The common simile of someone being shunned like a leper is an irony considering we still don't know how leprosy is transmitted. Leprosy (now usually referred to as Hansen's Disease) is still being diagnosed in the US, with an annual incidence of about 150 cases a year and a prevalence of about 3000 cases. Those 3000 cases under treatment are probably an underestimate, since the disease is difficult to diagnose and there is little knowledge or experience with it among health care providers.
EurekAlert notes a report to be presented at the upcoming meeting of the American Society of Tropical Medicine and Hygiene summarizing the current status:
Although researchers do not clearly understand how leprosy is transmitted, they do know that it is a slow, chronic disease that attacks the peripheral nervous system and motor skills often leading to disability and disfigurement. According to the NHDP, the onset of infection and symptoms can take three to 10 years, making it difficult for researchers to find the origin of where or how people acquire the disease. As the disease progresses, patients lose their sense of touch in their fingers and toes leaving them open to repeated burns and cuts which then get infected. The effects of repeated damage will initiate bone absorption and motor nerve deterioration causing fingers to shorten and curve, resulting in a claw-like appearance. Although leprosy can be fully treated with medicine when diagnosed in early stages, once the disease has advanced nerve damage cannot be reversed. (EurekAlert)
The skin lesions of Hansen's Disease (HD) are often mistaken for a fungal infection and treated as local lesions. But HD is caused by an acid-fast bacterium (Mycobacterium leprae) in the same genus as tuberculosis. The principal tissues affected are skin, mucous membranes and nerve cells. It has never been grown in cell free media or even cell culture, although it has been grown in mouse foot pads (CDC). Typically a disease of tropical climes and poor communities (90% of cases worldwide are in a handful of countries: Brazil, Madagascar, Mozambique, Tanzania, and Nepal), HD does strike people who have never been outside the US.
Contrary to xenophobe Lou Dobbs, the disease is not on the rise in the US, although it is true it was brought here by immigrants and then became endemic in the Gulf region -- French immigrants in the 1700s.
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Probably worth doubly emphasizing the point made in the quoted section, that leprosy is a completely treatable disease. There seems to be a superstitious dread of the disease, as if it's a death sentence, which is of course completely wrong.
The ASTMH meeting is in Louisiana, and the
National Hansen's Disease Clinical Center
is in Baton Rouge.
http://www.hrsa.gov/hansens/
According to the website, there are also a
fair number of incident cases in CA, MA,
and NY
An important pathway for eradication of intracellular pathogens (including mycobacteria) is via autophagy.
http://www.landesbioscience.com/journals/autophagy/article/4272
Intracellular pathogens that persist are those that can subvert the process of autophagy. Autophagy is inhibited under conditions of oxidative stress, the ATP powered proton pump that acidifies the lysosome is inhibited by oxidative stress. I suspect that is an energy conservation mechanism to conserve ATP under conditions of high ATP demand (such as running from a bear). Nitric oxide regulates the ATP level and a state of oxidative stress is always a low NO state as well as a low ATP state.
During an acute immune system stimulation, the NO level is acutely increased, which increases ATP levels. That very likely accelerates autophagy and increases the turn-over of cellular contents including intracellular pathogens.
That may be part of the mechanism behind the old technique of fever therapy to treat neurosyphilis.
We have been seeing more Hansen's disease cases from the island of Micronesia here in Hawaii (from migrants) over the past ten years or so.
http://www.wpro.who.int/NR/rdonlyres/45DD5F3F-D0A6-437E-B75C-902C1E954A…
Sorry...islands (plural) of Micronesia...mainly migrants from the Federated States of Micronesia and the Republic of the Marshall Islands. These were part of the former U.S. Trust Territories after WWII. The US gave lots and lots of government monies to the Trust Territories begining in the 1950's and accelerating in the 1960's-1970's. After Reaganomics the monies slowed to a trickle....the health infrastructure has fallen apart since then and look what we see now....islands where both commicable and non-communicable diseases are rampant (kids may be malnourished and have Vitamin D deficiencies and adults have obesity and diabetes).
To see leprosy these days in a former US "colony" is appalling. We in Hawaii know about this because of the old leper colony at Kalaupapa on Molokai.
Most people (apparently about 90% of us) are naturally immune to the disease. HD is endemic in the nine-banded armadillo population in the South, though supposedly all or most of the cases currently being treated in the US are in immigrants or their family members and armadillo-human transmission isn't to blame. The Hansen's Disease Research Center at LSU has a whole colony of armadillos.
Last year, I visited the former leprosarium in Carville, Louisiana. It was a plantation (sugar, I think) before it was turned into a leprosarium, and now it is a museum and part of a military installation. It really is a wonderful place to visit for anyone interested in infectious disease and/or history. They had some lovely photos, even documenting their Mardi Gras celebrations. Some people spent their entire lives there--even after they were allowed to leave, many of them stayed on. When it's the only thing you've ever known, how do you leave, especially when you'd have to face the world as "a leper"?
While I was there, I had a chance to chat with a man whose brother lived there for most of his life and ultimately married another patient--I believe their children were sent off while the couple remained at the hospital as patients. It was really a moving story, and I believe the woman actually wrote a novel about it.
Again, a great place to visit if you're ever in the neighborhood.
Same for a trip to Molokai:
http://www.muleride.com/