take precaution...........
Eye on an Invasion
West Nile Spreads to New States, Teaches New Lessons
By Melinda T. Willis
Aug. 6 — In just a few years, West Nile virus has gone from an obscure, isolated ailment to a growing threat in much of the United States.
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IN DETAIL
• Mosquito-based Disease
First isolated in Uganda in 1937 and spread by mosquito, the virus was discovered in New York City in 1999, when more than 60 people suffered from the disease and seven died.
It has since moved quickly across the country. According to the Centers for Disease Control and Prevention, 34 states as well as the District of Columbia have confirmed animal cases of the disease as of Aug. 2.
Already this year, 36 human cases have been reported to and confirmed by the CDC. Of those, 31 have occurred in Louisiana, where public health officials report four people have died as a result of complications, prompting Gov. Mike Foster last week to declare a statewide emergency.
But as the virus spreads, researchers acknowledge they need to learn much more about who is at risk and what can be done to prevent future deaths.
"We don't know how large a public health problem West Nile is going to eventually be, because it's an emerging problem that has never been seen here before," says James Meegan, program officer in virology at the National Institute of Allergy and Infectious Disease in Bethesda, Md. "It's newly introduced in the United States and it's evolving and establishing itself in new ecological areas as it spreads."
Establishing Risk
Many cases of infection are mild, but there are risks of serious and potentially fatal complications. The severe form of the disease is characterized by the swelling of tissues surrounding the brain, known as encephalitis.
According to a paper published this week in Annals of Internal Medicine, people at greatest risk for these complications are those aged 50 and older. All four fatal cases of suspected West Nile in Louisiana were in people over 50.
"That doesn't mean that the mosquitoes are only biting those people. They're biting everybody," explains Meegan. "We're still learning about that, so it might be that younger people are getting a little 'summer flu' — but it's not enough to go into the doctor, and only the older folks are getting the more severe disease."
Because people suffering from minor illness may not see their physicians, this leaves researcher uncertain about the virus's true impact.
"We would love to study that more, especially in children and middle-aged people, to make sure there are no long-term problems that might have developed even though [the infection] was mild," adds Meegan.
A Surprising Introduction
Disease experts have learned a few surprising lessons with West Nile.
"I think that all of us studying mosquito-borne disease were surprised first of all that it occurred in downtown New York City. No one would have expected that because no one would think of it as a place where a lot of mosquitoes live," says Meegan.
The virus' New York premiere was also unexpected because diseases spread by mosquitoes typically enter through port cities like Philadelphia or New Orleans where ships bring in mosquito larvae that can carry infectious agents. The specifics about West Nile's introduction are unknown, but they raise the possibility that cities like New York with large international airports are port cities of a new breed.
Another lesson for experts was the rapid nature of the virus' spread throughout the United States.
"It's spreading fast. It's making its way west and we're certainly trying to stay out in front of it," Dr. Julie Gerberding, President Bush's newly appointed head of the CDC, told Good Morning America's Charlie Gibson. "It's really an infection that exists in birds, and the mosquitoes transmit it from bird to bird and sometimes people and horses. Wherever birds go, there is a risk the West Nile virus is going to follow."
While birds provide a highly mobile vector of virus transmission, they can also provide researchers with a sense of what regions may be affected next.
"States that know they have the disease and the [infected] birds can get aggressive about implementing other measures to control mosquitoes," adds Gerberding. "That can help control cases and human loss."
Pest Prevention
Researchers hope the lessons learned so far can help them limit the future spread of disease, while preventing and treating serious complications.
The National Institute of Allergy and Infectious Disease, for instance, is exploring the development of a West Nile virus vaccine as well as antiviral medications targeted specifically at treating West Nile infection. Right now, those who are infected or become ill with the disease can only have their symptoms treated.
Additionally, researchers are looking at improving diagnosis methods and conducting basic science research into the virus itself, including how it replicates and is transmitted.
But even those without advanced degrees in virology can take steps to halt West Nile transmission by preventing mosquito bites as well as stopping them from breeding. Some prevention tips include:
Avoid being outdoors at dusk and dawn. Those are times when mosquitoes are most active.
If you are outdoors during those periods, wear long-sleeved shirts and pants to eliminate the amount of skin exposed and left vulnerable to bites.
Use mosquito repellants. Those containing a chemical known as DEET are the most effective.
Eliminate reservoirs of standing water around your home. Culprits include kiddie pools, birdbaths, flower pots, wheelbarrows and clogged downspouts. Mosquitoes can use these unlikely suspects as breeding grounds.
Eye on an Invasion
West Nile Spreads to New States, Teaches New Lessons
By Melinda T. Willis
Aug. 6 — In just a few years, West Nile virus has gone from an obscure, isolated ailment to a growing threat in much of the United States.
Print This Page
Email This Page
See Most Sent
• Why Some Wineries Choose Screw Caps
• Suicide Bombs Spread Rat Poison, Disease
• What Really Caused AA Flight 587 to Crash?
IN DETAIL
• Mosquito-based Disease
First isolated in Uganda in 1937 and spread by mosquito, the virus was discovered in New York City in 1999, when more than 60 people suffered from the disease and seven died.
It has since moved quickly across the country. According to the Centers for Disease Control and Prevention, 34 states as well as the District of Columbia have confirmed animal cases of the disease as of Aug. 2.
Already this year, 36 human cases have been reported to and confirmed by the CDC. Of those, 31 have occurred in Louisiana, where public health officials report four people have died as a result of complications, prompting Gov. Mike Foster last week to declare a statewide emergency.
But as the virus spreads, researchers acknowledge they need to learn much more about who is at risk and what can be done to prevent future deaths.
"We don't know how large a public health problem West Nile is going to eventually be, because it's an emerging problem that has never been seen here before," says James Meegan, program officer in virology at the National Institute of Allergy and Infectious Disease in Bethesda, Md. "It's newly introduced in the United States and it's evolving and establishing itself in new ecological areas as it spreads."
Establishing Risk
Many cases of infection are mild, but there are risks of serious and potentially fatal complications. The severe form of the disease is characterized by the swelling of tissues surrounding the brain, known as encephalitis.
According to a paper published this week in Annals of Internal Medicine, people at greatest risk for these complications are those aged 50 and older. All four fatal cases of suspected West Nile in Louisiana were in people over 50.
"That doesn't mean that the mosquitoes are only biting those people. They're biting everybody," explains Meegan. "We're still learning about that, so it might be that younger people are getting a little 'summer flu' — but it's not enough to go into the doctor, and only the older folks are getting the more severe disease."
Because people suffering from minor illness may not see their physicians, this leaves researcher uncertain about the virus's true impact.
"We would love to study that more, especially in children and middle-aged people, to make sure there are no long-term problems that might have developed even though [the infection] was mild," adds Meegan.
A Surprising Introduction
Disease experts have learned a few surprising lessons with West Nile.
"I think that all of us studying mosquito-borne disease were surprised first of all that it occurred in downtown New York City. No one would have expected that because no one would think of it as a place where a lot of mosquitoes live," says Meegan.
The virus' New York premiere was also unexpected because diseases spread by mosquitoes typically enter through port cities like Philadelphia or New Orleans where ships bring in mosquito larvae that can carry infectious agents. The specifics about West Nile's introduction are unknown, but they raise the possibility that cities like New York with large international airports are port cities of a new breed.
Another lesson for experts was the rapid nature of the virus' spread throughout the United States.
"It's spreading fast. It's making its way west and we're certainly trying to stay out in front of it," Dr. Julie Gerberding, President Bush's newly appointed head of the CDC, told Good Morning America's Charlie Gibson. "It's really an infection that exists in birds, and the mosquitoes transmit it from bird to bird and sometimes people and horses. Wherever birds go, there is a risk the West Nile virus is going to follow."
While birds provide a highly mobile vector of virus transmission, they can also provide researchers with a sense of what regions may be affected next.
"States that know they have the disease and the [infected] birds can get aggressive about implementing other measures to control mosquitoes," adds Gerberding. "That can help control cases and human loss."
Pest Prevention
Researchers hope the lessons learned so far can help them limit the future spread of disease, while preventing and treating serious complications.
The National Institute of Allergy and Infectious Disease, for instance, is exploring the development of a West Nile virus vaccine as well as antiviral medications targeted specifically at treating West Nile infection. Right now, those who are infected or become ill with the disease can only have their symptoms treated.
Additionally, researchers are looking at improving diagnosis methods and conducting basic science research into the virus itself, including how it replicates and is transmitted.
But even those without advanced degrees in virology can take steps to halt West Nile transmission by preventing mosquito bites as well as stopping them from breeding. Some prevention tips include:
Avoid being outdoors at dusk and dawn. Those are times when mosquitoes are most active.
If you are outdoors during those periods, wear long-sleeved shirts and pants to eliminate the amount of skin exposed and left vulnerable to bites.
Use mosquito repellants. Those containing a chemical known as DEET are the most effective.
Eliminate reservoirs of standing water around your home. Culprits include kiddie pools, birdbaths, flower pots, wheelbarrows and clogged downspouts. Mosquitoes can use these unlikely suspects as breeding grounds.
