Viral Hepatitis: Guide for Investigating Outbreaks in Health Care Settings

Purpose of this guide

This guide provides a framework for state and local health departments to investigate possible health care-associated viral hepatitis transmission events.

These steps are intended to address investigations in a variety of inpatient, outpatient, and long-term care settings. They do not include guidance for transplant- or transfusion-related transmissions.

Transmission of the hepatitis B virus (HBV) and hepatitis C virus (HCV) has occurred in health care settings by:

• Patient-to-patient transmission through infection prevention and control breaches when handling shared medications or patient equipment (e.g., administering injections, performance of blood glucose monitoring).
• Provider-to-patient transmission, largely through diversion of controlled substances by infected health care personnel (HCP).
• Patient-to-patient transmission through infected blood, organs, and tissues.

In outbreak investigations, case definitions are based on laboratory profile and clinical evidence rather than surveillance case definitions, which may omit asymptomatic cases.

Step one: Verify the infection

Verify the HBV or HCV infection by reviewing medical records and interviewing the physician and the index patient.

Download a sample questionnaire here.

The form captures information on exposure occurring before symptoms typically begin to show. Usually this is 6 weeks to 6 months for acute HBV infections and 2 weeks to 6 months for acute HCV infections.

In certain instances, this time period may need to be extended. For example, in the case of a documented seroconversion (e.g., anti-HCV negative to anti-HCV positive), the time period should include the 6 months prior to the most recent negative test result up until the time of the first positive test result.

Acute HBV infection

Most patients with acute hepatitis B are asymptomatic. When symptoms do develop, they can include:

• Abdominal pain, nausea, and/or vomiting
• Dark urine or clay-colored stools
• Fatigue
• Fever
• Jaundice
• Joint pain
• Loss of appetite

To determine if a hepatitis B case is acute, review the person's medical history, information obtained from case investigation, and serologic findings. Markers indicating acute infection:

• Positive hepatitis B surface antigen (HBsAg), and
• Positive immunoglobulin M antibody to hepatitis B core antigen (IgM anti-HBc).

Acute HCV infection

Most patients with acute hepatitis C are asymptomatic. When symptoms do develop, they can include:

• Abdominal pain, nausea, and/or vomiting
• Dark urine or clay-colored stools
• Fatigue
• Fever
• Jaundice
• Joint pain
• Loss of appetite

To determine if a hepatitis C case is acute, review the person’s medical history and information obtained from case investigation. Test for hepatitis C antibody with reflex to HCV RNA if antibody is reactive. To evaluate whether an infection could be recent :

• Medical history
• Information from case investigation
• New finding of hepatitis C antibody or RNA positivity in a person not previously known positive (whether or not symptoms or alanine aminotransferase [ALT] elevation are present).

Step two: Determine potential exposure

Using information from step one, weigh the likelihood that the infection is due to health care exposure vs. other factors. For example, a remote history of an STD, incarceration, or injection drug use would not necessarily exclude a relevant health care exposure occurring during the likely exposure period.

Examples that are concerning for health care transmission and deserve thorough investigation include diagnosis of acute hepatitis B or hepatitis C (or documented seroconversion) occurring in a:

• Cancer patient
• Hemodialysis patient
• Transplant patient
• Long-term care resident, a
• Child without household members
• Routine blood donor.

Step three: Track the investigation

Health departments should consider entering relevant information into an electronic database whether they decide to pursue investigation of health care exposure or not. It will be important to have documentation if in the future you identify and report additional cases with overlapping health care exposures.

To help identify future patterns, capture the following information in the investigation database:

• Facility/provider names
• Date of investigation
• Disease
• County
• Lead investigator
• Identity of case being investigated
• Status of investigation

Step four: Assess and evaluate encounters

Look for encounters and additional related cases during the exposure period to help determine if other people are at risk. To do this:

1. Create a chronological list of all health care encounters during the likely exposure period of the index case.
2. List procedures performed during each encounter, especially those involving percutaneous exposures or that are invasive (e.g., injections, infusions, skin puncture with a needle/lancet). Include HCP(s) involved in care, equipment used, medications administered, and room(s) where procedure(s) was performed.
3. Review the investigation database to see if there is a pattern of exposure with this facility/provider and enter the facility/provider(s) into the health care database.
4. Contact the facility to inform them of the investigation and determine if they are aware of the current case(s) under investigation or any additional infections.
5. Evaluate the health care facility by doing the following:
   1. Conduct a site visit
   2. Develop a list of potentially exposed patients
      
   3. Identify additional cases

Conduct a site visit

The purpose of the site visit is to gather information about the facility using the infection prevention and control checklist as your guide. You will interview staff and observe the same procedures as those performed on the index patient, ideally by the same HCP(s). If the facility is not performing the same procedures during the visit, consider having HCP(s) perform mock procedures so you can observe typical practices.

Medication and equipment

Pay attention to medications or equipment used for more than one patient and any opportunities for diversion of theft of controlled substances. This should include handling and preparation practices of drugs like opioids, psychotropic drugs, and performance-enhancing drugs (e.g., epoetin, darbepoetin) the facilities may stock.

Facility staff as the source

You should assess the potential for facility staff to be the source of infection (e.g., through diversion of narcotics, sexual abuse of residents).

Facility differences

Evaluate each facility based on its unique features and practices, focusing on procedures involving percutaneous exposures, injections, and intravenous medications. For example:

• In a long-term facility, pay attention to assisted blood glucose monitoring and periodic visitors like dentists, podiatrists, or wound care specialists.
• In a hospital, assess admissions and the patient's room, but also observe all areas of the hospital where the patient received care or had procedures done like the operating room, radiology, or the emergency department.
• In all types of facilities, consider the behavior and practices of individual residents including potential sexual activity.

If a complete investigation is not possible, then you should, at a minimum, send a follow-up letter to potentially impacted health care facilities as a reminder to review their infection prevention practices, and continue to monitor surveillance data for several months to ensure no additional cases are identified.

Develop a list of potentially exposed patients

This list should contain all people who were seen on the same day or at the same time as the index patient. You can then develop a chronologic listing of patients who may represent additional cases or sources of infection for the index patient.

The appropriate time period before and after the index patient visit is typically 1–2 days, but this will depend on a number of factors including the:

• Index case's number of facility visits
• Patient volume of the facility
• Types of procedures being performed
• Infection prevention practices observed during the visit

For example, if the facility was a hospital, the list might only include patients from the relevant unit or patients who overlapped in the same operating room.

Identify additional cases

Identify additional cases by cross-matching your list with acute and chronic disease registries and lab reports. Cross-matching may not result in additional findings. Recent studies estimate that about 50% of chronic hepatitis C cases and an estimated 68% of chronic hepatitis B cases nationwide remain undiagnosed. Given this high proportion of undiagnosed infections, targeting testing can be more beneficial.

If multiple encounters have been identified, you should prioritize your investigation based on the following:

• Information obtained from the investigation database and regulatory complaints.
• Types of procedures the facility performed on the index patient (prioritize those involving percutaneous exposures, e.g., injections, infusions, skin puncture with a needle/lancet).
• Timing of these procedures in relation to the likely exposure period for those infected.
• Settings and procedures where outbreaks have been reported.

If a complete investigation is not possible, then you should, at a minimum, send a follow-up letter to potentially impacted health care facilities as a reminder to review their infection prevention practices, and continue to monitor surveillance data for several months to ensure no additional cases are identified.

Step five: Respond

During the site visit you may identify a major breach in infection control. This could include staff reusing the same syringe or needle among multiple patients or reentering medication vials that are being used for more than one patient with the same syringe or needle. It is not safe to change the needle and reuse the syringe as this practice can transmit disease. If an investigator identifies such a breach, they should immediately correct the behavior and advise the staff to notify all patients who were potentially exposed.

Health departments can consult the following resource for more information on high-risk breaches: Outbreaks and infection control breaches in health care settings: considerations for patient notification.

In the event of a major breach, you should immediately:

• Advise the facility to stop unsafe practices.
• Notify potentially impacted people and HCPs for testing. A patient notification recommending bloodborne pathogen testing should be conducted for all potentially exposed patients, even if additional cases and/or a source patient are not identified. The scope of notification may depend on how long the unsafe practice has been occurring in the facility.
• Report the facility to the appropriate regulatory authority.

Consider following these steps whether a major breach is detected or not:

1. Evaluate the likelihood of epidemiologic links between identified cases (potential source case(s), index case, additional cases) based on their temporal and spatial overlap in the facility. Additionally, it’s important to identify shared medications and equipment, as well as potential exposures.
2. Reach out to CDC to discuss the possibility of conducting viral genetic sequencing. This can be an important step to fully evaluate epidemiologic links between identified cases. A finding that patient samples are very closely related based on viral genetic sequencing is consistent with associated cases being part of the same chain of transmission. However, note that a finding of more distantly related patient samples does not rule out transmission occurring in the facility (for example, there may have been multiple or unidentified source cases). If viral genetic sequencing cannot be performed, viral genotype information, sometimes available from medical records, may be considered when evaluating epidemiologic links between identified cases.
3. Attempt to identify additional cases through targeted patient notification and testing. Note that potential source case patients may present to a health care facility sporadically, and infection control breaches may be regular or intermittent. Some past investigations have identified multiple, temporally distinct transmission clusters at a single facility.
   1. For example, an investigation of a hepatitis C outbreak in an outpatient cardiology clinic detected two separate transmission clusters in June and December of the same year (see Transmission of Hepatitis C Virus During Myocardial Perfusion Imaging in an Outpatient Clinic); also, an investigation of a hepatitis C outbreak in a dialysis center identified cases involving patients infected over a period of more than 5 years (see Hemodialysis-Associated Infections). CDC is available to consult about best practices for conducting patient notifications and sharing lessons learned from previous investigations.
4. If the index or potential source case patient(s) declines to provide samples, or available sample volume is insufficient for additional testing, consider attempting to identify additional cases through targeted patient notifications.
5. If results of viral genetic sequencing suggest that the index or potential source case patient(s) is not part of the same chain of transmission:
   1. Send a follow-up letter to all health care facilities identified during the investigation to remind them to review their infection prevention practices.
   2. Continue to monitor state/local health department surveillance data for additional cases that may be linked to the facility or provider in question.
6. If only the index case is identified (with no potential source case(s) or additional cases), consider sending follow-up letters to health care facilities where the index case had percutaneous exposures during the likely exposure period and continuing to monitor surveillance data.

Assess and respond to need for notification

See the following resources:

• Outbreaks and Infection Control Breaches in Health Care Settings — 2020: CDC offers an expanded framework for patient notification based on ethical principles including transparency, beneficence, and autonomy.
• Framework for Healthcare-Associated Infection Outbreak Notification: This resource includes guidance for health-associated infection outbreak notification, developed by the Council for Outbreak Response: Healthcare-Associated Infections and Antimicrobial-Resistant Pathogens.
• Patient Notification Toolkit: This is a communications framework for state and local health departments to use for public notification as part of public health response to possible bloodborne pathogen exposures in a variety of health care settings.

CDC is available to assist at any time. Contact us!

Comments and resources

CDC would like to thank the health departments who graciously reviewed and provided comment on this algorithm.

Download a PDF copy of this page (archived version last approved 2020).