Dengue fever is emerging as a major public health problem in most areas along the Texas-Mexico border, in particular South Texas, Dr. Frank Cortez-Flores said at the annual meeting of the American Society for Tropical Medicine and Hygiene.
"Although nearly eradicated in the 1960s, the Aedes aegypti mosquitoes that carry the disease are now present in abundant numbers in the Americas and the Caribbean and are present year round in the southernmost areas of Texas," said Dr. Cortez-Flores, of the Department of International Health, Loma Linda University School of Public Health, Loma Linda, California.
The increased disease incidence, combined with increased frequency of epidemic dengue cause by multiple virus serotypes, has increased the risk of epidemic dengue hemorrhagic fever, one of the leading causes of hospitalization and death among children in Southeast Asia, he said.
"Although dengue fever is not endemic in the United States, imported cases in U.S. residents returning from travel to endemic areas are diagnosed each year, and additional cases are probably undetected," he said.
"Mosquitoes are flying syringes, and mosquito control measures are the backbone of dengue prevention and control," he said.
According to the Centers for Disease Control and Prevention and the Pan American Health Organization, the incidence of dengue is increasing in the Caribbean, Central and South America, and Mexico. Most of the recent reports of suspected cases in Texas resulted from intensified surveillance by the Texas Department of Health because of an epidemic of dengue in the adjoining state of Tamaulipas, Mexico.
Factors responsible for such increases include a greater than usual number of tropical storms and increasing urbanization. "The mosquito is a highly domesticated urban species vector and is adapted to living with humans," he said.
Effective prevention and control programs will depend on integrated community efforts and on improved surveillance designed to provide early warning of dengue epidemics, he said. "Citizens can take significant steps themselves to reduce the risk. Mosquito control is the responsibility of everyone in the community, not just those in government."
Since the mosquitoes that carry the virus travel only a few hundred feet from where they are hatched, the best way to control the spread of disease is to eliminate standing water around the house where mosquito eggs hatch, such as rain barrels, discarded containers, old tires, and birdbaths, he advised.
Adequate screening on windows can also help, because mosquitoes look for a place to hide during the day and may be present in dark areas like closets, bathrooms, behind curtains, and under beds. Although mosquito activity is greatest in the early morning and in the late afternoon, they may feed at any time during the day, especially indoors, in shady areas, or during overcast periods, he noted.
Dengue fever is an acute viral illness with severe flu-like symptoms often accompanied by a rash on the feet or legs beginning 3 to 4 days after onset of fever. More severe forms are dengue hemorrhagic fever and dengue shock syndrome. The fatality rate for persons with untreated dengue hemorrhagic fever can be as high as 50%.
Virologic surveillance is the most important component in an early warning system. "Effective dengue surveillance can provide an early warning capability permitting emergency mosquito control measures to be implemented and major epidemics to be averted along the Texas-Mexico border," Dr. Cortez-Flores emphasized.
The American Society for Tropical Medicine and Hygiene (ASTMH) is the principal organization in the United States representing scientists, clinicians, and others with interests in the prevention and control of tropical diseases through research and education. Additional information on the meeting can be found at http://www.astmh.org/presskit.htm.