bannerHON
img
HONnews
HONnews
img PATIENT / PARTICULIER img PROFESSIONNEL DE SANTE img WEBMESTRE img
img
 
img
HONcode sites
Khresmoi - new !
HONselect
News
Conferences
Images

Themes:
A B C D E F G H I
J K L M N O P Q
R S T U V W X Y Z
Browse archive:
2017: N O S A J J M A M F J
2016: D N

 
  Other news for:
Bites and Stings
Brain
Infection
Memory Disorders
Muscular Diseases
 Resources from HONselect
West Nile's Long-Term Bite: Impact on Brain May Last Years

By Amy Norton
HealthDay Reporter

TUESDAY, Nov. 7, 2017 (HealthDay News) -- Some people with a history of West Nile virus may show symptoms such as muscle weakness or foggy memory years later, a preliminary study suggests.

West Nile is a mosquito-transmitted infection that turned up in North America in 1999. Since then, outbreaks have occurred across the United States each summer -- with more than 47,000 reported cases overall, according to the U.S. Centers for Disease Control and Prevention.

However, the true number is estimated to be much higher -- more than 3 million -- largely because most people with West Nile either do not get sick, or have flu-like symptoms such as a fever and headache.

A small number -- fewer than 1 percent -- develop serious inflammation of the brain or surrounding tissues. About 10 percent of those patients die, according to the agency.

The new study suggests that some patients have lingering issues up to eight years later. And that may be true even among people whose initial infection was never recognized, the researchers said.

Of 117 people the study evaluated, nearly half had some kind of symptom during neurological exams. Most often, that meant decreased muscle strength, problems with reflexes or tremors.

In addition, 22 percent showed signs of "impairment" on memory tests.

It's not possible to definitively point the finger at the patients' past West Nile infections, senior researcher Dr. Kristy Murray noted.

However, these patients developed neurological issues at a much higher rate than would be expected in the general population, said Murray, an associate professor at Baylor College of Medicine in Houston.

In addition, her team found evidence of brain-tissue thinning among 30 people who underwent MRI brain scans.

And when the researchers focused on those who'd developed severe West Nile infections, they found tissue degeneration in several areas of the brain. That included regions related to movement and balance, plus essential functions like breathing and speaking.

Murray said the tissue damage was consistent with what could happen after an infection causes severe brain inflammation.

Greg Ebel is a professor of microbiology, immunology and pathology at Colorado State University.

He agreed there are some questions about whether the symptoms in these study patients can be pinned on West Nile itself. However, Ebel called the findings "important," and said more research is needed to understand what's going on.

"It's important for us to know the extent and nature of the damage to the central nervous system," Ebel said.

The findings are based on 262 Houston-area residents who enrolled in a long-term study of West Nile starting in 2002. All had a history of the infection, but had suffered varying degrees of symptoms. Some weren't sickened at all, and had their infection discovered during routine blood-donor screening.

Of the 57 people who showed neurological issues, seven had never noticed any symptoms from their West Nile infection, according to the researchers.

That was a "surprise," Murray said, and it's unclear whether the infection directly caused the neurological symptoms in those people.

Unfortunately, there is no treatment to reverse the damage seen in some of these patients, according to Murray. But "supportive care" might ease symptoms like muscle weakness or tremors, she suggested.

Ebel said the findings underscore the importance of preventing West Nile infections in the first place.

Avoiding mosquito bites is key, he said. The CDC advises Americans to be aware of West Nile "activity" in their local area, and use insect repellent and clothing to ward off mosquitoes when outdoors.

To Murray, the study argues for more investment in finding a West Nile vaccine.

"This is impacting people long term," she said, "and we still have no vaccine for it."

The findings were scheduled for presentation Tuesday at the annual meeting of the American Society of Tropical Medicine and Hygiene, in Baltimore. Studies presented at meetings are generally considered preliminary until published in a peer-reviewed journal.

More information

The U.S. Centers for Disease Control and Prevention has an overview of West Nile virus.

SOURCES: Kristy Murray, Ph.D., D.V.M., associate professor, pediatrics-tropical medicine, Baylor College of Medicine, Houston; Greg Ebel, Sc.D., professor, microbiology, immunology and pathology, Colorado State University, Fort Collins, Colo.; Nov. 7, 2017 presentation, American Society of Tropical Medicine and Hygiene annual meeting, Baltimore

Copyright © 2017 HealthDay. All rights reserved. URL:http://consumer.healthday.com/Article.asp?AID=728300

Resources from HONselect: HONselect is the HON's medical search engine. It retrieves scientific articles, images, conferences and web sites on the selected subject.
Infection
Brain
Bites and Stings
Research Personnel
Muscles
Memory
Tissues
Tremor
The list of medical terms above are retrieved automatically from the article.

Disclaimer: The text presented on this page is not a substitute for professional medical advice. It is for your information only and may not represent your true individual medical situation. Do not hesitate to consult your healthcare provider if you have any questions or concerns. Do not use this information to diagnose or treat a health problem or disease without consulting a qualified healthcare professional.
Be advised that HealthDay articles are derived from various sources and may not reflect your own country regulations. The Health On the Net Foundation does not endorse opinions, products, or services that may appear in HealthDay articles.


Home img About us img MediaCorner img HON newsletter img Site map img Ethical policies img Contact