CONCORD — State investigators are looking into the possibility the hepatitis C outbreak at an Exeter Hospital lab was caused by an employee abusing hospital narcotics, the state's public health director said Saturday.

“It has happened before in other states,” said Dr. Jose Montero.

Four more patients who had been treated at Exeter Hospital's cardiac catheterization lab have been diagnosed with hepatitis C, the state Division of Public Health Services announced Saturday.

That brings to 14 the number of individuals diagnosed with the same strain of the virus linked to the facility, including one hospital employee.

And with the source of the outbreak still unknown, Montero told the New Hampshire Sunday News that one potential cause under investigation is “the possibility of drug diversion” by a hospital employee.

In previous outbreaks at other facilities, he explained, the cause of infection eventually was traced to an employee who used a syringe to take narcotics and then used the same syringe on a patient, passing on the virus in that manner. “That's one of the possibilities,” he said.

He said state investigators also are looking at the hospital's “policies and procedures and the use of supplies and disposables.”

Exeter Hospital has contacted 879 patients who were treated at the hospital's cardiac catheterization lab (CCL) and its recovery unit between April 1, 2011, and May 25 of this year, according to a hospital news release.

All 14 patients who tested positive have been notified. It will take seven to 10 days from the time a patient's blood is drawn for his or her primary care physician to receive information about negative test results, according to the release.

Montero said the discovery of additional cases was expected. He noted the state has tested 473 blood samples that showed no sign of infection, with 55 additional tests pending.

He also expects the hospital will send blood samples from about 350 additional patients to the state lab to test for the strain of the virus that is linked to the outbreak.

Montero said there is no need to expand the testing “at this time.” But he said if the state continues to find positive cases involving individuals who had procedures done at the CCL, the time period could be pushed back even earlier than April 1, 2011.

The public health lab's testing also turned up two additional cases of hepatitis C, but both involved different strains of the virus and were determined to be unrelated to the hospital outbreak, Montero said.

Hepatitis C, a viral infection transmitted by blood, causes inflammation of the liver, which can lead to chronic health problems. It is passed from person to person through contact with an infected person's blood, according to the state health department.

The hospital's CCL closed after the first hepatitis C cases were discovered, but the state health department determined it was safe to resume normal operations starting last Tuesday.

Any patients who were treated at the CCL beginning April 1, 2011, should call Exeter Hospital's Information and Referral Center at 580-6124 to make an appointment for testing.

-- For information about hepatitis C, go to the websites for the Centers for Disease Control and Prevention (www.cdc.gov/hepatitis) or the state Department of Health and Human Services (www.dhhs.nh.gov), or call the state Bureau of Infectious Disease Control at 271-4496.

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Shawne Wickham may be reached at swickham@unionleader.com.