Podoconiosis

Worldwide, 4 million people are living with podoconiosis (Wanji S et al 2021).

Prevalence. Tropical Africa, Central America, Northwest India (Ethiopia, Cameroon, Rwanda, Burundi, Uganda, Tanzania, Kenya, Sudan, Islands of Cape Verde, Bioko, Sao Tome, Principe). A high prevalence is observed among the rural population of the affected regions (in Ethiopia: 6% of the rural population).

Unknown; a genetic disposition is suspected; various risk factors such as contact with volcanic red clay soil, high altitude (above 1000 m), high seasonal precipitation (above 1000 mm/year), and occupation (e.g., farmers) are associated with the risk of podoconiosis. A chronic foreign body reaction is discussed due to silicate particles that penetrate the skin from the soil, are taken up by macrophages and transported away via the lymphatic system. Chronic (foreign body-induced?) lymphangitis and lymphadenitis lead to a progressive obliteration of the lymphatic drainage pathways and consequently to chronic, initially intermittent and later persistent lymphedema. On the basis of the chronic lymphedema, the different degrees of severity of papillomatosis cutis lymphostatica develop (in untreated patients).

In the initial phase of the disease, there is usually a unilateral, uncharacteristic prodromal stage with interdigital itching and pain and mild swelling of the dorsum of the feet. No fever. Moderately painful regional (inguinal lymph node) lymphadenitis. Recurrent only mildly symptomatic intial phase with soft lymphedema, is followed by persistent, increasingly fibrotic, "hard" lymphedema of the foot(s) and lower leg(s). Gradual development of papillomatosis cutis lymphostatica with formation of a planar papillomatosis of the skin described initially as "moss-like" and later as verrucous. Persistence of the podoconiosis for decades leads to first solitary later confluent fibrotic nodules, later to mutilations of one or both legs, walking disabilities with deleterious socio-economic consequences.

Lymphedema caused by filariae species (see filariasis, lymphatic).

Congenital lymphedema

Acquired lymphedema following recurrent erysipelas (see below Lymphedema). See also Papillomatosis cutis lymphostatica.

In 2011 Podoconiosis was recognized as a neglected tropical disease by the WHO.

1. Davey G et al (2007) Podoconiosis: non-infectious geochemical elephantiasis. Trans R Soc Trop Med Hyg 101:1175-1180.

2. de Godoy JM et al (2012) Control of lymphorrhea and treatment of warty excrescences in elephantiasis. Case Rep Dermatol Med PubMed Central PMCID: PMC3505637.

3. Enbiale W et al (2022) Podoconiosis: clinical spectrum and microscopic presentations. PLoS Negl Trop Dis 16: e0010057.

4. Ferguson JS et al. (2o13) Assessment of skin barrier function in podoconiosis: measurement of stratum corneum hydration and transepidermal water loss. Br J Dermatol 168:550-554.
5. Földi, E (1985) Conservative treatment of lymphoedema of the limbs." Angiology 36: 171-180
6. Molyneux, D (2012) Tropical lymphedema control and prevention. N Engl J Med 366:1169-1171
7. Price, E. W (1972) A possible genetic factor in non-filarial elephantiasis of the lower legs." Ethiopian medical journal 10: 87
8. Price, E. W (1975) The mechanism of lymphatic obstruction in endemic elephantiasis of the lower legs. Transactions of the Royal Society of Tropical Medicine and Hygiene 69: 177-181.
9. Price, E. W. et al. (1978) The elemental content of lymphatic tissues of barefooted people in Ethiopia, with reference to endemic elephantiasis of the lower legs." Transactions of the Royal Society of Tropical Medicine and Hygiene 72: 132-136.
10. Taye B et al (2013) Podoconiosis and Soil-Transmitted Helminths (STHs): Double Burden of Neglected Tropical Diseases in Wolaita Zone, Rural Southern Ethiopia. PLoS Negl Trop Dis PubMed Central PMCID: PMC3597475.

11. Wanji S et al (2021) Podoconiosis - From known to unknown: obstacles to tackle. Acta Trop. 2021 Jul;219:105918.