By Steven Reinberg
THURSDAY, Oct. 30, 2014 (HealthDay News) -- Leprosy, although quite rare, continues to appear in the United States, a new U.S. government study reports.
Approximately 100 new cases are reported in the United States each year, researchers at the U.S. Centers for Disease Control and Prevention said. That compares to about 250,000 cases that occurred worldwide in 2008, according to the CDC.
Most U.S. cases occur in people who traveled to the United States from areas of the world where the bacterial infection is endemic, the study authors said.
"It's a surprise to most people that leprosy is still in the United States," said lead researcher Dr. Leisha Nolen, an epidemic intelligence service officer with the CDC.
"Many people think leprosy is something limited to underdeveloped nations and has been eliminated from the United States," she said.
Leprosy does infect a few people born in the United States -- about 20 to 40 a year -- but is mostly a problem for people born outside the country who were infected before arriving here, Nolen said.
The rate of infection for those born in the United States hasn't changed in the past 15 years, Nolen said. Infections are mostly confined to areas where leprosy is still found, such as in Texas and Louisiana, according to past research.
In these states, the bacteria can be found on armadillos, and they can pass the infection to humans, Nolen explained.
According to the report, from 1994 to 2011, there were just over 2,300 new cases of leprosy -- also called Hansen's disease -- diagnosed in the United States.
The yearly incidence rate of leprosy from 1994 to 1996 was 0.52 cases per 1 million people in the United States. From 2009 to 2011, that rate dropped to 0.43 cases per 1 million people, the researchers found.
The rate for people born abroad is 14 times higher than that of those born in the United States, the findings showed. The study found that the highest rate is among those born in the South Pacific who traveled to Hawaii.
"The rates of leprosy in people born overseas is going down," Nolen said. "There's been a 17 percent decrease from 1994 to 2011."
"These data further emphasize the value of considering travel and residence history as part of the standard physical examination, as it may help clinicians detect otherwise potentially rare diseases in some individuals," said Richard Truman, chief of the Laboratory Research Branch of the National Hansen's Disease Program at the U.S. Department of Health and Human Services.
Leprosy is a treatable disease. "Most people think you can't do anything about it, but leprosy is a disease that's treatable with antibiotics," Nolen said.
Without treatment, however, leprosy can progress to a debilitating disease with nerve damage, tissue destruction and loss of function, according to the study.
Nolen added that leprosy is a hard disease to catch. It can only be passed through close contact with an infected person, she explained.
"It takes four to seven years before somebody develops symptoms. This bacteria grows exceptionally slowly," Nolen said.
Doctors should be aware that leprosy is still present in the United States, she said. "It's rare. It's not like they are going to see a case, but it would be tragic if they miss it," Nolen said.
Leprosy usually appears as a skin rash that is lighter than the person's normal skin, and the patient may have no feeling in that area, she explained.
Leprosy is still a problem in the United States, but it's not something to be afraid of, Nolen added. "People aren't going to be sent off to leper colonies as they were in the past. It's something that can be treated," she said.
The new study was published Oct. 31 in the CDC's Morbidity and Mortality Weekly Report.