Leprosy pathogen found slumbers in squirrels - a risk for humans?

Squirrel infected with leprosy: low risk of infection for humans
Researchers have found that most red squirrels in the UK are infected with leprosy. This could endanger the preservation of these animals. However, the risk of infection is low for humans.

Still a danger to people
Leprosy still poses a great danger to people in many parts of the world. Infectious disease is considered a disease of the poor. Scientific advances in leprosy research have been made in recent years, but vaccination still does not exist. In Europe, the disease is considered to be eradicated. But researchers are now reporting that most red squirrels in the British Isles are infected with leprosy.

Pathogens found in squirrels
Scientists from Switzerland and Scotland have identified the same pathogens in red squirrels in England, Ireland and Scotland that can cause leprosy in humans. They were able to detect the pathogens Mycobacterium leprae and Mycobacterium lepromatosis in the bodies of the animals using DNA tests. The results of the study have now been published in the scientific journal "Science".

"This has never been observed before"
Only some of the squirrels had symptoms, but one of the two pathogens was found in almost all animals. "It was completely unexpected that M. leprae triggered squirrel disease centuries after it disappeared from humans in Britain," said microbiologist Stewart Cole, professor at the École Polytechnique Fédérale de Lausanne (EPFL) in a statement. "This has never been observed before."

Humans rarely come into contact with squirrels
According to the researchers, the study shows that pathogens can survive unnoticed in nature for centuries. "The next logical step would be to examine the population of red squirrels outside the British Isles," said Andrej Benjak from EPFL.

"But even if there is leprosy in red squirrels in continental Europe, the risk of transmission to humans is generally low, since they rarely come into contact with humans and hunting for red squirrels is prohibited in most European countries," said Benjak.

Mutilations caused by leprosy
Although leprosy is considered curable, up to four million people worldwide live with mutilations caused by leprosy. In the past, the disease was also called "leprosy" because the victims were "exposed" and had to live outside human settlements.

In countries with developed health care, the disease is considered to be almost eradicated. According to the Robert Koch Institute (RKI), six cases were counted in Germany in 2012 and 2013, all of them imported from other countries. According to the researchers, there has also been no leprosy infection in Great Britain for decades.

From the point of view of species protection, it is worrying
From a conservation perspective, the discovery of leprosy in the British red squirrel is worrying. This species is already in distress in Great Britain due to the increasing spread of the American gray squirrel.

"We need to understand how and why the disease affects the red squirrels and spreads among them," said Anna Meredith. "Then the disease would be better controlled with this species."

Other animals can also carry leprosy. Years ago it was reported in the "New England Journal of Medicine" that armadillos can be used as carriers of leprosy in the USA. (ad)

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