By SUE VORENBERG
Scripps Howard News Service
November 18, 2005
The United States until the 1960s and Russia until the 1990s developed at least one type of bacteria - F. tularensis - into a biological weapon. The bacteria causes the disease tularemia, which is transmitted by rodents and acts like a severe form of the flu. It is fatal 30 percent of the time.
Now, the University of New Mexico is leading an effort to create a vaccine for the rare disease in case a weaponized form makes it into the wrong hands, said Rick Lyons, director of the university's Center for Infectious Disease and Immunity.
"The disease in nature is very rare, but it's very infectious," Lyons said. "It's thought that only a few organisms are needed to infect a person. The problem is if a weaponized version of the disease is released on the public, there aren't any vaccines available to the public right now to fight it."
Tularemia - also called rabbit fever - affects between 150 and 300 people in the United States each year, mostly in the Southwest. It is spread by fleas, ticks and mosquitoes that bite infected animals and then bite humans.
By studying cases and looking at how the disease affects mice, rats and other small animals, researchers from the university and its partners hope to create a vaccine for the public in the next three to five years, Lyons said.
The university is leading the effort for Cerus Corp, a California medical research company. The work is funded from a $2.8 million, three-year grant from the National Institutes of Health, which was awarded in early October.
Lovelace Respiratory Research Center in Albuquerque, Arizona State University and the University of Texas are also involved in the project. The groups will model how the disease attacks the immune systems in small animals and look at strategies to block transmission, Lyons said.
"We know a little bit about how the disease works in humans from historical information," Lyons said. "Now we're looking for more defined circumstances: How exactly does it attack a human host? What mechanisms does it use to infect us?"
Because there are so few cases every year, mysteries remain about how tularemia latches on to the human body and spreads, he added.
When cases occur naturally, tularemia is treated with antibiotics, but because symptoms mimic the flu, tularemia is often misdiagnosed until symptoms have become severe and life-threatening.
Even when the vaccine makes it to the general public, people probably won't have to worry about a new series of needle pricks, said Justin Skoble, a scientist at Cerus.
"I don't foresee it being very likely that a tularemia vaccine would be given to the whole U.S. population," Skoble said. "The hope is if people are exposed, we'll have a vaccine we can use retroactively to protect the population from getting infected."
The federal government is creating vaccines for a host of biological agents, such as anthrax, and this work with tularemia is part of those efforts, Skoble said.
"It might not sound like a major threat, but if a weaponized version of this were released, it could be very deadly," Skoble said. "If you can make an aerosol out of it - make it airborne - and the infectious dose is in the range of 10 bacteria, it sure wouldn't take much to kill people."
The vaccine could also be used to protect people from the regular form of the disease as an added bonus, Lyons said.
"The threat is a little hard to define, but it would certainly be useful to have a vaccine for natural cases as well as biological," he said. "Hopefully, we'll learn a lot as we continue working on this."
Distributed by Scripps Howard News Service.
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