Infectious Disease Outbreak and Surveillance Data and Health Implications/PHE4095

This is the APA format citation for the book.

Dworkin, R.H.F.M. S. (2010). Essentials of Environmental Health. [South University]. Retrieved from https://digitalbookshelf.southuniversity.edu/#/books/9781449688059/

CHAPTER 12 Controlling an Outbreak of Shigellosis with a Community-Wide Intervention in Lexington, Kentucky

Janet Mohle-Boetani, MD, MPH

Kentucky, 1991

INTRODUCTION

“There’s a large outbreak of shigellosis in Kentucky, and we wondered if you could help out.” This was the request to me from Dr. Patricia Griffin of the Enterics Branch in the first week of June 1991. Dr.Griffin was in the middle part of her career as a supervisor in the Enterics Branch for the Centers for Disease Control (CDC). She was known by the EIS officers as a supervisor who paid attention to details in an outbreak investigation. She was also very friendly, and I had often talked with her about interesting outbreaks when I ran into her in the elevator in the CDC building.

I had just about completed my first year of EIS in the Bacterial Meningitis and Special Pathogens Branch and had watched enviously as my colleagues in the Enterics Branch, just down the hall from me, were sent to investigate cholera in South America and botulism in Egypt (Todd Weber). Before joining the EIS, I went to Stanford Medical School, where I developed an interest in epidemiology from our pathology classes and worked on epidemiologic studies of ovarian cancer and breast cancer. In my internal medicine residency at Stanford, I developed an interest in infectious diseases; I thought that the EIS program would be an ideal place to both further explore infectious diseases and expand my skills in epidemiology. In Atlanta, I had worked on engaging and complex projects including a cost-effectiveness analysis of preventive measures for neonatal group B streptococcal disease, but I had yet to be involved with a large epidemic, or even a sizable outbreak. Although Lexington, Kentucky did not seem to be the most exotic location to be sent on an outbreak investigation and shigellosis could not have been a more common disease, the opportunity to work on a large outbreak outside of Atlanta was very appealing to me. I enthusiastically accepted the offer.

After a day spent reading all that I could about shigellosis and its control and packing my bags for an estimated 2-week trip, I boarded a plane for Lexington. I remember immediately being struck by the vast grasslands surrounding the airport. There were horse pastures seemingly everywhere; the health department was in close proximity to a fair ground where horses competed in weekly shows. I arrived at the health department at 9 a.m., and the office was bustling with activity. After being introduced to the Commissioner of Health, Dr. John Poundstone, and a crew of public health nurses, I set to work looking into the statistics that had been gathered on the outbreak.

There were 138 culture-confirmed Shigella sonnei infections with onsets from January through May; most of these cases were in persons who attended or worked at child care facilities or elementary schools. The public health nurses had been attempting to control the outbreak using standard public health procedures. Cases were defined as laboratory evidence of infection with Shigella sonnei. Cases were reported through standard laboratory surveillance. Each case triggered a public health investigation that included a home visit, collection of stools for Shigella culture from close contacts, and instruction in handwashing before meals, after toileting, and after diaper changes.

Shigella is a Gram-negative organism that is spread through the fecal–oral route or person to person and causes fever, diarrhea, and stomach cramps about 1 to 2 days after ingestion. The diarrhea is often bloody, and symptoms usually resolve within 1 week. The organism is carried (by persons who are infected but do not have symptoms) and causes disease in only humans (not in other animals). Because the infectious dose is very low and most infected people are only mildly ill and thus remain in contact with other people, outbreaks are common.

Shigella is a Gram-negative organism that is spread through the fecal–oral route or person to person and causes fever, diarrhea, and stomach cramps about 1 to 2 days after ingestion.

Shigella organisms were discovered more than 100 years ago by Shiga, a Japanese scientist. There are three major species of Shigella. Shigella sonnei causes two thirds of infections in the United States, and the other third of infections are primarily caused by Shigella flexnerii. Shigella dysenteriae type 1 cause toxic diarrheal epidemics in the developing world.

Public health professionals (primarily public health nurses) also visited all schools and child care centers that were attended by children with culture-confirmed shigellosis. All classmates of culture-confirmed cases were tested for shigellosis. Children in preschool or daycare were excluded while symptomatic (with diarrhea) day care center staff, teachers, and elementary school children were excluded from school or work until they had three consecutive stool cultures negative for Shigella.

In March, the health department mailed a notification to the directors of all licensed child care facilities (preschools, day care centers, and family day care homes). The notification included information about the outbreak and advised them to require handwashing on arrival to the facility, after diaper changes, after toileting, and before eating or preparing food.

Despite these meticulous and well-documented investigations, exclusion policies, and notifications, the outbreak persisted and spread throughout the community through the end of May. There was understandable frustration in not being able to control the outbreak, despite following standard public health practices. There was also concern that the outbreak would be exacerbated by summer activities. Because Shigella infections are spread person to person and through food handling, shigellosis typically increases in the summer because of increased congregations of people in areas without hygienic facilities (e.g., at camps) or sharing home prepared food items (e.g., weekend picnics). For these reasons, assistance in controlling the outbreak was sought first from the state health department and then from the CDC.

Because Shigella infections are spread person to person and through food handling, shigellosis typically increases in the summer because of increased congregations of people in areas without hygienic facilities (e.g., at camps) or sharing home prepared food items (e.g., weekend picnics).

INITIAL INVESTIGATION AND RECOMMENDATIONS

In the afternoon of my first day, one of the public health nurses took me to a few of the child care facilities that had outbreaks of shigellosis. Despite recent training and written notifications by the public health nurses regarding the need to wash hands, we observed barriers to handwashing in most of the centers we visited. For example, the sinks were too high for children to reach, and no step stools were readily available for the children to get access to the sink after going to the toilet. Also, sinks were not easily accessible to the areas chosen for diaper changing.

After reviewing the data and conducting observations at child care facilities for a few more days, my supervisor in Atlanta, Dr. Griffin, and I developed recommendations for the Lexington Health Department. We recommended promotion of handwashing community wide, surveillance for diarrhea, and rapid diagnosis and treatment of shigellosis. We emphasized handwashing promotion over collection of stool specimens.

I worked diligently on the weekend and called Dr. Griffin at her home to check in on the wording of some of the recommendations. In the middle of one of these very intense conversations, she exclaimed “Wow, he did it!” I asked, “What?” “My son just pooped in his potty chair—his first time!” I found this particularly comical given that we had just been talking about how to phrase our recommendation to wash hands after helping children use the toilet.

An additional recommendation that Dr. Griffin and I developed was that the health department should stop collecting stool specimens from asymptomatic convalescing school children, teachers, and day care staff. We felt that these groups, even though recently infected, would be very unlikely to transmit Shigella if they had formed stools and could be relied on to wash their hands after going to the toilet. We also recommended against the practice of testing asymptomatic contacts of persons with shigellosis. We reasoned that the decreased burden of specimen collection, ensuring exclusions from work or school, and following up on multiple stool culture results would permit the public health professionals to focus on handwashing in key locations where people congregated and would permit a proactive rather than reactive approach.

Because we could not be certain that preschool aged children could be expected to wash their hands reliably, we recommended that asymptomatic convalescing preschool aged children be excluded from group child care until two stool cultures were negative for Shigella. This recommendation was a policy change from the practice of excluding children from child care facilities only during the time that they had diarrhea. Although we anticipated an increased workload in following these children, we expected that there would be a substantial decrease in workload in following cultures from asymptomatic contacts and from asymptomatic, convalescing, school-aged children and adults.

INITIAL RESPONSE

The Lexington County Health Department responded vigorously to our recommendations. On June 10th, the day after we provided our recommendations, the Commissioner of Health created a Shigella Task Force consisting of health department staff from the clinic, the laboratory, the field service section, the school health section and the environmental health division. The commissioner called a meeting with key leaders in each of these areas and presented our recommendations. I believe the commissioner created the task force to empower the leaders to take responsibility for controlling the outbreak. I credit the commissioner’s leadership skills as responsible for the effectiveness of the committee. The leaders decided to implement a community-wide handwashing campaign with monitoring of handwashing at sites controlled by community services considered to be at high risk of transmission. The task force initiated onsite handwashing promotion at day care centers, summer schools, summer camps, and free lunch sites. The handwashing promotion included problem solving at each site to ensure that appropriate handwashing could be accomplished everyday.

I believe the commissioner created the task force to empower the leaders to take responsibility for controlling the outbreak.

In the 3 to 4 days after the creation of the task force, I accompanied public health professionals on several of their site visits to child care facilities, elementary schools, summer camps, and free lunch sites. At each of these sites, I observed the direct advice and problem solving of the public health professionals and recorded and photographed key areas of concern regarding handwashing. For example, we observed and recorded children lining up for free lunches without handwashing and a paucity of handwashing facilities available at summer camps. At child care centers, we observed sinks that were too high for the children to reach to wash their hands. At schools, we observed that no soap was available in some of the bathrooms; this was a safety issue because children would squirt soap on the floor and then slip on the soap. I planned to return to each of these sites in a few weeks to observe changes in the accessibility of soap and water and handwashing practices.

Watching the community join together to implement rapidly community-wide handwashing was one of the most rewarding experiences of my tenure at the CDC. After creating the task force, assistance in handwashing promotion was sought from the community at large. To engage the community, Dr. Poundstone held a press conference and sought cooperation from the media, the Parks and Recreation Office, the Community Services Agency, and the school board. A local television station aired a video several evenings each week that emphasized the prevention of shigellosis through handwashing and taught proper handwashing technique. The Community Services Agency and the Parks and Recreation provided liquid soap and water to all free lunch sites and summer camps. The school board ensured that all summer students viewed a video on shigellosis and handwashing and that all students would be monitored in handwashing on arrival to school, after using the toilet, and before eating lunch or snacks. I believe that it was Dr. Poundstone’s leadership and a strong local public health infrastructure that permitted the rapid implementation of these community-wide preventive actions within a week of my arrival to Lexington.

An additional change that was implemented was enhanced surveillance for diarrhea.

An additional change that was implemented was enhanced surveillance for diarrhea. Child care facilities and elementary summer schools were directed to keep track of illnesses from school or day care and to advise those with diarrhea to seek rapid diagnosis and treatment at the health department clinic. The health department set up a special diarrhea clinic so that persons with diarrhea would not need to wait for an appointment to get tested and treated. All patients were instructed in handwashing in the clinic.

After observing the implementation of the hand-washing campaign, I needed to leave Lexington to attend the international conference on AIDS in Florence, Italy. This was a conference that I funded on my own, to present a paper from work I had done during my internal medicine residency. Coincidentally, some of the work that I collaborated on regarding bacillary angiomatosis while I was an EIS officer was also being presented (this is an unusual systemic disease occurring primarily in immunocompromised persons due to infection with the bacteria Bartonella quintana or Bartonella henselae). As can be imagined, I had a very enjoyable week, both at the conference and traveling in Italy with my boyfriend (now husband) Mark. Mark lived in California while I was in Atlanta, and we very much appreciated any time that we could spend together.

THE SECOND PHASE

The week away was also ideally timed from an investigation standpoint. My departure from Lexington permitted the health department and greater community to implement the handwashing campaign unencumbered by meetings with me. I returned to Lexington just before the 4th of July, and I remember spending a great day with the family of one of the public health nurses; we swam in her backyard swimming pool and ate lots of watermelon. The personal relationships developed in the context of an intense outbreak investigation are a major unspoken reward of field investigations. The public health staff members that I met in Lexington were warm, gracious, and appreciative. Their dedication to public health and collaborative spirit were a large part of the inspiration leading to my decision to pursue a career in public health instead of academic medicine.

After my return to Lexington from Europe, my goals were to (1) observe the implementation of handwashing in a diversity of sites in the community and (2) conduct a study to attempt to determine risk factors for outbreaks of shigellosis in child care facilities. Although many child care facilities had outbreaks, there were several that had no cases or only one case; we wanted to determine whether there were predictors for the spread of shigellosis in child care facilities that could be modified to prevent outbreaks in the future.

My first goal was met through going back to the same sites I had originally visited in the week just before the handwashing campaign. I was elated to see dramatic changes at all of the sites that I visited. For example, at a summer camp where there had been limited access to handwashing facilities, handwashing stations were set up close to the latrines. In the outside picnic area where the children had lunch, two outside sinks were designated as handwashing sinks, and I observed the Parks and Recreation staff requiring children to line up and wash their hands before receiving their lunch. At the camp site, they even incorporated handwashing into one of their routine cheers (“Give me an H, give me an A, give me an N…. What’s that spell?”).

At a free lunch site in the middle of a housing project, soap dispensers were installed in the two outside sinks, and I observed the community service workers monitoring children in washing their hands before providing them with their lunches. At child care centers, I noted the addition of step stools to sinks to ensure that young children could reach the sinks and that nurses had worked with facilities to create diaper changing areas that were close to handwashing facilities (this was particularly challenging at times). I observed elementary schools lining children up to wash their hands before lunch. I documented all of these changes with “afterintervention” photographs. The collection of before and after photos was used to create an instructional video directed to local health departments on controlling a community-wide shigellosis outbreak.

To accomplish the second goal, I worked together with an epidemiologist from the state public health department, Margaret Stapleton, MSPH. My supervisor in Atlanta had also changed. Dr. Griffin was on a summer vacation, and Dr. Paul Blake, the Enterics Branch chief, was filling in. I found it refreshing to have a new supervisor for this phase of the investigation. By this point, I had learned a lot from Dr. Griffin about controlling the outbreak and providing recommendations to a local agency. In this next stage of the investigation, I hoped to do a field analytic study that would provide practical recommendations; I was not disappointed.

On another memorable weekend call, Dr. Blake and I developed a plan for a case-control study. In the information collected by the health department, I had noted that some child care centers had large outbreaks, whereas others had no cases. We wondered whether those centers with no cases were different than those that had large outbreaks. We reasoned that if we could determine factors associated with large outbreaks we could use them in recommendations to prevent outbreaks in the future. We decided to conduct a case-control study in which the “case” was a center with at least three cases of shigellosis among children and a “control” was a center with no cases of shigellosis. Although this method differs from the standard case-control study in which cases are defined as illness in individual people, we felt that the method should work in comparing centers with and without outbreaks.

The health department supplied me with a list of all licensed child care centers and family day care homes in the county as well as basic characteristics of those facilities and the number of culture-confirmed cases of shigellosis identified among children attending each facility. I found that all centers with at least three cases enrolled diapered children and children whose child care fees were paid through a federally funded program (indicating a low socioeconomic level). Because both having children in diapers and low socioeconomic status are known risk factors for outbreaks of shigellosis, we felt we needed to control for these factors. Given the small size of the study (only six “case centers”), we felt the most efficient method of controlling for socioeconomic status was to restrict the control centers to those with diapered children, at least five children who had fees paid by the federally funded program, and no cases of shigellosis. Thirteen centers met the criteria for control centers.

Ms. Stapleton and I collected the information for the case-control study through onsite interviews. First we created a questionnaire addressing policies and procedures and observations. Ms. Stapleton interviewed the directors about practices and policies while I asked the same questions of a staff member who cared for diapered children. We also collected the number of children by age group and the number of toilets used by each age group. Comparing notes with Margaret after our respective interviews was another memorable part of this field investigation. The discordance between the director and staff interviews was notable.

We found an association between having a food preparer (a staff who mixed formula or a cook) who changed diapers and having at least three cases of shigellosis in the facility (100% of case centers vs. 46% of control centers, P = 0.04). We found a greater median toddler-to-toilet ratio (the number of 3 year olds per flushable toilet) in the case centers than in the control centers (the ratio was 20 in case centers and 13 in the control centers, P < 0.05). We also found an association between the provision of transportation from home to the center and shigellosis (83% of case centers provided transportation vs. 15% of the control centers).

Differences in the response of directors and staff to hygiene questions were identified. Although 42% of staff reported that a cook changed diapers, only 11% of directors reported these combined duties. Directors were also more likely than staff to report that they had policies to prevent diarrhea (89% vs. 32%).

Thus, the case-control study did reveal features of centers amenable to changes that could help to prevent diarrheal outbreaks. Food should be prepared by persons who do not change diapers, if possible. The high toddler-to-toilet ratio found in the case centers could be a reflection of inadequate sinks to permit accessible handwashing. We felt that the finding of transportation associated with the case centers might be a reflection of a tendency to mix different age groups of children, permitting the introduction and spread of communicable diseases such as shigellosis. The discordant answers to questions by staff and directors highlights both (1) the importance of querying staff, in addition to directors, when doing investigations in facilities, and (2) that staff in child care centers may need additional training in infection control.

The second part of my investigation was also rewarding because I was able to observe a rapid decline in the reported cases of shigellosis. The epidemic curve showed an abrupt decrease in cases in the week after community-wide interventions were initiated in mid June ( Figure 12-1 ). 1  Although in June there were 42 cases, in July there were only 10 and subsequently cases were reported at a very low rate, 2 to 14 per month. With the outbreak under control, I spent the last weekend at a horse show and visiting the Appalachian mountains (as suggested by Margaret), where I acquired a woolen blanket, hand woven by students in Berea College that I use to this day.

FIGURE 12-1 Timeline of shigellosis outbreak in Lexington-Fayette County, Kentucky, 1991.

Data from Kolanz M, Sandifer J, Poundstone J, Stapleton M, Finger R. Shigellosis in child day care centers—Lexington-Fayette County, Kentucky. MMWR 1992;41:440–442.

CONCLUSION

During this investigation, I learned several lessons. First, some standard public health practices such as stool collection among contacts can divert precious public health resources from health promotion and prevention. Second, community-wide interventions are possible with strong leadership and an effectively functioning health department that is able to collaborate productively with the community at large. Third, the case-control study approach can be used with the facility as the unit (for a case or control) to determine facility characteristics that are associated with disease. Fourth, I learned the rewards of direct field investigation and developed a deep respect for local public health professionals. Finally, I learned that you do not need to be in an exotic location or work on an exotic disease to have a rewarding experience investigating an outbreak. Working on this shigellosis outbreak in Lexington, Kentucky was definitely one of the most gratifying experiences of my EIS career and was a turning point in my decision to work in public health at the local level.

REFERENCES

1.

Mohle-Boetani, JC, Stapleton M, Finger R, et al. Community wide shigellosis: control of an outbreak and risk factors in child day-care centers. Am J Public Health 1995;85:812–816.

LEARNING QUESTIONS

1.

This outbreak illustrates the importance of promoting an effective intervention in a community setting. What did the author and her collaborators do to maximize the success of hand washing promotion?

2.

The author refers to finding discordance in her case-control study of day care centers. What discordance was found and how may its recognition have been helpful to the author and the health department?

3.

Which steps of outbreak investigation are illustrated in this chapter? Where in the chapter are those steps illustrated?