Oh Good, the Plague Is Still a Thing

Rodents are infecting people in New Mexico.

Jun 29 2017, 9:45pm

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Just when you thought things couldn't get any worse (the warming planet, healthcare "reform," toxic air, etc), plague is in the news. The New Mexico Department of Health recently announced that two women had plague, bringing the number of cases in the state this year to three. The two women and one man were hospitalized and released after a few days.

News of a plague "outbreak" conjures images of the Black Death ravaging cities in the Middle Ages, like in that Monty Python sketch. There's no need to go all Fear the Walking Dead yet, though. New Mexico has long suffered a handful of yearly plague cases: Last year the state saw four cases, with no fatalities; in 2015, four people contracted plague, and one person died. But the fact that there were three cases announced this month alone is the opposite of comforting.

According to the Centers for Disease Control and Prevention (CDC), plague occurs in rural and semi-rural states in the western US, particularly New Mexico, Arizona, and Colorado. Fleas feed on rodents and mammals infected with the plague bacterium, Yersinia pestis, and then transmit it to humans by biting them. One expert told The New York Times that environmental factors make New Mexico especially plague-friendly: vegetation there supports plenty of rodents, which in turn support plenty of fleas. As the disease picks off one rodent species, it can jump to another, which eventually puts it in contact with humans.

Still, even New Mexico has only a few cases every year. The CDC notes that plague arrived in the United States around 1900, and between then and 2012, there were only 1,000 confirmed or probable cases reported. Recent decades have seen an average of about 7 cases a year. The World Health Organization found 3,248 reported cases globally between 2010 and 2015, 584 of which were fatal.

Antibiotics have made plague much less lethal than it was in the past: The CDC says that from 1900 to 1941, the mortality rate for US plague infections was 66 percent; today, thanks to antibiotic treatments, that rate is closer to 11 percent.

But there are caveats: plague has to be treated quickly, and some forms are more deadly than others. There are three types of plague: bubonic, pneumonic, and septicemic. All produce fever and general weakness, some come with chills and headaches—symptoms easily mistaken for the flu. Bubonic plague, the most common form and the one known as the "Black Death," is marked by swollen lymph nodes, is the least deadly. (Eighty percent of cases in the US are bubonic.) Pneumonic plague produces severe pneumonia that can be deadly; septicemic plague attacks the blood cells, causing tissue to blacken and die.

Obviously, if you have any of these plague symptoms, you should see a doctor. Generally, though, while "plague" sounds archaic, alien, and uniquely threatening, it's also incredibly rare and treatable. Three cases in New Mexico this year isn't quite the start of a real #tbt to the days of "bring out your dead," but, you know, keep up with those flea treatments on your pets.

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