1. Outbreak Investigations
Matthew Cartter, MD, MPH
Connecticut Department of Public Health
August 24, 2016

2. Why investigate outbreaks?
To take immediate action to protect people
To learn how to prevent similar occurrences

3. Outbreak/Epidemic Occurrence of more cases of disease than expected
In a given area or among a specific group of people
Over particular period of time
Outbreak is often the preferred word, as it may escape sensationalism associated with the word epidemic

4. How do we detect outbreaks?
Review of routinely collected or surveillance data
The astute clinician!
Reports from patients or members of the community
Media stories

7. Conn. Agencies Regs. §19a-36-A6
Conn. Agencies Regs. §19a-36-A6. Investigation and control of reportable disease and outbreaks by the department
The department, in cooperation with the local director of health, in the investigation and control of reportable disease shall make or cause to be made such investigation as it deems necessary and shall secure all such data as may assist it in establishing adequate control measures.
In order to investigate and control any apparent outbreak or unusual occurrence of reportable disease, the department shall institute such special disease surveillance, follow-up reports and control measures as it deems necessary.
(Effective October 25, 1989.)

8. Epidemiologic Investigation Environmental Investigation
Laboratory Investigation
New, reemerging or drug resistant infections whose incidence in humans has increased within the past two decades or whose incidence threatens to increase in the near future. Institute of Medicine Report, 1992

10. If cases are continuing to occur...
Goal: prevent additional cases
Objective:
Assess extent of outbreak and size and characteristics of population at risk
Design and implement appropriate control measures

11. If outbreak appears to be almost over...
Goal: prevent outbreaks in the future
Objective:
Identify contributing factors
Design and implement measures that would prevent similar outbreaks

18. Rabid Terrestrial Animals Connecticut, 1991-2014
Wild Animals Raccoon 5192 (76%) Skunk 1454 (21%) Fox 105 Woodchuck 75 Deer 6 Coyote 6 Bobcat 5 Otter 1 Opossum
Domestic Animals Cat 140 (72%) Cattle 23 (12%) Dog 9 Horse 9 Goat 4 Sheep 5 Rabbit 2 Donkey 1 Ferret 1 194

19. E. coli O157
Bacteria, can live in gastrointestinal tract of healthy cattle, goats, and sheep
People can get infected through
Contaminated food or drink
Contact with infected people
Contact with infected animals or their environment

20. E. coli O157
Exposure to very small number of bacteria can cause illness
Can survive a long time in the environment (>42 weeks)*
Takes between 1-10 days for symptoms to appear
Symptoms include diarrhea (often bloody), abdominal cramps, and vomiting
5–10% develop kidney complications or failure (hemolytic uremic syndrome)
Children most vulnerable
* Varma, JAMA.

21. Outbreak Detection Involved
March 24, 2016 – CT Department of Public Health (DPH) identified cluster of seven cases of E. coli O157 infections
Six (86%) reported visiting same goat farm prior to illness
Joint multi-agency investigation
CT Department of Public Health
CT Department of Agriculture
Local health department
Centers for Disease Control and Prevention

23. Investigation Goals Determine scope of outbreak
How large of a problem?
How severe are the illnesses?
Determine potential causes of infection
How did people get sick?
Institute control measures to prevent more illnesses
Develop recommendations to prevent similar outbreaks in future

24. Investigation Methods
Epidemiologic
Interview cases by telephone to collect illness and exposure information
Environmental
Collect environmental and animal samples at farm
Assess facility using NASPHV* guidance
Laboratory
Conduct testing of human, animal, and environmental samples
Compare “genetic relatedness” of bacteria found in human, animal, and environmental samples
* National Association of State Public Health Veterinarians, 2013 Compendium of Measures to Prevent Disease Associated with Animals in Public Settings

25. Epidemiologic Investigation
50 confirmed cases linked to the outbreak
Age range: 10 months – 50 years
Median age: 5 years
11 (22%) cases hospitalized
3 (6%) cases diagnosed with HUS
No deaths

26. Outbreak Curve

27. Laboratory Investigation
61 environmental samples tested
28 (46%) positive for E. coli
17 samples from goats tested
16 (94%) positive for E. coli
Environmental, goat, and human samples shared similar “genetic fingerprints”

28. Environmental Investigation
Farm hosted events allowing public interaction with goats starting March 5, 2016
Estimated 1,500 visitors between March 5 – March 24, 2016
No handwashing facilities available at farm
No signage encouraging use of hand sanitizer
No educational materials to inform visitors about potential risks of disease
Farm allowed direct contact with animals and soiled bedding

29. Conclusions
Investigation highlighted importance of implementing infection prevention measures
Lack of adequate hand washing stations and education materials might have contributed to increased risk of infection to visitors

30. Recommendations
Hands should always be washed with soap and clean running water and dried with clean towels
Immediately upon exiting areas containing animals
After removing soiled clothing or shoes
Before eating and drinking
Standard procedures for cleaning, disinfection, and facility design should be adopted to minimize risk
Restricting young children (<5 years) access to ruminants should be considered to minimize risk to this vulnerable population