Researchers Working to Eliminate Dengue Fever

After studying 150 generations of the dengue-carrying mosquito, Aedes aegypti, for the last l2 years, researchers told an audience on the St. Croix campus of the University of the Virgin Islands on Tuesday they have found a way to genetically engineer the insect, eradicate the pest and eliminate the dengue fever virus.

“In an island like St. Croix, you could get rid of the insect,” said Hadyn Parry, chief executive
officer of Oxitec Ltd., a British biotech company. Parry described the work of Oxitec as “research and development of sterile insects.”

Parry said dengue fever has been killing people for more than 130 years. During the construction of the Panama Canal, more than 20,000 construction workers died. There are around 50 million cases of dengue every year and 25,000 deaths, according to the World Health Organization.

“It’s now the world’s most important viral disease,” Parry said.

There still is no way to prevent the virus and there is no known treatment. Currently fogging is “our state of the art” treatment, he said.

“We’re not really winning and it’s barely a draw,” Parry said.

The Oxitec method to control mosquitoes is environmentally friendly and more effective than fogging and pesticides, Parry said. The mosquitoes can only fly 100-200 yards so if they no longer procreate, the insect and the virus eventually disappear.

Only the female Aedes aegypti bites humans and spreads the virus from one infected person to another. The Oxitec method treats male mosquitoes with an artificial tetracycline-based formula in water as larvae and pupae. As an adult, “sterilized” males are released to breed with females, who lay up to 100 eggs at a time. The offspring, genetically altered larvae, will never hatch.

“In a few days, the mosquitoes die; the offspring die. It’s a dead end,” Parry said.

Oxitec’s method is preferable to fogging, he said, because it is non-allergenic and environmentally friendly, and homes and buildings are not invaded with clouds of pesticides.

Dr. Derric Nimmo, Oxitec’s head of public health research, said there are several stages to eliminate the Aedes aegypti using Oxitec’s program. Since the eggs can survive up to nine months, there is a maintenance period to insure the mosquito population has been eradicated. He said it can take as little as six months to see the desired results.

Parry and Nimmo cited statistics during their presentation at the UVI Great Hall about their programs in Malaysia and South America. In Jacobina, Brazil, Oxitec constructed the “largest mosquito factory” that produces male mosquitoes that are distributed every hundred yards in the community of 50,000. Nimmo said that, in four trials/programs, there was a reduction of mosquitoes by 81-95 percent.

“Removing it (the Aedes aegypti) in the wild actually restores the environment,” he said.

Oxitec, founded in 2002, uses genetics to control harmful insects such as the Aedes aegypti, the olive fly, pink bollworm and medfly that cause significant damage to crops around the world. Currently the Federal Drug Administration is conducting an assessment of the dengue fever prevention program.

“We are certain this does work. Other companies have tested the results worldwide,” Nimmo said.

The Oxitec partnership with UVI began when a St. Thomas resident contacted Dr. Albert Heath about the genetic elimination plan. Heath then enlisted support from David Hall, president of the university. After a videoconference with Parry and Nimmo, UVI and Health Department officials, Hall invited the researchers to the territory to explain their project to the community.

Parry and Nimmo spoke on the St. Croix campus Tuesday and on the St. Thomas campus Monday.

“From the university’s standpoint, the research is very critical,” Hall said. “Dengue in St. Croix is no longer seasonal, but endemic – 20-30 cases a month.”

Hall said he hopes the Oxitec research presentation will motivate public and private sectors to get involved.

“They’re here to explain there are no downsides,” Hall said. “What I hope happens is, after FDA approval, to do a trial. I would hope we could have a trial here.”

More information on the Oxitec research project is available by contacting Jennilee Beth Robinson, assistant biology professor at UVI. She can be contacted at [email protected]

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