Buruli ulcers are a skin condition caused by infection with the bacterium, Mycobacterium ulcerans. Infection passes through three stages: preulcerative, ulcerative and inactive disease. Initially, the infection appears as a painless bump or nodule. The area may swell and enlarge. The bacteria produce a toxin that causes the destruction of tissue. Within weeks to months, the preulcerative lesion can turn into a large ulcer. Somehow the bacteria are able to suppress the body's immune response to the infection, enabling the ulcer to spread without any evidence of pain or fever in the patient. In some cases, the ulcers can grow quite large, covering an extensive area of the body. Eventually, the ulcer may heal, leaving behind a disfiguring scar. If the scar forms over a joint, the limb may be permanently fixed in an awkward, bent position.

Buruli ulcers are very rare here in the U.S. However, the infection is much more common in some parts of Africa and Australia. The World Health Organization estimates, more than 42,000 cases have been reported since 1978. The ulcers occur in people of all ages, but are most commonly seen in children under 15. No one knows how the disease is transmitted. But incidence is higher in areas along bodies of water or recent flooding.

Finding a Treatment In the early stages, Buruli ulcers are often treatable with the antibiotics, rifampicin and streptomycin/amikacin. But many of the patients with Buruli ulcers don't have access to healthcare or are unable to afford treatment. If the infection progresses to the ulcer stage, surgery is often needed to remove the dead tissue, cover the defects and correct deformities that occur.

At Arizona State University, Microbiologist Shelley Haydel, Ph.D., and Geochemist Lynda Williams, Ph.D., are looking into a treatment from a seemingly unlikely source - clay. Williams says the idea for the study came from a woman working in health clinics along the Ivory Coast and in New Guinea. She had been using two green clays from France to treat her patients with Buruli ulcers and was noticing some remarkable healing effects. Her son posted a message on a computer message board asking for help in analyzing the contents of the clays.

Haydel and Williams analyzed the two clays and found some similarities and subtle differences between the two samples. Next, she placed samples of various types of bacteria into the clays to study the effects on the germs. One of the clays promoted the growth of bacteria. But the second clay inhibited the growth of several important types of bacteria, like E. coli, Salmonella typhimurium, Pseudomonas, and Mycobacterium marinum. The second clay also was able to partially inhibit the growth of a multi-drug resistant strain of Staphylococcus aureus.

The researchers documented the "natural" antibiotic effects of the clay on a patient with a Buruni ulcer on the hand. After just one treatment, the dead tissue within the ulcer could easily be removed. Within three to four months of daily clay dressing changes, the infection had healed and a soft, supple scar remained at the site. The patient even regained used of the fingers and the ability to grasp objects.

Williams says there is much work to done to understand how the healing clays work and what properties they use to kill bacteria. Eventually, scientists may be able to isolate those healing components and duplicate them in a lab. Williams cautions consumers shouldn't try to make their own versions of a healing clay because clays can absorb some harmful elements and chemicals that are in the environment.

For general information on Buruli ulcer disease:

World Health Organization, who.int