Doctoral project: Camino Verde and social capital
Camino Verde: Community mobilization, social capital, and statistical modelling
This PhD was related to the Camino Verde trial of community mobilization for dengue prevention in Mexico and Nicaragua.
The work included a systematic review and meta-analysis of cluster randomized controlled trials of interventions for Aedes aegypti control. From 848 papers identified by the search, eighteen met the inclusion criteria: eight for chemical control, one for biological control and nine for community mobilization. Seven of the nine CRCTs of community mobilization reported significantly lower entomological indices in intervention than control clusters; findings from the eight CRCTs of chemical control were more mixed. In the meta-analysis of 10 studies, community mobilization (four studies) was consistently effective, the single CRCT of biological control was effective, but the five studies of chemical control did not show a significant impact on indices. The review concluded that governments should consider adding community mobilization to their prevention efforts and recommended more well-conducted CRCTs of complex interventions, including measurement of impact on dengue risk.
A secondary analysis of data from the Camino Verde trial examined associations between social capital and mosquito vector indices. Factor analysis combined responses to questions about aspects of social capital to create a social capital index with four constructs, combined into a single scale. Among the 10,112 households, those in rural communities were much more likely to have a high social capital score. Households in intervention sites had higher social capital, although the association was not significant at the 5% level. Households with high social capital were more likely to be negative for mosquito vector indices. There was interaction between intervention status and social capital; in multivariate analysis, a combined variable of intervention/high social capital was associated with vector indices. The findings support the idea that the Camino Verde intervention worked partly through an interaction with social capital.
Finally, a compartmental mathematical model, using data from the Camino Verde cluster randomized controlled trial, examined the dynamics of dengue infection with different levels of community participation, taking account of gender of respondents and exposure to temephos.
Simulation of dengue endemicity showed community participation affected the basic reproductive number of infected people. The greatest short-term effect, in terms of people infected with the virus, was the combination of temephos intervention and community participation. There was no evidence of a protective effect of temephos longer term.
Degree: PhD UAGro
Student: Victor Alvarado-Castro