Outbreak of Acute Hepatitis C Virus Infections at an Outpatient Hemodialysis Facility

Background: Chronic hemodialysis patients are at increased risk of hepatitis C virus (HCV) infection; previous outbreaks have been attributed to blood contamination of injected medications and environmental surfaces.  In March 2009, a cluster of acute HCV infections was identified among patients treated at a hemodialysis facility (Facility A) located in a geographic area with high HCV infection prevalence.

Objective: To evaluate potential sources of HCV transmission in Facility A and recommend control measures.

Methods: We reviewed medical records and antibody to HCV (anti-HCV) screening results for the 170 patients treated at Facility A between January 2008 and April 2009. An acute case was defined as a patient with documented seroconversion (from anti-HCV negative to positive) after admission to Facility A. Anti-HCV positive patients who were known to be positive either upon admission to Facility A or prior to 2006 were considered previously infected. Sera from anti-HCV positive patients (both previously and acutely infected) were tested for HCV RNA by PCR; HCV NS5b and hypervariable (HVR1) regions were sequenced to determine relatedness.  The treatment shift and dialysis station were determined for patients with related viral sequences. Infection control practices and policies were assessed. A forensic chemiluminescent agent was used to visualize residual blood on surfaces. 

Results: Of 163 Facility A patients with known serologic status, 56 (34.4%) were previously infected with HCV.   Eight of 107 susceptible patients had acquired acute infection (attack rate 7.5%).  The attack rate was 2.3% for patients treated on the 1^st shift compared to 11.4% for later shifts (p= 0.13), and 11.1% for patients with catheter access compared to 4.6% for those with grafts or fistulas (p= 0.24).  HVR1 sequence analysis of HCV RNA positive specimens found that 4 acute cases were closely related to three previously infected patients (range 97.2-100% maximum nucleotide identity). These previously infected patients preceded their related acute case-patients by one treatment shift and underwent treatment at the same or adjacent dialysis station.  Lapses in hand hygiene and handling of parenteral medications, including saline flush for catheters, were documented. Recent training in aseptic technique received by staff who administered injections at Facility A was insufficient. Although environmental cleaning and disinfection practices were suboptimal, widespread blood contamination of surfaces was not detected.

Conclusions: Multiple episodes of HCV transmission occurred among patients in Facility A.  Poor medication handling and infusion practices may have contributed to transmission and remediative actions were recommended. Proper training of personnel on aseptic technique is needed to prevent HCV transmission in hemodialysis facilities.