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The Miami-Dade County Health Department's Office of Epidemiology and Disease Control (OEDC) received a phone call from the director of a child care facility on September 1, 2000, concerning a possible outbreak of gastroenteritis in the infant and joy rooms (special room for sick infants) at the facility. According to the director, several infants had developed symptoms of diarrhea and fever or vomiting, with the first case starting on August 28. This childcare facility was a 24-hour, 7 day a week facility with about 300 attendees a week.

The initial case definition was onset of diarrhea or vomiting in a childcare facility staff person or infant from the infant or joy rooms since August 21. An OEDC investigator visited the facility, along with representatives from the Division of Environmental Health, Miami-Dade County Health Department, Division of Child Care Licensing, Department of Children and Families, and Child Abuse Registry. General information was collected from childcare facility staff, and parents of ill infants were contacted. Stool specimens were collected from all ill infants and one from all staff members for bacterial, parasitic, and viral testing.

On Friday, September 1, 2000, oral and written instructions were given to all childcare facility employees, but these were not fully implemented until September 5 due to the Labor Day weekend. Staff persons were given instructions about disease prevention measures, including proper hand washing techniques, recognition of illness, a video presentation, and a copy of the Centers for Disease Control and Prevention’s ABC's of Safe and Healthy Child Care Handbook.

On September 5, 2000, Phase I control measures were implemented due to a suspected enteric outbreak. These included:

Exclude any child or staff member from the facility if she or he has any diarrhea or vomiting and readmit no sooner than 24 hours after cessation of symptoms.

All people, including children, parents, siblings, staff, visitors, and service personnel, must wash their hands:

• When they enter the day care
• After assisting with diaper changes or toileting
• After using the bathroom
• After playing outside before and after handling food or eating
• immediately after gloves are removed even if the hands look clean.
• All staff members must wash children’s hand after each diaper change.
• No staff involved in food preparation may change diapers

All staff will ensure:

• Hand toys are limited to single use between cleaning and sanitizing
• Swimming pools are not used
• Playing with dough or clay is not allowed
• Tables and other contact surfaces are regularly cleaned during the day using an appropriate germicide
• Potty chairs are cleaned and sanitized after each use
• Bathrooms are cleaned frequently during the day and sanitized at least once a day

By September 1, a total of eight infants had developed symptoms. Subsequent to the initial investigation, an OEDC investigator went to the day care regularly to assess adherence to recommendations and control measures. It appeared that recommendations and control measures were being followed. On September 14, Shigella sonnei (Group D) was identified in a stool. Therefore, it was thought that this was a Shigella outbreak. There were two new cases on September 14. Because this was longer than two incubation periods (usual incubation period for shigellosis: 2-4 days but range up to 7 days) after implementation of phase one control measures, phase two control measures were implemented.

A letter was sent home to every parent about the illness at the center. All ill staff members and infants were excluded from day care until free of symptoms for at least 24 hours. Staff members and infants were cohorted into two different rooms. One room for previously ill staff and infants, and one room for well staff and infants. All staff members and visitors were required to wash their hands upon entering and leaving the infant or joy rooms. (Phase I control measures and recommendations were still being followed). All previously ill infants and staff members had to have two negative stools or have been on appropriate treatment for 24 hours before they could leave the cohort room. After Giardia lamblia was identified from one of the infant’s stools, this was changed to three negative stools or after 72 hours of being on appropriate treatment.

There were 3 additional cases (2 Giardia, 1 unknown) after implementation of Phase II control measures. The last case had an onset date 6 days after implementation of phase II control measures. Cohorting was discontinued on November 1, 2000. There have been no further diarrheal illnesses after September 20.

Between August 28, and September 20, 2000, 27 (59 %) of 46 infants had developed illnesses that met the case definition. The 27 infants were all from the infant or joy rooms. The ill infants ranged in age from 16 weeks to 1 year of age. One infant was hospitalized, and three others showed signs of dehydration. There were 250 children enrolled in the child care center who were not in the infant and joy rooms, but there were no other cases outside the infant and joy rooms. Three (19%) of the 16 infant room staff persons also had illnesses that met the case definition. Their onsets ranged from September 5 to September 8.

Stools from all staff persons were collected including the three symptomatic staff persons. All were negative except for one asymptomatic staff person whose stool tested positive for Giardia lamblia. Stools were collected from all 27 symptomatic infants. Of these, five (19%) tested positive for Cryptosporidium sp., three (11%) Giardia lamblia, one (4%) Shigella, two (7%) Giardia lamblia and Cryptosporidium sp., and one (4%) Cryptosporidium sp. and Norwalk-like virus (G2 strain). In addition, the stool (4%) of one infant, tested by her provider, was positive for rotavirus. No pathogen was identified from the stools of 14 (52%) of the symptomatic infants. Eight asymptomatic infants were also tested, and no pathogens were identified from their stool specimens.

Discussion

This diarrheal outbreak appeared to be due to multiple organisms. The index case was diagnosed with rotavirus infection although the first laboratory result available to us was a specimen positive for Shigella. Subsequently, Norwalk virus, Cryptosporidium sp., and Giardia lamblia were identified from stool specimens. The pathogen for 14 cases among infants was not identified possibly due to late collection of stools. The epidemic curve is hard to interpret due to no pathogen being found for 17 symptomatic infants and staff and because some infants had more than one organism. However, the curve is consistent with person-to-person transmission.

This was our first experience using the new guidelines for control of outbreaks of enteric disease in childcare settings. It is not possible to judge the effectiveness of the new guidelines based on this one outbreak, and this outbreak involved four different organisms. Even though phase one measures were not sufficient to contain this outbreak, it is our impression that the focus of phase one on good hygiene did contribute to stopping the outbreak. Testing of symptomatic infants was essential because only one of the children was tested by his provider (the child with rotavirus) even though many had sought medical care. We chose to use cohorting because of the hardship exclusion of asymptomatic children would pose for parents, and the belief that the parents would take their children to other childcare facilities. Cohorting seemed to be effective. It will be important to evaluate these guidelines with further outbreaks.

The Gasparilla Festival and the Superbowl football game attracted hundreds of thousands of visitors to the Tampa-St. Petersburg area during a period of about two weeks at the end of January and beginning of February. With that influx came the increased risk for disease outbreaks, whether natural or purposefully initiated. During the critical time period surrounding these events, the Hillsborough and Pinellas County Health Departments, assisted by the Bureau of Epidemiology and the Centers for Disease Control and Prevention conducted enhanced medical surveillance in five major area hospitals. The county health departments used two different aberration detection surveillance methods currently being tested by the Florida Department of Health (Statistical Process Control) and the CDC (syndromic aberration detection). Both of these methods attempt to identify significant variations in patient registrations in hospital emergency rooms. The CDC and DOH staff provided frequent trend analysis and feedback to the counties. County health department staff investigated all significant variations identified. (There were no significant findings.) In addition to providing actual surveillance related to the events, this program allowed further testing of the aberration detection algorithms, and will provide insight to the management of "special event" surveillance.

Further details regarding the audio-conference call and PowerPoint files will be posted on the Bureau of Epidemiology Intranet web site. Be sure and register on-line for nursing CEU's and contact hours for environmental health professionals (when applicable). Information about upcoming topics and presenters will also be posted in future Epi Updates. If either of these access points is unavailable to you, please e-mail Melanie Black at [Melanie_Black@doh.state.fl.us] or telephone (850) 245-4444 ext. 2448 (SunCom 205-4444 ext. 2448) to request presentation materials.

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