Buruli ulcer

ABOUT BURULI ULCER

Buruli ulcer is a chronic neglected tropical disease caused by Mycobacterium ulcerans, primarily affecting the skin and soft tissue in tropical and subtropical regions with limited healthcare access. It typically starts as a painless nodule or swelling; the bacterium's toxin, mycolactone, destroys tissue while suppressing immune response, allowing extensive ulcers to form with little pain. Transmission is linked to wetlands and slow-moving water, though person-to-person spread is not confirmed.

Left untreated, the disease can cause severe tissue damage, disability, and stigma, making early detection critical. It's curable with a combination of antibiotics (typically rifampicin and clarithromycin) over several weeks; advanced cases may need wound care, physiotherapy, or reconstructive surgery. Buruli ulcer remains a public health concern in parts of West and Central Africa, and in select areas of Australia, Asia, and the Americas, with lasting social and economic impact on affected communities.

THE DISEASE

Where is Buruli ulcer found?

Buruli ulcer occurs in tropical and subtropical regions worldwide, particularly near wetlands, rivers, swamps, and slow-moving water. It has been reported in more than 30 countries across Africa, the Americas, Asia, and the Western Pacific. Most cases occur in West and Central Africa, especially Côte d'Ivoire, Ghana, Benin, Cameroon, and the Democratic Republic of the Congo. The disease is also found in coastal Victoria, Australia, as well as in Papua New Guinea, Japan, and parts of South America.

Buruli ulcer is most common in rural communities with limited healthcare access. Children under 15 are frequently affected, though people of all ages can develop the disease. Since the exact mode of transmission is still unknown, public health efforts focus on early detection, prompt treatment, and raising awareness in affected communities.

How is Buruli ulcer spread?

The exact way Buruli ulcer is transmitted is not yet fully understood. The disease is caused by the bacterium Mycobacterium ulcerans, which is commonly associated with aquatic environments such as wetlands, swamps, rivers, and slow-moving water bodies in endemic areas. Current evidence suggests that people may become infected through environmental exposure, particularly when bacteria enter the body through cuts, abrasions, or other breaks in the skin. In some regions, aquatic insects and mosquitoes have also been investigated as possible contributors to transmission, although their exact role remains unclear. Unlike many infectious diseases, there is no strong evidence that Buruli ulcer spreads directly from person to person through casual contact, touching, or sharing food and household items. People living with Buruli ulcer do not need to be isolated from their families or communities. Because the source and route of infection are not fully understood, prevention focuses on avoiding exposure to potentially contaminated environments where possible, keeping wounds clean and covered, and seeking medical attention promptly if suspicious skin lesions or swellings develop. Early diagnosis and treatment are essential to prevent severe tissue damage, disability, and long-term complications.

Is Buruli ulcer curable?

Yes. Buruli ulcer is a curable disease, especially when diagnosed and treated early. The World Health Organization (WHO) recommends an eight-week course of antibiotics, most commonly a combination of rifampicin and clarithromycin, which can effectively eliminate the infection and stop disease progression. Early treatment can prevent the development of large ulcers, permanent scarring, disability, and other complications. In addition to antibiotics, proper wound care is essential to promote healing and reduce the risk of secondary infections. For advanced cases, patients may require supportive treatments such as physiotherapy to maintain mobility and prevent contractures. In some situations, reconstructive surgery may be needed to repair damaged tissue and restore function. Because the disease is often painless in its early stages, people living in endemic areas should seek medical attention promptly if they notice a painless nodule, swelling, plaque, or unexplained skin lesion. Early diagnosis and treatment offer the best chance of complete recovery and minimize the risk of long-term disability.

Vaccines against Buruli ulcer

Currently, there is no vaccine specifically approved to prevent Buruli ulcer. However, the Bacille Calmette-Guérin (BCG) vaccine, which is primarily used to protect against tuberculosis, may provide some short-term protection against Buruli ulcer. Studies suggest that this protection is limited and does not provide long-term immunity. Researchers continue to investigate new vaccines that target Mycobacterium ulcerans, the bacterium that causes Buruli ulcer. Several experimental vaccines have shown promising results in laboratory and animal studies, but none have yet been approved for routine use in humans. Because there is currently no effective vaccine specifically for Buruli ulcer, prevention focuses on early detection and treatment, reducing exposure to potentially contaminated environments in endemic areas, and seeking medical care promptly for any painless swelling, nodule, plaque, or skin lesion that does not heal. Continued research into the disease, its transmission, and vaccine development remains an important priority for reducing the burden of Buruli ulcer in affected communities worldwide.

Mycobacterium ulcerans and the challenges of developing a Buruli ulcer vaccine

A key feature of the Mycobacterium ulcerans  is its ability to produce mycolactone, a powerful toxin that damages tissue, suppresses the immune response, and allows the infection to progress with little pain or inflammation in its early stages. Developing an effective vaccine against Buruli ulcer has proven challenging for several reasons. First, the exact mode of transmission of M. ulcerans remains unclear, making it difficult to determine how best to target prevention strategies. Second, the bacterium's toxin plays a major role in disease development and can interfere with the body's ability to mount a protective immune response. Another challenge is the relatively low number of reported cases compared with diseases such as tuberculosis and malaria, which has limited research funding and slowed vaccine development. In addition, Buruli ulcer mainly affects rural communities in low-resource settings, where conducting large-scale vaccine trials can be difficult. The Bacille Calmette-Guérin (BCG) vaccine, used primarily against tuberculosis, has shown some temporary protective effect against Buruli ulcer, but this protection is incomplete and does not provide long-term immunity. Researchers are therefore exploring new vaccine approaches that specifically target M. ulcerans and its mycolactone toxin. Although several experimental vaccine candidates have shown promise in laboratory and animal studies, no vaccine has yet been approved for the prevention of Buruli ulcer. Continued research is needed to better understand the bacterium, its transmission, and the immune responses required for long-lasting protection. Until an effective vaccine becomes available, early diagnosis, antibiotic treatment, proper wound care, and community awareness remain the most important tools for reducing the burden of Buruli ulcer in affected populations.

How is VALIDATE Helping?

VALIDATE bringing together researchers, clinicians, public health experts, and industry partners from around the world, and helps accelerate scientific collaboration and innovation in vaccine research. For Buruli ulcer, VALIDATE supports research aimed at improving understanding of Mycobacterium ulcerans, the immune responses it triggers, and the mechanisms by which it causes disease. This knowledge is essential for identifying promising vaccine targets and designing effective prevention strategies. The network provides funding opportunities, training, workshops, and collaborative research platforms that enable scientists from endemic and non-endemic countries to share expertise and resources. VALIDATE also promotes multidisciplinary research, helping to bridge gaps between laboratory discoveries and practical vaccine development. Although no vaccine against Buruli ulcer is currently available, initiatives such as VALIDATE are playing an important role in advancing research, supporting innovation, and moving the field closer to the development of safe and effective vaccines for populations at risk.

Further reading about Buruli ulcer vaccine development:

LINKS TO VALIDATE FUNDED Projects