What are the causes of lymphedema in the Pacific region?

From the Guidelines

Lymphedema in the Pacific region is primarily caused by lymphatic filariasis, a parasitic infection transmitted by mosquitoes carrying Wuchereria bancrofti, Brugia malayi, or Brugia timori worms, as stated in the most recent study 1. The Pacific Islands have historically had high prevalence rates due to favorable mosquito breeding conditions in tropical climates, limited healthcare infrastructure, and challenges in implementing preventive measures. Some key points to consider:

• The mode of transmission is through the bite of mosquitoes, including Aedes spp., Anopheles spp. and Culex, as noted in 1.
• Clinical presentation includes acute fever and localized skin inflammation with lymphadenitis and lymphangitis, followed by chronic lymphoedema, as described in 1.
• Secondary causes of lymphedema in the region include cancer treatments, particularly following breast cancer surgery with lymph node removal, trauma, obesity, and venous insufficiency, as discussed in 1 and 1.
• Environmental factors specific to the region, such as limited access to healthcare in remote island communities, delayed diagnosis, and inadequate treatment options, exacerbate the problem.
• Prevention focuses on mass drug administration programs using combinations of diethylcarbamazine, albendazole, and ivermectin to kill microfilariae, along with vector control through insecticide-treated bed nets and environmental management to reduce mosquito breeding sites, as recommended in 1.
• Early detection and management are essential to prevent progression to advanced stages characterized by skin thickening, recurrent infections, and disability. It is also worth noting that:
• Obesity is a risk factor for lymphedema, and weight loss is recommended for those who are overweight or obese, as stated in 1.
• Physical activity, such as supervised, slowly progressive resistance training, may reduce the likelihood of arm swelling among breast cancer survivors at high risk for lymphedema, as noted in 1.

From the Research

Causes of Lymphedema in the Pacific Region

• Lymphatic filariasis, transmitted by mosquitoes, is the commonest cause of lymphedema in endemic countries, including those in the Pacific region 2, 3.
• The disease is caused by thread-like nematode worms, including Wuchereria bancrofti, Brugia malayi, and Brugia timori, which reside in the lymphatics and lymph nodes and induce changes that result in dilatation of lymphatics and thickening of the lymphatic vessel walls 4.
• The infection can lead to lymphedema, elephantiasis, and other pathological conditions, with an estimated 67.88 million cases worldwide, including 16.68 million lymphedema cases 4.
• Bacterial infections, mainly streptococci, can also contribute to the development of lymphedema by causing recurrent acute attacks of dermato-lymphangio-adenitis in the affected limbs 2.
• Other factors, such as poor hygiene and skin conditions like interdigital fungal infections, injuries, and eczema, can also increase the risk of developing lymphedema 2.

Prevalence and Distribution

• Lymphatic filariasis is found in underdeveloped regions of the Pacific, as well as in South America, Central Africa, and the Caribbean 3.
• The disease has been estimated to affect 120 million people worldwide, with a significant proportion of cases found in the Pacific region 2, 3.
• The World Health Organization has implemented mass drug administration programs to control the spread of the disease, but continued research on new drugs and vaccinations is needed to reduce microfilarial levels in the human population 5.