Dr. Kacey Ernst (far right) and students from the University of Arizona are going door-to-door in Key West, Florida, and Tucson this summer collecting data for a dengue prevention study.

A group of students from the desert are spending part of their summer knocking on doors 2,000 miles away to help fight a spreading tropical disease that infects millions worldwide.

Public health students from the University of Arizona are going door-to-door in Key West, Florida, and Tucson this summer collecting data for a dengue prevention study.

Dengue is a mosquito-borne viral infection that causes sudden fever and acute pains in the joints. Found in tropical and sub-tropical regions around the world, transmission has increased in recent years in urban and semi-urban areas and has become a major international public health concern according to the World Health Organization (WHO).

There is no specific treatment for dengue or severe dengue, but early detection and access to proper medical care lowers fatality rates below one percent, according to WHO. Prevention depends on controlling the mosquito population.

Key facts • Dengue is a mosquito-borne viral infection. • The infection causes flu-like illness, and occasionally develops into a potentially lethal complication called severe dengue. • The global incidence of dengue has grown dramatically in recent decades. • About half of the world's population is now at risk. • Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas. • Severe dengue is a leading cause of serious illness and death among children in some Asian and Latin American countries. • There is no specific treatment for dengue/severe dengue, but early detection and access to proper medical care lowers fatality rates below 1%. • Dengue prevention and control solely depends on effective vector control measures. Source: World Health Organization

Dengue infects millions of people worldwide every year. It is transmitted by the bite of infected Ae. aegypti mosquitoes. This type of mosquito is well established in most of the southern United States. In the rest of the country, outbreaks have occurred in Key West (2009-2010) and in Brownsville, Texas (2005).

Many factors impact whether or not dengue will emerge in an area, explains Kacey Ernst, PhD, MPH, an infectious disease epidemiologist at the University of Arizona’s Mel and Enid Zuckerman College of Public Health.

“Understanding the dynamics of how infectious diseases emerge is critical to determining the risk that an outbreak could occur in a community,” said Ernst. “We want to understand more about differences among areas where dengue has emerged and where the mosquito is established but no dengue transmission has yet occurred. Understanding the potential for emergence will allow policy makers and health planners to prepare accordingly.”

Ernst is the principal investigator of a $400,000 grant from the National Institutes of Health to collect data on the mosquito that carries dengue in Key West, an area that has had an outbreak. She will then compare it to Tucson, an area with the mosquito established but no recorded transmission.

“We’re looking at the differences in survival, competence, bloodfeeding behaviors and density,” said Ernst. “One of our working hypotheses is that the climate in Tucson cannot support survival of the mosquito long enough for it to transmit dengue,” Ernst said.

They are also examining differences in knowledge, attitudes and practices surrounding dengue and mosquito-borne diseases in residents of both cities.

The other part of the study is a survey to understand what individuals are doing to prevent mosquito-borne illness in a community after an outbreak and to learn what residents know about dengue and other mosquito-borne diseases in a community that has not yet had transmission.

In Key West, student surveyors are easily identifiable by their matching UA t-shirts and name tags as they go door-to-door interviewing residents about their knowledge of dengue. With permission, they will also inspect property to identify any mosquito larvae or standing water that might be present. Surveyors will also help distribute dengue prevention door hanger magnets as part of the survey process. The goal is to complete at least 400 surveys in Key West by July 13.

“Lessons learned in Key West will be valuable to other communities that may face a future outbreak. We hope to identify factors related to prevention and control activities that can be expanded into successful programs,” said Ernst.

The students will be back in Tucson going door-to-door conducting the survey in late July through mid-August.

Other University of Arizona researchers collaborating with Ernst on the dengue study include Mike Riehle, associate professor of Entomology and Kathleen Walker, assistant professor of Entomology from the UA Department of Entomology in the College of Agriculture & Life Sciences; and Andrew Comrie, professor of Geography at the School of Geography and Development in the UA College of Social & Behavioral Sciences.

In addition, Ernst is working with scientists and public health professionals across many organizations including the Florida Keys Mosquito Control District, Monroe County (Fla.) Health Department, The National Center for Atmospheric Research, Pima County Health Department, and the Arizona Department of Health Services Office of Border Health.