Academic journal article Journal of Environmental Health

A Potential Risk Assessment of a Dengue Outbreak in North Central Texas, USA (Part 2 of 2): Development of a Practical Prevention Strategy

Academic journal article Journal of Environmental Health

A Potential Risk Assessment of a Dengue Outbreak in North Central Texas, USA (Part 2 of 2): Development of a Practical Prevention Strategy

Article excerpt

Introduction

Dengue is a disease transmitted by the mosquito and causes about 50 million cases per year worldwide. More than 100 countries are dengue-endemic and currently two-fifths of the world's population are considered at risk for infection (World Health Organization, 2002).

The distribution of dengue largely depends on presence of its main vector, Aedes aegypti (Linnaeus), the yellow fever mosquito, of which abundance is positively influenced by factors such as vegetation density, degree of shade, precipitation and humidity, abundance of water-holding containers, and ambient temperature (Barrera, Amador, & Clark, 2006; Clark & Quiroz Martinez, 2001; De Garin, Bejaran, Carbajo, De Cacas, & Schweigmann, 2000; Scott et al., 2000; Thavara et al., 2001). The geographical distribution and incidence of dengue has increased in recent decades (Guzman & Kouri, 2003) and is facilitated by an increase in air travel, urbanization, and population growth (Gubler, 2002). A rise in the use of disposable, non-biodegradable containers around human dwellings and a lack of effective mosquito control are additional factors contributing to the geographic extension of dengue distribution (Rigau-Perez, Gubler, Vorndam, & Clark, 1994).

Potential dengue outbreaks have remained a public health concern in south Texas due to the vector activity of Ae. aegypti and Aedes albopictus (Skuse) (the Asian tiger mosquito) (Hofmann & Killingworth, 1967; Micks & Moon, 1980; Mitchell, Miller, & Gubler, 1987; Sames, Bueno, Hayes, & Olsen, 1996) as well as its endemic transmission in northern Mexico. Although the incidence of dengue in this region is currently low, the anthroponotic transmission of the dengue virus via the vectors requires recognition of both locally acquired and imported cases.

Dallas County is the urban center of north central Texas with a healthy economy and resulting population growth. In 2005, 27% of the Dallas County population was Hispanic, with 75% of this group originating from Mexico. The number of immigrants from dengue-endemic countries has increased, and more travel from dengue-endemic countries in Latin America is expected (Dallas Fort-Worth International, 2005; Homedes & Ugalde, 2003).

In 2005, three imported dengue cases were reported in north central Texas. The expected increase of travel to dengue-endemic countries and the recent imported dengue cases could introduce a potential source of dengue transmission and lead to an outbreak in the region.

To develop a practical strategy of minimizing dengue outbreak potentials in the region, the dengue vector abundance, habitat factors, and their associations with Hispanic neighborhoods were assessed to identify areas where a local government may need to target.

Materials and Methods

Vector Mosquito Abundance

The study was conducted in Dallas County, Texas, from June to November 2006. Six zip codes in the county and nine sites within each zip code were randomly selected to monitor abundances of dengue vectors (Ae. aegypti and Ae. albopictus) using oviposition traps.

Habitat and Demographic Data Collection

Habitat variables were recorded on site August 10-18, 2006, and included the following: woody vegetation cover (V = woody vegetation cover 1 m or taller within 10 m radius of trap), shade (SH = percent shade within 10 m radius of trap, woody vegetation cover with shrub and other small vegetation, and structures), containers (C = containers capable of holding water within 10 radius of trap), and pets (P = presence of dogs or horses within 10 m radius of trap).

The populations of Latin American countries, most of which are dengue endemic, were considered of Hispanic origin in the Census data, and the most recent data were obtained from a publicly accessible database (ESRI, 2005).

Statistical Analysis

The association of the number of Ae. …

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