One of my absolute favorite authors is Sir Arthur Conan Doyle. I just love the Sherlock Holmes mysteries, and have read all of them many, many times. As I read his books, one of the things I find so fascinating is the old medical terminology and how it has changed. Terms like apoplexy, which changed to stroke, and boils and carbuncles which are now abscesses, cysts, and/or cellulitis. Today I saw a research letter from the Centers for Disease Control and Prevention’s (CDC) Emerging Infectious Diseases journal, which talked about another very old condition, leprosy, which now is called Hansen’s disease, and I found it so interesting, I just had to share.
When I think of Hansen’s disease, I think of the stories from Sunday school about the leper colonies, and when I was a child, I thought it was a wide-spread condition because of those stories. I thought Hansen’s disease was less common now for the same reason many other bacterial conditions are less common, we have better sanitation. But that is not true. Hansen’s disease is quite rare, and it’s always been rare. About 95% of people are naturally immune to Hansen’s disease. Unlike immunity we get from disease exposure, the immunity most of us have to Hansen’s disease is genetic.
Hansen’s disease is a chronic infection caused by the bacteria, Mycobacterium leprae. Hansen’s disease has been around for thousands of years. The first documented cases in individuals were in China and India nearly 2,700 years ago. The Bible describes cases even farther back than that. I think that’s why I thought it was a prevalent disease at one time. Because of the Bible stories, I had this picture in my
head of whole communities stricken with leprosy. Despite its rarity, it might have been that way because of that genetic component. In Biblical times, people rarely traveled more than a few miles from the place they were born, so communities did tend to have multiple family and therefore, genetic, ties.
Hansen’s disease is considered an emerging infectious disease, not because it’s new, but because it’s starting to be seen more commonly in the U.S. Cases in the last decade have doubled in this country. 70% of those cases have happened in Florida, California, Louisiana, Hawai’i, New York, and Texas. In previous years, the Hansen’s disease that was seen in the U.S. involved people who immigrated from areas with more common, also known as endemic, rates of Hansen’s disease, but that has changed. In the last 5 years, over 30% of Hansen’s disease cases in the U.S. were acquired locally. Central Florida is seeing the largest number of cases currently, over 20%, making it an area of concern by the CDC.
In ancient times, no one really knew who was susceptible to leprosy or how it was spread. Which is why leper colonies were formed. It was a way to quarantine people and keep the disease under control. Even today, because Hansen’s disease is so rare, we still aren’t completely sure how it’s transmitted between people. We do know it’s not spread through casual contact, sexual transmission, or from mother to fetus. Most experts believe it is transmitted to genetically susceptible people through prolonged contact with infected people who have built up a large amount of the Mycobacterium leprae in their noses. There is also a small risk of Hansen’s disease from armadillos. Armadillos in the Southern U.S. can be carriers of the bacteria that causes Hansen’s disease. Animal to human transmission is very rare with this disease, but it can still happen, and experts recommend taking precautions around armadillos to avoid transmission. When someone is infected, exposure to others
does need to be avoided until they have had a few days of treatment, especially with family members because of the genetic immunity component. Thankfully, the quarantines and leper colonies of the past are no longer necessary.
The good thing is with Hansen’s disease is it can be treated easily with antibiotics, especially in the early stages. Treatment lasts quite awhile (up to 2 years) because the bacteria grow very slowly. That slow growth also means it can be months to years between when someone is exposed and when they start to show symptoms. Symptoms are related to the skin and peripheral nerve damage that the bacteria cause. The longer someone goes without treatment, the more damage the disease can cause to the point where nerve damage can be severe enough to cause muscle weakness. The stories in the Bible of disfigurations were likely due to both the skin damage and the injuries that resulted because of nerve damage like burns or wounds in non-visible areas that became infected and didn’t heal correctly.
Again, Hansen’s disease is very rare, and most of us are naturally immune. However, because it is becoming more common in the U.S. the CDC is asking health care providers to consider Hansen’s disease in someone who is showing symptoms and may have been in Central Florida in recent years. Thankfully, it’s not something most of us will ever have to worry about.
