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

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.

Economic and Disease Burden of Dengue in Mexico

“…An EF can be calculated as the analyst’s best estimate of the total number of dengue cases in a population divided by the number of reported cases considered dengue (EF = 1/reporting ratio) [ 59 ]. We estimated total episodes of dengue by multiplying reported episodes (41,333 episodes in 2010, and 20,548 in 2011) by an empirical EF derived from a prospective cohort study in Morelos [ 60 , 61 ].…”

“…The prospective cohort study was conducted in a dengue-endemic urban area in Morelos, Mexico, to assess the rate of DENV infections among the neighbors of reported dengue cases [ 61 ]. Set in the towns of Tepalcingo and Axochiapan during the 2011–2012 dengue season (June 2011-March, 2012), the study contained 1,172 participants aged 5 years and above.…”

Peridomestic Infection as a Determining Factor of Dengue Transmission

“…Subjects not susceptible to follow-up were excluded. The study protocol was previously published [ 26 ]. The calculated sample size was 1,178 subjects.…”

Seroprevalence of Neutralizing Antibodies Against Dengue Virus in Two Localities in the State of Morelos, Mexico

“…A cross-sectional nested cohort study was performed. 26 The cohort included subjects ages 5 years and older who were residents of the Axochiapan and Tepalcingo localities in the state of Morelos, Mexico. Axochiapan is located at an altitude of 1,030 m and has a population of 17,508, and Tepalcingo is located at an altitude of 1,160 m and has a population of 12,053.…”