February 22, 2008

To many Kentuckians, mosquitoes may be nothing more than a summertime nuisance. But the World Health Organization estimates that one mosquito-borne disease, Lymphatic Filariasis (LF), also known as Elephantiasis, has put more than a billion people at risk worldwide.

The University of Kentucky Research Foundation has received a $5.3 million grant from the Bill & Melinda Gates Foundation to develop new tools to aid in the effort to eliminate LF in the South Pacific. UK entomologist Stephen Dobson will head up the effort, which will continue late into 2012.

“LF is a painful disease that can cause irreparable damage to the lymphatic system and disfigurement, which can lead to disability, severe social stigma, inability to work and a dramatic reduction in the quality of life of affected people,” Dobson said. “Our goal is to break the cycle of LF transmission by eliminating the mosquitoes that are required for disease transmission, stopping the spread of infection.”

LF transmission is similar to dog heartworm here in the United States. Mosquitoes pick up worms that then develop inside the mosquito into the infective stage. The process usually takes seven to 21 days in the mosquito. The larvae then migrate to the mosquitoes' mouth-parts, ready to enter the skin of the next person the mosquito bites, thus completing the cycle.

The approach is to release male mosquitoes infected with Wolbachia bacteria, with the goal of reducing the number of biting females. Male mosquitoes don’t bite (i.e., blood feed) or transmit disease. This biological control will be combined with new insecticidal approaches. The researchers believe this integrated approach can eliminate the mosquito responsible for transmitting LF. They plan to start with small islands, to simplify logistics. If successful, they plan to ‘scale up’ to larger sites.

The WHO reports that in its most obvious manifestations, LF causes enlargement of an entire leg or arm, the genitals, vulva and breasts. In endemic communities, 10 to 50 percent of men and up to 10 percent of women may be affected.

In 1997, the World Heath Assembly called for the elimination of LF by 2020, noting that historically it is the leading cause of disability in the Western Pacific, with as much as 40 percent of the population affected on some islands.

This is not the first time Dobson has been chosen to deal with a mosquito-borne, tropical disease. In 2005, Dobson was funded as part of a team of 11 worldwide researchers that received a Grand Challenges in Global Health grant to fight dengue fever, a rapidly expanding disease in most tropical and subtropical areas of the world. Dengue-related illnesses range from a severe, flu-like sickness to the deadly dengue hemorrhagic fever.

“Dr. Dobson being chosen to be part of the solution in these disease battles speaks volumes about the quality and excellence of his work,” said Nancy Cox, UK College of Agriculture associate dean for research and the director of Kentucky’s Agricultural Experiment Station. “He could really make a global impact on human health. Although these diseases are not a problem in Kentucky at this time, increasing international travel technically is making our world a much smaller place and there may be a time when these diseases, or similar ones, affect our citizens.”

Dobson said that fighting mosquito-borne diseases in other countries isn’t much different than doing it right here at home in Kentucky.

“New approaches for stopping mosquito-borne disease overseas will have a global impact on health and can also affect Kentuckians,” he said. “It hasn’t been that long ago that West Nile virus came on the scene in Kentucky along with two types of exotic mosquitoes. A few additional tools for combating mosquitoes would have been nice, and the approaches that we are developing could be useful here as well.”

Dobson will lead a team of international researchers to focus on biological and insecticidal approaches to eliminate LF transmission by mosquitoes and then integrate the new approach with the current strategy of ‘Mass Drug Administration.’ The research will be closely integrated with the existing WHO infrastructure and with regional governments. The efforts will strengthen and extend the global outreach of the University of Kentucky and establish new international collaborations.

Other collaborators include Oxford University in England; two Australian institutions - James Cook University and the University of Sydney; the Institut Louis Malardé in French Polynesia; and the University of California, Berkeley.

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