Two people who were on the bus with the man also die under similar circumstances. The terrible truth dawns on the doctors: Madagascar is dealing with a plague outbreak. In three months, 2417 people become infected, of whom 209 die.
The epidemic shows that the bacteria that caused the Black Death in the Middle Ages is still very much alive. And according to various studies, it can become resistant to antibiotics. If that happens, the bacteria will pose a global threat.
Fortunately, weapons to fight the disease are being developed – such as genetically modified tomatoes and a nasal spray containing a cold virus.
The plague is still alive
Every year, about 2,000 people are infected with the plague, mainly in Madagascar, Congo and Peru. And left untreated, 30 to 100 percent of them die within ten days.
Behind the scenes, the disease lurks continuously and around the world. Once every ten years, this leads to epidemics that claim hundreds or thousands of lives.
The plague is caused by the bacteria Yersinia pestis and comes in three varieties.
The most common form is bubonic plague, which occurs when the bacteria penetrate the skin and travel with the lymph fluid to the lymph nodes. Here it multiplies, causing the lymph nodes to swell and form bumps in which the tissue gradually dies.
The condition also often leads to gangrene in the fingers, toes, lips or nose. But with a mortality rate of 40 to 60 percent (without treatment), this is the least dangerous variant.
In rare cases, the plague bacteria enters the bloodstream, leading to septicemia and bleeding from the nose, mouth and rectum. Eventually the organs fail, and without treatment the victim usually dies within 24 hours.
In the third form, the bacteria enters the lungs through airborne droplets, leading to severe pneumonia. The patient coughs up blood and has difficulty breathing. Without treatment, respiratory arrest occurs after a few days.
Epidemics are often a cocktail
Usually, the plague thrives in animals and rarely spreads to humans. More than 50 species of mammals can carry the bacteria, especially rodents such as prairie dogs, marmots and rats.
Animals are also responsible for many infections between humans. The bacteria can be transmitted via fleas, which bite an infected person and then jump to the next.
Flea bites usually cause bubonic plague, but sometimes the bacteria can reach the lungs through bodily fluids. People with pneumonic plague will cough and sneeze, allowing the bacteria to spread further.
A plague outbreak is therefore almost always a cocktail of two epidemics: bubonic plague and pneumonic plague.
During the 2017 epidemic in Madagascar, 83 percent of those infected had pneumonic plague and 17 percent had bubonic plague. In only one person, the bacteria caused the extremely deadly form of plague in the blood.
Which form of the plague predominated during the medieval Black Death is unknown. But scientists do have a suspicion.
Black death threatens again
The Black Death probably reached Europe on Italian merchant ships, which brought infested rats and fleas from Central Asia. These animals did feed on the poor hygiene in the Middle Ages and probably caused a bubonic plague epidemic in the first place.
However, the question is whether bubonic plague alone could spread as quickly as it did. For example, just three years after arriving in Italy, the plague had killed more than half the population of Norway—thousands of miles to the north.
Such a rapid spread is more conceivable if the contamination is via the air. That points to pneumonic plague as the driving force behind the Black Death.
Be that as it may, today we are better equipped against the plague. The bacteria is very sensitive to antibiotics. Unfortunately, that could soon change.
As early as 1995, plague bacteria were discovered that were resistant to various types of antibiotics. And in 2007, a study found that salmonella bacteria can transfer their antibiotic resistance genes to plague bacteria.
Since drug-resistant salmonella is widespread, there is a real risk that we will suddenly be confronted with a plague bacteria that is resistant to antibiotics.
Nasal spray should stop epidemic
Because of the fear of new plague epidemics, researchers are busy developing vaccines against plague. Plague vaccines have been around since 1897, but have never worked well. And at the moment there are no plague vaccines approved in the EU or the US.
Until now, the vaccines used weakened plague bacteria or fragments of the bacteria to train the immune system, but researchers are now turning to new methods.
In 2021, for example, a Russian research group used gene technology to create a bacterial ghost (ghost bacteria) – an empty, lifeless shell, which looks like a plague bacteria from the outside but is completely harmless.
The ghost bacteria have been shown to provide some protection against the plague in mice, but the method needs improvement before it can be used in humans.
Microbiologist Jian Sha and his colleagues at the University of Texas are a little further ahead. In recent years, they have tested nasal sprays with a genetically modified cold virus. The virus is adapted so that it does not harm the body and contains genes from the plague bacteria to teach the immune system to fight the plague.
The vaccine was tested on mice and monkeys, which were then heavily infected with bubonic plague or pneumonic plague.
The unvaccinated animals died within four days. But the vaccinated animals were fully protected and showed no complaints during the month that the trial ran.
Vaccinate wild animals
A third vaccine is … a tomato, which you just have to eat. The tomato is genetically modified and contains a number of proteins from the plague bacteria. Such a vaccine is easy to distribute (without injections or other aids) and can be produced cheaply on a large scale.
The modified tomatoes showed promising results in mouse tests. They have not yet been tested in humans, but that is not necessarily the intention. American researchers are experimenting with giving edible vaccines to wild animals in nature.
In 2017, for example, epidemiologist Tonie Rocke of the National Wildlife Health Center in Wisconsin, USA, distributed plague vaccine bites to wild prairie dogs. The goal is twofold.
First, the vaccine must protect the animals. Prairie dogs often become infected with the plague bacteria and almost always die from it. The vaccinated animals are more likely to survive, and since prairie dogs are prey to many predators, their survival is important for the entire ecosystem.
Second, it must prevent epidemics among humans. If the plague cannot spread among wild animals, the chance of the bacteria jumping to us decreases.
Tonie Rockes trial was a success. The animals willingly ate the vaccine and were subsequently found to be partially protected against the plague bacteria: in areas where the vaccine was used, about twice as many prairie dogs survived the plague infection as elsewhere.
The new plague vaccines therefore seem to be proving their worth. And soon they will be ready to prevent violent epidemics like the one in Madagascar and finally end the threat of a global recurrence of the Black Death.