Researchers analyzed the corpses of red squirrels in the British Isles and determined that they were hosts for Mycobacterium leprae, the bacteria responsible for leprosy. This disease that was thought to only affect humans but, due to recent findings, it appears that wildlife species are serving as incubators for this deadly pathogen.
The research team determined that leprosy was once endemic for the human inhabitants of the British Isle and that red squirrels of England, Scotland, Ireland, and Brownsea Island harbor the disease.
Leprous squirrels in the UK
The study was led by Charlotte Avanzi from the Global Health Institute located in Switzerland, but the other researchers mainly hail from British institutions. The field team collected over 100 squirrels, among which all of the 25 collected from Brownsea Island were diagnosed to be infected with Mycobacterium leprae.
Other subjects were infected with Mycobacterium lepromatosis, another pathogen responsible for causing leprosy. Despite the findings, not a single case of leprosy has been reported on Brownsea Island, but there have been 139 reported cases of the disease in England and Wales since 2003.
Avanzi noted that the finding does not need to find human infection to be meaningful, but rather it reveals concerning information about deadly diseases residing in wildlife.
“The main message of this is that the number of non-human reservoirs of leprosy might be much higher than previously thought. This is of particular interest in countries where leprosy is still endemic in human[s], where maybe a part of the new cases number could be explained by the presence of an animal reservoir,” she stated to Live Science.
At first, scientists believed that leprosy was native to humans, but in 2011 the bacteria responsible for leprosy has been found in U.S. armadillos, which curiously have more contact with humans than red squirrels in the UK. Armadillos,
The Mycobacterium leprae strains discovered in the red squirrels were also determined to be the same that caused the UK’s leprosy pandemic in medieval times. Researchers noted that a probable cause could have been that people in the middle ages hunted squirrels for their meat and fur.
A stigmatizing disease
Leprosy is an ancient disease, even appearing in the Bible. The most ancient record of leprosy dates from 2,000 BC, found in the bones of a middle-aged adult male in Northern India. The remains show deformations and degenerative joint disease in line with leprosy’s symptoms.
The disease, characterized by painful skin sores on arms and legs, was first thought to be curable only by mutilation while also being extremely contagious. In reality, infection from human to human only occurs when one comes in contact with leprous bodily fluids.
The World Health Organization estimates that, currently, at least 180,000 people are infected with leprosy, most of them being located in Asia and Africa, but the disease is also present in the United States where at least 100 cases are reported each year. The greatest number of leprosy cases reside in India, which contains over half of the world’s leprous patients. Second is Brazil and then Indonesia.
Leprosy was first determined to have originated in East Africa, making its way to the rest of the world through human migration routes. There are four main strains of leprosy. The first originated in Pacific Asia and East Africa, the second in Ethiopia and North India, the third in Europe and North Africa, and the fourth in West Africa and the Caribbean.
The primary methods through which leprosy disseminated were colonization and slave trade, which were the cause of massive movements of people to settle in foreign lands as they traveled in unsanitary conditions.
Besides the skin sores, leprosy can cause nerve damage that leads to muscle weakness and loss of extremity sensation.
One of the most concerning characteristics of leprosy is that it may take years to show any characteristic symptoms on the patient, mainly due to the disease’s incubation period. This makes it so doctors cannot effectively determine that a patient has the disease unless there are clear symptoms.
Despite its fame as a historical incurable disease, leprosy can now be cured, as over 16 million people have defeated the disease. The primary method of fighting it is through antibiotics. There are different variations on the type of treatment that the doctor will prescribe, but antibiotic use is not able to restore nerve damage caused by the disease. Treatment can last from several months up to a year, but it may even be longer if the patient is diagnosed to be severely infected.
If left untreated, leprosy can evolve into disfiguration, erectile dysfunction, and infertility. It can also cause short-term damage to the kidney, and brain and spinal cord nerves, mostly those that branch out the extremities.