by Charles John Palenik, MS, PhD, MBA
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In early January 2008, through routine disease investigation and surveillance activities, the Southern Nevada Health District identified a cluster of three cases of acute hepatitis C.
Local physicians reported the cases to authorities. In the end, six case patients reported undergoing procedures requiring injectable anesthesia at the Endoscopy Center of Southern Nevada. A seventh case came from a sister facility of the ECSN. Five of the cases had procedures requiring injected anesthesia on the same day. The SNHD contacted the Centers for Disease Control and Epidemiology, and within a week, SNHD and CDC personnel met with ECSN management. A review of clinic records, patient charts, and interviews with current and former staff members followed.
Investigators detected unsafe injection practices related to the administration of anesthesia medication, which placed patients at risk of exposure to bloodborne pathogens. This was sufficient to warrant notification of patients of their risk and to recommend testing for bloodborne pathogens (HCV, HBV, and HIV). The basis of the decision was the identification of the unsafe injection practices and the determination that these practices had been a standard procedure at the clinic since its remodeling in March 2004.
On Feb. 7, the investigators requested a list of patients and specific contact information from March 2004 through Jan. 7, 2008. The clinic provided 39,592 names. Verification of the list's completeness was not possible at the time, and the information provided by the clinic did not include procedure dates. Reports of treatment from former patients not on the list soon started to appear. The SNHD established the Hepatitis C Registry for patients of the ECSN and the Desert Shadow Endoscopy Center. Design of the registry is to collect procedure types and dates, as well as any laboratory test results.
Of the acute hepatitis C cases, five had procedures on Sept. 21, 2007. Each case underwent procedures 35 to 90 days prior to the onset of symptoms. The incubation range for HCV is 15 to 150 days with an average of 50 days.
Patients seen at the clinic on Sept. 21 were nearly 28 million times more likely (p=0.000000001) than nonpatients to develop an acute hepatitis C infection. By comparison, Clark County (Las Vegas), Nevada — on average — reports only two cases of acute hepatitis C annually. Genetic comparisons of the viral genomes were similar for the five Sept. 21 cases. This suggests a common source. Viruses from the other cases were different.
Surveillance of hepatitis C is difficult; 60% to 75% of acute cases are asymptomatic. Current laboratory tests cannot distinguish acute from chronic hepatitis C infections. Thus, underestimates of HCV transmission may be common.
During initial observations of clinic procedures, the investigators observed the reuse of "single use" Propofol vials on multiple patients. Propofol sedates patients during endoscopic and other diagnostic procedures. It has a rapid onset (about 40 seconds) and a short duration of action.
The number of Propofol vials used was less than the number of patients seen. Staff indicated that reuse of vials and syringes were office policy. There were reports of one clinic physician who stated reuse of syringes and other single-use equipment was "standard practice."
Senior clinic staff indicated reuse of disposables began after the remodeling in 2004 and was consistent to the present. In the end, it was determined that the reuse of syringes to redose a patient, combined with the reuse of single-use vials for multiple patients, was the most likely source of transmission during the outbreak. Continuing the practice during the course of a day could have serially contaminated vials.
Review of a number of other possible sources of exposure leading to the outbreak also occurred and included endoscope reprocessing. Procedures used appeared to be correct. Case patients did not share the same endoscope. But reuse after disinfection of single-use biopsy forceps did occur. Clinic management denied reuse.
Auditing indicated 7,200 biopsies or polyp removal procedures in 2007 and the purchase of only 6,200 forceps or removal wires. A similar scenario existed for bite blocks used on upper endoscopies. Not all case patients had biopsies or upper endoscopies. After testing, no HCV infections were present among the current staff, including physicians.
Dr. Charles John Palenik is the director of Infection Control Research and Services at the Indiana University School of Dentistry. In 2003, he was chairman of the Executive Board of OSAP, dentistry's resource for infection control and safety. Direct infection control questions to [email protected].
