The Rise of Dengue

The incidence and spread of dengue fever is growing at a rapid rate while traditional methods to combat the disease, such as insecticides, are becoming less effective against as mosquito vectors develop immunity.

The viral disease is now present through much of the Americas, a dramatic change from even 30 years ago, including southern areas of the United States. The disease has emerged as a significant public health threat. In more serious cases, dengue develops into dengue hemorrhagic fever, a life-threatening condition.

Barry J. Beaty, a distinguished professor at Colorado State University, outlined the growing challenges posed by dengue fever and some of the gains that have been made during the Frank Black Memorial Lecture at the School of Public Health. Black was a distinguished researcher at Yale from the 1950s through the mid 1990s. Two of his sons attended Thursday’s talk.

Beaty, who was formally part of the Yale Arbovirus Research Unit, told the gathering in Winslow Auditorium that mosquito control is essentially “out of control” in many parts of the Americas and the problem is likely to get “even worse” as the arsenal of traditional insecticides are losing their efficacy in many cases. He likened it to what is happening with bacterial resistance to many antibiotics.

One low-tech approach that can make a difference is keeping mosquitoes, which he described as viruses “with wings and six legs” out of homes, where humans are easy prey and the disease can be passed to numerous people in a short time. His research team has found up to 40 mosquito vectors inside individual homes in Mexico, where they are largely safe from aerial or truck-based spraying campaigns 

Many such homes lack adequate screening or insecticide-treated curtains and air conditioning, which results in people leaving windows and doors open to cool off their homes. In fact, a stark difference can be seen in dengue infection rates on the northern (American) and southern (Mexican) sides of the Rio Grande river. On the U.S. side, where more homes have air conditioning and screening on all of their doors and windows, the disease is less pronounced.

Beaty does much of his work in Mérida, the capital of Mexican state of Yucatán. Outbreaks of dengue can be so severe that they quickly drain local resources. “You find patients stacked up everywhere,” he said. “People are just overwhelmed.”

In addition to vector control efforts, Beaty also summarized his research team’s work to develop non-invasive methods for better diagnosis and prognosis. Some promising approaches are about to undergo a first round of testing. 

This article was submitted by Denise Meyer on February 7, 2013.