JOHN YANG: Summertime means more time outdoors, and that means more chances for tick bites and the risk of Lyme disease.

According to the Centers for Disease Control, as many as 476,000 people in the United States contract Lyme disease every year.

And climate change and our encroachment into wilderness areas means ticks.

And the Lyme disease causing bacteria they can carry are more common in more places.

Dr. Linden Hu is an immunology professor at Tufts University Medical School.

He's also co-director of the Tufts Lyme Disease Initiative.

Dr. Hu, what does Lyme disease do to us?

What are the symptoms and how serious can it be?

DR. LIDEN HU, Immunology Professor At Tufts University Medical School: Yeah.

So Lyme disease typically enters into your body after the bite of a tick, and the bacteria cause a rash, usually right at the spot of the bite, and then spread rapidly from there to other skin sites, but can also get to the brain, can get to the heart, and can get to the joints, causing more severe disease.

JOHN YANG: How easily is it treated?

LINDEN HU: So for most people, antibiotics are pretty effective, especially if you get treated early.

And there are a number of different antibiotics that work very well against Lyme disease.

There are a small percentage of people, probably somewhere in the range of ten to 15%, who will continue to have symptoms after treatment for Lyme disease.

JOHN YANNG: And have ticks been spreading into more areas of the country, and why is that?

LINDEN HU: I think it's a combination nation of things.

The ticks have spread a little bit, but they've always been there.

The disease has spread into the ticks so that more ticks in more areas going up further north along the northeast shore and further south again along the Atlantic Seaboard are carrying Lyme disease now and I think that's just the natural spread.

As more and more ticks get infected in the air area and then continue to move outwards.

JOHN YANG: Any idea of why more ticks would become infected?

LINDEN HU: I think it has to do with the numbers of infected animals.

So the ticks pick up the infection from mice and other small rodents as well as birds and as they spread and they don't move very fast or very far geographically as that gradually spreads and more infected mice spread down, you get more infected ticks in those areas.

JOHN YANG: It used to be you thought of this as something you got when you went hiking in the deep woods, but now is it prevalent in suburban areas as well?

LINDEN HU: Yeah, I think, you know, both the deer that are very important for the ticks but don't carry Lyme disease as well as the mice have become suburban creatures and so they're living amongst us in the suburbs all the time, so there's more and more interaction between people and the ticks that are infected.

JOHN YANG: Does climate change play a role in any of this?

LINDEN HU: It's interesting, it's hard to predict exactly what climate change does.

You know, the warmer weather certainly can mean that more mice and more deer survive the winter, which can mean more ticks and more infection.

But it can also mean that when there are periods of drought, these ticks need moisture to survive during the summers and if there's a long drought you can actually see decrease.

So it's variable what climate change could do to Lyme disease year to year.

JOHN YANG: Earlier you said it's important that Lyme disease be treated early.

Should anyone who gets a tick bite go to the doctor?

Or is there some warning sign that would trigger someone to go to the doctor?

LINDEN HU: Yeah, I think the funny thing with Lyme disease is that most people don't even know that they've been bitten by a tick.

So, certainly if you've been bitten by a tick, it's probably worth giving your doctor a call because there are preventative medicines you can take if you take it within the first couple of days after you've been bitten.

I think the key thing to look out for if you know that you've been bitten by a tick for Lyme disease is to watch for that erythema migraines rash.

JOHN YANG: And there are other tick borne diseases, it's not just Lyme disease, there are other reasons why you should be wary of a tick bite.

LINDEN HU: Absolutely.

And these ticks that carry Lyme disease also carry five other diseases.

Most of those don't have anything as characteristic as the rash of Lyme disease.

So what you have to be watching out for are fevers, chills, muscle aches, things like that happen in the.

JOHN YANG: Summer and talk about the research that's going on now.

What are -- are there potential new developments in prevention, in treatment?

Is a vaccine possible?

LINDEN HU: Yeah, I think there have been advances, especially on the vaccine front, even in the last couple of years.

So, there is a human vaccine that is now in phase three trials, which is the final phase of trials before approval that I think we're probably a couple of years off from.

It's very similar to a previous vaccine that was approved and used in U.S. maybe 20 years ago, but this is a new variation on that, and we're very hopeful that it'll have very similar effects without side effects.

The other thing that just got approved last week is a vaccine for mice, actually.

And there if you can treat the mice and vaccinate them and prevent them from carrying the disease, then the ticks don't get it.

And then if you don't have infected ticks, you have less infected humans.

JOHN YANG: How do you vaccinate mice in the wild?

LINDEN HU: So, yeah, you're right.

Mice do not line up for vaccines.

So what you need to do is you need to put it in food and they put it in baits that the mice will eat, and they become vaccinated that way.

JOHN YANG: Dr. Linden Hu of Tufts University.

Thank you very much.

LINDEN HU: Thank you so much.