Abstract. Chagas disease represents a major public health concern in most of Latin America, and its control is currently based on vector control and blood bank screening. We investigated the geographic distribution and seasonal variations in triatomine populations in the Yucatan peninsula of Mexico to obtain entomologic data for the optimization of potential control programs. We collected domiciliated and peri-domiciliated Triatoma dimidiata from 115 houses in 23 villages distributed throughout most of the peninsula. A high abundance of bugs was observed in the northern part of the peninsula, indicating a prioritary area for vector control. Part of this distribution could be attributed to the type of vegetation. We also documented strong seasonal variations in T. dimidiata populations, with a higher abundance during the hot and dry season in April-June. These variations, associated with reduced year-round colonization of houses and the analysis of developmental stage structure, suggest that flying adults seasonally invading houses may play a larger role than domiciliated bugs in transmission of Trypanosoma cruzi to humans. The importance of this transmission dynamics may not be limited to the Yucatan peninsula, but may be a general mechanism contributing to natural transmission that should be taken into account in other regions for the design and optimization of control strategies.

BackgroundDengue is an increasingly important public health problem in most Latin American countries and more cost-effective ways of reducing dengue vector densities to prevent transmission are in demand by vector control programs. This multi-centre study attempted to identify key factors associated with vector breeding and development as a basis for improving targeted intervention strategies.MethodsIn each of 5 participant cities in Mexico, Colombia, Ecuador, Brazil and Uruguay, 20 clusters were randomly selected by grid sampling to incorporate 100 contiguous households, non-residential private buildings (businesses) and public spaces. Standardized household surveys, cluster background surveys and entomological surveys specifically targeted to obtain pupal indices for Aedes aegypti, were conducted in the dry and wet seasons.ResultsThe study clusters included mainly urban low-middle class populations with satisfactory infrastructure and –except for Uruguay- favourable climatic conditions for dengue vector development. Household knowledge about dengue and “dengue mosquitoes” was widespread, mainly through mass media, but there was less awareness around interventions to reduce vector densities. Vector production (measured through pupal indices) was favoured when water containers were outdoor, uncovered, unused (even in Colombia and Ecuador where the large tanks used for household water storage and washing were predominantly productive) and –particularly during the dry season- rainwater filled. Larval infestation did not reflect productive container types. All productive container types, including those important in the dry season, were identified by pupal surveys executed during the rainy season.ConclusionsA number of findings are relevant for improving vector control: 1) there is a need for complementing larval surveys with occasional pupal surveys (to be conducted during the wet season) for identifying and subsequently targeting productive container types; 2) the need to raise public awareness about useful and effective interventions in productive container types specific to their area; and 3) the motivation for control services that-according to this and similar studies in Asia- dedicated, targeted vector management can make a difference in terms of reducing vector abundance.

BackgroundLong-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013.MethodsSequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment.ResultsLLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention.ConclusionsThese safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide.

Dengue prevention efforts rely on control of virus vectors. We investigated use of insecticide-treated screens permanently affixed to windows and doors in Mexico and found that the screens significantly reduced infestations of Aedes aegypti mosquitoes in treated houses. Our findings demonstrate the value of this method for dengue virus vector control.

This qualitative study reports the findings from 6 focus groups conducted at a clinic in Southern Mexico with caregivers of morbidly obese children. This study was developed with the purpose of gaining a further understanding of caregivers' perceived role in addressing their children's obesity within the family context and identifying topics that could be considered when providing health care in similar sociocultural environments. We identified that although caregivers acknowledge the role of modifiable factors in obesity prevention and treatment, they held beliefs about determinism in obesity. In addition, diet was the more frequently identified means of reducing the impact of obesity. The importance of role modeling and promoting healthy behaviors in the family context are topics that could be addressed in clinical practice.