Donald G. McNeil Jr. / New York Times News Service

A simple, fast and inexpensive new test for leprosy offers hope that, even in the poorest countries, victims can be found and cured before they become disabled or disfigured like the shunned lepers of yore.

American researchers developed the test, and Brazil's drug-regulatory agency registered it last month. A Brazilian diagnostics company, OrangeLife, will manufacture it on the understanding that the price will be $1 or less.

“This will bring leprosy management out of the Dark Ages,” said Dr. William Levis, who has treated leprosy patients at a New York hospital outpatient clinic for 30 years.

Many consider leprosy, formally called Hansen's disease, a relic of the past, but annually about 250,000 people worldwide get it; Brazil is among the hardest-hit countries, as are India, the Philippines, Indonesia and the Democratic Republic of Congo. The U.S. has 150 to 250 new diagnoses each year. Leprosy is curable, so better detection may mean that someday it could join the short list of ailments, like polio, on the brink of eradication, experts say.

The new test gives results in under 10 minutes and is far simpler than the current diagnostic method of cutting open nodules, often in the earlobe, and looking for the bacteria under a microscope.

“It works like a pregnancy test and requires just one drop of blood,” said Malcolm Duthie, who led the test's development at the Infectious Disease Research Institute in Seattle. “I can teach anyone to use it.”

Even more important, he said, it is expected to detect infections as much as a year before symptoms appear. And the earlier treatment begins, the better the outcome. Leprosy is caused by a bacterium, Mycobacterium leprae, related to the one that causes tuberculosis, but reproducing so slowly that symptoms often take seven years to appear.

M. leprae is transmitted only after prolonged, close contact. The bacteria spread under the skin in the coolest parts of the body: the hands, feet, cheeks and earlobes.

The first visible signs are usually numb, off-color patches of skin, which are often misdiagnosed as fungus, psoriasis or lupus. The victim may get repeated cooking burns or cuts. Feet develop sores from something as simple as a stone they cannot feel in a shoe.

After about six months, the nerve damage is permanent. So even if a patient is cured — and a cure normally requires taking three kinds of antibiotics for six to 12 months — there is still a lifelong risk of developing ulcers that can become infected. The standard antibiotics are provided free through the World Health Organization.