Podoconiosis: Endemic Non-filarial Elephantiasis

Abstract

Podoconiosis is an endemic, non-filarial lymphoedema of the lower limb which needs to be differentiated from filarial elephantiasis, lymphoedema of systemic disease and leprotic lymphoedema. The disease (affecting genetically susceptible individuals who go barefoot) is linked to long-term exposure to red clay soil. Interactions between genetic and environmental factors trigger an inflammatory response that leads to lymphoedema and fibrosis. Patients with podoconiosis develop signs and symptoms in the second and third decades of life with the disease being common up to the sixth decade. The disease is bilateral but asymmetrical and almost always limited to below the knees. Globally, there are about four million people with podoconiosis, mainly in tropical Africa, central and South America and Southeast Asia. Tropical African countries bear the highest disease burden with about one million people living with podoconiosis in Ethiopia and a further 500,000 in Cameroon. The key strategies for podoconiosis control are prevention of contact with irritant soil (primary prevention) and lymphoedema morbidity management (secondary and tertiary prevention). The main challenge faced in podoconiosis is lack of awareness that the condition exists and that it is different from lymphatic filariasis and other main cause of lymphoedema in the tropics. This lack of awareness and diagnostic confusion with lymphatic filariasis has led to podoconiosis-affected communities being treated with DEC and albendazole. Research directed at the mapping of podoconiosis will have important consequences in planning the control and future elimination of the disease. Mapping of the disease burden of podoconiosis will help target resources, monitor control progress and advocate for investment in podoconiosis prevention, control and ultimately elimination. Mapping of disease must be accompanied by development of endemicity classifications and criteria for disease elimination before policies can be finalised. Controlling podoconiosis is achievable because no biological agent or vector involved in podoconiosis has been identified, the global scale of the problem is relatively small, the means for podoconiosis prevention and control are safe and additional strategies for prioritisation of resources such as the use of family health history and risk maps can be implemented.