State public health officials sent letters in mid-October to 612 people who received treatment at Dr. Tahir Javed's clinic between March 1, 2000, and Dec. 31, 2001, asking them to be tested for the blood-borne pathogen.

At least 430 people were tested before Friday's deadline.

It takes about two weeks for tests to be completed. Those who were tested early and had negative results have received letters.

If tests come back positive, a confirmation test will be conducted at an out-of-state clinic before the patient is contacted, said Dr. Tom Safranek, state epidemiologist.

There was no immediate word on how many positive or negative cases there were.

No one was in immediate danger, and testing for the disease was voluntary.

In most patients, hepatitis C has no symptoms. It can cause liver failure but usually only after 20 years or more, Safranek said.

Investigators suspect the outbreak began with a patient who came to the clinic with the disease.