West Nile virus focus of CSU lab research

Health scares over West Nile virus and other vector-borne diseases is bringing research-grant money into Northern Colorado, with about $5 million coming in annually to researchers at Colorado State University’s Anthropod-Borne Infectious Disease Laboratory.

Simply defined, a “vector” is an animal or insect that carries microorganisms from one animal to another. In Colorado, vectors are usually ticks or mosquitoes but can also include rodents, such as mice and prairie dogs.

West Nile virus first appeared in Northern Colorado in the summer of 2002 in horses in Weld County. Ken Olson, a virologist and director of the Arthropod-Borne Infectious Disease Laboratory at Colorado State University in Fort Collins, said West Nile has killed more than 50 people in the state and has infected about 3,000 horses. A Milliken man, Wayne Trowbridge, died Feb. 14 of complications of West Nile virus.

CSU in major role

There isn’t yet a cure or vaccine for West Nile, but researchers are working hard to find one. Dr. John Pape, state epidemiologist, is spearheading the effort against West Nile in Colorado. The Fort Collins branch laboratory of the Atlanta-based U.S. Center for Disease Control is also taking a major role in the effort to battle West Nile.

CSU researchers are trying to understand how vectors can survive with microorganisms that cause deadly diseases inside them — at least long enough to pass them on to people and animals. “We’re trying more to understand all of this because, in the long-term, that’s when you’ll find more options,´ said Dr. Chet Moore, a researcher at AIDL.

It’s painstaking work. Researchers must go out and find wintering mosquitoes in places such as culverts in the form of eggs or larvae, vacuum them up with a vacuum backpack-like device, take them back to the lab, sort them out and test them for the presence of the virus that causes West Nile.

Olson said CSU is receiving about $5 million a year in federal grants to learn more about West Nile, with a focus on controlling the insects.

The AIDL studies many vectors in Colorado, including deer mice for Hantavirus, prairie dogs for plague and ticks for Rocky Mountain spotted fever. But those carriers have taken a back seat to West Nile-carrying mosquitoes because the disease is proving virulent and spreading rapidly across the nation.

But just locating a West Nile mosquito is not easy. In a sample group of about 1,000 mosquitoes, the chances of one having a serious virus such as Western Equine Encephalitis is about 0.1 percent, Moore said. Work done by AIDL shows that — in the same size sample — the chances for a mosquito to have West Nile is 2 percent. While that might not sound high, when compared with the 0.1 percent for encephalitis, it’s “an extraordinarily high infection rate,” Moore said.

Olson said research on West Nile has so far yielded a diagnosis for the disease, which means they can now identify animals and people that have contracted it.

Funding for AIDL pays for researcher salaries, equipment, laboratory and field studies. “The equipment for the lab testing itself is kind of expensive,” Moore said.

Spraying helps

Fort Collins sprayed for West Nile last summer and plans to resume the battle this year. Gaye Morrison, spokeswoman for the Weld County Department of Health, said Weld County expects to receive a grant from the state for surveillance. “It’ll provide money for setting out mosquito traps and testing the bugs that spread it,” she said.

While spraying for West Nile is one option that’s apparently having some effect, researchers are also looking at more-natural ways of controlling mosquitoes. “There is a small group here looking at diseases of the mosquito,” Moore said. The idea is to infect the mosquito with a disease that kills the mosquito before it has a chance to pass on West Nile to someone else.

“The problem here is being able to make enough of the stuff that causes the mosquito disease and getting all the approvals and whatnot before you release it into the wild,” he said.

Another problem is adaptation. Even if someone at AIDL figures out a mosquito disease that works, the mosquito may soon adapt to where the disease doesn’t work anymore.

The West Nile strain has been in Africa for generations, and this particular strain has been virulent, killing about 280 across the United States, with Colorado — at 55 deaths — the state with the highest death toll so far.

That gives finding a vaccine, natural control or effective spray even greater urgency. “It has given us a glimpse at some of the problems part of the world faces every day,” Olson said.

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