Plague is caused by the bacterium Yersinia pestis and is considered a potential bioterrorism agent. It was responsible for the Black Death pandemic in the 14th century that killed over 20 million people in Europe. The pneumonic form of plague can spread from person to person via respiratory droplets and is the most likely presentation in a bioterrorism attack. Standard respiratory droplet precautions are recommended for suspected pneumonic plague cases until at least 48 hours after antibiotic treatment begins. Prompt treatment with antibiotics is important as pneumonic plague can be fatal if treatment is not initiated within 24 hours of symptom onset.

1. Plague
CDC, AFIP

2. Diseases of Bioterrorist Potential
Learning Objectives
 Describe the epidemiology, mode of transmission, and
presenting symptoms of disease caused by the CDC-
defined Category A agents
 Identify the infection control and prophylactic measures
to implement in the event of a suspected or confirmed
Category A case or outbreak

3. Plague
History & Significance
14th Century: “Black Death” responsible for >20
million deaths in Europe
Used as a BW agent by Japan in WW II
Studied by Soviet and, to a smaller extent, U.S.
BW programs
1995: Larry Wayne Harris arrested for illicit
procurement of culture via mail

4. Plague
Epidemiology
Caused by Yersinia pestis
About 10-15 cases/year U.S.
 Mainly SW states
Human plague occurs from bite of an infected flea
(bubonic)
Only pneumonic form of plague is spread person-to-
person
 Last case of person-to-person transmission in U.S. occurred in 1924

5. Yersinia Pestis
 Gram negative, non-
motile, non-spore-
forming bacillus
 Resistant to freezing
temperature and
drying, killed by heat
and sunlight Source: Centers for Disease Control and
Prevention, Division of Vector-Borne
Infectious Diseases, Fort Collins, CO

6. Plague
Case Definition
• Characterized by fever, chills, headache, malaise,
prostration, & leukocytosis that manifests in one
or more of the following clinical forms:
– Regional lymphadenitis (bubonic)
– Septicemia w/o evident bubo (septicemic)
– Plague pneumonia
– Pharyngitis & cervical lymphadenitis (pharyngeal)
MMWR 1997;46(RR-10)

7. Plague
Case Definition, cont.
Laboratory criteria for diagnosis:
Presumptive
Elevated serum antibody titers to Y. pestis F1 antigen (w/o
documented 4-fold change) in a patient with no history of plague
vaccination OR
Detection of F1 antigen in a clinical specimen by fluorescent assay
Confirmatory
Isolation of Y. pestis from a clinical specimen OR
4-fold or greater change in serum antibody titer to Y. pestis F1 antigen
MMWR 1997;46(RR-10)

8. Plague: Case Classification
Suspected: Clinically compatible case w/o
presumptive or confirmatory lab results
Probable: Clinically compatible case with
presumptive lab results
Confirmed: Clinically compatible case with
confirmatory lab results
MMWR 1997;46(RR-10)

9. Plague
Clinical Forms
 Bubonic plague
Most common naturally-occurring form
Mortality 60% untreated, <5% treated
 Primary or secondary septicemic plague
 Pneumonic plague
Most likely BT presentation
From aerosol or septicemic spread to lungs
Survival unlikely if treatment not initiated w/in
24 hours of the onset of symptoms

10. Pneumonic Plague
Clinical Presentation
Incubation: 1-6 days (usually 2-4 days)
Acute onset of fever with cough, dyspnea, and chest pain
Hemoptysis characteristic; watery or purulent sputum
also possible
Prominent GI symptoms may be present, including
nausea, vomiting, diarrhea, and abdominal pain

11. Pneumonic Plague
Clinical Presentation
Other symptoms include headache, chills,
malaise, myalgias
Rarely, cervical bubo present
Rapid progression to respiratory failure & shock

12. Bubonic Plague
 Incubation: 2-8 days
 Sudden onset nonspecific symptoms: fever, chills,
malaise, muscle aches, headache
 Regional lymphadenitis (buboes)
Swollen, very painful lymph nodes
Typically inguinal, femoral, axillary, or cervical
Erythema overlying skin
May have surrounding edema
Concurrent with or shortly after onset of other symptoms

13. Septicemic & Bubonic Plague
Source: CDC NVBID

14. Plague
Infection Control
Person-to-person transmission via respiratory
droplets
Standard respiratory droplet precautions
Treatment = 10 days antibiotics
 Case isolation for at least the first 48 hrs of antibiotic
treatment
Bubonic plague - standard precautions

15. Plague
Infection Control
Antibiotic prophylaxis for close contacts
Duration: 7 days or duration of risk of exposure +
7 days
Close contacts refusing prophylaxis:
Observe 7 days after last exposure and treat if
fever or cough develop
Bubonic contacts:
Observe 7d and treat if symptoms develop

16. Plague
Summary of Key Points
The most likely presentation in a BT attack is
pneumonic plague.
Unlike other forms of plague, pneumonic plague
is transmitted person to person, and thus
respiratory droplet precautions are indicated in
suspected cases until 48 hours after the initiation
of antibiotic therapy.

17. Case Reports
 Plague
Plague Pneumonia - CA. MMWR 1984;33(34)
Pneumonic Plague -- Arizona, 1992. MMWR 41(40)

18. Resources
 Centers for Disease Control & Prevention
 Bioterrorism Web page:
 CDC Office of Health and Safety Information System
(personal protective equipment)
 USAMRIID -- includes link to on-line version
of Medical Management of Biological Casualties
Handbook http://www.usamriid.army.mil/
http://www.bt.cdc.gov/
http://www.cdc.gov/od/ohs/

19. Resources
 Office of the Surgeon General: Medical
Nuclear, Biological and Chemical Information
 St. Louis University Center for the Study of
Bioterrorism and Emerging Infections
http://www.nbc-med.org
http://bioterrorism.slu.edu