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Ah, the joys of summer: afternoons in a cool 08252012-6 pool, walks in the woods, hanging out with friends, endless reading time and a pile of books no one assigned, shorts and tank tops, mosquito bites and itchy ankles. Wait! What was that last one? Along with the perks of summer come those pesky blood-sucking insects that hover persistently, waiting for the moment to sink their proboscis into your exposed skin. This year, mosquitoes have delivered not only itchy bites but a potentially deadly virus that has sickened scores of people.

Health departments throughout the United States are reporting a record high 08252012-2 number of West Nile virus cases. The Centers for Disease Control has reported positive tests in 42 states for West Nile virus in birds, humans, and mosquitoes. At least 1,118 people have contracted the disease, the largest outbreak since 2004. 80% of those cases are in Mississippi, Oklahoma, and Texas.

08252012-7 Officials in Dallas, Texas declared a state of emergency in the wake of an outbreak. On Thursday (August 16, 2012), Dallas residents heard the hum of airplanes sent to spray the vicinity with insecticide. On Wednesday, August 22, Houston took its turn being sprayed. Blanketing an area with insecticide is rare; it has been over 45 years since Dallas officials conducted an aerial spray. States of emergency are not often declared in the United States. But then, this is an unusual year.Over a dozen people have died of West Nile virus this year in Texas. Clearly the little mosquito carries a mighty foe. How else do you stop a mosquito-borne virus? Arm yourself with a better understanding of West Nile virus. 

What you need to know about West Nile virus—

08252012-1 West Nile virus is what doctors and scientists call a vector-borne disease.  Vector-borne diseases need three things to spread: the disease microbe, a host, and a vector. “Vector” is Latin for “bearer” and in a disease cycle, the vector carries the disease microbe from one host to another. For West Nile, the disease is caused by a virus, the mosquito serves as the vector, shuttling the virus from one host to another with each bite. The mosquito does not cause the illness but spreads it. West Nile virus’ original hosts were birds and mosquitoes spread the virus to humans. Some of the most pervasive and deadly diseases are vector-borne: Lyme disease, malaria, Rocky Mountain spotted fever, West Nile disease. Mosquitoes serve as vector for several of these.

The first West Nile virus patient was diagnosed in Uganda in 1937. Sixty-two years later, in 1999, the virus first appeared in North America. Learn more about its history and its arrival to the United States and how scientists diagnosed the first American patients—avian and human. Watch four PBS video segments: West Nile arrives, West Nile in the Rockies part 1 and part 2, and West Nile in Southern California.

The Centers for Disease Control is an excellent first stop to discover what you need to know about West Nile virus. Their fact sheet covers the basics and more: What is West Nile virus? What are symptoms? Who is at risk? Read more about how West Nile virus is spread. Familiarize yourself with common myths associated with West Nile virus.


Predict ways to prevent or reduce the spread of the virus, then check your answers against the CDC’s Fight the Bite. Watch a series of six video clips designed to help you protect yourself and your community. Watch the CDC’s public service announcement: Tell Mosquitoes to Buzz Off. Pet owners may wonder if pets are at risk and how to protect cats and dogs.

Outbreak 2012—

08252012-4 The CDC has kept annual records of West Nile incidents in the United States since its arrival. View the CDC record of 2012 West Nile human infections. View this year’s incidents of West Nile virus by state. Compare these statistics to the human infections and state outbreaks for the previous year.

The CDC predicts this year’s outbreak is not yet over. Listen to the NPR story, Preventing the Spread of West Nile Virus, for more information. Hear from the mayor of Dallas speak about why he decided to authorize an aerial insecticide spray.