A aegypti breeding places more effectively than the use of chemicals spraying, and that the combination of both treatments can reduce its efficiency, possibly because of the false expectancy of protection that spraying creates. The KAP surveys seemed to have very limited value in evaluating quantitatively the programmes of eradication of the dengue vector.