Buruli Ulcer
A rare and exotic infection
that can lead to permanent
disfigurement

Buruli ulcer is a disease caused by bacteria. These bacteria are found in various aquatic environments and mainly affect the skin and sometimes bone as well. If Buruli ulcer is not treated in time, it may lead to permanent disfigurement and long-term disability. Though it can be cured by early detection, there is no prevention for the disease and mode of transmission to humans is also not known.

The disease is found in 33 countries from Africa, South America and western pacific regions with tropical, subtropical and temperate climates.

What causes Buruli Ulcer

Buruli ulcer is a disease caused by the bacteria known as Mycobacterium ulcerans. It belongs to the same family that causes tuberculosis and Leprosy. Aquatic environments are the main reservoir of Mycobacterium ulcerans. The bacteria grows at temperatures between 29–33 °C and can live in oxygen concentrations as low as 2.5%. A Unique toxin called mycolactone is produced by the organism which damage tissue and inhibits immune system.

Buruli ulcer is not contagious and cannot be transmitted between infected individuals. How exactly humans become infected is unknown. Mosquitos are suspected to play a role in infection, with the bacteria entering through contact with puncture wounds left by them.

A mosquito rests on a piece of fabric
Photo: Mosquito resting on a piece of fabric.

Where is Buruli Ulcer found

The bacteria are mainly found in countries with tropical, subtropical and temperate climates. Africa and Costal Australia remain major endemic areas where cases have been reported since the 1930s. Sporadically cases are found in Japan and the Americas. Most cases are however found in West and Central Africa, namely Benin, Cameroon, Côte d’Ivoire, Democratic Republic of the Congo, Ghana, Liberia and Nigeria.

Buruli ulcer tends to occur in rural areas near slow-moving or stagnant water. Frequently, the disease tends to appear near water that has experienced human intervention, such as the building of dams or irrigation systems, flooding, or deforestation.

Image: Buruli Ulcer cases, geographical distribution

What are the symptoms of Buruli Ulcer

The first sign of Buruli ulcer is a painless swollen bump, plaque or diffuse swelling of the arm, leg or face.  It is often similar in appearance to an insect bite.

Over the course of a few weeks, the original swollen area expands to form an irregularly shaped patch of raised skin. The disease may progress with no pain or fever. Without treatment or sometimes during antibiotics treatment, the nodule, plaque or edema will ulcerate within 4 weeks. In some people, the ulcer may heal on its own or remain small but linger unhealed for years. In others, it continues to grow wider and sometimes deeper, with skin at the margin dying.

Large ulcers may extend deep into underlying tissue, causing bone infection and exposing muscle, tendon, and bone to the air. When ulcers extend into muscles and tendons, parts of these tissues can be replaced by scar tissue, immobilizing the body part and resulting in permanent disability.

Symptoms are typically limited to those caused by the wound. The disease rarely affects other parts of the body.

Photo: Buruli ulcer lesions. Top-left, an early ulcer. Top-right, a larger ulcer across the lower arm and wrist. Bottom, a large ulcer on the thigh.

How can Buruli Ulcer be prevented

Buruli ulcer can be prevented by avoiding contact with aquatic environments in endemic areas, although this may not be practically possible for people living in these areas.

The risk of acquiring it can be reduced by:

  • Wearing gloves, use long-sleeved shirts and trousers when working outdoors.
  • Use of insect repellents to avoid insect bites.
  • Cuts and abrasion should be covered as soon as they are noticed.

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Early detection followed by antibiotic treatment is the next step in prevention of developing the actual disease.

There is no specific vaccine for preventing Buruli ulcer. The BCG vaccine typically given to children to protect against tuberculosis offers temporary partial protection.

How is Buruli Ulcer diagnosed

Treatment is often initiated by a clinician based on signs and symptoms alone.

Microscopy detects M. ulcerans in just 30 to 40% of infected people, making it a relatively insensitive diagnostic test.

Diagnosis can be confirmed by polymerase chain reaction (PCR) tests, such as the ones made available by the WoIDMo.

The early symptoms are occasionally confused with boils, lipomas, ganglions, lymph node tuberculosis, onchocerciasis nodules or deep fungal subcutaneous infections. Once it progresses and ulcerates, the condition is often confused with tropical phagedenic ulcers, chronic lower leg ulcers due to arterial and venous insufficiency, diabetic ulcers, cutaneous leishmaniasis, extensive ulcerative yaws and ulcers caused by Haemophilus ducreyi.

Image: Early signs of Buruli Ulcer.

How is Buruli Ulcer treated

Buruli ulcer is treated through a combination of antibiotics to kill the bacteria, and wound care or surgery to support the healing of the ulcer. The most widely used antibiotic combination is once daily oral rifampicin plus twice daily oral clarithromycin. Several other antibiotics are sometimes used in combination with rifampicin, namely ciprofloxacin, moxifloxacin, ethambutol, amikacin, azithromycin, and levofloxacin.

Small or medium-sized ulcers typically heal within six months of antibiotic treatment, whereas larger ulcers can take over two years to fully heal. Given the long healing times, wound care is a major part of treating Buruli ulcer. 

Edited by: Himanshu Arvind Kapadia

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