Northern America May Suffer New West Nile Outbreaks
Posted on: Friday, 4 July 2008, 13:10 CDT
A new strain of West Nile virus may thrive during the summer months, and is already spreading across the U.S., researchers reported on Thursday.
According to the U.S. Centers for Disease Control and Prevention, the West Nile virus infected nearly 175,000 people last year.
The virus, which is mosquito-borne, caused serious diseases such as encephalitis and meningitis in 1,227 people, caused nearly 35,000 cases of fever, and killed 117 people in 2007.
Another group of researchers reported that a new strain of West Nile has overtaken the original strain. They believe outbreaks may worsen in the North due to the new strains ability to survive hot weather.
Lyle Petersen, who leads West Nile Virus surveillance at the CDC, agreed. He believes North America may even suffer more than other regions of the world.
In 1999 the U.S. was introduced to West Nile during a steamy summer in New York City.
"In Europe, Africa and West Asia, where the virus was previously endemic, you'd see these big outbreaks and then they'd kind of disappear and then not come back for years on end," Petersen said.
"What we have seen in the United States, we've had repeated outbreaks every single year since 2002 -- in fact, big outbreaks. This is an unusual pattern that not been seen before."
Researchers like Petersen, and Marm Kilpatrick of the Consortium for Conservation Medicine and the University of California Santa Cruz, agree that hot American summers may be the culprit.
Earlier this week, Kilpatrick showed that the new strain duplicates faster in mosquitoes when the weather is warm.
"The warmer the temperature, the faster it replicates in mosquitoes and the faster the mosquito can transmit the virus," Kilpatrick said.
"It also indicates that increases in temperatures due to global climate change would have major effects on transmission of the virus."
West Nile virus normally infects birds but can spread to humans when mosquitoes bite both.
According to Kilpatrick and Petersen, mosquitoes transmit many diseases effectively in warm weather.
Petersen reported that researchers could no longer find the original West Nile strain. The strain seems to have evolved naturally.
The Kilpatrick findings fit in with what the CDC has seen, Petersen said.
"What we observed is, at least in temperate climates, these big West Nile Virus outbreaks tend to occur in heat waves."
But Petersen believes it is still too soon to link climate change with West Nile Virus outbreaks.
In hotter climates, mosquitoes die quicker, and therefore, cannot spread the infection as easily. According to Kilpatrick, the new strain should not have an advantage in southern states, but could make significant ground in northern states.
"It is probably going to push the northern boundary farther north," Kilpatrick added.
Source: redOrbit staff and wire reports
 |
 |
User Comments (1)
| 1. |
Posted by Mike on 07/05/2008, 19:16 Interesting! |
RSS Feeds