Modified
Mosquitoes - One of the world’s biggest killers, malaria
takes millions of lives each year and that number is on the rise.
But genetic engineers are working on modifying mosquitoes so they
can’t transmit deadly diseases. (1/28/03)
Climate
and Disease - As our planet heats up, diseases once thought
extinct, along with other diseases previously unknown to humankind,
gain a foothold in temperate areas. How can we protect ourselves
against these emerging diseases? (4/27/00)
Elsewhere on the web
CDC
West Nile homepage
West
Nile virus maps - USGS
Division
of Vector-Borne Infectious Diseases - CDC
Warmer months are coming, and that means another summer of coping with West
Nile virus.
And as this ScienCentral News video reports, scientists are now wondering if
the virus may be racking up frequent flier miles.
Jet-Setting Mosquitoes
Scientists studying the deadly West Nile virus have discovered the disease
may have found a new way to spread across the United States—via airplane.
The disease first appeared in the United States around the New
York City area in 1999. Since then it has spread to nearly every state
and, according to the Centers for Disease Control and Prevention, was responsible
for 274
deaths in 26 states in 2002.
While mosquitoes carry the disease to humans, mosquitoes get the virus from
sick birds. Until now, it’s been migration of those birds that's been
the main method of spreading the disease from state to state.
"Last year we were fairly confident the main route of transmission of
West Nile was in migratory birds," says Andrew
P. Dobson of Princeton University. He explains that the pattern had followed
migratory routes: "It started in New York in the summer, it spread down
the eastern seaboard, with migratory birds up the other side of Appalachia,
back down into Texas. We thought it would zigzag across the United States.”
A deadly outbreak of the disease in the South, followed by further reports
in the Midwest seemed to confirm the pattern. Near the end of 2002, the Centers
for Disease Control reported 60 deaths in Illinois, 50 in Michigan, 31 in
Ohio and 24 in Louisiana.
But then the disease took a great leap westward, turning up in a human in Los
Angeles and a horse near Seattle.
"That suggested it was moving much more quickly (and) that there are other
routes of transmission,” says Dobson. That route, he explained, might
very well be if a mosquito hitched a ride, probably on a commercial airplane.
How could they hitch a ride? “Some people pack in a hurry,” says
Dobson. “They may accidentally trap mosquitoes in their luggage.”
He adds, "So it looks as if the initial movement that may have been dominated
by birds is also now being complimented by perhaps movement of mosquitoes
probably on public transport."
Dobson speculates that, like international flights, the planes themselves may
have to be sprayed prior to landing. At least it’s one way to keep West
Nile (along with other diseases and pests) from racking up frequent flier
miles and getting a stronger foothold in the country.
Fast Facts
• In 2002, 44 U.S. states reported some sort of case of West Nile virus
in either humans or animals. The only six without a reported case were Oregon,
Utah, Nevada, Arizona, Alaska and Hawaii.
• West Nile Virus was first diagnosed in 1937 in the West Nile area of
Uganda. Other parts of the world have also experienced outbreaks. They include:
Algeria in 1994, Romania in 1996-97, the Czech Republic in 1997, the Democratic
Republic of the Congo in 1998, Russia in 1999, the United States in 1999-2001,
and Israel in 2000.
• According to the Centers for Disease Control, there are several things
you can do to reduce your risk from West Nile: use insect repellent; drain
standing water; wearing long-sleeved clothing. For details and other suggestions,
go to the CDC's
prevention
page.
