Leprosy is more than a biblical disease or a novelty from contact with cute armadillos. Leprosy, a mycobacterial infection related to tuberculosis, still affects hundreds of thousands of people, disproportionately burdening women. International Women’s Day, March 8, is a good time to highlight these disparities.
While there has been a huge reduction in leprosy—from 12 million to less than 250,000 active cases per year, there is still widespread disease, especially in India, Brazil, and some parts of Africa, and 150-250 new cases each year in the U.S. About 20% of the world’s 213,000 registered cases of leprosy occur in the Organization of Islamic Countries states. One point of note is that leprosy can remain silent and indolent for many years after infection, making it a bit harder to track progress. The immunosuppression from HIV can also mask signs and symptoms. Later, when someone begins anti-retroviral therapy, they get an immune reconstitution (IRIS) syndrome, and may have sudden and more severe manifestations of disease.
Like malaria, there is a genetic predisposition to this mycobacterial infection, and 95% of adults are unable to get the disease, even if exposed to it. So go ahead and barbecue your armadillo road kill, if you are feeling adventurous! I’ll pass.
How do people become infected with leprosy?
No one is entirely sure. The main route appears to be from infected secretions transmitted by prolonged or recurrent contact with droplets. Armadillos also become infected with leprosy and are the only known non-human reservoirper a 2011 New England Journal of Medicine report. There were three cases of leprosy reported last week in Florida, two linked to armadillo contact. Contact with armadillos–the state mammal of Texas–is thought to account for about a third of the U.S. cases.
Researchers wonder why leprosy sometimes pops up without clear exposure to other infected people or to armadillos. One cool study showed that the bacteria can live for months inside amoebae that may be found in soil, water, and even in human mucous. The amoeba can form cysts to survive dry conditions, protecting the bacteria within them, and then still be infectious months later.
The mycobacteria that cause leprosy are slow growing, and have an affinity for peripheral nerves and cooler parts of the body. Loss of nasal cartilage is characteristic, leading to a stigmatizing facial deformity. The bacteria causes nerve damage, leading to numbness. People can’t feel injuries, much as with severe diabetic peripheral neuropathy, and get infections. Ultimately, they lose fingers and toes, making the person unable to work, worsening the cycle of poverty and ostracism.