People in Madagascar are scrambling to get their hands on antibiotics and face masks, while public gatherings have been canceled, as a rare pneumonic plague epidemic spreads quickly across the country.
Plague is the deadly flea-borne bacterium you might associate with the Middle Ages, when the “Black Death” killed 50 million people, wiping out most of Europe’s population. But it’s still around today, even in the United States.
In some countries, particularly Madagascar, plague is endemic, and flare-ups cause public health emergencies on an almost annual basis — and right now, an uncontrolled epidemic that’s brewing there appears to be exceptionally worrying.
As of October 12, 684 plague cases have been identified, including 57 deaths. At least 35 of Madagascar’s 114 districts are now affected by the epidemic. Madagascar typically sees about 400 cases each year, when the disease surfaces from September to April. So it’s really early to see so many cases.
Plague has also now spread through the capital to coastal cities, “which we have not seen before,” World Health Organization spokesperson Tarik Jašarević told Vox. There’s already been international spread, too, to nearby Seychelles.
Also unlike previous outbreaks, this year’s involves mostly pneumonic plague, a more dangerous form of the disease than the much more common bubonic plague. Pneumonic plague attacks the lungs and spreads from person to person through droplets from coughing, like a cold, while bubonic plague spreads only from fleas to humans. (Some 474 — or 70 percent — of cases so far were classified as pneumonic plague, according to the WHO.)
“So it’s a worrying situation because it’s in an urban setting, and it’s transmissible from human to human,” Jašarević added. “We need to act quickly — to trace the contacts of those infected and put people on a preventive treatment.”
About 30 to 60 percent of people who contract bubonic plague die. Untreated pneumonic plague is always deadly, typically within 24 hours of disease onset. A timely antibiotics dose can, however, save lives, and that’s why the WHO delivered an emergency stockpile of nearly 1.2 million doses of antibiotics to the Indian Ocean island nation.
There are seven countries at high risk of plague outbreaks spreading from Madagascar
Health officials traced Madagascar’s current outbreak back to a 31-year-old man from Toamasina, a coastal city in Madagascar. On August 27, the man used public transport to travel about 500 miles, through Madagascar’s capital, Antananarivo, and died while en route.
Public health workers found out that many people he was in contact with had come down with plague, and they had spread the disease to others too. Since then, cases have been popping up elsewhere around the country. “Eighteen out of 22 regions in the country, including traditionally non-endemic areas, have been affected,” the WHO said in its latest briefing.
Because of trade and travel links to Madagascar, there are seven countries at high risk of a plague outbreak, according to the WHO: South Africa, Mozambique, Tanzania, Mauritius, Comoros, Seychelles, and Reunion.
A traveler already brought the disease to Seychelles, a chain of Indian Ocean islands, after returning from Madagascar — and a dozen patients with suspected plague remain in isolation there, raising fears that there may be more spread to come.
Pneumonic plague is a “public health nightmare”
Plague is caused by the bacterium Yersinia pestis. Wild rodents — chipmunks, mice, squirrels — can carry the bacteria. Fleas feed on the rodents and pick up plague, in turn spreading it to other mammals, including humans, through bites.
When people talk about plague, they’re usually talking about bubonic plague, the type that causes about 80 percent of infections in the US every year. Bubonic plague infects the lymphatic system, causing the lymph nodes to swell up and feel tender. These swellings, known as buboes, typically pop up in the groin, neck, and armpits. A blackish pustule will also arise at the site of the flea bite, and hemorrhaging can occur underneath the skin, causing it to blacken — part of the reason the plague is called “Black Death.”
When bubonic plague is left untreated, it can spread into the lungs to become pneumonic plague, or into the bloodstream to become septicemic plague. These types of plague are more rare — and more dangerous — because unlike bubonic plague, they can be passed directly from person to person.
“A person with pneumonic plague is a public health nightmare,” said Joe Hinnebusch, a plague researcher at the National Institutes of Health.
And again, it’s pneumonic plague that’s affecting Madagascar right now.
There is good news: Plague is not as contagious as some other pathogens, like flu or measles, and it requires close contact to spread, said Hinnebusch. People with plague also get sick (and, if untreated, die) so quickly after infection that the disease doesn’t travel as far as say, Ebola, which incubates in the body for days before causing symptoms.
“[Plague is] also fairly easily preventable once an outbreak occurs, and should be fairly easy to stop with simple measures like wearing masks, or isolating people who are sick so they aren’t contacting other people,” Hinnebusch added. Unlike with Ebola, we have a cure for plague in antibiotics.
“There would have to be a total breakdown of public health systems [for the epidemic to continue uncontrolled],” Hinnebusch said.
Still, it’s a highly unusual epidemic right now in Madagascar, with so many pneumonic plague cases so early in the season. And that’s a situation worth keeping an eye on, as infectious diseases expert Crawford Kilian warned on his blog. “Pneumonic plague in a big city is like Ebola in a big city: better to prevent it than suppress it, and prevention now seems out of the question.”
In much of the world, plague is associated with poverty
As this study in PLOS Medicine reports, poorer countries with bad sanitation and other risky practices can help spread the infection:
So it’s not surprising that on a global scale, plague is most common in places like Madagascar, where the per capita GDP is only $1,500. Plague turned up on the island in 1898 through trade routes, and outbreaks have popped up nearly every year since 1980. (For the past two decades, Madagascar has experienced the highest burden of plague cases in the world.)
But there are other factors that help spread plague: Humans have been encroaching on wildlife areas, putting them into contact with potential carriers of the disease. And this is as true for poorer countries as it is for developed places like the US. As this scientific study on US plague reports, “Plague in New Mexico has increasingly occurred in more affluent areas” — the result of building out suburban and exurban communities in previously underdeveloped areas where plague had been circulating in wild animals.