Hep A Case Study
Case Study: Hepatitis A Cluster with Unknown Source
FACILITATOR VERSION
Objectives
• List the steps in an outbreak investigation
• List sources of data within the local health department
• Interpret surveillance data
• Choose an appropriate public health response based upon interpretation of surveillance data
• Define the Incident Command System and identify triggers for activating it
• Create a table shell for a line listing
Instructions
Convene your local Epi Team, and provide each Epi Team member with a copy of the case study (participant version). Choose one person to act as the facilitator. This person should use the facilitator’s version of the case study.
Guidance for facilitating the case study can be found on page 3. The case study begins on page 4.
Time Allotted: 1.5 hours
Background Materials
The following trainings, found at the North Carolina Center for Public Health Preparedness Training Web site (), are recommended for Epi Team members without prior outbreak investigation experience. They can be viewed prior to completing the case study.
1. An Overview of Outbreak Investigations (FOCUS on Field Epidemiology Volume 1, Issue 1)
2. Federal Public Health Surveillance and Analysis of Surveillance Data (E is for Epi Session 4.2)
3. Case Finding and Line Listing: A Guide for Investigators (FOCUS on Field Epidemiology Volume 1, Issue 4)
4. Incident Command System (ICS) for Public Health
Resources
Centers for Disease Control and Prevention. Hepatitis A Fact Sheet. 2007. Available at .
Centers for Disease Control and Prevention. Update: prevention of Hepatitis A after exposure to Hepatitis A virus and in international travelers. MMWR Morb Mortal Wkly Rep 2007;56:1080-1084.
Heymann DL, ed. Control of Communicable Diseases Manual. 18th ed. Washington DC, USA: American Public Health Association; 2004.
Guidance for Facilitators
Goal
The goal of working through a case study is active learning through engaged participation by each Epi Team member.
Role of Facilitator
As a facilitator, your job is to:
• Guide the Epi Team through the case study
• Involve every team member
• Moderate discussion drawing on the suggested answers to discussion questions
• Ensure key points are covered for each question
• Keep an eye on the clock
Active Participation
All team members should be involved in the discussion. One strategy for getting everyone involved is to have team members take turns reading aloud and attempting to answer questions. Facilitators should:
1. Ensure that the room set-up encourages group participation, ie. everyone seated around a table or chairs in a circle.
2. Select one team member to read aloud the first update and the first question.
3. Encourage that team member to attempt to answer the first question (regardless of his/her background).
4. Encourage other team members to add information and discuss the question.
5. Use the suggested answers to cover key point(s) that were not addressed during the discussion.
6. Have the next person read aloud the next update or question and begin an attempted answer as above – move in sequence to include everyone.
Follow this sequence until the scenario is completed, pacing discussion in order to finish the entire scenario.
Facilitation Tips
• Read the case study ahead of time so you are prepared for the discussion.
• Always remember the learning objectives for the case study.
• If one person is dominating the conversation, call on other team members.
• If someone in the group is not participating, ask his or her opinion.
• When someone asks a question, encourage other team members to provide the answer.
• Do not spend too much time providing the suggested answers to the group. Instead, encourage the team to share their opinions about possible responses to the given scenario.
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Question 1: What is the first step in an outbreak investigation?
Suggested answer: The first step in an outbreak investigation is to verify the diagnosis and confirm the outbreak. In order to verify the diagnosis you need to get information from each patien, such as description of symptoms, date of symptom onset, relevant medical history, and demographic information. You would also get more information about the type of laboratory tests that were conducted and ask for copies of the laboratory results. Next, you need to confirm the outbreak. An outbreak is defined as an increase in the observed number of cases of a disease compared with the expected number of cases among a specific group of people in a given place over a particular period of time.
At this time, you may also notify other members of your local Epi Team of the possible hepatitis A cluster.
Question 2: How could disease surveillance data be useful during this investigation? Why is it important to perform surveillance on diseases like hepatitis A?
Suggested answer: Surveillance data can give you information about trends in hepatitis A incidence and help you determine whether an outbreak is occurring. To confirm the existence of an outbreak, compare the usual rate of disease in a given population with the observed rate during the possible outbreak. The usual rate of disease is often obtained from surveillance data.
It is important to perform surveillance for other reasons besides detecting outbreaks. Surveillance data can also be used to:
• Monitor risk factors of disease;
• Assess disease burden;
• Identify infected persons requiring counseling and medical follow-up;
• Identify contacts of infected people requiring counseling and/or post-exposure prophylaxis;
• Detect changes in health practice;
• Assess the safety of drugs or procedures;
• Identify research needs;
• Facilitate planning of public health interventions;
• Respond to media inquiries; and
• Evaluate public health control measures.
Question 3: Where should you look for baseline surveillance data about hepatitis A in County K and throughout North Carolina?
Suggested answer: [Facilitator’s note: There are several possible sources of surveillance data, and Epi Team members should discuss the specific location of this information in their own health department.] Some health departments have annual reports with communicable disease surveillance data. Since hepatitis A is a reportable disease, it should be included in these surveillance reports. The epidemiologist and/or communicable disease nurse on your Epi Team should know how to access these data. State level surveillance data about hepatitis A can be found on the North Carolina Communicable Disease Control Branch Web site (). Documents containing state-level surveillance data from 1991 to the present are listed under “Statistics”. There are also some reports with county-level data on the Web site.
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Question 4: Based on this information, do you think the 3 cases in your county represent an outbreak?
Suggested answer: Yes, the 3 cases probably indicate an outbreak. This many cases in your county in the same week is certainly an increase over the expected number of cases since County K averages between 5-6 cases of hepatitis per year and there were less than 3 cases per year for 3 of the past 6 years.
Question 5: At this point, should you contact any other public health agencies? If so, which ones?
Suggested answer: Yes, you should report the hepatitis A cases. Hepatitis A is reportable by law within 24 hours of the report, and all communicable disease outbreaks (whether a reportable disease or not) must be reported. Begin by contacting the NC Communicable Disease Control Branch to notify them of the outbreak, and then contact your Public Health Regional Surveillance Team (PHRST). If your health department does not have enough resources to conduct an outbreak investigation, the PHRST and/or Communicable Disease Control Branch should be available to assist. You should also meet with the rest of your health department’s Epi Team to share information and plan next steps. Finally, you probably want to notify other North Carolina counties by posting information about the hepatitis cases on the NC Health Alert Network (HAN). If any of the 3 cases live in another county, it would be wise to contact that local health department directly.
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Question 6: What do you know about hepatitis A that will help you in your investigation? Complete the chart below with disease information. Hint: You do not need to memorize all of this information. Instead, consult the Control of Communicable Diseases Manual.
Hepatitis A Facts
|Symptoms | |
|Incubation Period | |
|Mode of Transmission | |
|Duration of Illness | |
|Diagnosis | |
|Treatment | |
|Other | |
Suggested answer:
|Symptoms |Abrupt onset of fatigue, loss of appetite, nausea, diarrhea, and fever followed a few days|
| |later by jaundice |
|Incubation Period |Average: 28 days, Range: 15-50 days |
|Mode of Transmission |Usually spread by putting something in the mouth that has been contaminated by the feces |
| |of an infected person (fecal-oral transmission) |
| |Sexual transmission |
| |Foods associated with hepatitis A transmission include raw shellfish and uncooked fruits |
| |and vegetables |
|Duration of Illness |40 years, IG is preferred; vaccine can be used if IG cannot be obtained.
• For children aged 2 weeks after exposure. Consult the NC Communicable Disease Control Branch at the Division of Public Health for recommendations specific to the situation.
It is not too early to prepare educational materials for the general public about prevention of hepatitis A. Your health educator or public information officer should be preparing these materials, as well as drafting a possible press release about the current outbreak based on the information you know so far.
Activity
Defining a case is an important step in an outbreak investigation. Case definitions provide a simple, uniform way to determine who should be considered a case and who should not. As a team, decide upon an initial (working) case definition. Keep in mind that your case definition will change as you obtain more information. A case definition should always include both clinical information and elements related to person, place, and time.
|Clinical Information (e.g. disease signs and symptoms, lab | |
|results) | |
|Person | |
|Place | |
|Time | |
Suggested answer: At the beginning of an outbreak, a case definition may be general. It is important to remember that a case definition may change as more information is gathered during an outbreak. The following is an initial definition for a suspect case. A confirmed case would also have a positive IgM antibody test for hepatitis A.
|Clinical Information (e.g. disease signs and |Jaundice and/or elevated serum aminotransferase levels AND at least two of the |
|symptoms, lab results) |following symptoms: fatigue, fever, loss of appetite, nausea, vomiting, or |
| |diarrhea |
|Person |Any person |
|Place |Associated with Farm A |
|Time |With onset of symptoms between July 1 and present* |
*Note that the date range for the case definition may vary, and that the case definition may be expanded to include symptomatic contacts of confirmed cases.
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Question 9: What is the purpose of ICS?
Suggested answer: ICS, or Incident Command System, is a management and organizational tool used to prepare for and respond to emergencies. ICS provides all responders--public health, fire, police, and emergency management—with a common language and structure. ICS can be used in any stage of incident management, and becomes increasingly useful in situations that involve more than one agency or more than one jurisdiction. ICS is scalable, so it can be adapted to the size of the event.
Increasingly health departments are encouraged to use ICS to respond to more traditional disease outbreaks to gain experience working within the ICS framework.
Group Brainstorm
Choose one member of your Epi Team to record responses on a flip chart. As a group, discuss the following question.
Question 10: Generally, what are some triggers for activating ICS in your health department?
Suggested Answer: Triggers for activating ICS may include:
• Disease outbreaks, particularly those involving cases in multiple states or jurisdictions;
• Acts of terrorism or bioterrorism;
• Incidents affecting populations with language or cultural differences;
• Extreme shortage of resources following a disaster;
• High media demand situation;
• High risk of life and property situations; or
• Incidents involving several agencies with on-scene responsibility
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Question 11: If you were the environmental health specialist, what water sources/environmental specimens would you collect for hepatitis A testing?
Suggested answer: You should test the water supply at several points, including the stream, spring, spigot, and overflow hose. You should also test water in food preparation areas, bathroom facilities, and areas used for growing produce. It is always a good idea to contact the North Carolina State Laboratory of Public Health for specific instructions about the type of samples to collect.
Question 12: Should you offer hepatitis A vaccine and/or immune globulin (IG) to the wife and child of the farm owner? Why or why not?
Suggested answer: Because the disease onset date for the 58 year-old man was July 15th, it is likely that the wife and child were exposed to hepatitis A more than 2 weeks ago. There is no documentation of vaccine efficacy >2 weeks after exposure. However, it may be advisable to offer IG to the wife and/or child. You should consult with the NC Communicable Disease Control Branch for guidance specific to this situation.
Question 13: Are you concerned that the produce grown on the farm could be a source of hepatitis A transmission? Why or why not? If so, do you make any recommendations about the produce?
Suggested answer: Hepatitis A has been transmitted via raw fruits and vegetables contaminated with fecal matter. If the produce was contaminated directly by an ill person, or through contact with the septic system, it could be a source of disease transmission. The NC Department of Agriculture and Consumer Services is the appropriate agency to make recommendations about the produce. It is probably safest for the produce to be destroyed; at the least, it should not be sold at local markets.
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Question 14: You would like to interview these contacts to find out if they’ve been sick. What are some strategies that you can use to find these individuals?
Suggested answer: It will be difficult to find all of these people. For the individuals with a full name and city of residence, you can look them up in the phone book. If you get in touch with anyone, you can ask them for the names of others who stayed at the farm during the same time. However, it may be impossible to track down everyone with so little information. Because of this, it is important to enhance passive surveillance by posting notices on the NC Health Alert Network, or HAN, () and the national Epi-X network (). An Epi-X alert is appropriate in this situation since you know some of the campers were from states other than North Carolina. In most situations, the state epidemiologist will post the Epi-X alert. The HAN and Epi-X notices should provide your case definition and advise other public health professionals to report suspect and confirmed cases of hepatitis A to your health department.
You should also remind local healthcare providers and laboratories to report possible cases. Many health departments use blast fax or email notification to contact local health care providers.
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Question 15: What actions should you take now?
Suggested answer: Although you may have already recommended some disease control measures, the laboratory confirmation of fecal coliforms in the spring water should lead to stricter control measures. For example, you might issue a boil water advisory for residents of the farm, recommend the use of bottled water, prohibit the sale or sharing of produce grown on the property, destroy crops, eliminate the spring as a potential water source, defer planting for at least 6 months, and limit visits to the farm by anyone without documented immunity to hepatitis A.
If you have not done so already, it would be important to notify the NC Division of Water Quality about the presence of fecal coliforms in a drinking water source.
Since the state park is next to the farm, it would be a good idea to notify the park of the investigation results.
This is an appropriate time for your health educator and/or public information officer to provide education to the farmer and his family about preventing transmission of hepatitis A. You may also want to use this opportunity to educate health care providers and the general public.
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Question 16: How should you organize information about the cases?
Suggested answer: After you have created the case definition and conducted case finding, you need to tabulate and orient the data regarding person, place, and time. In other words, you need to create a line listing.
Group Brainstorm
Choose one member of the Epi Team to record responses on a flip chart. As a group, discuss the following question.
Question 17: The Incident Commander has requested that your Epi Team create a line listing of the 19 cases. What information would you include in the line listing?
Suggested Answer: A line listing should include identifying information (e.g. name, contact info), demographic information (e.g. gender, age, occupation), clinical information (e.g. signs and symptoms, dates of onset, laboratory tests and results, vaccination history), and risk factor information (e.g. date of farm visit, food consumed on the farm, water source, etc.) The specific variables used in a line listing may vary by outbreak. A partial example of a line listing table is shown below. The actual line listing would probably include additional information about possible sources of exposure.
NameSexDOBOnset DateJFNVDAppFatVaxIgMDate of Farm StayWater Source at FarmDOB = Date of Birth, J = Jaundice, F = Fever, N = Nausea, V = Vomiting, D = Diarrhea, App = Loss of Appetite, Fat = Fatigue, Vax = Hepatitis A Vaccine, IgM = IgM antibodies to hepatitis A virus
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Group Brainstorm
Often, after an outbreak investigation, an Epi Team reviews the investigation in a “hot wash” or after-action review. The questions below are examples of questions that could be used in such a review. Choose one member of the Epi Team to record responses on a flip chart. As a group, discuss one or more of the following questions.
What aspects of the investigation were successful?
All outbreaks present unique challenges. What characteristics of this outbreak made it challenging?
What areas of the investigation could have been improved?
If a similar outbreak occurred in your county, do you think that your Epi Team would be prepared to handle it?
References
Moore Z. Trip Report: Hepatitis A Outbreak, Madison County, NC, 2006.
Moore Z, Sobsey M, Ganova-Raeva L, et al. Hepatitis A associated with contaminated spring water -- North Carolina, 2006. Poster presented at the Infectious Diseases Society of America 45th Annual Meeting; October 4-7, 2007; San Diego, CA.
-----------------------
|Update: September 10th |
|On August 26th, you received confirmation of hepatitis A virus in the|
|spring water samples. |
| |
|You have not had much success tracking down and interviewing visitors|
|to the farm. However, you receive several reports of suspect cases |
|through other health departments, private health care providers, and |
|laboratories. Through all of these methods, you identify 16 |
|additional cases; 5 men and 11 women. Onset dates range from July 5th|
|to September 1st. These additional cases live in North Carolina, |
|Virginia, and California. None of the cases had received the |
|hepatitis A vaccination prior to their visit to the farm. There are |
|now a total of 19 cases associated with this outbreak. |
| |
|Update: August 20th |
|The North Carolina State Laboratory of Public Health (SLPH) confirms |
|that the water samples taken from a spigot outside the farm house |
|contained fecal coliform bacteria. Spring water samples are being |
|sent to the Department of Environmental Sciences and Engineering at |
|the University of North Carolina School of Public Health, where the |
|samples will be tested for hepatitis A virus (HAV) using PCR |
|techniques. |
| |
|Update: Later on August 19th |
|Together with the EIS officer, you interview the owners of the farm |
|about people that have visited their property. Since the average |
|incubation period of hepatitis A is almost a month long, you ask them|
|about any visitors since June 1st. They admit to not knowing all of |
|their visitors, and having very little information about some of them|
|since there is no registration system for people camping on the |
|property. Here are your notes from that conversation: |
| |
|June 12 – Joy and Steve from New Jersey (stayed for about 3 days) |
|June 15 – young guy (mid-20s) from Statesville, NC |
|June 16 or 17 – Ann and Alice Bennington from Oakwood, Virginia |
|(stayed 2 nights) |
|June 24 or 25 – Brian Hack |
|July 1 – Pam, Linda, Jeff, Bernice, and Marcus from Modesto, |
|California (stayed for 1 week) |
|July 3 – several hikers, names unknown |
|July 10 – Clarence and Jen from Wilmington, NC (stayed for 1 night) |
|July 22 – Bobby Cunningham |
|July 24 – three or four hikers (stayed for 1 night) |
|July 29 – Roy and Sheryl from Richmond, Virginia (stayed 2 nights) |
| |
|You begin case finding activities on Monday, August 20th. |
| |
|Update - August 19th |
|An Epidemic Intelligence Service (EIS) officer from the NC |
|Communicable Disease Control Branch comes to your health department |
|to help with the outbreak investigation. Together you, your |
|environmental health specialist, and the EIS officer visit the farm |
|implicated in the outbreak where the index case lives with his wife |
|and child. The farm has a greenhouse and a fruit and vegetable garden|
|and they occasionally sell their produce at local markets. However, |
|the farm owner says no produce has been sold at the market since |
|early April. |
| |
|The farm is adjacent to a popular state park and it has a camping |
|area away from the main house where hikers often stay, sometimes |
|without the knowledge of the owners. The camping area is near a |
|stream that runs through the property, and is downhill from the |
|house. In addition to the stream, there is also a spring that |
|provides water to the house, as well as to spigots used to irrigate |
|the gardens and a hose near the camping area. The septic tank sits |
|directly over the spring water that is used in the house and |
|greenhouse (see diagram). The team decides to take water samples. |
| |
|Update - Saturday, August 18th |
|Your health director tells you that she is activating the health |
|department’s Incident Command System or ICS to respond to this |
|outbreak. |
| |
|Update - Afternoon of August 17th |
|You call the communicable disease nurse back and ask her questions |
|about the cases. She informs you that one person is a 58 year-old |
|male who lives on a farm in a remote part of the county, and that the|
|other 2 cases are adults who visited the same farm from July 1-3. |
|Besides their connection to the farm, the nurse has not identified |
|any other common factors among the cases. |
| |
|You contact the farm owners and arrange to visit the farm tomorrow. |
|Here is a summary of the information about the 3 cases. All 3 have |
|positive IgM antibody results for hepatitis A. |
| |
|Case #1: 58 year-old male, onset of fatigue, fever, and abdominal |
|pain on July 15th, jaundice on July 18th. |
| |
|Case #2: 45 year-old male, onset of fatigue, loss of appetite, |
|vomiting, and nausea on August 1st, followed by jaundice on August |
|3rd. |
| |
|Case #3: 39 year-old female, onset of fever, nausea and loss of |
|appetite on July 29th, followed by jaundice on August 2nd. |
| |
|Update - Friday, August 17th |
|You contact the NC Communicable Disease Control Branch and your PHRST|
|to ask for assistance investigating this possible outbreak. The |
|earliest someone will be able to come to County K to assist you is in|
|2-3 days. You are to continue with the outbreak investigation in the |
|meantime. |
| |
|Update - Baseline Surveillance Data |
|From your health department’s records, and the NC Communicable |
|Disease Control BranchWeb site, you gather the following information |
|about the total number of cases of hepatitis A in North Carolina and |
|your county over the past several years. |
| |
|Hepatitis A Cases |
|Year |NC |County K |
|2001 |94 |9 |
|2002 |41 |6 |
|2003 |51 |1 |
|2004 |84 |14 |
|2005 |49 |2 |
|2006 |118 |1 |
Background - Thursday, August 16th
It’s your second week working at the county health department in County K, North Carolina. When you arrived at work this morning, you had the following voicemail message from a communicable disease nurse at the county hospital.
“I’m just calling to let you know that we’ve had 3 patients test positive for hepatitis A in the last week. This is pretty unusual, so I’m afraid it might be part of something larger. Call me back at 987-6543.”
Being new to the county, you are unfamiliar with local incidence rates of hepatitis A and are not sure what to do next. You wonder whether it is appropriate to initiate an outbreak investigation.
Conclusion: September 30th
Thanks to your efforts, the outbreak appears to be contained. All of the people with hepatitis A have either recovered or are recovering, and no additional cases have been reported. After consulting with the NC Department of Agriculture and Consumer Services, the health director issued a declaration and abatement order to the owners of the farm on September 20th. The order required that all crops stored or cultivated on the property be destroyed, and the spring be eliminated as a possible water source. They were also advised to limit visits from anyone without documented hepatitis A immunity (either a history of hepatitis A or two doses of hepatitis A vaccine) until a safe water source was in place.
Your health department will continue to conduct surveillance for hepatitis A cases associated with the contaminated spring. You will also continue to follow up with the farm owners to ensure the abatement orders are followed.
To date, your investigation has not uncovered the original source of hepatitis A that resulted in water contamination.
Reminder
As the facilitator, you are the only team member with the suggested answers to discussion questions and activities. Other Epi Team members have only the scenario updates and questions.
-----------------------
Health department visits farm.
Epi Team performs case finding activities.
Health department requests assistance from PHRST and state health department.
August
Health director activates ICS.
3 confirmed cases of hepatitis A reported.
Health department requests assistance from PHRST & state health department.
August
Health director activates ICS.
Health department visits farm.
August
3 confirmed cases of hepatitis A reported.
The three cases visited the same farm July 1-3.
Health director activates ICS.
Health department visits farm.
Health director activates ICS.
3 confirmed cases of Hepatitis A reported.
Health department requests assistance from PHRST and DPH.
August
August
3 confirmed cases of hepatitis A reported.
The three cases visited the same farm July 1-3.
Health department requests assistance from PHRST and DPH.
Health director activates ICS.
Health department visits farm.
3 confirmed cases of hepatitis A reported.
Health department requests assistance from PHRST and state health department.
August
The three cases visited the same farm July 1-3.
The three cases visited the same farm July 1-3.
Health department requests assistance from PHRST & state health department.
The three cases visited the same farm July 1-3.
Epi Team performs case finding activities.
Epi Team performs case finding activities.
Water tests positive for HAV
Sept. 10, 19 cases associated with outbreak. Sept. 20, Abatement Order issued.
Health department requests assistance from PHRST and DPH.
August
3 confirmed cases of hepatitis A reported.
3 confirmed cases of hepatitis A reported.
The three cases visited the same farm July 1-3.
3 confirmed cases of hepatitis A reported.
August
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