How pneumonic plague spreads, and how it is and isn't like COVID

Catch up quick: In late September, a woman who worked at an anti-plague research institute in Russia's Irkutsk region broke a test tube that contained a pneumonic plague pathogen, according to local media reports.

• She reportedly died days later at a nearby hospital after showing plague symptoms. Authorities instituted quarantines at five hospitals in the region and placed about 200 people under medical observation.
• The White House, State Department and Department of Health and Human Services are monitoring the suspected outbreak.

The big picture: Plague can be treated with antibiotics, with a high success rate if treated within the first 24 hours after symptoms begin.

• Person-to-person transmission is generally rare and requires close exposure to a coughing patient. CDC says asymptomatic transmission has not been documented.
• But it can still cause epidemics, making it a global concern.

Here's what to know and how it's different than COVID.

What is pneumonic plague?

Pneumonic plague is a rapidly progressing lung infection caused by Yersinia pestis, a bacterium that caused the Black Death.

• Pneumonic plague differs from bubonic plague, which can result from flea bites, and septicemic plague. All three can be transmitted via flea bites or coming into contact with infected bodily fluids.
• Pneumonic plague can also be transmitted through respiratory droplets expelled when a person, or an infected animal, sneezes or coughs.
• "Pneumonic plague is the most serious form of the disease and is the only form of plague that can be spread from person to person," according to the Centers for Disease Control and Prevention.
• Person-to-person transmission happens after close exposure to a coughing patient, per the CDC.

Symptoms, treatment of pneumonic plague

Symptoms can start within one to three days after inhaling infected air droplets, according to the CDC.

• Main symptoms include: fever, headache, weakness, quickly developing pneumonia, shortness of breath, chest pain, cough, and bloody or watery mucus.
• Several types of antibiotics can be used to combat any form of the plague, including pneumonic, according to the Mayo Clinic.

How deadly is pneumonic plague?

The pneumonic plague can be fatal if left untreated for 24 hours, according to the World Health Organization.

• "Recovery rates are high if detected and treated in time," the WHO says.

Pneumonic plague vs. COVID-19

Context: Scattered reports of a dangerous, transmissible disease overseas have revived memories of the early days of the COVID-19 pandemic.

Yes, but: When COVID-19 took off, it was a newly identified disease that scientists were still working to understand.

• Pneumonic plague has been studied for more than a century, with treatments and control measures in place.

Zoom in: COVID-19 is a disease caused by a coronavirus. The pneumonic plague is caused by a bacterium.

• Pneumonic plague generally moves from person to person when someone is around an infected patient who is coughing.
• COVID can spread through airborne particles from people who show few to no symptoms.
• Community spread is uncommon for the pneumonic plague, the CDC says, whereas COVID can spread rapidly through groups, depending on vaccinations and the variant.

Threat level: The two diseases are similar in that they can both affect the lungs, but in very different ways.

• However, pneumonic plague's quicker incubation period makes it easier for health officials to determine if someone is sick.
• People exposed to pneumonic plague can receive antibiotics before developing symptoms, too, per WHO.
• Someone with COVID-19 may not show symptoms for two to 14 days (or may have no symptoms at all). Treatment for mild COVID cases can include antivirals or home care.

The bottom line: Pneumonic plague is tremendously dangerous for the patient and for anyone exposed to an infected person. But modern medicine, along with control measures like masks and isolation, can keep the threat at bay.