Hepatitis C Spread Through a Nurse's Drug Diversion: Washington, 2017–2018

Between January 22 and March 23, 2018, a local health department in Washington learned that two people had been diagnosed with acute hepatitis C virus (HCV) infection. Neither had any of the behaviors that usually put people at risk. What they shared was a hospital emergency department (ED): each had been given injectable opioids there by the same nurse, on December 6 and December 16, 2017.

The investigation that followed, reported in CDC's Morbidity and Mortality Weekly Report by the Washington State Department of Health, the Tacoma-Pierce County Health Department and CDC, uncovered an outbreak of at least 12 HCV infections among patients of a nurse who admitted diverting injectable narcotics for her own use. Drug diversion means taking a drug prescribed for one patient for someone else's illicit use, and tampering with injectable narcotics can expose patients to infection.

Two patients, one nurse

The first patient, a man in his 60s, came to the ED with abdominal pain on December 6, 2017, and received injectable narcotics from two nurses. He returned on January 12, 2018, having had jaundice and abdominal discomfort. His liver enzymes were raised and he tested positive for HCV antibodies (anti-HCV) and HCV RNA. In December 2016 he had tested negative in routine screening offered to people born in 1945–1965.

In February 2018 both nurses who had treated him had withdrawn injectable narcotics from the automated dispensing system far more often than other staff, more than 3 standard deviations above the mean. On March 19 one of them, nurse A, tested positive for anti-HCV but negative for HCV RNA; a week later her RNA test was positive at a level below 15 IU/mL, too low to sequence. She had tested negative for both when she gave blood in 2013. She admitted diverting injectable narcotic and antihistamine drugs from patients for her own use at the ED, without saying how. Nurse B tested negative for anti-HCV on March 27. Neither nurse had HIV or hepatitis B.

The second patient, a woman in her 50s, was given injectable narcotics for neck pain by nurse A on December 16, 2017. She returned on March 23, 2018, with jaundice and tested positive for anti-HCV and HCV RNA.

CDC's Division of Viral Hepatitis sequenced virus from both patients. Both carried HCV genotype 1a with more than 96% similarity in nucleotide sequence, the level that points to a common source. Nurse A's own virus could not be compared because her levels were too low.

Finding everyone exposed

Nurse A worked in the ED from August 4, 2017, to March 23, 2018. The hospital identified 2,985 patients who had received injectable narcotic, sedative or antihistamine drugs in the ED while she was on duty, whether or not she was caring for them. On April 28, 2018, it wrote to the 2,762 (93%) who were still living, including 208 (7.5%) she had treated herself, explaining the possible exposure and offering free testing for HCV, hepatitis B and HIV.

By November 1, 2018, 1,863 (67%) had been tested, including 175 (84%) of nurse A's own patients.

No one tested positive for HIV and no new hepatitis B infections were found. No other ED worker had treated most of the 13 patients with the matching virus.

How the outbreak unfolded

Twelve of the 13 patients with matching virus were newly diagnosed and had received injectable drugs from nurse A between November 22 and December 26, 2017. The thirteenth already had chronic hepatitis C and had been given injectable narcotics by nurse A twice, on August 17 and November 8, 2017. The investigators suggest nurse A may have picked up the virus from that patient on November 8 and then been infectious from November 22 to December 26, when at least 12 of her patients were infected.

The evidence against her as the source was strong on three counts: she used the dispensing system unusually often and admitted diversion; she had turned antibody-positive after an earlier negative test and then tested RNA-positive, a sign of recent infection; and she was the only link common to all 13 patients with matching virus. Infections among patients she had not treated were caused by strains unrelated to one another and to the outbreak strain.

Earlier investigations elsewhere had found health care workers passing HCV to patients while diverting drugs, in some cases by injecting themselves with the patient's drug, refilling the syringe with water and injecting the water into the patient. Because people can be reinfected after clearing the virus, nurse A may have had more than one acute infection between 2013 and 2018, and patients infected outside the outbreak period may have been missed.

What followed

Every screened patient with a positive RNA result was referred for care, including hepatitis C treatment for those who developed chronic infection. The local health department continued reaching out to the 33 (16%) of nurse A's patients who had not yet been tested. The Washington State Nursing Commission investigated nurse A's conduct and suspended her license.

U.S. health care facilities are required to prevent, detect and report any loss, diversion or theft of controlled substances. The report urges them to store controlled substances securely, actively monitor dispensing systems and access logs to catch unusual patterns, and have a plan for testing exposed patients and preventing further spread when diversion is found.

Sources

• Njuguna HN, Stinson D, Montgomery P, et al. "Hepatitis C Virus Potentially Transmitted by Opioid Drug Diversion from a Nurse — Washington, August 2017–March 2018." MMWR 68(16). https://www.cdc.gov/mmwr/volumes/68/wr/mm6816a3.htm
• The report's figure is not reproduced here because the report was prepared jointly with state and local health departments.
• The report gives 25% for the 15 other patients with active infection, which does not match its counts; this page gives the counts only.