Sample Selection In Guerrero
Guerrero is a very mountainous State where dengue occurs mostly in its lower-lying part along the Pacific coast. Three administrative units, or regions, span this portion of the State: Acapulco, Costa Grande and Costa Chica, with a total population of 1.6 million people. Using the State Health Secretariate’s register of all communities, we selected a random sample of 90 clusters, stratified by region.
We conducted the baseline study in all 90 clusters. After the baseline was completed and analysed, the sample was randomised by a blinded process into 45 intervention clusters and 45 control clusters. Stratification variables for the ramdomisation included cluster size, overall disease rates reported by informants, disease rates among children aged three to nine years, incidence of recent infection and household entomological rates (presence of larvae and/or pupae).