Though Hansen's disease has existed since ancient times, it wasn't until the early part of this century that treatment other than quarantine was discovered.
Named for the Norwegian physician who pinpointed the bacteria in 1873, Hansen's disease attacks body tissue slowly, and symptoms can take several years to appear. Left untreated, it can cause skin sores and discoloration, pain, blindness and accidental mutilation caused by loss of feeling in the limbs.
It is still not completely understood by scientists.
Despite its reputation as highly contagious, scientists now believe it can be transmitted only by repeated, long-term, human-to-human contact with a carrier. But evidence that Hansen's also can afflict armadillos may suggest unknown transmission routes, according to researchers.
Treatment is still developing, said Dr. Thomas Rea, a dermatologist who heads the Hansen's disease clinic at Los Angeles County-USC Medical Center.
In the 1950s, the drug dapsone stopped the spread of the disease by halting the bacteria's ability to multiply. But it did not kill the bacteria that already existed, and scientists soon found patients who were resistant to dapsone.
In the 1970s, multi-drug therapy was recommended by the World Health Organization. This worked so well that the organization declared a goal to cure Hansen's disease worldwide by 2000.
But Rea doubts the goal will be reached. Belgian scientist S.R. Pattyn released a study recently showing a 20% relapse rate after 10 years of multi-drug therapy, Rea said.
"Even the most die-hard optimist would admit that's not acceptable," he said. More effective drugs were discovered in 1990, but Rea said they are expensive and have not yet been proven safe.
Though most cases are imported into the United States--Rea said he has never seen a case originate in California--stopping the inflow has proven difficult. Patients are supposed to receive treatment before entering the United States, said Dr. John Trautman of the National Hansen's Disease Center, but the long incubation period and lack of a simple detection method makes the disease hard to spot.
Said Trautman: "The best way to control it in the U.S. is to control it worldwide."