A scientist believes people living in the Northeast might be at greater risk of contracting Lyme disease this year than ever before.

That's the unsettling assessment by Richard S. Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies in Millbrook, N.Y.

The mild winter didn't help, but Ostfeld primarily bases his theory on the record-low acorn crop this past fall.

Two autumns ago, the mast crop in the Northeast was at a 20-year high. That led to a huge population of white-footed mice, the main carriers of Lyme disease.

But the Cary Institute last fall recorded the smallest acorn crop in its research history. That likely meant a significant die-off this past winter in the population of white-footed mice.

The mice are popular hosts for deer ticks, also known as blacklegged ticks, which transmit bacteria that causes Lyme disease in humans.

Without the mice around as hosts, the deer ticks this spring and summer will be looking for other warm-blooded creatures to suck blood from — namely, humans.

That's not good news for Pennsylvania, which had the most Lyme disease cases in the nation in 2010, with 3,805 confirmed or probable cases.

Within the state, the highest incidence of the disease is in the southeast.

Not everybody, however, goes along with Ostfeld's theory, including Steve Jacobs, a Penn State Extension urban entomologist.

Jacobs doesn't doubt that the upcoming season will be tick-prone, but is dubious about calling it the worst-ever based on speculation about mice populations.

"We just don't have a handle on this disease," he said. "We don't know when populations of ticks are going to explode."

White-footed mice do affect tick numbers, he said, but so do the number of deer in an area and the weather.

Mild winters are not that strong a factor because deer ticks are cold- tolerant and are buried in insulating leaf litter when it's cold, Jacobs said.

Conversely, a dry summer with low humidity could kill large numbers of ticks, Jacobs said, because they can't survive in those conditions.

He agrees with Ostfeld that this will be a year to watch out for ticks.

"Ticks are expanding and every year we see more and more," he said.

The state Department of Health's recommendations for avoiding deer ticks include using repellents, wearing long-sleeved shirts and pants and checking for and promptly removing attached ticks.

The Health Department recommends an insect repellent containing 10- to 30-percent DEET placed on exposed skin (except for the face) and clothing. Also, do not place it on the hands of young children.

If a tick is found attached to your body, use tweezers to remove it as close to the skin as possible.

"Avoid folklore remedies such as 'painting' the tick with nail polish or petroleum jelly, or using heat to make the tick detach from the skin," the Health Department advises.

"Your goal is to remove the tick as quickly as possible — not waiting for it to detach."

acrable@lnpnews.com