GWEN IFILL: Next: the rising toll of Lyme disease and the questions surrounding treatment.

Jeffrey Brown has the story.

JEFFREY BROWN: Lyme disease was first identified in the 1970s, but it now turns out that it's much more common than previously estimated, about ten times more.

The CDC reported this week that an estimated 300,000 Americans get the tick-borne disease every year. Symptoms can include fatigue, fever, skin rashes, and a headache. Left untreated, it can lead to arthritis, facial palsy, and problems with the nervous system. The number of cases has been increasing. Most are concentrated in the Northeast, with 96 percent of them in 13 states.

There's also been a long-running debate around treatment for the disease.

And for all this, we turn to Beth Daley of The Boston Globe. She has been working on a series about the disease and its impact.

Well, welcome to you.

So, first of all, how significant are these new numbers, more cases than previously thought?

BETH DALEY, The Boston Globe: You know, they're really significant, politically especially.

For years, scientists and those, I would say, who work with patients who have Lyme disease have felt like the numbers were off. There were estimates in the '90s that said Lyme disease was under-reported by three- to 12-fold, but no one had a really good hand on those numbers.

So, you know, sort of politically, when you talk about funding to protect people against Lyme, it was sort of really low on the totem poll. But with this new research, which is not yet complete, and the numbers could go much higher, 300,000 people is far different than the 30,000 that the CDC has been talking about.

JEFFREY BROWN: You know, you talk about under-reporting. How well understood is Lyme disease, even at this point?

BETH DALEY: Yes.

So, some things about Lyme disease, scientists know about, but there's much to be discovered. And this sort opens the door to this incredible controversy in Lyme disease that many people aren't aware of, that some doctors have had to travel with bodyguards to protect themselves from patients who have given them death threats.

It's a very controversial disease, in large part because there are so many questions about treatment and lingering symptoms of people with Lyme and if people actually have Lyme disease who are sick.

JEFFREY BROWN: Well, just to get to the controversy, first, tell us that what is the normal course of treatment? What is it -- how does it stand now?

BETH DALEY: So, traditionally, you get bit by a tick, you might see a rash or feel a fever or you go to the doctor.

They sort of diagnose you through tests or clinically. And you would probably get three to four weeks of oral antibiotics. And that is -- most people agree, is usually enough to knock the disease from your system completely. Sometimes, it goes a little bit longer if it's more involved, but short courses of antibiotics overall.

However, a large segment of people believe that their symptoms linger for years sometimes, and the only way to treat them is to use long-course antibiotics, often through intravenously or orally, for years on end to -- so they can live, so they can really get out of bed in the morning.

And that is a controversy. The medical establishment says, listen, there's no proof this longer course of antibiotics work at all. And these Lyme patients say, yes, it does. Just look at us. We can get out of bed in the morning.

And a lot of the debate centers on, a lot of insurance companies won't pay for those antibiotics. And, as a result, lots of people go bankrupt. They lose their house. They sell their car to pay for these drugs.

JEFFREY BROWN: So, you have talked to a lot of people in these circumstances who have been told that while the treatment is done, you should be cured, but they still know something is going -- they feel something is going on?

BETH DALEY: They do.

And it's actually complicated by the fact that the medical establishment acknowledges and agrees that up to 25 percent of people who have been treated for Lyme have lingering symptoms, sometimes for days, sometimes longer, but they believe sort of the -- it sort of falls off very quickly.

But there is something -- something is going on there, and they're not sure quite what it is or what -- it could be many things. But what we're talking about are people who have been sick for years and months and months and months, and they just don't get better. They complain of fatigue. They complain of being tired. They complain of shooting pains, something called brain fog, that they just can't really remember how to drive home in the middle of the day. And those are the symptoms and the -- that's where the debate lies.

JEFFREY BROWN: And I know you have you been at a conference even that is ongoing now there in Boston about Lyme disease.

Is there -- how much is there a debate within the research establishment there about the treatment?

BETH DALEY: Yes, that's a really good question.

There doesn't seem to be a great deal of debate within the medical establishment that patients with Lyme who have lingering systems should use long-course antibiotics. No one I know has said that to me.

But what is interesting is that, there is slowly -- because people agree that some people remain sick, there's really good research going into why. There's some work at Yale that is looking at, maybe the bacteria, once it's killed off by antibiotics, leaves some bits of protein behind.

There's a study at Tufts that says, well, maybe -- in animal studies, the bacteria does survive. It seems weakened in some way and maybe doesn't make people sick, but they're trying to find out if that is true in humans. And that may be part of the answer.

JEFFREY BROWN: And just very briefly, as you said, so, the new numbers, though, are expected -- you expect them -- will push this debate forward even politically?

BETH DALEY: I think so.

If you just consider Massachusetts, which is -- where The Boston Globe is, we spend $10 million a year and more on mosquito control. We spend $60,000 on tick-borne diseases. The disparity is great. And as Lyme disease burden grows on public health, hopefully -- I think people are hoping that the political forces will come to bear, that they will start seeing money to eradicate ticks in the environment or help people learn more about them.

JEFFREY BROWN: All right, Beth Daley of The Boston Globe, thanks so much.

BETH DALEY: Thank you.