Plague Outbreaks: History, Transmission, And Epidemiology

1. BT Response TeamTraining: Plague Jane A. Rooney, D.V.M. State Public Health Veterinarian

2. The Organism

3. Yersinia pestis • Family Enterobacteriaceae • Gram negative coccobacillus (pleomorphic) • Aerobic, Facultatively anaerobic • Facultative intracellular pathogen • Survival • Briefly in soil • Soft tissue ~1 week • Frozen - years

5. History

6. History • Outbreaks • Justinian’s pandemic: 540-590 • Black Death pandemic: 1346~1400 • Great Plague of London: 1665 • Hawaii, 1899 • San Francisco, 1900 • Last U.S. outbreak, 1924, Los Angeles • 32 pneumonic cases/31 deaths

7. Black Death Pandemic • Sudden appearance in Europe 1347 • Rattus rattus and Xenopsylla cheopis • Quarantine • Impact on England greatest of all countries • Sporadic outbreaks throughout 14th century • 17-55 million perished (1/3 of population)

8. Great Plague of London • Began 1664 • Foundations of public health laid • Reporting of sick persons, shutting up homes • “Lord have mercy upon us” • Killed dogs and cats • Peak mortality of 7,000/week • Total mortality 1/5th of pop.

9. United States • Hawaii 1899 • San Francisco 1900 • 1924 Epidemic Los Angeles • 32 pneumonic cases/31 deaths • Spread throughout the western U.S. • From Rattus norvegicus and Rattus rattus to sylvatic rodents • Primarily ground squirrels

10. California 1900 Oregon 1934 Utah 1936 Nevada 1937 Idaho 1940 New Mexico 1949 Montana 1987 Arizona 1950 Colorado 1957 Wyoming 1978 Oklahoma ~1980s Texas ~1920 Washington 1907 New York 2002 U.S. - First Human Cases

11. Plague as a Disease • Class 1 quarantinable disease (WHO) • CDC Division of Quarantine • Reportable disease

12. Transmission

13. Transmission to Humans • Flea bite ~78% • Especially those associated with ground squirrels • Direct animal contact ~20% • Tissues, body fluids, scratches, bites • Y. pestis enters through break in skin • Aerosol (ie, cough) ~2% • Cats • Human cases, April-November

14. Flea Vectors • Can live off host for months • Many species can transmit • Oropsylla montana • Rock and California ground squirrels, prairie dogs • Excellent vector • Most important flea vector in United States

15. Flea Transmission • 27°C (80.6°F) blood clots in flea gut and transmission occurs more readily • 27°C blood clot in flea gut dissolves and transmission less likely

16. Epidemiology

17. Where Are Cases Found? • Southwest • Northern New Mexico • Northern Arizona • Southern Colorado • California • Accounts for ~90% of all human cases

18. Human Plague U.S. 1970-1991(295 cases)

20. Human Cases • United States • 1925-1964 41 cases, avg. 2 cases/year • Since 1970 avg. 13 cases/year • Worldwide • 1,000-3,000 cases/yr • 18,739 cases from 1980–1994 • 2,603 cases in 1999 from 14 countries • 181 deaths • Africa (76% of all cases)

21. 6 cases Plague, reported human cases, U.S. 1970-2000 Prairie dog and rock squirrel epizootic 0 5 10 15 20 25 30 35 40 45 Reported Cases 1970 1975 1980 1985 1990 1995 2000 Year

23. Plague Epidemiology in Nature • Sylvatic (wild) • Urban (domestic) • Reservoirs • Rock squirrels • Ground squirrels • Prairie dogs • Mice • Voles • Others

24. Sylvatic Plague • Enzootic • Plague maintained at steady level in rodent populations • Low death rates • Mice, voles

25. Sylvatic Plague • Epizootic • Large die-offs, fleas change hosts • Amplifying hosts: prairie dogs, ground squirrels, rock squirrels, woodrats, chipmunks • Expansion into human occupied areas • Greatest threat to humans

26. Robert B. Crave. Plague. Infectious Diseases, 5th ed. J.B. Lippincott Co. 1994.

27. Urban Plague • Infected fleas or rodents move to urban area • Interface areas around homes • Western U.S. cities: suburban-wilderness zone • Commensal (domestic) rodents • Roof rat, Norway rat • Rat fleas may feed on humans • Poverty, filth, homelessness

28. West Virginia • No natural reservoir of infection in West Virginia • Implications for case investigations • Urgent investigation • Identify potential natural exposure (travel to endemic area, importation/exposure to sick animal) • BT

29. Plague as a Biological Weapon • 1970 WHO estimate • 50 kg agent • City of 5 million • 150,000 pneumonic cases • 36,000 deaths • 80,000-100,000 hospitalized • 500,000 secondary cases • Up to 100,000 deaths total

30. Disease in Humans

31. Bubonic: Cutaneous infection Swollen, tender lymph glands (buboes) Fever, chills, headache, exhaustion Septicemic Multiplication in bloodstream Fever, chills, prostration, abdominal pain, shock, bleeding into skin Human Disease

32. Human Disease • Pneumonic: • 1 – 4 day incubation period • Infection of the lungs • High fever, chills, cough, difficulty breathing, bloody sputum • Most likely for BT (may also see gastrointestinal manifestations) • 100% fatal if not treated early

33. Laboratory Confirmation • Acceptable specimens • Material from infected bubo • Blood specimen (Series taken 10-30 minutes apart) • Bronchial or Tracheal Wash • Sputum (Not the best) • Office of Laboratory Services

34. Laboratory Diagnostic TestsPLAGUE Colonial Morphology on SBA at 72 hrs Gram Stain

35. Plague Treatment and Prophylaxis • Without treatment: Death 2-6 days after exposure • Treatment is effective if begun early • Symptomatic Exposed (cough or fever) • Streptomycin or Gentamicin • Doxycycline or Tetracycline • Ciprofloxacin • Post-exposure Prophylaxis • Doxycycline or Ciprofloxacin (7 days) • Fever/Cough watch

36. Health Workers • Droplet precautions • Gown, gloves, eye protection, mask • Post-exposure antibiotic prophylaxis

37. Response to BT Plague(Life-saving interventions) • Early recognition and reporting • Case-finding • Fever or cough in known outbreak • Early initiation of treatment • Isolation of cases • Contact tracing and case investigation • Initiate post-exposure prophylaxis • Monitor exposed for symptoms • Antibiotic susceptibility testing

38. Training/Preparation Considerations • Physicians and Hospitals • Recognition, reporting, treatment, and infection control • Labs • Confirmation of clinical diagnosis • Local Health Departments • Investigation and pharmaceutical supply assessment • State Health Departments • Investigation, communication, support LHD, etc… • Increasing overall surveillance and reporting

39. Additional Information • CDC, Division of Vector-borne Infectious Diseases http://www.cdc.gov/ncidod/dvbid/index.htm • CDC, plague information http://www.bt.cdc.gov/agent/plague/index.asp

40. Plague: Surveillance Protocol

41. Plague may occur from an unintentional exposure to infected rodents and their fleas or through an intentional exposure such as a bioterrorism (BT) event. When necessary this protocol addresses unintentional and intentional exposures separately; otherwise the protocol applies to both situations. This protocol applies if a case of plague is highly suspected and does not apply to non-specific pulmonary, gastrointestinal, or rash illnesses.

42. Public Health Action Prior to the occurrence of a case of plague: • Protect employee health • Identify high risk employees • Educate high risk employees • Personal Protective Equipment (PPE) • Assemble and train BT response teams • Assemble BT response teams • Responsibilities of BT response teams • Surge capacity for BT response teams • Train BT response teams

43. Protect employee health • Identify high risk employees: • Identify high risk employees who will be involved in the response to a bioterrorism (BT) event or may have direct contact to plague cases • laboratory workers who test specimens and environmental samples • state and local epidemiologic response teams, healthcare workers and support workers in hospitals, and EMS staff who may come into contact with plague cases • hazmat teams, industrial hygienists, health department sanitarians, and other personnel that may collect environmental samples • first responders such as law enforcement, EMS, and fire department personnel that respond to a BT event.

44. Protect employee health • Educate high risk employees • Educate high risk employees about plague from a BT event • respiratory droplet precautions and isolation of cases • Personal Protective Equipment (PPE) • Educate employees on the use of proper PPE • Provide appropriate PPE to employees for use during an outbreak • Ensure fit testing for employees for respirator use (see Preventive interventions)

45. Assemble and train BT response teams • Assemble BT response teams • Identify staff for two BT response teams (an epidemiology response and a vaccination / medication team) that can adequately respond to a large outbreak by conducting surveillance and epidemiologic response and by providing prophylaxis or treatment after a BT event • Responsibilities of BT response teams • Specific team responsibilities are described in WV Public Health Preparedness Plan for Surveillance and Epidemiologic Response

46. Assemble and train BT response teams • Surge capacity for BT response teams • Identify pools of individuals for surge capacity for the response teams during large outbreaks. A detailed plan for surge capacity is described in the WV Public Health Preparedness Plan for Surveillance and Epidemiologic Response • Train BT response teams • Periodically train and pre-drill individuals on the teams in their respective responsibilities during an outbreak

47. Public Health Action • Educate health care providers and the public in the recognition and diagnosis of plague • Educate providers and laboratories to report plague to the local health department in the patient’s county of residence immediately • Educate veterinarians to report confirmed or suspected cases of plague in animals to the West Virginia Department of Agriculture

48. Public Health Action When a plague case is reported: • Confirm cases • Confirmation of an intentional or unintentional exposure and Notification Procedure • Activate the BT response teams • Protect employee health

49. Case Finding • Develop a working case definition • Begin enhanced passive surveillance • Prepare for active surveillance • Confirm new cases • Develop line list of cases

50. Contact tracing • Identify contacts • Direct contacts • Direct contacts are defined as any person who has had face-to-face contact (within 2 meters) with a suspected, probable, or confirmed case of plague during the infectious period (See Infectious Period section) • Interview all suspected, probable, and confirmed cases and identify all persons who had direct contact with the case since the case’s onset of symptoms (henceforth referred to as a case-contact). Continue interviews daily and record contacts until case is no longer infectious (See Infectious Period section). For each case develop a line list of all case-contacts including all household members of case-contacts using plague contact tracing forms