Use of Epidemiology in Field Settings and Experiences on the Front Lines of Public Health: The Life of an EIS Officer

1. Use of Epidemiology in Field Settingsand Experiences on the Front Lines of Public Health:The Life of an EIS Officer Jennifer Gordon Wright, DVM, MPH, DACVPM Centers for Disease Control and Prevention jgwright@cdc.gov

2. Public Health “is what we, as a society, do collectively to assure the conditions in which people can be healthy.” Institute of Medicine, The Future of Public Health, 1988

3. The Veterinary Oath • Being admitted to the profession of veterinary medicine, I solemnly swear to use my scientific knowledge and skills for the benefit of society through the protection of animal health, the relief of animal suffering, the conservation of animal resources, the promotion of public health, and the advancement of medical knowledge.

4. Emerging Zoonoses • 1415 species of infectious agents reported to cause disease in humans • Viruses, prions, bacteria, rickettsia, fungi, protozoa, helminths • 868 (61%) are known to be zoonotic • 175 species considered “emerging” • 132 (75%) are known to be zoonotic Taylor et al. Risk factors for disease emergence. 2001, Philosophical Transactions, The Royal Society, London

5. The Long and Winding Road… Bachelor of Science in Microbiology, Auburn University • Interest in working at CDC, but in what capacity? • DVM from Auburn University, 1998 • Planned a career in small animal practice or with a drug company • Turning point – a lecture in sophomore PH lecture about a human case of plague • Went into practice for a few years • Found the EIS program while searching the web for jobs • Began MPH work in 2000, worked at CDC • Entered EIS in July 2002

6. History of CDC • 1946 - Communicable Disease Center founded in Atlanta by Dr Joseph W Mountin • 400 employees, mostly engineers and entomologists working on malaria prevention • Original focus on vectorborne and zoonoses • Growing awareness that expansion to all communicable diseases was necessary

7. CDC today • One of 13 components of DHHS • >8000 employees • Headquarters – Atlanta, Morgantown, Ft. Collins, Cincinnati, Hyattsville • State health departments • International reputation • Applies research and findings to improve daily lives • Respond to health emergencies • Not just infectious diseases • Chronic diseases, injuries, workplace hazards, disabilities, environmental health threats

8. How CDC operates • Jurisdiction over: • Cruise ships docking in US ports • Importation of people/animals with communicable disease • Otherwise, need invitation of the state or reservation to assist

9. Veterinarians at CDCAs of December 2005

10. What is the EIS Program? • Epidemic Intelligence Service (aka “Disease Detectives”) • Established in 1951 • Mission: To prevent & control communicable diseases • A 2 year training program in applied epidemiology • Domestic and International Service • Respond to Requests for Epidemiologic Assistance

11. EIScontinued • 55-75 officers, 6-9% are veterinarians • Applications are due in October for the following year’s class • Additional training or experience in public health encouraged prior to application • http://www.cdc.gov/eis/about/about.htm

12. So What is Epidemiology? • The science of studying patterns of disease in populations and the factors that determine such patterns and the utilization of such knowledge for diagnosis, control, and prevention

13. So What is Epidemiology? • The science of studying patterns of disease in populations and the factors that determine such patterns and the utilization of such knowledge for diagnosis, control, and prevention • The study of why some get sick and some don’t

14. So What is Epidemiology? • The science of studying patterns of disease in populations and the factors that determine such patterns and the utilization of such knowledge for diagnosis, control, and prevention • The study of why some get sick and some don’t • The study of skin… 

15. Epidemic • Dorland’s defines as: • Disease attacking many people at the same time, widely diffused and rapidly spreading • Excessive occurrence of disease

16. Descriptive epidemiology • Who • is affected (gender, age, race/ethnicity) • What • disease is causing the problem • Where • is outbreak occurring • When • did the outbreak occur

17. Analytic epidemiology • Why • Did the outbreak occur • How • Risk factors for illness • Examples: • Eat a certain food item • Swam in contaminated lake • Exposure to ticks

18. Establishing Causality (continued)Hill’s Causal Criteria • Strength of association • Magnitude of the risk (Odds Ratio, Relative Risk) • Temporality • Exposure must precede outcome • Dose-response • The greater the dose the greater the risk • Consistency • The association between risk factor and outcome is consistent across studies, samples, populations, etc.

19. Establishing Causality (continued)Hill’s Causal Criteria • Biological plausibility • Association is biologically rational • Coherence • Association is consistent with pathogenesis of disease, similar known associations exist • Specificity • one exposure equals one outcome

20. Outbreak investigation • Establish a case definition (epi vs. lab) • Find cases • Determine if an epidemic has occurred • Characterize the epidemic in space and time • Investigate risk factors • Formulate/test hypotheses (case-control) • Design control/prevention strategies • Monitor and evaluate for recurrence

21. Risk factors • Specific exposures or characteristics associated with disease, i.e. age, gender, breed, race, nutritional status, physiological status, activities, employment, housing, etc.

22. Characterizing risk factors • Relative Risk • Odds Ratio • Attributable Risk

23. The Association between a Risk Factor and a Disease Risk Ratio A A+B divided by C C+D Disease Risk Factor/exposure Yes No Yes A B A + B No C D C + D Odds Ratio AD BC A + C B + D

24. Come Sail Away:Cruise Related Illness, Caribbean, 2002

25. Vessel Sanitation Program (VSP) • 24 hours before arrival in US port ship physician must report number of passengers seen for acute gastroenteritis (AGE) • > 2.0% of passengers/crew with AGE – special report • > 3.0% of passengers/crew with AGE – outbreak investigation

26. Timeline • September 28, 2002 • 1980 passengers, 941 crew • October 2, 2002 • 79 (4.0%) of 1980 passengers with acute gastroenteritis (AGE) • No crew reported illness • October 3, 2002 • CDC team boarded the ship in the Cayman Islands

27. Objectives • Determine the etiologic agent • Determine the source of the outbreak • Implement control measures

28. Epidemiologic Case Finding -GI logs -Survey Case-control study -Survey data Illness onset Symptoms of illness Illness-associated risk factors Other Environmental inspection Stool collection -Laboratory testing Viral Bacterial Methods

29. Survey Case Definition • Diarrhea (3 or more loose or watery bowel movements in a 24-hour period) OR • Vomiting with 1 of the following: • Abdominal cramps, nausea, fever AND • Onset September 28 - October 4, 2002

30. Case-Control Definitions Case • Illness onset 9/29 or 9/30 • Excluded secondary cases: • Persons who met the case definition but cabin mate had onset of illness > 24 hours prior Control • Persons on the cruise who did not report diarrheal illness, vomiting or accompanying symptoms between September 28 and October 4, 2002

31. Results

32. Laboratory Results • 4 of 11 specimens – Norovirus

33. Norovirus • ssRNA, Caliciviridae • Norwalk-like virus • Incubation • 24 to 48 hours • Acute onset • Vomiting, non-bloody diarrhea • Duration • 24 to 60 hours • Asymptomatic – 30% • Transmission – easy

34. Survey Results • Response Rate • 1897 (96%) of 1980 • Attack Rate • 356 (19%) of 1897 • We randomly selected 83 ill persons and 152 controls from our returned surveys • 55 cases: onset September 29 • 28 cases: onset September30

35. Cases of vomiting or diarrhea among passengers and crew, cruise ship C, by date of onset (6-hour periods), Sept 27 to Oct 4, 2002 Date of embarkation

36. Cases of vomiting or diarrhea among passengers and crew, cruise ship C, by date of onset (6-hour periods), Sept 27 to Oct 4, 2002 Case Control Study period Case Control Study period Date of embarkation Date of embarkation

37. Descriptive Results • Age • Cases: median 54 years • Controls: median 51 years • Gender • Cases: males 43% • Controls: males 42%

38. Risk Factors • Significant • Restaurants • Food • Activities • Not Significant • Unbottled water consumption

39. Restaurants • 4 main restaurants • 1 and 2 shared a galley • 3 and 4 shared a galley • 6 specialty restaurants • Additional cost to eat in these

40. Restaurant-Illness associations

41. Food, Restaurants 1 and 2onset of illness Sept 29

42. ActivitiesOnset of illness Sept 30

43. Limitations • Number of food items served • >200 in 2 days • Time between exposure and survey • 6 days after suspect foods served • Passenger discussions • Asymptomatic infections as high as 30% • Controls could have been infected

44. Discussion • Foodborne • Galley worker reported illness 9/27 • Distributor prior to bringing on ship • Norovirus outbreak • Illness onset on Sept 29th • due to a food item • Illness onset on Sept 30th • Person-to-person spread • Aggressive control measures by cruise line may have led to less person-to-person spread than in other outbreaks

45. Control Measures • Before CDC team arrival • Heightened disinfection: 1000 ppm chlorine on hard surfaces • Food serving procedures: gloves, no self serve buffets • After CDC team arrival • Soft fabric disinfection • Cruise line mandated any ill passenger be confined to cabin for 24 hours

46. Recommendations • Prompt and aggressive control • Environmental contamination • Food safety • Proper handling • Hand washing • Strategies to improve employee reporting of illness

47. First Outbreak of Monkeypox in the Western Hemisphere, 2003

48. Monkeypox • Orthopoxvirus, related to smallpox • Restricted to Africa (West Africa, DRC) • Zoonotic disease • Wildlife reservoir unknown • Antibodies to virus found in rodents • Primates and humans accidental hosts • Clinically resembles smallpox • Vesicular rash • Lymphadenopathy • Case fatality < 15% • Limited potential for human-to-human spread • 9 day incubation period

49. Purchase PD at swap meet PD bites child Child ill 5/ 27/03 5/ 31/03 5/ 12/03 5/ 13/03 5/ 14/03 5/ 15/03 5/ 16/03 5/ 17/03 5/ 18/03 5/ 19/03 5/ 20/03 5/ 21/03 5/ 22/03 5/ 23/03 5/ 24/03 5/ 25/03 5/26/03 5/ 28/03 5/ 29/03 5/ 30/03 6/1/03 6/2/03 6/3/03 6/4/03 6/5/03 6/6/03 6/7/03 6/8/03 6/9/03 6/ 10/03 5/ 11/03 6/ 11/03 On May 20, 2003 a 3 year old Wisconsin girl became ill with fever and presumed cellulitis. Lesions appeared at site of a bite from a sick PD on May 13th. Family had purchased 2 PDs from a swap meet on May 11th. Multistate Monkeypox Outbreak, 2003

50. Skin Lesions, Index Case (3 year old child) Marshfield Clinic, WI DAY 11