WASHINGTON —  Sen. Charles Schumer, D-N.Y., is receiving treatment to prevent Lyme disease after being bitten by a tick during a recent tour of dams in upstate New York.

Schumer, a senator since 1998, apparently was bitten during a May 7 dam tour in the Hudson Valley region. He and other lawmakers have called for improvements to many small dams in the area to prevent flooding.

"I went tramping through the woods with Congressman John Hall to check dams," the senator said.

He later found a tick, and spotted a telltale "bulls-eye" mark on his leg that is an early sign of infection.

Schumer is now undergoing a 21-day treatment with antibiotics, which can cause fatigue in some patients.

He said he hasn't noticed any symptoms and is being treated "to prevent it from developing into the disease."

Lyme disease is transmitted by the black-legged tick, also known as the deer tick.

Symptoms include lethargy, joint pain, fever, limping and loss of appetite. Even after treatment, symptoms can recur in some patients.

Last summer, amid concerns that a new, aggressive type of tick had migrated from southern states to New York, Schumer proposed legislation that would have authorized $100 million for Lyme disease research.