In Madagascar, if you have a question about family matters, or want blessings for fertility, you seek out your ancestors’ help. Sometimes, that means unburying them.

Hundreds of people from the community gather at the family crypt during a traditional Famadihana, or “the turning of the bones.” In these ceremonies, the Malagasy, or people of Madagascar, crack open the tombs every five to seven years, and gently lift the bodies out to be rewrapped in silk. The bodies are lifted over dancing revelers, and trumpeters punctuate the air with jubilant notes.  Descendants ask for guidance from the ancestors (and of course, catch them up on the latest village gossip). Finally, the bodies are returned at an auspicious hour to their crypts.

But reverence for the dead is entangled with a national health problem: The plague is alive and well in Madagascar.

Although it is often thought of as a medieval disease, the plague — which caused what was known as the Black Death in the Middle Ages — strikes hundreds of people every year, with its highest concentrations currently in Africa. Photojournalist Christian Werner traveled to Madagascar in 2014 to document the health crisis. He photographed at hospitals and even funerals where he constantly shifted his position to avoid being downwind from the victim.

Madagascar is the most severely affected country in the worldSince 2010 it has been the site of over half (and one year, 90 percent) of worldwide incidents of the plague. Last year, 63 people died in Madagascar, out of a total of 275 cases, according to the World Health Organization.

Plague victims’ corpses are to be buried immediately to prevent the spread of the disease. This means that they may be interred near a city hospital, instead of in the family crypt. But families will go so far as to stealthily unearth their loved ones to bring them back to their own villages for burial. Plus, there is a chance that families may anticipate not being able to bury their family members properly and decide to not bring their relatives to the hospital at all, said Ken Gage, chief of Flea-Borne Diseases Activity at the CDC. Among officials’ tactics is burying the corpses with concrete tombs to try to discourage the unearthings, Werner said.

Madagascar has seen lower numbers of deaths from the plague in the past two years, but an alarmingly higher rate of contracting the pneumonic form of the disease — the kind that is airborne and can kill you in 24 hours.

The infection process is simple. Structured like a fruitcake, biofilm with bits of plague bacteria lodged in it starts to build up in a freshly infected flea’s body. That biofilm eventually blocks the stomach and starves the flea, so the flea tries to clear the blockage out. In essence, as an infected flea is chomping on a victim, it will puke the blood back into the wound, and along with it little chunks of the plague.

Called a “disease of poverty,” by the World Health Organization, the plague flourishes in areas where hygiene practices are poor and health infrastructure is weak.  Madagascar has a constellation of such manmade problems that contribute to the persistence of the plague.

Madagascar’s health system was dealt a major blow after a tumultuous political coup in 2009. Foreign aid shriveled and living conditions rapidly declined. Hundreds of health clinics were shuttered, according to the Pulitzer Center.

In the absence of a health clinic, these are the rural population’s medical options: They can make a trip to a city hospital, or turn to traditional healers, who use hand mirrors to seek advice from ancestors.  Jean Rivoson, 16, died from the plague after seeing one such healer, who spit on him to cure him, according to Werner. “Never have any of my patients died,” another healer, Narcisse Rasatarisoa told him. He claims he can fix any ailment.

Within the villages, people have another dangerous habit: keeping their cattle, chickens and crops inside their houses to keep them from being stolen. Naturally, this attracts rats, which carry the fleas.

The effect can be compounded in the rainy season, to which outbreaks have been correlated. During this time, rat populations decrease, but flea counts increase.

Even in the U.S., a few infections pop up every year. Four people died last year, out of a total of 16 cases, according to the CDC. Most of the cases in recent years are contracted in rural areas of the Western U.S., where there is more contact with rats, prairie dogs, and squirrels.

The possibility of a plague flare-up in the U.S. is unlikely for a few reasons. First, there is less contact between people and animals that might carry infected fleas. And also, the main culprit of plague transmission, the Oropsylla montana, is not as effective at transmitting the disease as its counterpart in Madagascar, the Xenopsylla cheopis.

For the abundantly cautious, however, the CDC recommends wearing long pants outdoors, using bug spray, and avoiding contact with rodents, and even being careful of flea-laden pets. Such was the case of a man in Oregon who caught the plague from his cat. It had gotten an infected mouse stuck in its throat.

Despite a low number of cases worldwide, the disease is on the federal shortlist of potential bioterrorism weapons. With its Tier 1 designation, it keeps company with diseases like Ebola and ranks above the poison ricin. That means it has the greatest potential for mass casualties and public infrastructure destruction. That is, provided that the plague can be aerosolized.

The Soviet Union and the U.S. previously conducted research to turn the plague into a biological weapon. And the Japanese are believed said to have dropped plague-infected fleas on China during World War II.

To guard against a bioterrorism attack, the federal government has spent millions on periodic TOPOFF drills to solidify federal, police officers and CDC responses to such potential attacks.

The plague remains a lingering cloud not just in the history books, but in real life and as a potential biological threat. And it’s not going anywhere anytime soon, said Dr. Natalie Kwit of the CDC, “mainly because the bacteria that causes plague has a reserve in rodents in the wild…Unless we eradicate the fleas, not going to happen.”