Notre Dame expert: Dengue fever outbreak

Author: William G. Gilroy


One of the worst dengue fever outbreaks in decades is spreading across Latin America and the Caribbean, and a University of Notre Dame biologist who was instrumental in mapping the genome of the Aedes aegypti mosquito that transmits the dengue parasite to humans believes the outbreak is part of a larger trend.

There is clearly an upswing in cases in the Caribbean region, partly due to recent hurricane activity, but case numbers and fatalities were already going up there and across the globe,biologist David Severson said.There has been a lot of discussion on recent outbreaks in Singapore, for example. Singapore was previously looked upon as a stellar example of how to prevent, or control, dengue infections. Oddly enough, Cuba has one of the best dengue prevention programs and it specifically targets Aedes aegypti control. I was there in August and some of their people are being tapped as advisers for Singapore.

The Aedes aegypti mosquito spreads an estimated 100 million cases of dengue fever each year. Dengue fever usually starts with a high fever and chills and may include headaches, backache and muscle and joint pain. Dengue hemorrhagic fever is a potentially deadly disease characterized by a high fever and may be accompanied by loss of appetite, nausea, vomiting, abdominal pain and nose or gum bleeding.

Dengue virus occurs most often is Southeast Asia, Africa and Central America because Aedes mosquitoes do not survive well in cold climates.

The Caribbean and Latin America dengue outbreak has caused joint pain for hundreds of thousands of people and killed an estimated 200 so far this year. The U.S. Centers for Disease Control and Prevention has posted advisories for people visiting the region, urging the use of mosquito repellants.

The idea of wiping out whole mosquito populations with insecticides has proved unworkable because mosquitoes evolved and became resistant to the chemicals.

As an alternative, Notre Dame scientists have been researching the development of genetically engineered mosquitoes that would be incapable of transmitting disease.

For example, biologist Malcolm Fraser is attempting to develop a new approach to suppress the replication of dengue virus within Aedes mosquitoes, using genetic engineering to introduce a molecular mechanism that can harness the virusown genetic molecule to activate a cell death pathway that kills infected cells. Thisdeath upon infectionstrategy would provide immunity against dengue in transgenic mosquitoes. Coupling the immunity with a selectable gene would allow the immune mosquitoes to compete with native mosquitoes, effectively reducing the number of infected mosquitoes and thus limiting the capability of Aedes to transmit disease.

The Aedes genome sequence led by Severson and Vishvanath Nene of the Institute of Genomic Research (TIGR) could lead to a variety of different research approaches to control mosquitoes and the pathogens they transmit to humans.

The genome is the complete set of genetic material, including genes and other segments of DNA, in an organism.

_ Contact: David W. Severson, professor of biological sciences, 574-631-3826,_ " "

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