Buruli ulcer

Buruli ulcer

    Overview

    Buruli ulcer is caused by a bacterium called Mycobacterium ulcerans. It often affects the skin and sometimes bone and can lead to permanent disfigurement. The bacterium produces a toxin that causes skin damage. Without early treatment, Buruli ulcer (BU) can lead to long-term disability, stigma associated with socioeconomic burden. The exact mode of transmission remains unknown. Buruli ulcer has been reported in 33 countries in Africa, the Americas, Asia and the Western Pacific. Most cases occur in tropical and subtropical regions except in Australia and Japan. Out of the 33 countries, 14 regularly report data to WHO. More than 90% of global cases are reported in Africa where nearly 50% of the people affected are children under the age of 15 years.

    The annual number of suspected Buruli ulcer cases reported globally was around 5000 cases up until 2010 when it started to decrease. In the WHO African region, the trend of annual cases of BU is like the global one, since more than 90% of global cases are reported in Africa. In 2022, 1775 cases were reported in Africa Region compared to 4850 in 2010 (70% reduction in reported cases).

    Transmission, signs and symptoms

    Transmission

    The exact mode of transmission of Mycobacterium ulcerans (M. ulcerans) is still unclear. Buruli ulcer usually occurs near slow moving or stagnant bodies of water, where M. ulcerans is found in aquatic insects, molluscs, fish and the water itself. It is not clear how M. ulcerans is transmitted to humans.

    Signs and symptoms

    Buruli ulcer often starts as a painless swelling (nodule), a large painless area of induration (plaque) or a diffuse painless swelling of the legs, arms or face (oedema). The disease may progress with no pain or fever. Without treatment or sometimes during antibiotics treatment, the nodule, plaque or oedema will ulcerate within 4 weeks. Bone is occasionally affected, causing deformities.

    The disease has been classified into three categories of severity: Category I, single small lesion (32%) less than 5 cm on diameter; Category II, non-ulcerative and ulcerative plaque and edematous forms between 5-15 cm (35%); and Category III lesions more than 15 cm in diameter including, disseminated and mixed forms such as, osteomyelitis and joint involvement, lesions at critical sites (head, breast, genitalia), (33%).

    Lesions frequently occur in the limbs: 35% on the upper limbs, 55% on the lower limbs, and 10% on the other parts of the body. Health workers should be careful in the diagnosis of Buruli ulcer in patients with lower leg lesions to avoid confusion with other causes of ulceration such as diabetes, arterial and venous insufficiency lesion.

    Diagnosis and treatment

    Diagnosis

    Differential diagnoses of Buruli ulcer include tropical phagedenic ulcers, chronic lower leg ulcers due to arterial and venous insufficiency (often in elderly populations), diabetic ulcers, cutaneous leishmaniasis, extensive ulcerative yaws and ulcers caused by Haemophilus ducreyi.

    Early nodular and papular lesions may be confused with insect bite, boils, lipomas, ganglions, lymph node tuberculosis, onchocerciasis nodules or deep fungal subcutaneous infections. Cellulitis may look like oedema caused by Mycobacterium ulceransinfection but in the case of cellulitis, there is pain and fever. Four standard laboratory methods can be used to confirm Buruli ulcer: IS2404 polymerase chain reaction (PCR), direct microscopy, histopathology and culture. The bacterium grows best at temperatures between 29–33 °C (Mycobacterium tuberculosis grows at 37 °C) and needs a low (2.5%) oxygen concentration.

    In 2019, WHO established the Buruli ulcer Laboratory Network for Africa  to help strengthen PCR confirmation in 9 endemic countries in Africa. Thirteen laboratories participate in this network, supported by the American Leprosy Missions, Anesvad, Raoul Follereau Foundation and coordinated by the Pasteur Center of Cameroon.

    In 2021, WHO completed an online consultation for a draft document on Target Product Profiles to develop rapid test for the diagnosis of Buruli ulcer. With the availability of simple oral treatment for Buruli ulcer, a rapid test to allow early confirmation of diagnosis can facilitate the timely treatment of the disease. The current turnaround time of a PCR test is too long to guide early treatment decisions.

    Treatment

    Treatment
    Oral treatment of Buruli ulcer - Credit Yves Thierry Barogui

    Treatment consists of a combination of antibiotics and complementary treatments. A combination of rifampicin (10 mg/kg once daily) and clarithromycin (7.5 mg/kg twice daily) is now the recommended treatment. Interventions such as wound and lymphoedema management and surgery (mainly debridement and skin grafting) are used to speed up healing, thereby shortening the duration of hospitalization. Physiotherapy is needed in severe cases to prevent disability. Those left with disability require long-term rehabilitation. These same interventions are applicable to other neglected tropical diseases, such as leprosy and lymphatic filariasis.

    The WHO has developed a treatment guidance for health workers.

    HIV infection complicates the management of the patient, making clinical progression more aggressive and resulting in poor treatment outcomes. WHO has published a technical guide to help clinicians in the management of co-infection.

    Factsheet

    Key Facts

    • Buruli ulcer is the third most common mycobacterial disease affecting humans, after leprosy and tuberculosis.
    • The mode of transmission is not clear but somehow the bacteria get into the skin and start to grow and there is no prevention for the disease.
    • In the African region, 13 out of the 47 member states are known to be endemic.
    • Nearly half of the people affected in Africa are children under the age of 15 years.
    • Integrated early detection and antibiotic treatment are the cornerstones of the control strategy.

    Sources:

    Data are from WHO : The Global Health Observatory and integrated African Health Observatory.

    Photography: @WHO/Harandane Dicko | @WHO/Valerie Fernandezi, @WHO/Dr Yves Thierry Barogui.

    Check out our other Fact Sheets in this iAHO country health profiles series: https://aho.afro.who.int/country-profiles/af

    Fact Sheet Produced by: Monde Mambimongo Wangou, Berence Relisy Ouaya Bouesso, Sokona Sy, Serge Marcial Bataliack, Humphrey Cyprian Karamagi, Lindiwe Elizabeth Makubalo., Dr Yves Thierry Barogui, Dr Dorothy Achu.

    Burden of disease

    Status of endemicity of Buruli ulcer is declared in the countries have reported a case of Buruli ulcer at least once.

    africa map
    • In 2022, 13 of the 47 countries in the African Region were endemic for Buruli ulcer (see Figure 1).
    • 8 countries were classified as previously endemic for Buruli ulcer in the African Region, in 2022.
    • In the African Region, Buruli ulcer essentially occurs in a tropical and sub-tropical climate areas.

    Histogram
    • The average annual number of Buruli ulcer cases reported in African Region was around 5,000 cases until 2010 when it started to decrease.
    • The reductions seen in 2020 and 2021 could be linked to the impact of COVID-19 on active detection activities (see Figure 2).
    • In 2022, 1775 cases were reported from Benin, Cameroon, Congo, Côte d’Ivoire, Democratic Republic of the Congo, Gabon, Ghana, Nigeria, and Togo (see figure 3).
    • More details regarding the trend of Buruli ulcer by country can be found on The Global Health Observatory.

    Distribution - Africa map

    Prevention and control

    There are currently no primary preventive measures for Buruli ulcer. The mode of transmission is not known. Bacillus Calmette–Guerin (BCG) vaccination appears to provide limited protection.

    The objective of Buruli ulcer control is to minimize the suffering, disabilities and socioeconomic burden. Early detection and antibiotic treatment are the cornerstones of the control strategy. In many countries, community health workers play a critical role in case detection.

    These are the core indicators to measure the progress in the control of Buruli ulcer in the NTD road map 2021-2030.

    • proportion of cases in category III (late stage) at diagnosis
    • proportion of laboratory-confirmed cases
    • proportion of confirmed cases who have completed a full course of antibiotic treatment.

    WHO response

    WHO provides technical support, develops policies, guidelines, standard recording and reporting forms, health promotional materials, and coordinates control and research efforts. WHO brings together all major actors involved in Buruli ulcer on a regular basis to share information, coordinate disease control and research efforts, and monitor progress.

    WHO provides antibiotics to endemic countries to ensure access to treatment free of charge for all patients.

    WHO supports worked towards three research priorities:

    • understand the mode of transmission
    • develop rapid diagnostic tests
    • establish best-case antibiotic treatments.

    To ensure efficiency, sustainability and scale, WHO recommends that Buruli ulcer control should be integrated within skin NTDs approach adapted to the diseases present in a particular country. WHO has developed online courses and a Skin App for Androidand iOS to assist health workers in the field in the diagnosis of skin NTDs including Buruli ulcer.

    NTD

    Declarations and WHO Resolution

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    For more information

    1. WHO. 2023. “Buruli ulcer (Mycobacterium ulcerans infection)”. Available at https://www.who.int/news-room/fact-sheets/detail/buruli-ulcer-(mycobacterium-ulcerans-infection)
    2. WHO. 2023. “Buruli ulcer (Mycobacterium ulcerans infection) fact sheet”. Available at https://www.who.int/health-topics/buruli-ulcer#tab=tab_1
    3. WHO. “Buruli ulcer overview”. Available at https://www.afro.who.int/health-topics/buruli-ulcer
    4. WHO. “Neglected tropical of diseases-Buruli ulcer”. Available at https://www.who.int/data/gho/data/themes/topics/indicator-groups/indicator-group-details/GHO/buruli-ulcer
    5. WHO. “Status of endemicity of Buruli ulcer”. Available at https://www.who.int/data/gho/data/indicators/indicator-details/GHO/buruli-ulcer
    6. WHO. “Number of new reported cases of Buruli ulcer”. Available at https://www.who.int/data/gho/data/indicators/indicator-details/GHO/number-of-new-reported-cases-of-buruli-ulcer
    7. WHO, 2006. “Recognizing Buruli ulcer in your community”. Available at https://apps.who.int/iris/bitstream/handle/10665/69313/WHO_CDS_NTD_GBUI_2006.14_eng.pdf?sequence=1
    8. A road map for neglected tropical diseases 2021–2030 ”. Available at https://www.who.int/publications/i/item/9789240010352
    9. “Framework for the integrated control, elimination and eradication of tropical and vector-borne diseases in the African Region 2022–2030”. Available at https://apps.who.int/iris/bitstream/handle/10665/361856/AFR-RC72-7-eng.pdf?sequence=1&isAllowed=
    10. “Strategic framework for integrated control and management of skin-related neglected tropical diseases”. Available at https://www.who.int/publications/i/item/9789240051423  
    11. Framework for development country NTD master plan 2021 - 2025 ”. Available at https://espen.afro.who.int/system/files/content/resources/NTDMasterPlan_Guidelines_WHOAfrRegion_Version3_160321.pdf
    12. Laboratory diagnosis of Buruli ulcer ” . Available at https://espen.afro.who.int/system/files/content/resources/NTDMasterPlan_Guidelines_WHOAfrRegion_Version3_160321.pdf
    13. “Target product profile for a rapid test for diagnosis of Buruli ulcer at the primary health-care level”. Available at https://www.who.int/publications/i/item/9789240043251
    14. Treatment of Mycobacterium ulcerans disease (Buruli Ulcer) ” available at https://www.who.int/publications/i/item/9789241503402
    15. “Standard recording and reporting using BU 01, BU 02 and BU 03 forms”. Available at https://www.who.int/teams/control-of-neglected-tropical-diseases/buruli-ulcer/objective-and-strategy-for-control-and-research#Reportingandrecordingforms
    16. Fourth annual meeting of the network of Buruli ulcer PCR laboratories in the WHO African Region, Mundi complex, Yaoundé, 24-26 October 2022. Available at https://www.who.int/publications/i/item/9789240077911
    17. Other publications ”. Available at https://www.who.int/publications/i?healthtopics=46e0b136-0538-42f3-8761-190b7013265b&publishingoffices=ef806e9e-be4b-423a-91c9-9db2a8706e74&healthtopics-hidden=true&publishingoffices-hidden=true

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