November 9, 2012

Doctors observe hints of mutating, more deadly West Nile virus

They say it's causing more brain damage than before, but federal officials express doubts.

By BRIAN VASTAG The Washington Post

The West Nile virus epidemic of 2012, the worst in a decade, may be notorious for yet another reason: The virus, in some cases, is attacking the brain more aggressively than in the past, raising the specter that it may have mutated into a nastier form, say two neurologists who have extensive experience dealing with the illness.

click image to enlarge

Mosquitos are sorted at a lab. Some doctors worry that the virus is mutating and is attacking the brain more aggressively.

File photo/The Associated Press

One doctor, Art Leis in Jackson, Miss., has seen the virus damaging the speech, language and thinking centers of the brain -- something he has never observed before. The other, Elizabeth Angus in Detroit, has noticed brain damage in young, previously healthy patients, not just in older, sicker ones -- another change from past years.

Angus, who has treated West Nile patients for a decade, and Leis, who has more experience treating severe West Nile illness than perhaps any doctor in the country, both suspect the virus has changed -- a view bolstered by a Texas virologist whose laboratory has found signs of genetic changes in virus collected from the Houston area.

"I've been struck this year that I'm seeing more patients where the brain dysfunction has been very much worse," said Angus, of Detroit's Henry Ford Hospital. "It makes you wonder if something's different, if something's changed."

And while the virus in the past has typically invaded the brain and spinal cord only of people who have weakened immune systems, such as the elderly and transplant or cancer patients, Angus this summer treated a severely affected woman in her 20s and a man in his 40s.

Leis said he is seeing much more severe encephalitis -- inflammation of the brain -- than he has in the past. "It is clearly much more neuroinvasive, neurovirulent," he said.

Four patients who Leis treated this summer had lost their ability to talk or write. Another was paralyzed on one side, as often seen in strokes, not West Nile infections. Others experienced recurring seizures.

In all, 11 of the first 12 patients Leis saw this year at the Methodist Rehabilitation Center in Jackson had more severe brain damage than he had seen previously. The outlook for such patients varies, but most will face years or a lifetime of disability.

"For the first time, we have radiographic evidence, clinical evidence of the virus attacking the higher cortical areas," said Leis, who has published 15 scientific papers describing previous West Nile patients.

Marc Fischer, an epidemiologist at the Centers for Disease Control and Prevention who tracks the West Nile virus, said the federal agency has not noticed the changes described by Leis and Angus. "There's just a lot more cases this year than anybody has seen in at least 10 years," he said. "You're just going to see more severe cases and probably a broader variety of manifestations."

Last month, Leis asked a Food and Drug Administration scientist who studies the genetics of the virus whether a new, more virulent strain was circulating.

"You are absolutely right . . . that new genetic variants of WNV might have appeared this year," the scientist replied in an Oct. 23 e-mail obtained by The Washington Post. The scientist continued that "it is not easy to correlate" the new mutations with any specific type of brain damage.

Thirty minutes after Leis received the message, another e-mail from the same scientist arrived. It said the previous message had been "recalled."

When contacted by phone, the FDA scientist, who works at the agency's Center for Biologics Evaluation and Research, declined to discuss the messages.

In an e-mail, FDA spokeswoman Heidi Rebello said that the agency is studying the genetics of West Nile viruses collected from 270 blood donors this year, but that "it is premature for us to draw any conclusions about new genetic variants . . . or of any possible association of new genetic variants with increased virulence."

(Continued on page 2)

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