Leprosy: a disease far from being eradicated, but still neglected
Despite existing treatments, leprosy continues to infect thousands of people every year. Faced with this disease, which mainly affects poor countries, research is continuing, but few laboratories devote funds to it.
Mathias Duck, a 44-year-old Paraguayan chaplain, already knew about leprosy, having worked in a hospital dedicated to the sick. However, when he himself was diagnosed in 2010, it took him “three years to be able to talk about it freely”, he told AFP.
A pathology often considered shameful, leprosy has the sad privilege of being one of the 20 tropical diseases considered neglected by the World Health Organization (WHO). Caused by the bacillus Mycobacterium leprae, this transmissible disease attacks the skin and peripheral nerves, with potentially very serious sequelae.
In 2022, just over 216,000 cases of leprosy were detected worldwide, particularly in Brazil and India, according to the WHO. Leprosy even remains “a major problem” in 14 countries in Africa, Asia and Latin America.
Figures which could be only the tip of the iceberg, according to doctor Bertrand Cauchoix, specialist in the disease at the Raoul Follereau Foundation, in France: “We know the number of patients screened, but we do not count the forgotten, undetected patients”, which could be much more numerous, he explains.
Because leprosy, favored by promiscuity and precarious living conditions, has a particularity: a very long incubation time, from a few years up to 20 years. To which is added a diagnostic delay, during which the patient can continue to infect relatives.
For decades, a medical treatment has existed, based on three antibiotics. For Mathias Duck, six months of treatment was enough: “I was very lucky, because I was diagnosed and treated in time, without any infirmity”.
But the treatment can be longer, up to twelve months, making it difficult to follow in countries without a health system.
“We need infrastructure with caregivers to dispense the drugs, this requires resources”, recalls Alexandra Aubry, professor of biology and specialist in leprosy, at the Center for Immunology and Infectious Diseases (Cimi) in Paris.
– ‘No money on leprosy’ –
In addition, the existing antibiotics are donated by the foundation of the Swiss laboratory Novartis – which produces them – via the WHO. Bertrand Cauchoix therefore points to “a risk of very great tensions” in the event of problems on the production line of these antibiotics.
More generally, pharmaceutical laboratories are not scrambling to produce new molecules that would be more easily administered. “There is no money for leprosy, only charitable donations,” laments Dr. Cauchois.
Indeed, the disease is now virtually absent from Western countries, and confined to a limited number of patients, in countries unlikely to pay new drugs at a high price.
In her research laboratory in Paris – one of the few in the world capable of carrying out tests on this bacterium, which does not survive in Petri dishes – Alexandra Aubry evaluates the effectiveness of each new antibiotic arriving on the market to treat other ailments.
“We are trying to identify associations of antibiotics,” she explains. “We are trying all possible ways of simplifying to have shorter treatments, for example once a month for six months.”
There are also vaccine projects, all the more rare as there too the funds are absent, in a disease whose onset is delayed.
“It is very complex to have funding for this. To assess the effectiveness of a vaccine, you have to follow the vaccinated population for 10 to 15 years”, recalls Professor Aubry.
“If we compare with what happened for the Covid, it’s really just a drop in the ocean”, adds Mathias Duck, who calls for both more research and more political will in around the world to eradicate the disease.