Responding to a Plague Bioterrorism Event

Epidemiologic Investigation

An epidemiologic investigation should begin as soon as a human case of plague has been detected. Initially, it will be important to determine the source of the infection and whether it was naturally acquired or the result of bioterrorism. If bioterrorism is suspected, a joint investigation by public health and law enforcement officials will be required. The investigation will seek to identify and isolate the affected population and the epidemiologic features of the case(s).

Pneumonic plague is the most likely clinical manifestation following an intentional release of Yersinia pestis. Patients with pneumonic plague pose a risk for person-to-person transmission. When interviewing symptomatic individuals in person, interviewers should take precautions including wearing appropriate personal protective equipment (PPE).

Interviewers should ask patients about:

  • Symptoms, including cough or other respiratory symptoms.
  • Anyone with whom they had close (<6 feet), sustained contact following the onset of cough.
  • Detailed information about places the patient has visited since the onset of cough to determine sites where additional people may have been exposed.

Identification of additional people with symptoms of plague will help investigators find the source of exposure and initiate appropriate treatment for those infected. It is also important to identify others who may have been exposed but not yet developed symptoms, so they can begin immediate antimicrobial prophylaxis and fever watch.

Public health responders should work with medical providers to isolate patients with suspected or confirmed plague, monitor patient outcomes, and report data to state public health authorities.

Enhanced Surveillance and Case Reporting

Detection of human plague cases suspected of being linked to a bioterrorism event will require the state public health authority to initiate and coordinate active surveillance. Additionally, state public health authorities and Centers for Disease Control and Prevention (CDC) staff will coordinate the epidemiologic investigation with other relevant state and federal authorities. Enhanced surveillance plans should include how to:

  • Identify the most likely exposure and ensure rapid identification and reporting of additional cases after an initial case is confirmed (within jurisdiction or elsewhere).
  • Conduct epidemiological analyses to estimate the population at risk, identify unexpected epidemiological features of the outbreak, and evaluate the characteristics and extent of the outbreak to develop the most effective containment and communication strategies.
  • Identify priority groups for consideration of pre-exposure prophylaxis.
  • Identify possible infected animal populations and where environmental evaluation or remediation may be necessary.

Case Reporting

Human plague is a nationally notifiable disease, which means cases of plague are reported to state or local health departments by healthcare providers and laboratories. State health departments then classify cases according to standard criteria outlined in the plague case definition and report confirmed and probable cases to CDC. Public health authorities use this information to make informed decisions about the best course of action to stop an outbreak.

Public health authorities might recognize a bioterrorism attack by an increase in reported cases. For example, several cases of pneumonic plague in an area would be considered a public health emergency, prompting public health authorities to respond immediately. Additionally, any case of plague outside areas where plague naturally occurs and in people without history of travel would be cause for added concern.

The extent of the outbreak and the resources available will affect the scope of investigation and how plague cases are reported.

In addition to standard surveillance practices, public health organizations can prepare for surveillance during a bioterrorism event by:

  • Educating medical, veterinary, and public health workers on the case definitions and clinical manifestations of plague.
  • Coordinating laboratory activities through the Laboratory Response Network (LRN) and other facilities.
  • Designating a centralized location for reporting suspect plague cases with 24/7 capability.
  • Identifying suspect cases and testing samples after hours and emergency notification systems and ensuring that on-call staff has appropriate access to communication resources.
  • Developing data management systems for cases of disease and for serious adverse events after postexposure prophylaxis or treatment.


Accurate and timely communication with key audiences will support a successful response to a plague emergency. CDC and other federal agencies will communicate about national-level efforts and assist state and local efforts. State and local public health authorities will be responsible for communicating to people within their jurisdictions about the response efforts that affect them.

Preparing to communicate effectively during a plague emergency is similar to preparing for any public health emergency. Prior emergency response work will be beneficial in informing communications. Below are some tips for public health organizations to prepare to communicate effectively during a plague emergency.

  • Be ready to answer questions from the media and the public about plague. This requires knowledge about clinical disease, how plague is spread, prevention, and recommendations for treatment and prophylaxis. Make sure you have knowledgeable people on staff who are able to talk to the media and the public. CDC’s Crisis & Emergency Risk Communications website has trainings and materials to help you prepare.
  • Make arrangements to establish a hotline on short notice.
  • Identify media outlets that can be used to inform the public about actions they should take if they may have been exposed to Y. pestis. Keep in mind special considerations to effectively reach and communicate with community members with functional, language, or cognitive needs.
  • Review rapid-alert communication systems to ensure timely communication capability between the state and local public health and medical communities. Upgrade the systems if necessary.
  • Clearly identify the relative roles of state and local public relations offices.
  • Prepare sample alert messages for the community and other partners. Format these messages for different media, including broadcast, print, web, and social media.
  • Translate messages into languages other than English that are spoken in the community. Confirm accuracy and cultural appropriateness of the messages.

During a plague emergency, your facility may be called upon to care for patients with the disease or suspected of having the disease. Plan now how your facility will respond quickly and effectively to diagnose and treat these patients.

Recognize and Diagnose Plague as Quickly as Possible

Signs and symptoms of plague depend on how a patient was exposed to Yersinia pestis. Pneumonic plague is the most likely clinical manifestation following an intentional release of Y. pestis as a bioweapon. In addition to the usual systemic plague manifestations of fever, chills, aches, and fatigue, patients with pneumonic plague may experience rapidly advancing shortness of breath, chest pain, and cough, and sometimes will have bloody or frothy sputum. Patients with pneumonic plague pose a risk for person-to-person transmission.

Clinicians should be trained to recognize the signs and symptoms of plague. Ensure staff know your facility’s plans for how to respond if plague is suspected; this includes notifying local and state health departments immediately and coordinating laboratory activities through the Laboratory Response Network (LRN).

Confer with state health departments to determine the appropriate specimens for diagnostic testing.

Isolate Infected Patients

Person-to-person spread of pneumonic plague is via respiratory droplets, not fine aerosols. All confirmed, probable, and suspected pneumonic plague case-patients should be isolated under standard and respiratory droplet precautions during the first 48 hours of antimicrobial therapy and until clinical improvement occurs, or until plague has been ruled out. If large numbers of patients make individual isolation impossible, patients with pneumonic plague may be cohorted while undergoing antimicrobial therapy. After 48 hours of antimicrobial therapy, isolation and droplet precautions can be discontinued, however standard precautions should be continued.

Although isolation of a limited number of confirmed, probable, and suspected pneumonic plague cases may be initially accomplished in a hospital setting, local and state health authorities should be prepared to activate and utilize alternative facilities for larger outbreaks of plague.

Patients being transported, during any point in their course of illness, should wear surgical masks. After transporting a patient with suspected or confirmed plague, disinfect any equipment used (such as gurneys, wheelchairs, etc.) using standard disinfection procedures and handle linens with care.

More Information on Infection Control

Care of Patients with Plague

Read the full treatment recommendations for plague in MMWR.

Plague is a very serious illness but is treatable with commonly available antimicrobials. Early treatment of plague is essential. To reduce the chance of death, antimicrobials should be given within 24 hours of symptom onset. Recommended duration of treatment is 10 to 14 days. Treatment may extend beyond 14 days if a patient remains febrile or has other concerning symptoms.

In the event of a suspected bioterrorism attack, two different classes of antimicrobials should be administered to ill patients. It is possible that Y. pestis strains used in a bioterrorism attack will be engineered to be resistant to one or more classes of antimicrobials. Consequently, antimicrobial resistance testing should be obtained if an intentional release event is suspected. Note that both antimicrobial classes do not necessarily need to be first-line for treatment of plague, but ideally at least one class should be.

In addition to providing medical care to the patient, consider other ways to support the patient’s general well-being. Patients in isolation may suffer from anxiety, depression, or report feeling stigmatized. They may also feel forgotten, as the need for personal protective equipment (PPE) reduces the frequency of interaction with clinical staff. Include in your facility’s plans ways to allow for visitors, especially for pediatric patients. All visitors should wear appropriate PPE.

Take Precautions and Use Personal Protective Equipment (PPE)

Healthcare and laboratory staff at potentially high risk for exposure during response activities should follow all standard and droplet precautions and use appropriate personal protective equipment (PPE). If appropriate precautions cannot be maintained due to surgical mask shortages, patient overcrowding, poor ventilation in hospital wards, or other crisis situations, certain groups such as emergency workers, healthcare providers, and environmental and public health investigators may consider taking pre-exposure antimicrobial prophylaxis [PDF – 1 page].

For staff who require pre-exposure prophylaxis, it is reasonable to discontinue use 48 hours after the last perceived exposure.

If plague is suspected, laboratory personnel should be notified when clinical specimens are sent so that they can take appropriate biosafety precautions.

Prior to an outbreak, train healthcare facility staff on:

Prior to interacting with a patient with plague, all staff should don the appropriate PPE:

  • Caregivers in close (<6 feet) contact with suspected or confirmed pneumonic plague patients are advised to follow droplet precautions in addition to standard precautions until a patient has been receiving antimicrobials for at least 48 hours.
  • Consistent with standard precautions, healthcare providers should wear a mask and eye protection or face shield when performing procedures likely to generate sprays or splashes, such as bubo aspiration.
  • Personnel participating in aerosol-generating procedures (e.g., intubation) should consider the use of a fit-tested N95 filtering facepiece respirator for additional protection.

Staff should remove all PPE, except for the surgical mask or N95 respirator (if worn), before leaving a patient’s room. After removing gloves, the staff member should wash their hands with soap and water or use an alcohol-based hand sanitizer. Maintaining proper hand hygiene will help limit the spread of disease.

Following a bioterrorism attack, healthcare responders who have had close, sustained contact with patients sick with pneumonic plague while not wearing appropriate PPE should receive postexposure prophylaxis. Responders who require postexposure prophylaxis should be given antimicrobials for 7 days.

Identify and Diagnose Plague as Quickly as Possible

Both wild and domestic animals can be infected with Yersinia pestis, either through bites of infected fleas, consumption of infected prey, or following inhalation of infectious droplets.

Pneumonic plague is the most likely clinical manifestation an animal would develop following intentional release of Y. pestis as a bioweapon. In addition to the usual systemic plague manifestations of fever and lethargy, animals with pneumonic plague may experience cough and sometimes bloody or frothy sputum. Characteristic symptoms of bubonic plague in animals include swollen, painful lymph nodes (buboes) in addition to systemic manifestations such as fever and lethargy.

Following an outbreak caused by the intentional release of Y. pestis, fleas may become infected after biting animals sick with plague. Fleas could then potentially transmit Y. pestis to additional animals through bites, resulting in zoonotic spread.

Veterinarians should be trained to recognize the signs and symptoms of plague in animals. Ensure staff know your facility’s plans for how to respond if plague is suspected; this includes notifying local and state health departments immediately and coordinating laboratory activities through the Laboratory Response Network (LRN).

Confer with state health departments to determine appropriate specimens for diagnostic testing.

Care for Animals with Plague

Plague is a serious illness but treatable with commonly available antimicrobials. Early recognition and treatment of plague is essential. To reduce the chance of death, antimicrobials should be given within 24 hours of first symptoms. In general, cats are more likely to develop life-threatening infections than dogs, but fatalities can occur in either group.

Take Precautions and Use Personal Protective Equipment (PPE)

Veterinarians and other staff should use appropriate infection control measures and wear personal protective equipment (PPE) when examining animals or handling tissues from animals with suspected plague. Appropriate PPE may include the use of surgical masks, gowns, and gloves. Workers participating in aerosol-generating procedures, such as necropsy on a plague-suspect animal, should also use a fit-tested N95 respirator or the equivalent and protective eye equipment for additional protection. Any material used for examination should be disinfected.

Currently, there are no vaccines available for the prevention of plague in domestic animals.

Antimicrobial postexposure prophylaxis may be considered for veterinary staff accidentally exposed to infectious materials and those who had close (<6 feet) contact with infected animals.

This two-part video series will help enable front-line healthcare providers to recognize, diagnose, and treat plague. These free online trainings serve as a valuable resource for providers who may encounter naturally occurring plague or plague caused by an intentional release.