A person died from pneumonic plague in Arizona last week, the first death from the disease in this region in nearly two decades.
This death might bring to mind the bubonic plague, the form of the plague that killed millions during the Middle Ages. This latest case is not the same form, and treatments have certainly advanced since that time. That said, I wanted to know what pneumonic plague is, how it’s spread and what its symptoms are. How is it diagnosed, and what treatments are available? What can people do to reduce the risk of contracting the disease? And how much should people be worried about plague?
To help with these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and clinical associate professor at George Washington University. She previously was Baltimore’s health commissioner.
CNN: What is pneumonic plague?
Dr. Leana Wen: Pneumonic plague is one of three types of plagues that are caused by the bacterium Yersinia pestis. The type of plague someone has is classified based on where the bacteria are concentrated. Bubonic plague infects lymph nodes. Septicemic plague is when the bacteria cause a whole-body infection through the bloodstream, and pneumonic plague affects the lungs.
CNN: How does someone contract plague? Can it be spread from person to person?
Wen: It depends on the type of plague. Bubonic plague is typically caused by the bite of an infected rodent flea. It can progress to septicemic plague, which can also arise as a result of handling infected animals such as rats and cats. Cats and other animals can contract the plague through eating rodents or through the bite of fleas.
Pneumonic plague develops when the bacteria spread to the lungs in someone who started out with bubonic or septicemic plague. It can also occur when the bacteria are directly transmitted through airborne droplets — if someone inhales droplets containing the Yersinia bacteria that are coughed by an infected person or animal. This is the only form of the plague that can be spread from person to person.
CNN: What are the symptoms of the three types of plague?
Wen: People infected with all three forms develop common infectious symptoms including fever, headache, chills and weakness. Those with bubonic plague have one or more swollen and painful lymph nodes, also called buboes. In septicemic plague, the seeding of bacteria to other parts of the body can cause multi-organ failure and total body shock. Pneumonic plague is characterized by a rapidly progressing pneumonia with symptoms of shortness of breath, cough and chest pain.
CNN: Is plague common?
Wen: No. There are an average of seven human plague cases reported each year in the United States, according to the US Centers for Disease Control and Prevention. Over 80% of cases are bubonic plague. Most human cases have occurred in two regions: northern Arizona, northern New Mexico and southern Colorado; and California, southern Oregon and far western Nevada.
Plague has also been reported in various parts of the world. According to the World Health Organization, most human cases since the 1990s have occurred on the African continent. The three countries where plague is the most endemic are the Democratic Republic of Congo, Madagascar and the South American country of Peru.
CNN: How worried should people be about pneumonic plague, if it would be transmitted person to person?
Wen: In Arizona, there was only one person diagnosed with pneumonic plague. There have not been reports of other infected individuals. Health experts there reiterate that the “risk to the public of exposure to plague remains low.”
CNN: How is plague diagnosed?
Wen: Diagnosis is made through laboratory testing of blood, sputum and parts of a swollen lymph node. Because the disease progresses very quickly and effective antibiotic therapies exist, prompt recognition is crucial. In cases where there is a high level of suspicion, antibiotics are often started in advance of confirmatory testing.
CNN: What treatments are available?
Wen: The good news is that there are accessible and effective therapies. Several antibiotics are effective against Yersinia pestis. In the US, gentamicin and fluoroquinolones are first-line treatments.
It’s crucial that antibiotic therapies are promptly started. If left untreated, the case fatality rate can be as high as 30% to 100%.
CNN: Is there a vaccine against plague?
Wen: A vaccine against plague had been authorized for individuals at high risk of exposure, but this vaccine is no longer available in the United States, in part due to how rare this disease has become. Some potential vaccine candidates are under development.
CNN: What can people do to reduce the risk of contracting the plague?
Wen: Most Americans do not live in areas where plague can be found. For those in Western US states where plague has occurred, there are several actions they can take to reduce their potential exposure.
First, avoid contact with wild animals. Do not handle wild rodents. Do not touch sick or dead animals.
Second, because most cases are associated with rodents, people should prevent rodent infestation by storing pet food in rodent-proof containers and removing brush and trash around homes.
Third, avoid fleabites. Wear long sleeves and use insect repellent containing DEET if you are hiking, camping or working outdoors. Keep fleas away from household pets by using veterinarian-approved flea control products.
Fourth, keep pets out of areas known to be inhabited by wild rodents. Be on the outlook for illnesses in domestic animals, especially indoor-outdoor cats, and seek prompt veterinary care.
All of this said, I think it’s important to be reminded of how uncommon plague is. People who live in areas where plague has been found should take preventive measures, and clinicians should ask about travel history to these areas. Most Americans, though, do not need to be concerned about plague based on this single recent case in Arizona.
