Article

2007-08-31 Science & Technology

Heavy summer rains along the Texas-Mexico border always raise concerns over dengue fever, a mosquito-borne illness that is also called break-bone fever because of the severe body aches it causes. The border region has seen periodic outbreaks of the tropical virus, which is carried by a mosquito that thrives in much of Texas. And public health officials worry that the more severe form of the disease, which can cause internal bleeding and death, appears to be on the rise.

Current flu vaccines and antiviral drugs don't work on dengue, but research into better treatments has been slow. Humans are the only creatures that get sick from the virus, and scientists didn't have a good animal model to use in studying dengue.

Researchers at Southwest Foundation for Biomedical Research now have developed a laboratory mouse that could change that. Scientists have successfully implanted the mice with the type of human immune cells, called dendritic cells, that get attacked by the invading dengue virus.

"We think our cells have receptors for this virus while other primates and animals do not," said Rebeca Rico-Hesse, a foundation scientist who developed the lab model by transplanting human cord blood cells into an adult mouse.

She now has a grant from the Robert J. Kleberg and Helen C. Kleberg Foundation to develop ways of transplanting human immune cells into newborn mice, which would make them a better tool for testing vaccine candidates and studying factors that contribute to disease severity.

Dengue is primarily a risk to travelers who visit Latin America and Asia. Most people get the milder form of the disease and recover after a few painful weeks. But more severe forms of dengue can cause internal bleeding and death, and scientists worry that this form is on the increase.

The mosquito that spreads dengue, Aedes aegypti, lives in Texas, and public health officials worry that the disease could move across the Mexican border and take hold in South Texas.

"We think it's just a matter of time (until) enough of our mosquitoes get infected and there is actual transmission of dengue in the United States," Rico-Hesse said.

Dengue has been an especially difficult problem for scientists because there are four viruses that can cause the disease, said James LeDuc, director of global health at the University of Texas Medical Branch in Galveston. Plus, he said, exposure to one form of the virus may actually prime people to get sicker from the other dengue viruses.

"So rather than making one vaccine, you are actually trying to make four vaccines and balance the immune response so you don't set people up for a more severe disease," said LeDuc. "It's one of the challenges we have faced forever.

"Having a mouse, especially if it mimics human response, will help this research," he added.

Posted by Anonymoose 2007-08-31 14:34|| || Front Page|| [11139 views ] Top

#1 so does this mean that the hospitals and other medical facilities down Texas-way will have to treat the 'undocumented' folks that show up all hurtin? seems to me that if a vaccine can be developed and administered, then anybody that shows signs of this has just earned a free trip south.
couse i am probably over-simplifying the problem a little bit.

Posted by USN, Ret. 2007-08-31 14:44|| 2007-08-31 14:44|| Front Page Top

#2 I knew a girl in central AZ who got it. red-haired Irish. She lived in apartments near railroad tracks, and started to get some really odd symptoms.

Doctors in southern AZ had been told to look out for it, but not in central AZ. She saw five, then her boyfriend asked me. After about 10 minutes on the Internet, I was able to match 15 for 15 symptoms. The next doctor she visited confirmed it.

Just one mosquito is all it takes.

Oh, and don't hold your breath for a vaccine. It can be one of four different viruses, none of which are easy to vaccinate against.

Usually, the first time you get it you are miserable for three weeks, and look like heck. But if you get it a second time, it can unpredictably turn into the hemorrhagic form, which behaves somewhat like ebola.

Nasty stuff. Best advise to the red-haired girl: move North of Colorado and never visit South again.

Posted by Anonymoose 2007-08-31 16:32|| 2007-08-31 16:32|| Front Page Top

#3 New Bugs, massive Spider webs and Chupacabras. Here on Guam, the only time I've seen such large spider webs is during a heat wave or after a heat wave - some Netters are arguing Earth is overdue for a massive solar flare???

Posted by JosephMendiola 2007-08-31 22:18|| 2007-08-31 22:18|| Front Page Top

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