Francesca Tomasi received her B.A. from the University of Chicago and is now a microbiologist.
Mutilating. Highly contagious. Incurable. Outcast. These words have been written and spoken in countless languages for thousands of years to describe a single affliction: leprosy. People with the disease were often terribly scarred, their faces marred, their skin almost scaly, and limb loss was not surprising.
The earliest possible account of what experts believe was leprosy can be found in an Egyptian papyrus dating back to 1550 BC. About a thousand years later, Indian writings began to depict a similar affliction. 500 years later, coinciding with the return of Pompeii’s troops from Asia Minor, Roman scrolls joined the collections of leprosy literature.
For millennia, leprosy was arguably the most stigmatized illness in the world. Infected people all over Europe, Asia, and Africa were shunned for their disfiguring illness. In Europe, these so-called “lepers” were forced to wear special clothing for easy identification, ring bells to signal their proximity to others, and walk against the direction of the wind so as to avoid propagating their plague across long distances.
What is leprosy, and why was it so scary? Now also known as Hansen’s Disease, leprosy is a bacterial disease caused by Mycobacterium leprae, a rod-shaped microbe that bears a physical resemblance to the causative agent of tuberculosis, Mycobacterium tuberculosis. Like tuberculosis, leprosy is a slow-growing disease. The incubation period of the diseases is at least 5 years, and symptoms may not even appear until 20 years after infection. We now know that the bacteria mainly affect the skin, peripheral nerves, mucosa of the upper respiratory tract, and possibly the eyes. Symptoms typically include patches of skin losing their pigmentation, and/or thickened peripheral nerves; patients tend to experience nerve damage that causes loss of sensation.
Damage to the peripheral nervous system is the primary cause of the legendary disfigurement affiliated with leprosy. Imagine having zero feeling in your foot and leg and going outside to work in a field. Somewhere along the way, you step on an upward-facing nail. But because your nerves are damaged in that food, you feel nothing and continue your work. A few minutes later, you’re still walking, oblivious to your injury, and you happen to land funny on a large rock, breaking your ankle. But without the signal to your brain to tell it you’re hurt, no pain radiates around your ankle and you continue walking, oblivious to the fact that your foot is now hanging crooked to the side, and all your weight is borne on your ankle. After a few hours of walking that way, bare bone has cut through your flesh, and your foot is dangling precariously on thinned ligaments. By the time you realize that something looks weird – even though nothing feels that way – chances are you’re going to lose your foot.
The above scenario sounds unnecessarily gruesome, but that’s exactly what used to happen to leprosy patients. The peripheral nervous system works by sending signals up to your brain from a point in your body that has been injured, and the brain creates a feeling of localized pain. A healthy person instantly feels pain and changes their behavior to address and minimize it. Someone with damaged nerves, however, will not. If your hand were resting on a burning stove but you didn’t feel the heat, you would have no reason to yank your hand off the stove.
It doesn’t seem so hard now to understand why nerve damage can cause such dramatic, even terrifying injuries, does it?
Today, leprosy still carries a stigma with it, albeit a smaller one than in the past. Leprosaria existed in many countries to sequester lepers into their own, isolated communities. In more modern times, these communities provided disease treatment and wound care. With the discovery of antibiotics to treat leprosy, patients were able to be cured of their infection and, barring societal discrimination, lead relatively normal lives.
The first treatment breakthrough occurred in 1945, when a drug called dapsone entered the market. Also known as diaminodiphenyl sulfone, or DDS for short, dapsone is now on the World Health Organization’s List of Essential Medicines, which outlines the vital medications in a basic health system. The antibiotic works by inhibiting the bacterial synthesis of dihydrofolic acid, which ultimately hinders DNA and RNA synthesis, killing the pathogen. Treatment with dapsone alone was long-term, possibly life-long, which meant lower-than-average compliance rates. Sure enough, in the 1960s, M. leprae strains emerged that were resistant to dapsone. Fortunately, however, around the same time, two other powerful drugs called rifampicin and clofazimine were discovered. Together, dapsone, rifampicin, and clofazimine make up today’s cocktail of multidrug therapy to combat leprosy. This course of treatment kills the bacteria and cures the patient.
Leprosy was eliminated as a major public health problem in 2000, thanks to multi-drug therapy. The prevalence rate of the disease has dropped by 90%, and with it, the global burden of the disease has dropped too. Today, leprosy is still considered endemic in Angola, Brazil, Central African Republic, Democratic Republic of Congo, India, Madagascar, Mozambique, Nepal, and the United Republic of Tanzania. However, full elimination of the disease is on the horizon, as no multi-drug resistant bacterial strains have emerged. Cases of the illness still arise in other parts of the world, too; notably, there has been a recent rise in cases in Florida. Since a primary carrier of M. leprae is the armadillo, doctors urge people not to come into contact with these animals, and it seems a prevalence of armadillos in Florida may be contributing to the rise in cases.
Today, the obstacles that need to be overcome for full leprosy eradication include political commitment in endemic countries and the integration of multidrug leprosy therapy into these places’ general health services. Of course, medical and financial resources need to continue to be available and accessible by anybody who needs them as well. Finally, the ancient stigma associated with leprosy still rears its head in the way of treatment. Patients are scared to self-report their disease and seek early treatment. Programs to change this environment into one in which nobody is hesitant to come forward for care are the only way to change this in favor of a leprosy-free world.