Dengue fever has been prevalent in the world since the fourth century A.D ., but researchers of the Eliminate Dengue Program are looking to get rid of the historical killer in the near future.  

The first cases of dengue fever were observed in China, but the fever simultaneously appeared in Asia, Africa and North America. This virus claims the life of around 100 million people annually, according to the World Health Organization. But soon, this will no longer be the case. Mathematical biologist Alun Lloyd, along with other scientists from the U.S . and Australia, was involved in the Eliminate Dengue Program.

The project aims to cease the Aedes aegypti mosquito, the vector for the dengue virus, from transmitting this virus between humans. Researchers claim the main barrier to this transmission is the Wolbachia bacterium.

According to Frank Scholle , microbiology professor and researcher, “Wolbachia is an insect bacterium that does not infect humans. However, when female mosquitoes mate with male mosquitoes that are infected with Wolbachia , their eggs will die.”

 In contrast, infected female mosquitoes are able to mate successfully but will pass the bacterium on to their progeny. This bacterium prevents the mosquitoes from getting infected with the dengue virus, and thus forbids the spread of the dengue fever to humans.

Dengue fever has engulfed the lives of millions of people around the globe. Though it is not so prevalent in U.S ., an outbreak was documented in Florida in 2009 and 2010 and about 5 percent of the population in Key West showed signs of exposure to the virus. 

The main vector that transmits the deadly dengue virus is a mosquito called Aedes aegypti . This species of mosquito is more common in the tropical areas and infects inhabitants of the tropics. Infection is largely based on the lifestyle of an individual and their exposure to Aedes aegypti . This species of mosquito has a tendency to breed in stagnant water puddles. Hence, researchers claim dengue is especially common in low-lying areas during heavy rains.

According to Lloyd, dengue is prevalent in Southeast Asia and South America.

“As of right now, Wolbachia is not being deployed on a large scale to combat dengue,” Lloyd said. “The tests that were carried out to date were designed to determine whether the Wolbachia infection would spread. In the near future, tests will be carried out in dengue-endemic areas to see what effect there is on transmission of dengue.”

Scholle cited a study along the U.S.-Mexican border that shed light on the lifestyle choices contributing to the spread of the virus.

“…A number of years ago [it] demonstrated this: Laredo and Nuevo Laredo are separated by the Rio Grande, on both sides the vector mosquitoes are present,” Scholle said. “On both sides, a similar percentage of mosquitoes are carrying dengue virus. However, cases of dengue fever are almost exclusively found on the Mexican side of the river.”

This observation demonstrates infected populations in Mexico tend to spend more time outdoors and are likely to open windows instead of using air conditioning to control indoor temperatures; whereas Americans are more indoors and keep their windows closed, according to Scholle . But Aedes aegypti has shown the likelihood of spreading into neighboring areas, resulting in a higher risk of acquiring the disease in the Southern U.S .

Despite all efforts, there has been no antiviral treatment or cure for dengue fever. Treatment consists only support therapy, including maintenance of fluids and delivery of pain medication. There are no vaccines for dengue, although the microbiology and biochemistry departments of the University are testing quite a few approaches.

“The problem is that any acceptable dengue vaccine will need to afford equal protection against all four serotypes simultaneously, and that has been a huge problem with vaccine development,” Scholle said. “The only prevention is to limit exposure to the mosquitoes.”

The Eliminate Dengue Program has helped prevent yellow fever and its efforts to prevent dengue have yielded success.

“I think among the academic community, the global problem with dengue is well appreciated and there are multiple efforts under way in vaccine and antiviral drug development, however, since the disease is not [yet] very prevalent in the U.S . itself in my opinion,” Scholle said. “It does not get the attention it deserves as far as research funding is concerned. I anticipate that with global travel and global warming we will see further expansion of the mosquito vectors into new areas, and with them the diseases they carry.”

But eliminating dengue isn’t just on the microbial level. Lloyd is taking an epidemiological view on the issue.

“I developed a model that described the population dynamics of mosquito populations and the Wolbachia infection,” Lloyd said. “Such a model can be used to predict the outcome of an experiment ahead of time, or to help interpret the results obtained in an experiment. In the Wolbachia paper, I used models to interpret the results obtained from their cage [semi-field system] experiments.”