A prospective cohort study to evaluate peridomestic infection as a determinant of dengue transmission: Protocol

Ruth Aralí Martínez-Vega,Jorge Argáez-Sosa,José Ramos-Castañeda,Jorge Velasco-Hernández,Miguel Nakamura,Rogelio Danis-Lozano,René Santos,Mariana González-Fernández,Susana Román,Fredi Alexander Díaz-Quijano

doi:10.1186/1471-2458-12-262

Abstract

BackgroundVector control programs, which have focused mainly on the patient house and peridomestic areas around dengue cases, have not produced the expected impact on transmission. This project will evaluate the assumption that the endemic/epidemic transmission of dengue begins around peridomestic vicinities of the primary cases. Its objective is to assess the relationship between symptomatic dengue case exposure and peridomestic infection incidence.Methods/DesignA prospective cohort study will be conducted (in Tepalcingo and Axochiapan, in the state of Morelos, Mexico), using the state surveillance system for the detection of incident cases. Paired blood specimens will be collected from both the individuals who live with the incident cases and a sample of subjects residing within a 25-meter radius of such cases (exposed cohort), in order to measure dengue-specific antibodies. Other subjects will be selected from areas which have not presented any incident cases within 200 meters, during the two months preceding the sampling (non-exposed cohort). Symptomatic/asymptomatic incident infection will be considered as the dependent variable, exposure to confirmed dengue cases, as the principal variable, and the socio-demographic, environmental and socio-cultural conditions of the subjects, as additional explanatory variables.DiscussionResults indicating a high infection rate among the exposed subjects would justify the application of peridomestic control measures and call for an evaluation of alternate causes for insufficient program impact. On the other hand, a low incidence of peridomestic-infected subjects would support the hypothesis that infection occurs outside the domicile, and would thus explain why the vector control measures applied in the past have exerted such a limited impact on cases incidence rates. The results of the present study may therefore serve to reassess site selection for interventions of this type.

Highlights

Vector control programs, which have focused mainly on the patient house and peridomestic areas around dengue cases, have not produced the expected impact on transmission
The scientific evidence derived from this study will make it possible to discern whether dengue transmission occurs in or outside the peridomestic areas of infected cases
Results indicating a high infection rate among the subjects exposed to symptomatic dengue cases would support implementing vector-control measures in the domiciles and vicinities of the cases, and would suggest the need to evaluate alternate causes for insufficient program impact, causes such as inadequate space nebulization techniques and vector resistance to applied insecticides

Summary

Introduction

Vector control programs, which have focused mainly on the patient house and peridomestic areas around dengue cases, have not produced the expected impact on transmission. This project will evaluate the assumption that the endemic/epidemic transmission of dengue begins around peridomestic vicinities of the primary cases. The most frequent vector-borne viral disease in the world, constitutes a public health problem in tropical and subtropical countries [1]. In Puerto Rico, from 1984 to 1994, dengue caused an average of 658 DALYs per million inhabitants per year, with a maximum of 2,153 DALYs per million inhabitants estimated for 1994. The greatest burden of disease was attributed to dengue fever [4]

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