west nile virus

Facts

West Nile willies

For a while, West Nile Virus seemed like it had infected the headlines--dire predictions for the seasonal, mosquito-borne virus were everywhere. The media fever seems to have worn off slightly, but West Nile is still out there.

A little bit of history.

West Nile isn’t native to the Americas; the virus first showed up in North America in 1999, when tests on a dead crow found in the Bronx Zoo revealed the virus’ presence (Audubon).
It then spread quickly across the nation, with infections reaching their peak in 2002. As of 2005 and 2006, West Nile seems to have died down a bit, at least for now.

How can it spread?

Mosquitoes: Mosquitoes with West Nile are the greatest threat to humans—they can bite infected birds, carry the infection in their blood, then bite and infect humans (and horses, and other birds, while they’re at it). (CDC)

Blood Transfusions and Organ Transplants: In very rare cases, West Nile has been known to spread when an infected donor gives blood or an organ (CDC). However, since 2003 the government has been screening the blood supply for West Nile (CDC). Organ donations are not currently screened—the CDC gives several reasons (CDC) for this. Most important of these is that the screening takes time, and the need for organ transplants is usually more urgent than the need for blood. Also, there are only four (HRSA) recorded cases of West Nile spreading through organ transplants.

How West Nile Cannot Spread: (CDC)

  • Person-to-Person contact

  • Person-to-Horse contact

  • Person-to-Bird contact

  • Eating infected animals

What are the symptoms?

Despite a lot of media attention, most people with West Nile will never know they’ve had it: (CDC)

80% of victims have no symptoms.

20% of victims have mild (headache, body aches, rashes) to moderate (fever, nausea, vomiting) symptoms

Less than one percent of victims (one out of 150) will have severe symptoms (high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis)

Less than one in one thousand people (<.1%) will die from the virus. (USGS)

How many people have it?

West Nile made headlines for its speedy spread, but infection rates seem to be dropping off from their peak in 2003: (CDC)

Total reported cases, 1999-2006: 19,709 (785 deaths)

(Keep in mind that because most people don’t have symptoms, the actual number of cases is probably a little higher than this.)

By comparison - reported cases of Lyme Disease

Lyme disease, also a media darling of sorts, is a good point of comparison for West Nile: they both hit in the summer, and both are bug-borne. (Lyme is spread ticks instead of mosquitoes) Lyme disease rarely--if ever--kills, though the symptoms can be severe and debilitating. (ALDF)

  • 2004: 19,804 Cases

  • 2003: 21,273 Cases

  • 2002: 23,763 Cases

  • 2001: 17,029 Cases

How is it treated?

Vaccine: Although a West Nile vaccine for horses exists (CDC), and one for humans is in the works (NIH), there’s no sure-fire prevention strategy. The National Biological Information Infrastructure recommends wearing long sleeves and insect repellent as well as eliminating mosquito breeding sites, such as standing water. (NBII)

Spraying:

Several states have set up pesticide-spraying campaigns that have proven controversial—supporters claim that they are necessary and important to prevent the disease’s spread, while opponents note that pesticides often create resistant mosquito populations, and are toxic to humans besides. (NYT)

How much is it costing?

Hard data are hard to come by, but one study estimates that the cost 2002 West Nile outbreak in Louisiana (one of the hardest-hit areas) was $20.1 million. (CDC)

The CDC has also pegged the national cost of the 2002 outbreak at $200 million. (CBS)

Links

Did we miss something, let some slant slip in, lose a link - or do you just have something to say? Drop a line below! In the spirit of open dialogue, cJ asks you keep it civil, keep it real and keep it focused on the message, not the messenger. See our policy page for more on what that all means.

Posted In
Home