Appendix C


SUMMARY OF SPECIAL DISEASE
OUTBREAK INVESTIGATIONS - 1998
By
Alan Oglesby, MPH
Epidemiology Resource Center
Indiana State Department of Health

Communicable disease outbreaks, while unfortunate, do provide public health officials with windows of opportunity to learn and add to the current scientific knowledge base. Competent, thorough outbreak investigations can supply invaluable information not only about the size and scope of the outbreak but can also detect emerging trends and provide direction for future prevention strategies. For these and other reasons, outbreaks or clusters of unusual disease incidence are reportable to the Indiana State Department of Health (ISDH) [IAC 410 1-2.1]. Ideally, outbreak investigations should be a collaborative effort between both the local and state health departments. ISDH would be unable to perform this function without the initiative and support of local health departments. Generally, it is the local health department’s responsibility to notify ISDH of the outbreak and to perform the majority of investigative procedures, while the ISDH’s role is primarily one of coordination and consultation. In large or complex outbreak situations, the ISDH may provide direct, on-site assistance. This narrative describes only those outbreak investigations in which the ISDH Communicable Disease Division (CDD) participated. The Food Protection Program (FPP), in addition to lending their valuable expertise and experience to CDD during these investigations, also investigates a substantial number of other food-related outbreaks and complaints for which the CDD never becomes involved.

The ISDH Communicable Disease Division investigated a total of 16 outbreaks in 1998 (Table 1). From January through June, thirty-six cases of probable pertussis were reported from a poorly immunized population in LaGrange County. Seven (19%) cases were less than one year of age, while an additional 27 (75%) were of preschool age. Of the remaining cases, one was in school (8 yrs. old), and the other was an adult. Thirty-one (86%) of the cases had received no pertussis containing vaccine, while 5 (14%) had received less than the recommended number of doses for their age. Pertussis is a highly communicable disease that is most commonly transmitted through airborne contact with respiratory droplets. Up-to-date immunization with pertussis vaccine is the most effective means to prevent illness.

In February, an outbreak attributed to Staphylococcus aureus toxin occurred at a state correctional facility in Parke County. At least 101 inmates were affected. The likely source was macaroni salad which was served in the commissary. Samples of leftover macaroni salad contained high levels of S. aureus as well as high aerobic plate counts, which indicated temperature abuse and mishandling. Additional tests confirmed the presence of Staph toxin in the sample. In May, twenty-seven people became ill with gastroenteritis following a catered office dinner in Marion County. A case-control study implicated barbecue pork as the likely food vehicle responsible for causing illness. Leftover samples of barbecue pork showed extremely high levels of S. aureus present. Food poisoning caused by S. aureus toxin can usually be attributed to time and temperature abuse.

In April, three cases of measles were confirmed within a single Marshall County household. These represent the first confirmed measles cases in Indiana since 1994. All three cases were unimmunized. The first case (15 yrs. old) was most likely exposed in Zimbabwe, and upon return to Indiana, exposed two younger siblings (8 and 12 yrs.). All three cases were serologically confirmed and measles virus was isolated from one case. The cases attended school in St. Joseph County, where all but three students had at least two doses of measles-containing vaccine. Those three students were given a second dose and no further transmission occurred at the school or in the community. Measles is primarily transmitted by direct contact with infectious droplets or by airborne spread. As with pertussis, up-to-date immunization against measles is the most effective preventive measure.

In April , an outbreak caused by Clostridium perfringens toxin affected at least 18 people following a catered office luncheon. A cohort study implicated baked pork as the likely food vehicle. Leftover samples of both baked and barbecue pork contained elevated levels of C. perfringens. Food poisoning due to this toxin is usually attributed to temperature abuse.

From April through July, an increased number of Salmonella serotype agona cases were reported through the Indiana State Department of Health's passive disease surveillance system. Several other states also noted increases of S. agona during this time as well. A multi-state outbreak investigation was initiated and toasted oats cereal sold under several brand names across the country was determined to be the source. The cereal was produced at an out of state facility, and federal investigators are conducting an ongoing investigation to determine how Salmonella could have been introduced and survived the manufacturing process. At least 55 cases and one death were reported in Indiana. In May, an outbreak of Salmonella serotype braenderup was reported in Parke County. Twelve cases were eventually identified, all of whom had eaten at a local Parke County restaurant. Follow-up at the restaurant identified a symptomatic foodhandler who was also confirmed to be infected with S. braenderup. Due to a lack of controls, an exact food source was not identified, but all of the cases did have some type of salad with their meal. It is possible that the infected foodhandler may have been the source and contaminated food items directly via inadequately washed hands but this was not confirmed. Salmonellosis can be prevented by thoroughly cooking foods of animal origin; thorough handwashing after using the bathroom and before preparing foods; and by washing cooking utensils after contact with raw foods of animal origin and before contact with other foods.

In May, an outbreak of E. coli O157:H7 occurred in both Johnson and Marion Counties. A case-control study implicated one particular Johnson County franchise of a popular restaurant chain. Cole slaw, prepared from unwashed heads of cabbage, was identified as the vehicle responsible. Twenty-seven cases were confirmed by stool culture or serology. E. coli O157:H7 was also recovered from a consumer's sample of cole slaw, which shared the same pulsed field gel electrophoresis pattern as the culture confirmed cases. E. coli O157:H7 can be transmitted through raw or undercooked foods of animal origin (particularly ground beef) or through foods cross contaminated by animal products. It can also be transmitted from unwashed produce, unpasteurized milk and fruit juices, and from person to person.

In August, at least 66 people became ill with gastrointestinal symptoms after attending a golf invitational at a St. Joseph County country club. Results from the case-control study implicated pasta from the final awards banquet to be the likely food item responsible. This cannot be confirmed however, due to the unavailability of leftover foods for sampling. A lack of timely stool cultures from affected cases also prevented the identification of a specific pathogen.

Five suspected viral outbreaks occurred all over the state. In most cases, they were linked to foods served raw (vegetable trays, lettuce, etc.) or to foods which were handled extensively after cooking (sliced meat, etc.). Food-borne viral outbreaks usually occur when an infected person handles food without thoroughly washing their hands after using the bathroom.

On December 25, extended family members gathered at a Clark County residence to celebrate the holidays. By December 30, two family members were admitted to separate hospitals for probable invasive meningococcal infection. Prompt antibiotic prophylaxis of the two cases prevented confirmation of the diagnosis by positive culture. However, additional public health response was initiated as a precaution. Approximately 40 other extended family members in six southeastern Indiana counties were contacted and referred to their healthcare providers for further evaluation regarding post-exposure prophylaxis. No other cases were reported. Meningococcal disease, caused by the bacterium Neisseria meningitidis, is spread from person to person by direct contact with an infected person's nose or throat secretions. This may occur after coughing or sneezing in someone's face, kissing on the mouth, or eating or drinking after someone. Good personal hygiene is the most effective measure to prevent the transmission of meningococcal disease. In certain high-risk situations, meningococcal vaccine and/or antibiotic prophylaxis may also be necessary to prevent transmission.

There were no waterborne outbreaks reported in Indiana in 1998.

Editorial note: Based on our experiences in disease investigation, the Communicable Disease Division and Food Protection Program make the following recommendations to local health departments for efficient and scientifically sound disease investigations: (Note: Because a majority of ISDH’s investigations are food-related, these recommendations are specific for food-related outbreaks. In special circumstances, such as the meningococcal and vaccine-preventable disease outbreaks, some of these recommendations will not apply).

Ensure that everyone involved in the process is working together. This may involve initial and even daily meetings among environmental and nursing staffs.

Inventory your supplies to make sure the health department is equipped to investigate outbreaks. Containers for collecting stool samples specific for bacterial pathogens (7A) should be readily available. These containers do have an expiration date so please make sure that they are current. New containers can be ordered or expired containers can be replaced by contacting the ISDH Containers Section at (317) 233-8105.

Before contacting ISDH for assistance, some basic information about the outbreak is helpful. This includes:

- type of event, location, date, number of meals served, and time of meal(s)
- source of food served (caterer, home, etc.) and contact person for the source
- number of exposed persons
- number of known sick persons
- range and times of illness onset
- main symptoms
- contact person for ill persons and phone number, if possible
- menu of all food and beverage items served