Plague in 2019? Why there's no reason to panic about China's recent cases

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It's not a headline that you expect to see in 2019. But plague is back in the news after China reported three cases of the infectious disease earlier this month.

The first cases were recorded in a middle-aged couple from the remote region of Inner Mongolia, who were sent to Beijing for observation after struggling to breathe.

The third case emerged last weekend: A hunter from the same region was diagnosed with bubonic plague after catching and eating a wild rabbit. About 28 people who were in close contact with the hunter were also put in quarantine.

It's actually the second time this year plague has been found in the region; in May, a Mongolian couple died reportedly after eating raw marmot kidney, leading to a six-day quarantine in that region that stopped nine tourists from leaving. 

While the "Black Death" wiped out millions of people in the 14th century, making the term synonymous with destruction, experts caution the plague is relatively rare — and treatable — today. 

"There are about 12 countries on the planet that have plague. And sporadic cases of plague, believe it or not, are expected in many of these countries," said Dr. Isaac Bogoch, an infectious disease specialist with Toronto General Hospital.

3 types of plague

The plague is caused by Yersinia pestis, a bacteria commonly found in rodents and their fleas.

Bubonic plague, the most common form, is typically transmitted to humans through flea bites, or possibly from handling an infected animal. 

If left untreated, the bacteria can spread to the bloodstream, leading to septicemic plague, or the lungs, causing pneumonic plague. 

Pneumonic plague — the type reported in the first two China cases — is particularly troublesome as it can spread human to human via respiratory droplets released through coughing.

Without medical intervention, these two forms can frequently be fatal, in part because plague is a rapidly progressing disease, said Dr. Paul Mead, chief of the bacterial diseases branch of the U.S.-based Centers for Disease Control (CDC).

Most people will seek treatment well before these stages, said Mead, because at this point, patients will likely be "very, very ill, perhaps within hours of death."

And while early symptoms of the plague are relatively mundane — fever, chills, headaches and weakness — there's also a "hallmark" sign that sends many to the hospital, adds Bogoch: Large, swollen and painful lymph nodes. 

Overall, upwards of 80 per cent of the world's cases are bubonic, easily treatable today with readily available antibiotics.

"In the Middle Ages, of course, this was the pre-antibiotic era," said Bogoch. "They didn't understand microbiology and how infections are acquired or transmitted, so the outcome was completely devastating."

But today, he said, the plague is simply a bacterial infection.

"Fortunately, in most places … there is the capacity to diagnose and treat this infection," said Bogoch. "People get treated and they get better. And most people who have timely access to medical care will live."

Even in the rare case of pneumonic plague, most modern health-care systems are much better equipped to contain it than in the 14th century, said Mead. 

"Relatively simple interventions, such as a face mask, can prevent it."

Where does it exist today?

According to the World Health Organization, there were 3,248 cases reported worldwide between 2010 and 2015, resulting in 584 deaths — a fatality rate of about 18 per cent.

Those numbers jumped in 2017, with an "unprecedented" outbreak in Madagascar, one of three countries where plague is endemic. (The others are the Democratic Republic of Congo and Peru.)

Over a few short months, 2,417 people were sickened, with about 200 deaths.

But even in endemic countries like Madagascar, the plague has an element of seasonality, said Bogoch, meaning health officials can prepare for it. In Madagascar, the disease tends to make a comeback in September, at the beginning of its humid, rainy season, when there's also an abundance of rats.

In some cases, officials may opt for antibiotic prophylaxis, providing medication before any potential outbreak, said Bogach.

The plague also exists closer to home. There are about seven cases reported in the U.S. each year, according to the CDC, all clustered in the country's southwest corner.

It is a nationally notifiable disease, said Mead, meaning local health officials monitor for it and report all cases. It's also enzootic, he said, meaning it regularly affects the animals of a particular region. 

"It cycles between certain rodents, and it has for a long time," he said. "For the most part, it's a disease of rural areas."

And though it's still rare by U.S. standards, Mead said health-care providers in certain regions know to look for it in patients. And those who work with wildlife are also monitoring for it.

A group of plague-infested prairie dogs shut down a park near Denver this past summer, and two campgrounds in the picturesque Yosemite National Park were shuttered in 2015 after a child was hospitalized with the disease.

The CDC says there have been 12 recorded deaths in the country since 2000. (By comparison, traffic deaths add up to around 40,000 Americans annually.)

In Canada, plague is exceedingly rare, though the Public Health Agency of Canada also monitors for it. The last human case of plague here was reported in 1939.

Panic in China

Still, the recent cases in China have sparked fear among some citizens, in part because the couple being treated for the contagious pneumonic plague were sent for treatment in the densely populated city of Beijing.

That prompted the Chinese Center for Disease Control and Prevention to put out a message on popular microblogging platform Weibo, cautioning that there was no need for residents to panic and that the risks of transmission were "extremely low," according to the New York Times. 

The patients were quickly isolated, the Chinese CDC said, and epidemiological investigations were conducted on anyone who might have been exposed.

While the three Chinese patients continue to be monitored, all this attention could actually be a blessing, said Dr. Shanthi Kappagoda, an infectious disease physician in Stanford, Calif., who specializes in travel-related illness.

"I think a high level of alertness is actually great, because then cases won't be missed and people will be treated early," she said. 

But for anyone still concerned, Kappagoda offers this advice.

"I think the general message should be: Do not panic," she said. "We have effective treatment for this and we have good control measures both in our hospitals and our public health systems."

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