Labus B, Sands L, Rowley P, Azzam IA, Holmberg SD, Perz JF, Patel PR, Fischer GE, Schaefer M. Acute hepatitis C virus infections attributed to unsafe injection practices at an endoscopy clinic—Nevada, 2007. JAMA 2008;299:2738–2740. (Reprinted with permission from American Medical Association.)
On January 2, 2008, the Nevada State Health Division (NSHD) contacted CDC concerning surveillance reports received by the Southern Nevada Health District (SNHD) regarding two persons recently diagnosed with acute hepatitis C. A third person with acute hepatitis C was reported the following day. This report raised concerns about an outbreak because SNHD typically confirms four or fewer cases of acute hepatitis C per year. Initial inquiries found that all three persons with acute hepatitis C underwent procedures at the same endoscopy clinic (clinic A) within 35-90 days of illness onset. A joint investigation by SNHD, NSHD, and CDC was initiated on January 9, 2008. The epidemiologic and laboratory investigation revealed that hepatitis C virus (HCV) transmission likely resulted from reuse of syringes on individual patients and use of single-use medication vials on multiple patients at the clinic. Health officials advised clinic A to stop unsafe injection practices immediately, and approximately 40,000 patients of the clinic were notified about their potential risk for exposure to HCV and other blood-borne pathogens.
Hepatitis C virus (HCV) transmission in the health care setting is a major mode of global spread, with the World Health Organization Global Burden of Disease study estimating that in 2000, contaminated injections led to 2 million HCV infections, or 40% of new infections worldwide.1 In the developing world, the absence of routine blood donor HCV screening in many countries along with unsafe therapeutic injections and other health care–related procedures contributes to this high level of transmission.1 In developed countries, the introduction of blood donor screening from the early 1990s led to marked declines in risk of health care HCV transmission,2 and enhanced capacity for infection control procedure implementation should ensure limited nosocomial HCV infection. However, this report provides evidence of ongoing HCV transmission in the health care setting.
Although HCV transmission between health care workers and patients has been described, the major means of health care–related HCV transmission is through patient-to-patient exposure.3 High HCV prevalence and ongoing transmission among patients receiving long-term hemodialysis has been reported, consistent with potential exposure related to repeated and prolonged vascular access in settings involving close contact with other patients.4, 5 Several HCV outbreaks have been described of patient-to-patient transmission through unsafe injection resulting in contamination of multidose vials or of equipment used for blood sampling or flushing intravenous lines.3 The largest such outbreak involved new HCV infections in 99 of 367 patients (27% attack rate) attending a hematology/oncology outpatient clinic in Nebraska and related to shared saline bags contaminated through syringe reuse undertaken by one nurse.6
The present report of an outbreak of acute HCV among patients attending an endoscopy clinic in Nevada adds another chapter to the unfolding story of health care–related HCV transmission. Initially, three patients who had endoscopies within 35 to 90 days of symptomatic onset of acute HCV infection were identified through public health surveillance authorities, triggering a joint investigation with the Centers for Disease Control and Prevention.7 HCV testing of the additional 120 patients who underwent endoscopic procedures on the same 2 days as these six patients is being sought. Following the identification of a breakdown in infection control practices, 40,000 people who underwent procedures requiring anesthesia at the clinic over a 4-year period were also notified and requested to seek testing for human immunodeficiency virus, hepatits B virus, and HCV. The most recent available report indicates that 6,000 patients have been tested so far, revealing two further cases of HCV.8 Reflecting the seriousness of this incident, the clinic involved has closed down, two doctors have lost their practice licences, and six nurse-anesthetists have surrendered their practice licences; meanwhile, regulatory, legal, and clinical enquiries continue.9 Given that all six cases had symptomatic presentations (generally seen in only 20% to 30% of new HCV infections), it is likely that additional cases will be identified through this investigation. All 38 health care workers involved in direct patient contact tested HCV-negative, suggesting that this outbreak resulted from patient-to-patient transmission. Following observation of infection control practices at the clinic, inappropriate reuse of syringes on individual patients and use of anesthetic medication vials for multiple patients was identified as the likely cause of HCV transmission.7
An association between endoscopic procedures and HCV transmission has been reported through molecular epidemiological case reports from Australia10 and the United States,11 as well as an incident case-control study in France.12 In the latter study, digestive endoscopy was reported during the risk period in 15.6% of cases compared with 2.2% of controls, with a multivariate odds ratio of 5.7 (95% confidence interval 1.4-23.8).12
Two prospective cohort studies have demonstrated that when infection control procedures including appropriate cleaning of endoscopic equipment are utilized, the risk of HCV transmission is extremely low. The first study, from northern Italy, involved retesting of 8,260 patients 6 months after digestive endoscopy. There were no incident HCV cases, with confidence intervals for the estimated risk per 1,000 person procedures of 0–0.47.13 Notably, 912 patients underwent endoscopy with the same instrument previously used on a patient with known HCV infection. An Australian study found that gastroscopes (n = 1,376) and colonoscopes (n = 987) cleaned by recognized protocols were rarely contaminated with detectable HCV RNA (n = 1 positive wash).14 In this latter study, low-level contamination with gastrointestinal bacterial flora was found in 1.8% of gastroscopes and 1.9% of colonoscopes, suggesting that bacterial biofilm may be difficult to remove.
The HCV outbreak in an endoscopy clinic raises several important issues. First, it highlights the relative efficiency of percutaneous HCV transmission in settings where infection control procedures are not strictly followed. The need for regular review of such procedures and adequate training for all health care workers with direct patient contact has been made clear through recent recommendations.3 These measures are particularly important for ambulatory and procedural clinics that are not integrated within larger hospitals with designated infection control staff. Second, it provides justification for enhanced surveillance for acute HCV through public health authorities. Diagnosis of acute HCV infection, particularly in the setting of symptomatic presentation and lack of readily identifiable risk factors, requires enhanced investigation of potential means of acquisition. The generally asymptomatic nature of newly acquired HCV infection makes detection of unusual modes of transmission more difficult, but it highlights the need for detailed exploration in those cases with a defined period of exposure. The early detection of acute HCV infection cases allows monitoring for viral clearance and institution of highly effective interferon-based therapy at 12 to 16 weeks after presentation in those cases with persistent viremia. Third, although several HCV outbreaks in health care settings have been described, when infection control procedures are followed, the population-level contribution from this form of transmission appears to be low. We have been involved in the Australian Trial in Acute Hepatitis C, a prospective cohort of early HCV natural history and interferon-based therapeutic intervention that has enrolled 167 cases of newly acquired HCV infection, none of which has been attributed to health care setting transmission. Finally, despite the relative infrequency of nosocomial infection in developed countries, enormous resources are expended in investigation of outbreaks, and considerable alarm is created among potentially exposed individuals. The growing burden of HCV-related advanced liver disease in Egypt, where a major contribution to the high-level prevalence was through contaminated injections involved in schistosomiasis eradication programs from 1960 to 1980,15 is a further reminder of the potential impact of a breakdown in infection control procedures.