Poor chimpanzee! After all the misfortunes that have happened to him then came the news that some chimpanzees living in freedom in some African forests have been infected with Hansen's disease, that is, leprosy, a dangerous contagious disease that causes visible damage to the skin and to the nervous system, and difficult to treat for its multiple symptomatic disabling aspects. All the time this disease was called exclusively leprosy, from Greek "Λέπρα" that means scaly: a disease that so called has always evoked a very dark period of our past.1

The ancient Greek Hippocratic philosopher Rufus of Ephesus and the epicurean Roman poet and philosopher Lucretius spoke first of the spread of leprosy in Egypt. Then this disease spread to Europe, first in Germany and then to other countries. But the earliest sources are older, they can even be traced back to the Bible, and superstition wanted it to be fought with macabre rites and animal sacrifices. It was probably the army of Alexander the Great who brought it to the West and probably from India, where it is still widespread.

In Italy, in 380 B.C. leprosy became endemic and the consequences were devastating for our country. Subsequently, according to some historical sources, in 868 A.D. it spread to Ireland, in 1000 to Portugal, in 1200 to France, etc., whoever came first or after the whole of Europe, got to know the consequences of this terrible disease. Over the centuries, the contaminated people were brutally marginalised, driven out of cities and imprisoned in a kind of lazaret and all their personal property was sold or confiscated. Not only did these lepers suffer the damage, but also the mockery. In addition to the physical devastation that disfigured them especially in the face, all the body rotted emitting unbearable smells. Superstition and ignorance for this disease considered a divine punishment did the rest; indescribable atrocities were committed against lepers. Then, on purpose, rumors were spread that the lepers were plotting to assume power, but in reality, it served to eliminate enemies or rivals in the exercise of power which was extremely uncomfortable in these very unfortunate cases. Lepers had to wear clothes that allowed their immediate recognition. The lepers were considered damned, sinners, even homosexuals and women were considered witches to be burned.

This unfortunate history of our civilization may continue, but after the 14th century leprosy cases in Europe and the rest of the world decreased a lot, but not completely. In fact, some scientists recently found out that this disease, as well as in humans, can also spread to monkeys, chimpanzees in particular.

But who spreads leprosy or Hansen's disease? The disease was named after Gerhard H.A. Hansen, a Norwegian doctor who in 1837 first isolated the pathogen bacillus (Mycobacterium leprae) (bacilli are a class of bacteria) although you have to wait until 2008, then 171 years later, to arrive at the determination of the sequence of its genome that then allowed the scientists to facilitate the prevention of the disease and its medical treatment. In essence, it took almost two centuries to understand how leprosy spread, that is who caused it. At first, there were many hypotheses, some without foundation. Leprosy for some scientists is spread by some wild animals, the first place from the armadillo (Dasypus novemcinctus) native to Central and South America, a very sweet twilight and nocturnal animal that by day loves to hide from man, in very deep burrows that they build themselves. The armadillo would transmit it through droplets of nasal origin or through eating its meat, which is quite widespread among the indigenous tribes of some countries, such as Brazil, India and Indonesia. In the Amazon forest, there had been one case for every ten thousand inhabitants. In fact, these figures refer not so much to scientifically conducted research, but to media reports that are often never subjected to scientific verification and before a series of consultations with expert scientists.

Another leprosy "plague-spreader" appears to be the red squirrel (Sciurus vulgaris), of which there are 23 different species, a small native mammal in Europe, certainly widespread in Great Britain and Ireland. The red squirrel also lives in Italy, but is endangered due to the introduction of a non-native species of squirrel, imported from America, the grey squirrel (Sciurus carolinensis). However, there may be several other wild species that can be considered potential reserves of Mycobacterium leprae. In this respect, in Great Britain, in the small island of Brownsea, South-East of England, just 2.88 km2, the disease spread among squirrels from Mycobacterium leprae whose origins can be traced back to the same sources as that which caused leprosy in humans during the Middle Ages, while the bacterium that caused leprosy in men in other areas of the United Kingdom and parts of Ireland was Mycobacterium lepromatotis probably originated from endemic leprosy in Mexico. The two bacilli seem to have a common ancestor (a strain) dating back about 27 thousand years, a long period of time if we consider that the birth of our civilization can trace it back to Mesopotamian civilization 6 thousand years ago when man began to build the first city-states.

In North America leprosy seems to have spread due to the trade in slaves carrying this disease from West Africa, from the countries that are along the Atlantic coast for a period dating back to the last 500 years.

Beyond all these very interesting and important studies, which we leave in the hands of scientists, one thing is certain, and that is that history, not so many epidemics and pandemics in the world, never teaches us anything. We all remember when Ebola, a terrifying infectious disease, spread in Africa. Well, in this case, those responsible for the epidemic were considered chimpanzees, or rather they were considered the primary culprits, not the way of life of the local people, of their food system, in general of their irresponsible behavior. Ebola first appeared in 1976 in Africa, precisely in the Democratic Republic of Congo that at the time was called Zaire, exactly near the Ebola River, hence the name. Ebola made the first casualties among a group of European nuns (perhaps for this reason the news came to Europe) who worked in the Yabuku Mission Hospital, along with some patients hospitalized for treatment of malaria, which in Africa is much more serious than Ebola and all other infectious diseases. In 1980 Ebola reached Europe exactly in Germany, causing some casualties, then in 1989, Ebola arrived in the United States of America. In this last case, it was not people who died, but monkeys who were kept in a research center. This made scientists think thought that the carriers of the virus were monkeys but that it was not dangerous precisely because it did not cause the death of man. In 1990 the virus reappeared in Gabon and in this circumstance it was reported that the people who died in this country had been infected by some chimpanzees because they had eaten their meat mainly the brains, but no evidence was ever found, no scientific checks were made.

Chimpanzees were also victims of another prejudice with another infectious disease, AIDS. In laboratories around the world, especially in the USA, thousands of chimpanzees have been brutally used and then 'sacrificed' for the production of an AIDS vaccine. The end result has been that there is still no vaccine against this disease and thousands of people in Africa, but not only, are still dying of AIDS, including children, although it must be said that far more people died of malnutrition and total luck of hygiene rather than AIDS. The truth is that chimpanzees have never been AIDS carriers and do not die even if infected by humans, as some researchers stubbornly tried to prove and have never done. Perhaps it has to be said that for centuries and centuries they have probably been exposed to the AIDS virus and have developed immune principles of defence against this disease. Finally, there is a consideration to be made about AIDS, which has little to do with virology and epidemiology, that is, psychological considerations which are typical of human beings. Is AIDS a disease that raises many sexual prejudices, better in a homosexual background and therefore a sinful disease and who more than the chimpanzees who look so much like us, have been able to spread this disease? No one else.

Now with leprosy, chimpanzees have reached the limit of their endurance. The good fact that results from this discovery are that chimpanzees have not been infected by humans and that the origin of this disease is still unknown in these animals, even if the effects are the same as in humans. To be precise the outbreak was discovered in Cantanhez Forests National Park in Guinea-Bissau. In chimpanzees, as in humans, the infection was caused by the same bacterium, Mycobacterium leprae, as reported by a troop of scientists led by Dr. Fabian Leendertz (Group Leader of Robert Koch Institut, Berlin, Germany). This time the scientists thought that leprosy was a typically human disease, unfortunately, the circumstances prove otherwise. Of course, chimpanzees do not think that the aesthetics of their body, is not important, but the fact is that this bacillus can be deadly too.

1 Grima, P. 2018. Lebbra. Nardò (LE), Salento Books.