We have news tonight about the explosion of the west nile virus. Now in 47 states. 41 have died. Look at this, one month ago, 29 reported cases. Tonight, more than 1,100. The cdc warned the next few... See More
We have news tonight about the explosion of the west nile virus. Now in 47 states. 41 have died. Look at this, one month ago, 29 reported cases. Tonight, more than 1,100. The cdc warned the next few weeks could be the worst. And dr. Richard besser is standing by right now to give us the details about the symptoms. First, here's abc's clayton sandell out in the field. Reporter: In this latest west nile outbreak, half of the cases are here in texas. THAT'S WHERE claire McCall was and she, years later, is unable to work. I have no short-term memory. I have trouble with word recall, trouble with remembering anything that has happened in the last five minutes. Reporter: Mccall is one of the few, less than 1% of west nile patients, that have the type of illness that makes headlines. Her first symptom, high fever. I was in total paralysis. Reporter: Her paralysis lasted four months. 60% of people with the most severe cases of west nile will still suffer symptoms five years later. Once the person has the infection, and if the infection becomes severe, the individual patient can experience lasting and permanent brain damage. Reporter: So, if you've been bitten, how do you know if you have west nile, if you're one of those rare dangerous cases? The vast majority, 80%, won't have any symptoms. Their bodies fight off the disease. For another 19%, the worst symptoms are mild, headaches, fever, nausea. But for less than 1% of people with west nile, severe symptoms, convulsions, paralysis, possibly even death. Salvador is out setting traps, hoping the airlierial assault swatted down the danger. If there's less mosquitoes, good news. Reporter: Mosquito abatement programs are one of the most effective ways to battle this, but they're threatened by budget cuts. Diane. Now dr. Richard besser. Everybody's got a mosquito bite, is going to be worried. How many days before symptoms set in? It can be as short as two days or two weeks. Two weeks? That's right. Let's go over again, why are people over 50 more at risk, more vulnerable? Well, for that severe disease, the virus has to cross over something called the blood/brain barrier, designed to keep infections out. We don't know for people over 50 if it's getting through easier or if their immune system isn't fighting it off. Those people as well as people are high blood pressure or heart disease are at more risk for severe disease. One of the things that drives us crazy is the symptoms we are given. The symptoms for thousands of things, fever, headache, nausea. How do you know if it's west nile? If you have flu-like symptom, you can treat that at home. If you develop confusion, weak neck, go see your doctor right away. They can give a medicine to decrease the swelling in the brain and reduce the amount of nerve damage. It won't be a close call if you have a severe symptom? It won't be a close call. For most people who have this infection, they won't even know it, their body will fight it off and they'll never get it again. But the severe symptoms will be marked. So go to the doctor right away. Thank you, rich besser.
This transcript has been automatically generated and may not be 100% accurate.