5 letters: PLAGUE, and the imagination gets carried away, fear takes hold of the minds, and all – or almost – relive the terrible episode of the black plague, described in great detail in the history books, which wreaked havoc in the 14th century, causing the death of 50 million people, half of them on the European continent. 

Bubonic plague: is it still present?

“There are no more indigenous cases, contracted in metropolitan France, for nearly 80 years,” reassures Professor Guillaume Desoubeaux, head of the unit of parasitology and mycology – tropical medicine at the University Hospital of Tours. The last cases, in France, date back to 1945. It was in Corsica. But if many believe it is now gone, it is not. “We continue to find it, mainly in Central and East Africa, Peru and Bolivia.

Cases around the world

There are 500 cases per year worldwide, at least half of which are in Madagascar. And it continues to wreak havoc there. “The bubonic form has a mortality rate of 30 to 60%”, recalls the World Health Organization (WHO). “Contagious infectious disease caused by Yersin’s bacillus and transmitted from rats to humans by flea bites.” This is the definition of Larousse, who continues: “We distinguish bubonic plague, directly transmitted by fleas, and pulmonary plague, transmitted from man to man by inhalation. Bubonic is by far the most common form.

Bubonic plague is a zoonosis. It is therefore transmitted from animals to humans through the bites of infected fleas, or through direct contact with the carcasses of small infected animals. Concretely, the plague first breaks out in rodents, most of the time rats, bitten by infected fleas.

Animals die quickly. Fleas, in search of new hosts, will then bite, and infect, humans. We owe to two bacteriologists – the Japanese Kitasato Shibasaburo and the Frenchman Alexandre Yersin – the simultaneous discovery, in 1894, of the bacillus responsible for the disease, Yersinia pestis.

The first symptoms

“The first signs appear one to seven days after the bite. Sometimes there is a fever. But above all, the bacillus enters the body during the bite, passes into the lymphatic system and reaches the nearest lymph node where it multiplies. The lymph nodes start to swell. “These big, red, hot, hard ganglia are called buboes. »In 20 to 40% of cases, the bubo suppurates and the patient recovers after a fairly long convalescence time.

Evolution without treatment

“But if treatment is not put in place very quickly, it evolves into systemic damage. In other words, bacteria can reach the lungs and the whole organism, ”warns Professor Desoubeaux. It starts with a fever, a strong cough, pain in the chest, then, if left unchecked, it very quickly progresses to sepsis, a generalized infection. “Mortality is then close to 100%.

At this stage, the disease can also be transmitted from one individual to another, through the lungs (coughing, sneezing, etc.). This is why the health authorities are very vigilant as soon as cases are reported, to avoid an uncontrollable spread of the epidemic. The pulmonary form is significantly more contagious and fatal than the bubonic form.

It is based on the presence of symptoms, travel to an endemic area, or contact with a sick person. If he suspects bubonic plague, the doctor will perform laboratory tests to confirm the presence – or not – of the bacteria Yersinia pestis.

“Confirmation takes place by isolating the bacteria in culture from a sample of the bubo (by aspiration or biopsy), during the initial phase of bubonic plague, or from a respiratory fluid or blood , during the later and more serious phase of pulmonary or disseminated plague. “

“When taken on time, treatments work very well. Streptomycin, tetracyclines and fluoroquinolones are the standard antibiotics. The improvement is then visible, in two to five days. “The main challenge is to start treatment quickly, 48 to 72 hours maximum after the onset of the disease. After this period, the bacteria have proliferated too much in the blood ”, endangering the vital prognosis. 

If you travel to an area where the plague is still circulating, the Institut Pasteur recommends “to avoid contact with rodents and to protect yourself from flea bites by active skin repellents in these endemic areas. “

To choose the right repellant, get advice from your doctor or pharmacist. It is also necessary to avoid any contact with a sick person, and at least, to wear a mask if you cannot avoid this encounter. “If we know that a person has been exposed to a patient, we will give him antibiotics as a precaution. “

“There have been vaccine trials, but the effectiveness has never been proven,” notes Professor Desoubeaux. These vaccines caused side effects, sometimes severe. “A new vaccine is being evaluated. “