MORRISVILLE — Wake County animal control workers are trying to identify and warn the people who were exposed to a litter of puppies in Morrisville. More than 50 people might require treatment because one of those puppies was found to have rabies.

There were seven puppies in all in the chow-shepherd mix litter. On Tuesday, one pup began to show signs of illness, and bit its new owner. Tissue from the euthanized dog was tested at the state laboratory. Results confirmed the puppy was rabid.

At least 20 people in the owner's neighborhood are now undergoing a series of anti-rabies shots because they handled the cute 4-month-old puppy.

Because the other puppies from the litter might also be carrying the virus, it is important to account for all the dogs and their present owners.

The puppies' mother was vaccinated against rabies, but five of the seven puppies dragged a raccoon carcass into their Morrisville yard about a month ago. Two of the puppies had already found homes prior to the raccoon incident. One remained with the mother dog's owners. Another is believed to have been killed by a car.

One dog has been traced to a Franklin County family. Two dogs remain unaccounted for.

Dickie Sloop, Wake County's animal control program director, said that three puppies have been tested for rabies, and only the originally suspect dog has been found to be rabid so far.

Raccoons show the highest rate of rabies in Wake County. In 1996 41 tested positive. Since July 1994, 83 animals -- 6 pets, and bats, raccoons and foxes -- have tested positive for rabies in Wake County.

To reduce exposure to animals from the wild, people are advised not to leave water or food outside for pets during the night and not to leave garbage outdoors in accessible places. Pets should also be vaccinated against rabies as soon as possible.

To better inform people of the danger of rabies, information packets are being distributed to physicians, the media and veterinarians' offices. Science teachers and health nurses in Wake County schools are getting special training.