Month: January 2017

Spatial Analysis of Dengue Seroprevalence and Modeling of Transmission Risk Factors in a Dengue Hyperendemic City of Venezuela

/ Matt Artz

ntdPLOS | Neglected Tropical Diseases, Published Online 23 January 2017

By Maria F. Vincenti-Gonzalez, María-Eugenia Grillet, Zoraida I. Velasco-Salas, Erley F. Lizarazo, Manuel A. Amarista, Gloria M. Sierra, Guillermo Comach, and Adriana Tami

Background
“Dengue virus (DENV) transmission is spatially heterogeneous. Hence, to stratify dengue prevalence in space may be an efficacious strategy to target surveillance and control efforts in a cost-effective manner particularly in Venezuela where dengue is hyperendemic and public health resources are scarce. Here, we determine hot spots of dengue seroprevalence and the risk factors associated with these clusters using local spatial statistics and a regression modeling approach.

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Dengue seroprevalence within Candelaria & Caña de Azúcar neighborhoods, Maracay city, Venezuela.

Methodology/Principal Findings

“From August 2010 to January 2011, a community-based cross-sectional study of 2012 individuals in 840 households was performed in high incidence neighborhoods of a dengue hyperendemic city in Venezuela. Local spatial statistics conducted at household- and block-level identified clusters of recent dengue seroprevalence (39 hot spot households and 9 hot spot blocks) in all neighborhoods. However, no clusters were found for past dengue seroprevalence. Clustering of infection was detected at a very small scale (20-110m) suggesting a high disease focal aggregation. Factors associated with living in a hot spot household were occupation (being a domestic worker/housewife (P = 0.002), lower socio-economic status (living in a shack (P<0.001), sharing a household with <7 people (P = 0.004), promoting potential vector breeding sites (storing water in containers (P = 0.024), having litter outdoors (P = 0.002) and mosquito preventive measures (such as using repellent, P = 0.011). Similarly, low socio-economic status (living in crowded conditions, P<0.001), having an occupation of domestic worker/housewife (P = 0.012) and not using certain preventive measures against mosquitoes (P<0.05) were directly associated with living in a hot spot block.

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Dengue seroprevalence within La Cooperativa neighborhood, Maracay city, Venezuela.

Conclusions/Significance
“Our findings contribute to a better comprehension of the spatial dynamics of dengue by assessing the relationship between disease clusters and their risk factors. These results can inform health authorities in the design of surveillance and control activities. Focalizing dengue control measures during epidemic and inter-epidemic periods to disease high risk zones at household and neighborhood-level may significantly reduce virus transmission in comparison to random interventions.”

Zika virus: Endemic and epidemic ranges of Aedes mosquito transmission

/ Matt Artz
jiph

Journal of Infection and Public Health, Volume 10, Issue 1, January–February 2017, Pages 120–123

By David F. Attaway, Nigel M. Waters, Estella M. Geraghty, and Kathryn H. Jacobsen

“As evidence linking Zika virus with serious health complications strengthens, public health officials and clinicians worldwide need to know which locations are likely to be at risk for autochthonous Zika infections. We created risk maps for epidemic and endemic Aedes-borne Zika virus infections globally using a predictive analysis method that draws on temperature, precipitation, elevation, land cover, and population density variables to identify locations suitable for mosquito activity seasonally or year-round.
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Global map of the locations suitable for seasonal presence (yellow) and year-round presence (red) of hematophagous Aedes mosquitoes.

“Aedes mosquitoes capable of transmitting Zika and other viruses are likely to live year-round across many tropical areas in the Americas, Africa, and Asia. Our map provides an enhanced global projection of where vector control initiatives may be most valuable for reducing the risk of Zika virus and other Aedes-borne infections.”