West Nile outbreak falls short of 2003 numbers

We're still more than two months from the end of the year, but the number of West Nile Virus (WNV) cases in the United States has already exceeded the second-highest annual total.

As of Tuesday, 4,531 cases of West Nile have been reported to the Centers for Disease Control and Prevention, including 183 deaths. This means the case count has surpassed the totals for 2006, when there were 4,269 cases including 177 fatalities.

But at this point in the year, it's unlikely that another 5,000 cases will develop, so the 2012 WNV season probably won't be the worst on record. That was in 2003, when there were 9,862 illnesses and 264 deaths reported.

Texas continues to be hardest-hit state, where more than a third of the total number of illnesses and nearly a third of the deaths have occurred.

About a month ago, Dr. Lyle Petersen, director of the CDC's Division of Vector-Borne Diseases, said he believes "the worst part of the epidemic is behind us."

Given that the Indian summer in some parts of the country is waning and cold temperatures have already moved into other regions, the environment for an expanding mosquito population is becoming more hostile.

"The cooler temperatures are going to lower the risk of mosquito-borne illnesses like WNV," says Dr. Erin Staples, a medical epidemiologist at the CDC's Arboviral Diseases Branch in Fort Collins, Colorado.  But she cautions that mosquito activity is still high in some regions, like the South, so people still need to protect themselves. Some protection tips:

– Use insect repellent.
– Wear long-sleeved shirts and long pants when possible.
– WNV mosquitoes are most active from dusk to dawn, so avoid being outside at those times if possible.
– Empty flower pots, water dishes, bird baths and anything else that may collect water and be potential mosquito breeding grounds.

Most cases of WNV never get reported because 80% of those infected will never have symptoms, according to the CDC. The other 20% go on to develop West Nile Fever, which can lead to symptoms including fever, headaches and body aches and the occasional rash.

About 1 in 150 of those people go on to develop a serious disease that can lead to brain infections like encephalitis or meningitis, which can be life-threatening.