Another HCV outbreak rocks ambulatory care

Seven infections, 1,200 patients alerted in NC

In a finding that will increase national calls for oversight of ambulatory care settings, seven patients reportedly acquired hepatitis C infection while undergoing stress tests at a cardiology practice in Larinburgh, NC. Initial findings suggest patient-to-patient transmission due to unsafe injection practices, the state health department reports.

The report comes on the heels of an HCV outbreak among outpatients in Las Vegas, which led to widespread demand for more regulation and oversight of freestanding ambulatory care clinics. North Carolina officials are trying to contact some 1,200 patients who were seen at the office of Matthew Block, MD, at the Scotland Cardiology clinic from June 25, 2007, through Aug. 26, 2008. The patients are being urged to be tested for HCV, hepatitis B, and HIV.

"We suspect that this was patient-to-patient transmission due to unsafe injection practices, but we have not pinpointed the specific practice like they were able to do in Nevada," says Zack Moore, MD, medical epidemiologist with the North Carolina Division of Public Health.

The date range corresponds with adoption of a procedure in the clinic that involved administering the radioactive agent technetium, a "tagging agent" used to identify potential heart problems via nuclear imaging. Investigators are trying to determine if an infection control breach involving needles and/or medication vials occurred during the procedure, he says. "We suspect that may be the case but we did not see that in our inspection — in our observations," he says. "They have denied reusing any of those [technetium] vials for multiple patients, but that is something we are certainly looking at as a possibility."

Two distinct clusters

Regarding the seven infected patients, investigators have identified two clusters on two different dates with distinct genotypes. That suggests patient-to-patient transmission on the days in question rather than a provider-to-patient route, says Moore, declining to say if any staff member in the practice was HCV positive. "There were clusters of four patients one day and three on another," he says. "Within each of those clusters we sequenced very closely-related viruses — indicating a common source of infection. We were never really suspicious of a single health care provider as a source because we knew that the patients fell into two different clusters [by] genotype."

No source patients have been identified among the clusters. "We are still looking into that, but none of the patients were aware of having HCV and had not been diagnosed with HCV [previously]," he says. "HCV is often asymptomatic, so we suspect that there was a person with chronic infection among those two clusters."

The health department was alerted about the outbreak by a clinic patient who tested positive for HCV. "He is a frequent blood donor and had clearly documented evidence of new infection," Moore reports. "He had no traditional risk factors but several health care exposures, so we started looking into those."

While the specific cause has yet to be identified, it is virtually certain from the epidemiological evidence that transmission involved a basic breakdown in standard infection prevention practices, he says. "In order for this to spread from person to person there has to be some sort of breach in infection control," Moore says. "That's clear."