Podoconiosis
Podoconiosis, also known as nonfilarial elephantiasis, is a disease of the lymphatic vessels of the lower extremities that is caused by chronic exposure to irritant soils. It is the second most common cause of tropical lymphedema after lymphatic filariasis, and it is characterized by prominent swelling of the lower extremities, which leads to disfigurement and disability. Methods of prevention include wearing shoes and using floor coverings. Mainstays of treatment include daily foot hygiene, compression bandaging, and when warranted, surgery of overlying nodules.
Signs and symptoms
Podoconiosis causes bilateral yet asymmetrical leg swelling with overlying firm nodules. Early on, symptoms may include itching, tingling, widening of the forefoot, and swelling which then progress to soft edema, skin fibrosis, papillomatosis, and nodule formation resembling moss, giving rise to the disease's alternate name of "mossy foot" in some regions of the world. As with other forms of tropical lymphedema, chronic disease can lead to rigid toes, ulceration, and bacterial superinfection. During acute episodes of adenolymphangitis, patients may develop fevers, extremity warmth, redness, and pain. These episodes are extremely debilitating and account for many days of activity and productivity loss each year.Psychological consequences
As a result of its appearance, podoconiosis can cause social stigmatization and discrimination. People with podoconiosis also report a lower quality of life than people in similar neighborhood circumstances except without podoconiosis and also higher levels of mental distress and depression.Pathophysiology
According to the World Health Organization "Evidence suggests that podoconiosis is the result of a genetically determined abnormal inflammatory reaction to mineral particles in irritant red clay soils derived from volcanic deposits".The pathophysiology of podoconiosis is a combination of genetic susceptibility, possibly through associations with HLA-DQA1, HLA-DQB1, and HLA-DRB1 variants, and a cumulative exposure to irritant soil. In susceptible individuals, irritant soil particles penetrate the feet and collect in lymphatic vessels. Over time, chronic inflammation within the lymphatic vessels leads to fibrosis and occlusion.
Diagnosis
Differential diagnosis
The differential diagnosis for podoconiosis includes other causes of tropical lymphedema, such as filariasis or leprosy, and mycetoma pedis.While filariasis is generally unilateral, podoconiosis affects the legs bilaterally albeit asymmetrically and in an ascending manner. Podoconiosis very rarely affects the groin while filariasis frequently involves the groin: a high ratio of lymphoedema/hydrocele cases in an area suggests podoconiosis as the dominant cause of lymphedema. In some cases, the history and clinical presentation alone cannot differentiate between the two causes of tropical lymphedema. Local epidemiology can also be a clue to diagnosis, as podoconiosis is typically found in higher altitude areas with volcanic soils while filariasis is common in low-lying areas where mosquitos are prevalent. Blood smears for identification of microfilariae and antigen detection techniques can be helpful in the diagnosis of lymphatic filariasis.
Lepromatous lymphedema can also mimic podoconiosis clinically, but the former will have a loss of sensation in the toes and feet, thickened nerves, and trophic ulcers. Other causes of lymphedema include Kaposi sarcoma, mycetoma, and elephantiasis nostras verrucosa.
Prevention
Elimination of podoconiosis relies on prevention with widespread shoe implementation, stringent foot hygiene, and floor coverings. Community-based initiatives are crucial to achieving the elimination of this disease. In Ethiopia, The Mossy Foot Treatment and Prevention Association works to transform patients into community podoconiosis agents who in turn visit patients, teach basic treatment techniques such as foot hygiene, and educate families about the disease. This model has been adapted by several other non-government groups as they have started programs in other regions of Ethiopia.In 2011, podoconiosis was added to the World Health Organization's neglected tropical diseases list, which was an important milestone in raising global awareness of the condition.
The efforts of the Global Programme to Eliminate LF are estimated to have prevented 6.6 million new filariasis cases from developing in children between 2000 and 2007, and to have stopped the progression of the disease in another 9.5 million people who had already contracted it. Dr. Mwele Malecela, who chairs the programme, said: "We are on track to accomplish our goal of elimination by 2020." In 2010, the World Health Organization published a detailed progress report on the elimination campaign in which they assert that of the 81 countries with endemic LF, 53 have implemented mass drug administration, and 37 have completed five or more rounds in some areas, though urban areas remain problematic.
Treatment
The cornerstone of the prevention and treatment of podoconiosis is avoidance of exposure to irritant soils. Wearing shoes in the presence of irritant soils is the primary method of exposure reduction. In Rwanda, a country of high disease prevalence, the government has banned walking barefoot in public, to prevent podoconiosis and other soil-borne diseases. Increasing the availability of footwear must be coupled with education on the benefits of wearing shoes as cultural influences, such as barefoot traditions, can hinder widespread use of footwear.Once the disease has developed, rigorous foot hygiene including daily washing with soap and water, application of an emollient, and nightly elevation of the affected extremity has been shown to reduce the frequency of acute attacks. Nodules will not resolve with these conservative measures, although surgical removal of the nodules can be performed.