Victoria has faced an ongoing Buruli ulcer outbreak for years, with 347 cases confirmed in 2024 alone.
A flesh-eating bug has become ‘endemic’ in one coastal town with fears growing that it will spread to Sydney. Concerns are rising that a flesh-eating ulcer could spread along the New South Wales coast to Sydney, following the identification of two linked cases in a popular holiday destination. Experts now warn that Batemans Bay has become an endemic hotspot for the Buruli ulcer, after genetic testing confirmed a connection between these recent cases and an earlier infection in another New South Wales town.
Until now, New South Wales has remained largely unaffected by the Buruli ulcer, but this could be changing. Infectious disease experts suspect that the flesh-eating bacteria may have been transmitted from possums to humans, similar to the situation in Victoria.
The bacteria has an incubation period of about five months, meaning it can take a long time for patients to show symptoms. Once they do, the ulcers release a toxin that eats away at flesh, leaving behind a painful, open wound.
In 2023, two cases were reported in Batemans Bay: a 94-year-old man developed an ulcer on his finger, while a 71-year-old man had an ulcer on his arm, according to the Sydney Morning Herald.
The Buruli Ulcer: Transmission by Mosquitoes
The Buruli ulcer, a neglected tropical disease, is a chronic, necrotizing skin infection caused by Mycobacterium ulcerans, a bacterium closely related to the pathogens that cause tuberculosis and leprosy. Characterized by large, open ulcers on the skin, Buruli ulcer primarily affects the skin and soft tissue, leading to extensive tissue damage and potentially severe disability if left untreated. Although the disease has historically been a major concern in several African countries, it is now recognized in other regions, including parts of Asia, the Pacific Islands, and even Australia.
One of the most important aspects of Buruli ulcer is its mode of transmission. While the exact mechanism is still not fully understood, emerging research points to mosquitoes as one of the primary vectors for the disease. This article explores how mosquitoes play a role in the transmission of Buruli ulcer, the symptoms and progression of the disease, and current efforts to prevent and treat it.
What is Buruli Ulcer?
Buruli ulcer is a severe, often disfiguring infection that starts as painless lumps or nodules in the skin, which can later evolve into large, open ulcers with necrotizing tissue. The disease is caused by the bacterium Mycobacterium ulcerans, which produces a toxin known as mycolactone. This toxin causes skin and soft tissue damage, leading to ulcers and significant disability in affected individuals. The disease is commonly seen in children and young adults, especially in rural areas of endemic countries.
Buruli ulcer can affect any part of the body but most often manifests in the limbs, where it can cause deformities and, in severe cases, loss of function in the affected body part. If not treated promptly, the disease can lead to permanent disability or even death.
Understanding the Transmission of Buruli Ulcer
The exact transmission route of Mycobacterium ulcerans remains a subject of ongoing research. For years, the mechanism of transmission was unclear, leading to a significant gap in our understanding of how the disease spreads. Traditionally, it was thought that Buruli ulcer might be transmitted through direct contact with contaminated water or soil, or via the bite of certain animals. However, recent studies have shifted the focus towards mosquitoes as a significant vector in the spread of the disease.
Mosquitoes, particularly those in the genera Culex and Anopheles, are now believed to play a crucial role in the transmission of Buruli ulcer. The bacterium Mycobacterium ulcerans is often found in aquatic environments, particularly in slow-moving or stagnant waters where mosquitoes breed. These waters may contain infected animals or contaminated organic matter, which provide a breeding ground for both mosquitoes and the bacterium. When a mosquito feeds on an infected animal, such as a frog, fish, or bird, it can ingest M. ulcerans bacteria, which then survive and potentially multiply in the mosquito’s system.
Subsequently, when the mosquito bites a human to feed on blood, it may transfer the bacteria into the skin through its saliva, infecting the individual and causing the characteristic lesions of Buruli ulcer. This route of transmission offers a plausible explanation for why the disease is often found in rural, swampy, and wetland areas where mosquitoes thrive.
The Role of Mosquitoes in the Spread of Buruli Ulcer
Recent studies and field research have shown strong evidence supporting mosquitoes as key vectors in the spread of Buruli ulcer. Researchers have found a correlation between areas with high mosquito populations and higher incidences of Buruli ulcer. Furthermore, certain types of mosquitoes have been identified as having the ability to carry the bacteria and transmit it through their bites.
The Culex mosquito, in particular, has been noted as a common vector in the transmission of various tropical diseases, including Buruli ulcer. This species is known to breed in stagnant water and often feeds on humans and other animals, making it a suitable candidate for spreading the bacteria.
The Symptoms and Progression of Buruli Ulcer
The symptoms of Buruli ulcer can vary, but the disease typically progresses in several stages. It often starts with the appearance of small, painless nodules or lumps on the skin. These may gradually enlarge, and the surrounding skin may become discolored or swollen. As the disease advances, the infected area can develop into a large ulcer with extensive tissue necrosis.
In many cases, the ulcers are painless at first, but they can become increasingly painful and debilitating as the infection spreads. The disease can lead to scarring, joint deformities, and loss of function, particularly if the infection affects the limbs. Without prompt medical treatment, the ulcer may continue to expand, resulting in severe disfigurement and permanent disability.
Diagnosis and Treatment of Buruli Ulcer
Early detection and treatment are critical in preventing the spread and progression of Buruli ulcer. The diagnosis is typically made based on clinical symptoms, patient history, and laboratory tests, including bacterial cultures and PCR testing. In many cases, the disease is mistaken for other skin conditions, which is why prompt and accurate diagnosis is essential.
Buruli ulcer is treated with antibiotics, particularly rifampicin and streptomycin, which are effective in killing Mycobacterium ulcerans. In more severe cases, surgery may be necessary to remove necrotic tissue and promote healing. Early treatment can often prevent significant scarring and disability, but delayed treatment may lead to permanent deformities.
Prevention of Buruli Ulcer: The Role of Mosquito Control
Given that mosquitoes are now recognized as a major vector for the transmission of Buruli ulcer, controlling mosquito populations is an essential part of preventing the disease. Mosquito control programs that focus on eliminating breeding grounds, such as stagnant water sources, and using insecticides to reduce mosquito numbers, have proven effective in other vector-borne diseases like malaria and dengue.
In addition to mosquito control, public health initiatives should focus on educating communities in endemic areas about the risks of mosquito-borne diseases and the importance of taking precautions. This includes using insect repellent, wearing long-sleeved clothing, and sleeping under mosquito nets. Furthermore, efforts to improve sanitation and reduce exposure to contaminated water sources are essential in preventing Buruli ulcer and other mosquito-borne illnesses.
The Way Forward: Research and Collaboration
While significant progress has been made in understanding the transmission of Buruli ulcer, further research is needed to fully unravel the complexities of how Mycobacterium ulcerans spreads and to develop more effective prevention and treatment strategies. Collaborative efforts between international health organizations, local governments, and researchers will be essential in tackling the disease and reducing its impact on affected communities.
In addition to mosquito control, future research may explore the potential for vaccines, improved diagnostic methods, and better treatment protocols to address Buruli ulcer more effectively. Moreover, a deeper understanding of the ecological factors that contribute to the presence of Mycobacterium ulcerans in the environment will be critical in reducing transmission risks.
Conclusion
The Buruli ulcer remains a significant public health challenge in many tropical and subtropical regions of the world. Although the disease has long been associated with water contamination and animal interactions, recent evidence strongly suggests that mosquitoes play a key role in its transmission. By targeting mosquito populations and raising awareness about the disease, it is possible to reduce the burden of Buruli ulcer in affected communities.
Continued research into the role of mosquitoes and other environmental factors in the spread of Mycobacterium ulcerans will be critical to understanding the disease and developing more effective prevention strategies. With concerted efforts, Buruli ulcer can become a disease of the past, allowing affected individuals to live healthier, more productive lives free from the burden of this debilitating illness.
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https://www.news.com.au/lifestyle/health/fears-flesheating-bug-will-spread-to-sydney-after-becoming-endemic-in-batemans-bay/news-story/97de9c5a131d50eab2d362481ed18f13