EPI Newsletter September 2008
ROB Allen, MPA
ISDH Field Epidemiologist, District 7
Karen Scully, RN
Infection Control Coordinator, Federal Correction Complex
On March 28, 2008, Dr. Thomas Webster, Clinical Director with the Federal Correction Complex (FCC), notified the Indiana State Department of Health (ISDH) of an outbreak of gastroenteritis occurring at the FCC in Terre Haute, Indiana. Approximately 35 prisoners had developed diarrhea and vomiting at the Federal Correctional Institute unit, one of three buildings that houses inmates at the FCC facility. At that time, the complex had approximately 3,200 prisoner population and 750 employees. The ISDH contacted the Vigo County Health Department (VCHD) to confirm that a gastrointestinal outbreak was occurring and to recommend infection control measures.
The VCHD and the ISDH initiated a collaborative investigation of the outbreak. A case was defined as any previously healthy person who was incarcerated or worked at the FCC and became ill with diarrhea and/or vomiting from March 27 to April 9. The ISDH developed a questionnaire which documented illness history and food and water consumption. FCC representatives interviewed inmates and staff, and it was determined from onset dates that the outbreak was not likely related to the facility’s food services. No food workers were reported ill prior to or during the outbreak, and the epidemiologic evidence pointed to a viral infection being transmitted from person to person. None of the employees reported ill household members.
Two data sets were collected during the investigation: a cumulative case count (N=124) and questionnaires (N=55). The two data sets were found to have discrepancies in the onset dates and likely contained duplicative cases. Due to federal confidentiality procedures, identifiers were not able to be provided during the outbreak. The investigative team determined that the cumulative count had the most accurate reference for onset dates, as these were collected directly by FCC officials during the outbreak. However, the questionnaires provided more detail on symptoms. Both sets collected data that would satisfy the established case definition.
The FCC interviewed 55 inmates using the ISDH questionnaire. Predominant symptoms included: diarrhea (98%), vomiting (87%), and nausea (80%). The mean duration of illness was 45.60 hours. The median incubation period could not be calculated due to the uncertainty of the start of the incubation period.
Once it was determined that the outbreak was not foodborne and the agent was confirmed Norovirus (see Laboratory Results), interviews were no longer conducted. The FCC collected onset and symptom data on an additional 69 inmates and staff; in total, 124 persons met the case definition (see Figure 1). The attack rate was 3.5 percent for the entire FCC prison population.
Inmates are housed in three buildings, each of which has its own cafeteria that provides food services. The majority of the ill inmates were housed in the Federal Correction Institute (FCI) unit. The FCI unit housed approximately 1,500 prisoners, 250 staff members, and had 103 reported cases. Only 21 cases were housed in the Federal Prison Camp (CAMP) and the United States Penitentiary (USP) units. However, many staff members and inmates travel among all three units. The FCC was also a major hub within the Federal Bureau of Prisons; over 6,000 inmates travel in and out of the facility within a year.
Figure 1: Epidemiologic Curve (N=124)
Thorough hand washing using soap and thorough cleaning and disinfection procedures using a 10 percent chlorine solution were implemented throughout the three unit facilities. Lockdown procedures were implemented in the FCI and CAMP units to contain the outbreak. Also, the Federal Bureau of Prison officials stopped transporting inmates until the outbreak was over. Inmates who were ill or became ill were isolated from other inmates, and staff members were excluded from the facility until symptoms ceased. Staff members were instructed to implement hand-washing procedures when entering another unit, and measures were implemented to limit staff movement between units. The FCC alerted visitors regarding symptoms associated with gastroenteritis and precautionary measures that should be implemented to prevent the spread of the disease.
Six stool specimens were submitted to the ISDH Laboratory for analysis. Five of the six specimens tested positive for Norovirus. Once the specimens tested positive for Norovirus, specimens were not tested for bacterial agents, based on the symptoms and rapid resolution of illness. Foods were not collected because epidemiologic evidence did not support a foodborne vehicle of transmission.
This investigation confirms an outbreak of gastroenteritis occurred at the Federal Correction Complex-Terre Haute between March 27 and April 9, 2008. During this time, approximately 113 prisoners and 11 staff members became ill with vomiting and diarrhea. The only common exposure among cases during the weeks of March 27 and April 9 was attendance at the FCC facility. No cases of gastroenteritis were reported outside of the facility.
The causative agent of this outbreak was Norovirus. Five cases tested positive for Norovirus, and clinical symptoms were compatible with noroviral illness. Evidence indicates that the illness was transmitted person to person rather than through a point source, such as food. Although the sharp increase in cases on March 28 and the gradual decline of subsequent cases shortly thereafter suggests a point-source transmission according to the epidemic curve (Figure 1), no common meal was identified, and no food workers were reported as ill. Person-to-person outbreaks can have patterns similar to point-source outbreaks if many people are exposed within a short amount of time. The subsequent peaks in the curve indicate secondary transmission.
Agents of viral gastroenteritis are passed in the stool or vomitus, and people generally become infected by ingesting stool from a person (fecal-oral route). The virus is easily spread by contaminated food or beverages, from person to person, and by contact with a contaminated object. These viruses can remain infectious on surfaces for up to 72 hours, and only a very small amount of virus is needed to cause infection. Symptoms include watery diarrhea, vomiting, cramps, nausea, headache, and fatigue. Symptoms usually begin 24-48 hours (range of 12-72 hours) after exposure and last 24-48 hours. The illness can last 72-84 hours in the elderly or in those with weakened immune systems. Most cases have no, or slight, fever.
In general, viral gastroenteritis can be prevented by strictly adhering to the following guidelines:
- Practice good hygiene:
- Thoroughly wash hands with soap and water after using the restroom; after changing diapers; after assisting someone with diarrhea and/or vomiting; after swimming; and before, during, and after food preparation (please refer to Quick Facts about Hand Washing).
- Clean food preparation work surfaces, equipment, and utensils with soap and water before, during, and after food preparation.
- Eat safe foods and drink safe water (Remember: Contaminated foods may look and smell normal):
- Wash all produce before eating raw or cooking.
- Use treated water for washing, cooking, and drinking.
- Protect others:
- Persons with diarrhea and/or vomiting should not prepare food or provide health care for others and should limit direct contact with others as much as possible.
- Persons with diarrhea and/or vomiting should not attend a child-care facility or school.
- Persons with diarrhea and/or vomiting shall be excluded from employment involving food handling (Indiana Retail Food Establishment Sanitation Requirements, 410 IAC 7-24-122).
- Do not change diapers near recreational water.
- Do not go swimming or use hot tubs if you have diarrhea and for at least two weeks after diarrhea stops.
Recommendations for Correctional Facilities
- Disinfect all common surfaces, including but not limited to countertops, chairs, desks, restrooms, floors, handrails, elevator buttons, phones, and computer keys, with a 10 percent solution of household bleach.
- Ensure all restrooms are fully supplied with soap, disposable towels and/or functioning hand dryers. Common towels should not be used.
- Stress the importance of hand washing to all inmates and staff within the facility.
- Isolate all inmates and exclude staff members who become ill.
- Cease transportation of prisoners through the facility until the outbreak is over.
- Limit the transfer of prisoners and staff from the affected buildings.
- Instruct inmates and staff to implement hand-washing techniques when entering building units.
The Indiana State Department of Health extends its appreciation for the outstanding professionalism demonstrated by the Vigo County Health Department and the Federal Correction Complex staff during this investigation.