Buruli ulcer: Encyclopedia - Buruli ulcer

Buruli ulcer

The Buruli ulcer (also known as the Bairnsdale ulcer) is an infectious disease caused by the Mycobacterium ulcerans, from the same family of bacteria which causes tuberculosis and leprosy. The infection causes painless swelling, with lesions developing in the skin later on. Further progression of this bacteria produces toxins that suppress the immune system and destroy skin, underlying tissue and bone, causing severe deformities. It predominantly affects the limbs.

Buruli ulcer - Identification and naming

It was first described in 1948 from the Bairnsdale district in south-east Australia. The disease was well known in Africa before this time but the mycobacterium had never been identified. James Augustus Grant, in his book "A Walk across Africa", describes how his leg became grossly swollen and stiff with later a copious discharge. This was almost certainly the severe oedematous form of the disease, and is the first known description of the infection. The name "Buruli Ulcer" comes from an area in Uganda where the disease was once most prevalent, especially during the 1960s.

Buruli ulcer - Infection

Being one of the less known diseases caused by mycobacteria, means of infection are not completely clear. However, the mycobacterium has been identified in stagnant or slowly moving water sources in endemic areas and in aquatic insects (Naucoridiae). Transmission to man may be by means of insects or by a contaminated aerosol generated from decaying vegetation in the water source. Infection in Australia has occurred in an alpaca, in koalas, possums and other marsupials.

Buruli ulcer - Symptoms

The infection in most instances presents as a subcutaneous nodule, which is characteristically painless. In southern Australia the presentation is more often as a papule (or pimple), which is in the skin (dermis) rather than subcutaneous (beneath the skin). The infection is mostly on the limbs, most often on exposed areas but not on the hands or feet. In children all areas may be involved, including the face or abdomen. A more severe form of infection produces diffuse swelling of a limb, which, unlike the papule or nodule, can be painful and accompanied by fever. Infection may frequently follow trauma, often minor trauma such as a small scratch. The disease is primarily an infection of subcutaneous fat, resulting in a focus of necrotic (dead) fat containing myriads of the mycobacteria in characteristic spherules formed within the dead fat cells. Skin ulceration is a secondary event. The mycobacterium produces a toxin, named mycolactone, which causes this fat necrosis and inhibits an immune response. Healing may occur spontaneously but more often the disease is slowly progressive with further ulceration, granulation, scarring, and contractures. Secondary infection may occur with other nodules developing and infection may occur into bone. Although seldom fatal the disease may result in considerable morbidity and hideous deformities.

Buruli ulcer - Treatment

Treatment is primarily by surgical excision (removal) of the lesion, which may be only a minor operation and very successful if undertaken early. Advanced disease may require prolonged treatment with extensive skin grafting. Presently available antibiotics are not effective in the primary treatment of the disease but may help to prevent recurrence after surgery. Surgical practice can be dangerous and scarcely available in affected third world countries.

Buruli ulcer - Global spread

The infection occurs in well defined areas throughout the world, mostly tropical areas - in several areas in Australia, in Uganda, in several countries in West Africa, in Central and South America, in south-east Asia and New Guinea. It is steadily rising as a serious disease, especially in West Africa and underdeveloped countries, where it is the third leading cause of mycobacterial infection in healthy people, after tuberculosis and leprosy. In East Africa, thousands of cases occur annually and in these areas the disease has displaced leprosy to become the second most important mycobacterial disease of man (after tuberculosis).

The disease is more likely to occur where there have been environmental changes such as the development of water storages, sand mining and irrigation.

Adapted from the Wikipedia article "Buruli ulcer", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki