Topline
Colorado health officials confirmed a rare human case of bubonic plague on Tuesday, urging people to be on the lookout for the lethal bacterial infection that propelled some of the deadliest pandemics in history and still sickens a handful of people in the U.S. every year.
Key Facts
Plague is caused by the Yersinia pestis bacterium that can infect humans and a wide range of animals, and particularly small mammals like rats, marmots, prairie dogs, rabbits, mice, squirrels and chipmunks.
Plague is most commonly spread through the bites of infected fleas, though humans can also be infected following direct contact with contaminated body fluids or tissue, such as handling an infected animal or caring for someone without protective gear, or by inhaling infectious droplets in the air, which could come from the coughs of infected people or animals like cats.
The disease manifests in three main ways depending on how a person is infected, with the most common, bubonic plague, being caused when the bacteria enters the body and multiplies in lymph nodes, and septicemic plague happening if the bacteria get into the bloodstream, which can happen directly or from an untreated case of bubonic plague.
Pneumonic plague is by far the most serious form of the disease and the only form of plague that can spread directly between humans, occurring when plague bacteria reach the lungs, emerging as quickly as a day after the inhalation of infectious droplets and killing in as little as 18 hours from onset.
Plague is an incredibly serious disease that can cause fever, chills, fatigue and headache, as well as painful, pus-filled swellings, known as buboes, for the bubonic form, the death and blackening of skin and tissue for the septicemic form and symptoms of severe pneumonia like difficulty breathing, chest pain and a cough for pneumonic forms.
While plague can be readily treated with antibiotics, the rapid progression of the disease means it must be diagnosed and treated very quickly—if treated in time and within around 24 hours of symptoms emerging, recovery rates for plague are high—and untreated, bubonic plague kills up to 60% of people, with pneumonic and septicemic plague invariably fatal.
How Can You Protect Against Plague?
Plague is worldwide in distribution, naturally circulating among animals and their fleas on all continents, except Oceania, according to the World Health Organization, and Antarctica. In the U.S. plague is most common in the rural West, Southwest and Rocky Mountains, such as Arizona, Colorado and particularly New Mexico. There are around seven cases in the U.S. each year, according to the Centers for Disease Control and Prevention. To reduce the risk of contracting plague, the CDC recommends taking steps to reduce the number of rodents around you and to protect yourself against potential flea bites. This includes using flea repellant on the skin during activities like camping or hiking that could expose you to fleas, applying flea control products to pets and clothing, and taking steps to “reduce rodent habitat” around homes, workplaces and recreational areas by removing junk and brush and securing pet and animal food, as well as making any buildings “rodent-proof.” While plague vaccines have been used since the late 1800s, they have not been evaluated to modern clinical standards and do not appear to be very effective. There is no commercial plague vaccine available in the U.S. and the shots are only used rarely in some countries for people with high exposure to plague through their jobs. New plague vaccines are in development but “are not expected to be commercially available in the immediate future,” the CDC said.
News Peg
The case in Colorado is one of several plague cases to have been reported in the U.S. this year. It comes several months after a man in New Mexico died after contracting plague in March and another case in Oregon in February, which was the first reported in the state in nearly 10 years.
Globally, cases are much higher, and between 2010 and 2015, 3,248 people were infected with plague, according to the CDC, most commonly in Madagascar, Democratic Republic of the Congo and Peru. Of those infected, 584 people died.
Key Background
While modern plague outbreaks are relatively small and infections treatable with antibiotics, this has not always been the case. Plague is infamous as one of history’s biggest killers and has terrorized humanity for centuries. The microbe Yersinia pestis is believed to be responsible for a number of humanity’s deadliest pandemics, including the Black Death, which wiped out a third of Europe’s population in the fourteenth century, some 25 million people, and the plague of Justinian, which scythed through Asia, Europe and parts of Africa around 800 years before that, killing around half the world’s population at the time, between 30 and 50 million people. In total, researchers believe plague has killed more than 200 million people over time.
Tangent
Despite the availability of antibiotics, health security experts are concerned Yersinia pestis could potentially be deployed as a bioterrorist weapon in the future and health authorities in the U.S. and other countries are prepared for potential attacks using the agent. It is considered a “high priority” agent in the U.S. on account of its “potential threat to national security.” Though experts stress it is unlikely a terrorist would deploy a plague bioweapon, there are multiple examples of the plague being used as a biological weapon throughout history.
Can Your Cat Or Dog Give You Plague?
The infected Oregonian is believed to have contracted the disease from a pet cat, officials said. The animals are considered vulnerable to exposure given their propensity to catch and eat rodents, which may be infected or host infected fleas. The CDC advises people living in areas the disease is known to circulate against allowing dogs or cats to sleep on their beds.
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