Plague (Pneumonic plague, bubonic plague)

What is plague?

Plague is a potentially severe disease caused by a bacteria, Yersinia pestis. It caused the "Black Death" in Europe during the Middle Ages, when approximately one-third of the European population died. Rats on ships brought plague from China to San Francisco in 1900. Today, it continues to cause disease in wild rodents (for example, ground squirrels and prairie dogs), cats and dogs in the southwestern United States, California and southern Oregon. Plague also exists in eastern and southern Africa, Southeast Asia, China, Russia and parts of South America.

Who gets plague?

Human plague is rare in the United States. Infections occur when persons come into contact with a plague-infected animal and either breathe in bacteria that the animal has coughed or get bitten by a flea that fed on the animal. In 2002, two travelers from New Mexico were diagnosed in New York City with bubonic (lymph gland) plague; however, their infections occurred at home before they flew to New York City.

Are there different kinds of plague?

Bubonic (lymph gland) plague: This illness is caused when the plague bacteria enters the skin. This usually is caused by a flea bite. If a flea feeds on an animal that has plague bacteria in its bloodstream, it will carry the bacteria and then transmit the infection if it bites a person. The bacteria travel to the lymph glands (nodes) in the groin, neck or armpit where they multiply and cause tender swellings called "buboes." This disease also can occur if a person is scratched or bitten by an infected animal, or if an infected animal carcass is handled within gloves and the bacteria enter through a break in the skin. Bubonic plague can be effectively treated with a variety of widely-available antibiotics. If untreated, it can be fatal in approximately 50-60% of infected persons.

Pneumonic (lung) plague:  This is a very severe illness. It can occur if a person breathes in plague bacteria that were coughed by an infected animal (e.g., a cat) or another person with pneumonic plague. After entering the lungs, the bacteria multiply and cause life-threatening pneumonia. Pneumonic plague also can develop from bubonic plague if the bacteria enter the bloodstream and are then transported to the lungs. If not treated with effective antibiotics soon after symptom onset, this illness is almost always fatal.

Septicemic (bloodstream) plague: Plague bacteria can enter the bloodstream either through the skin or from the lungs. If bubonic plague is not treated, it can spread into the blood stream from the lymph nodes (glands). Once in the bloodstream, plague bacteria can spread to the brain and cause meningitis. If not treated with effective antibiotics soon after symptom onset, this illness is usually fatal.

How is plague spread?

Bubonic plague is usually transmitted by the bite from infected fleas; however, transmission can occur by bites or scratches from infected wild rodents and cats, or after skin contact with tissue from infected animals. Pneumonic plague can be spread from person to person by sneezing or coughing.

What are the symptoms of plague?

Initial symptoms include fever, chills, muscle aches, headache, nausea, vomiting, diarrhea, abdominal pain, and extreme exhaustion. Swollen and tender lymph nodes near the spot where the plague bacteria entered the skin are typical of bubonic plague. Pneumonic plague usually presents with fever, cough, bloody sputum and difficulty breathing.

How soon after infection do symptoms appear?

Bubonic plague occurs 1-7 days after the bacteria enter through the skin. Pneumonic and septicemic plague occur 1-4 days after exposure to the plague bacteria.

How is plague diagnosed?

Plague is diagnosed by growing the bacteria from samples of sputum, blood, spinal fluid, or infected lymph nodes (glands). Antibody testing also can be done in some circumstances.

What is the treatment for plague?

A number of widely available antibiotics are usually effective against the plague bacteria. The recommended treatment regimen is 10 days.

Are there special concerns or considerations for children who may have plague?

Children have faster breathing rates than adults, so they may have an increased risk of getting pneumonic plague than adults in the same situation.  Children are more likely to have vomiting, seizures and lymph node (gland) pain and tenderness than adult plague patients.

How can plague be prevented?

When traveling in areas where plague is common, it is important to avoid being bitten by infected fleas, or having contact with plague-infected animals, or persons infected with pneumonic plague. Patients with pneumonic plague are isolated for 3 days after antibiotic treatment has been started. In places were plague naturally occurs, buildings should be rat-proofed, with appropriate storage and disposal of food, garbage, and refuse. Dogs and cats in such areas should be treated with insecticides to prevent flea infestation.

Is plague a potential bioterrorism threat?

The plague bacteria has been considered a potential agent for biological warfare and of biological terrorism.

Could a bubonic plague outbreak occur in New York City?

In New York City and other eastern cities, the rat flea that usually transmits bubonic flea (the oriental rat flea) is rare. Outbreaks of bubonic plague in these areas would be unlikely.

What has New York City done to address the threat of plague?

Many federal, State, and City agencies-including the New York City Department of Health and Mental Hygiene (DOHMH)-have been working together for several years to prepare for the detection and response to a bioterrorist event in New York City. In cooperation with other emergency response agencies, DOHMH has established a comprehensive surveillance system to improve our ability to detect and respond to the release of a biological agent.

As part of this plan, the DOHMH continuously looks for any indication of bioterrorism in the City. DOHMH regularly asks all health-care providers in New York City to be alert for any unusual disease clusters, and to immediately report such occurrences to us. Additionally, several surveillance systems are in place to quickly detect an increase in unusual illnesses, including monitoring of 911-ambulance calls and emergency department visits. The response plan includes coordinating with OEM and other City, State, and federal agencies; alerting hospitals and the medical care community; communicating with the public; and ensuring that appropriate medical care and prevention services are provided.

Updated July 2008