A healthy newborn boy, wearing only a T-shirt and wrapped in an orange towel, was left early yesterday morning in a picnic basket outside an Alexandria public health center. Attached to the brown wicker basket was a note reading: "Please take care of my baby. I'm too sick to take care of it."

The infant, dubbed "Baby Christopher" by hospital workers, was believed to have gone undetected for about an hour. "I thought it was somebody's lunch," said receptionist Phaye Russell, who had spotted the basket on her way to work.

Larry Daniels, a health center clerk, discovered the baby when he heard his soft cries. "I went to reach for the door," he said, "and I heard crying. I looked down, and I didn't see any baby. Then I saw the basket, and I said, 'Uh-oh.' "

A woman claiming to be the baby's mother telephoned the hospital at least three times last evening, according to hospital spokesman David Norcross. "We've had several contacts with her, but we can't keep her on the line long enough."

Norcross said a social worker was available to talk with her, but the woman sounded very emotional and hung up quickly each time. "She's torn," Norcross said.

The blue-eyed, brown-haired boy was taken from the Flora Krause Casey Health Center to the Alexandria Hospital at about 9 a.m., where doctors pronounced him in good health.

A hospital statement said the baby, who had a surgical clamp on his umbilical cord, was believed to be less than a day old and not a premature birth. A large yellow stuffed teddy bear was taken from the hospital nursery and placed on the top of his glass isolette. A white blanket and pacifier were placed by his side and his right ankle sported a white plastic tag identifying him as "baby boy."

The hospital was inundated yesterday with telephone calls from people seeking to adopt the baby and volunteering to babysit it. Hospital officials posted a guard nearby, fearing a recurrence of the 1979 infant kidnaping at George Washington University Hospital in Washington. "We've got a lot of very eager couples who would like to take that baby home," said Norcross.

Social worker Beverlee Heintzelman said, "It would help the baby if we could find out what sort of medications the mother might have been taking, or anything like that."

If his mother does not claim him, Heintzelman said, the baby will released to the Alexandria Department of Social Services within a few days.