PARIS – Leprosy has been called the world’s oldest recorded disease, an evil that humans have known for more than 3,500 years, as papyri from ancient Egypt testify. In modern times, drugs to cure leprosy have become cheap, plentiful and effective. So why is this biblical curse still around?
Doctors, speaking ahead of World Leprosy Day on Sunday, pointed to excellent news about the bid to stamp out the disease, though they also acknowledge sizable hurdles.
“There has been enormous progress in treating and controlling the leprosy epidemic,” said British microbiologist Stewart Cole. “Six million people have been cured by multidrug therapy.”
Multidrug therapy (MDT), is a cocktail of three antibiotics designed to kill the parasitic rod-shaped germ Mycobacterium leprosae, which after a long incubation spreads from nerve cells to muscles and other tissues. Several drugs are always used to treat the disease, as a single medication enables the germ to develop resistance to it.
Without treatment, the microbe causes crippling damage to the hands, skin, nose and eyes. The condition goes hand-in-hand with ostracism, even though scientists say that M. leprosae, which is transmitted by droplets from the nose and mouth, is generally not very infectious.
According to World Health Organization figures, roughly 5.2 million people were suffering with leprosy in 1985. The burden has fallen sharply, driven especially by free MDT treatment made available by the WHO to poor countries. With it, a patient can be cured in six to 12 months.
But even as the U.N. health body is demanding a “final push” against leprosy, the decline in new infections seems to have plateaued: In 2004, there were around 400,000 new cases, which fell to 228,000 new cases in 2010 and then to 219,000 the following year.
“The WHO is starting to wonder why this is the case,” said Cole, who chairs the scientific and medical commission of the Raoul Follereau Foundation, a French nongovernmental organization inspired by the 20th-century journalist and antileprosy campaigner. “For years, they told us that if we carried on using MDT, prevalence would gradually hit zero, but this hasn’t happened and we are concerned.”
Leprosy has been eliminated from 119 out of the 122 countries in which the disease was considered a public health problem in 1985. But tenacious pockets remain in parts of Brazil, India, Indonesia, the Philippines, Nepal, the Democratic Republic of Congo, Madagascar, Mozambique and Tanzania, according to the WHO.
Roch Christian Johnson, a leprosy specialist from the West African state of Benin, said one reason is poor medical facilities. Many sufferers are already excluded from their communities and clinics are often located far from people in need. As a result, many fail to get diagnosed swiftly and the germ incubates unseen for years.
Each year, around 12,000 people are diagnosed only after they have reached advanced stages of leprosy, when the damage is irreversible, Johnson said.
Another problem is multibacillary leprosy, a more contagious form that requires a tougher drug regimen. If undetected and untreated, it leads to more infections, which in turn might only be spotted a decade or two later.
Even though funding for research is a long-running concern, scientists say they are gaining useful insights into leprosy. Recent evidence suggests that M. leprosae has a natural reservoir in armadillos, for instance.
In humans, according to a study published last week, the germ hijacks key cells in the nervous system called Schwann cells and then reprograms them into muscle cells, thus helping them to spread into muscle tissue. And a team in Seattle is seeking authorization to carry out a leprosy vaccine on a small group of volunteers, the first in a three-phase trial process.
Ultimately, though, wiping out leprosy will come down to commitment and resources, many experts say.