Figure 2

Clinical algorithm for podoconiosis diagnosis. There is no point-of-care diagnostic tool for podoconiosis. Currently, podoconiosis is a diagnosis of clinical exclusion based on history, physical examination and certain disease-specific tests to exclude common differential diagnoses. All individuals included in the survey were tested for circulating W. bancrofti antigen using an ICT. Those found to be positive, regardless of the presence or absence of lymphoedema, were excluded from further clinical examination for podoconiosis. The common differential diagnoses of podoconiosis are lymphoedema due to LF, systemic disease and leprosya. The differentiation of podoconiosis from LF used a panel approach, including clinical history, physical examination, antigen and antibody tests. The swelling of podoconiosis starts in the foot and progresses upwards, whereas the swelling in LF starts elsewhere in the leg. Podoconiosis lymphoedema is asymmetric, usually confined to below the knees, and unlikely to involve the groin. In contrast, lymphoedema due to LF is commonly unilateral and extends above the knee, usually with groin involvement. In addition to the clinical history and physical examination, an antigen-based ICT was used to distinguish between the two causes of lymphoedema, although the majority of LF patients are also negative for the antigen-based test. To distinguish between podoconiosis and leprosy, clinical history and physical examination was used. Patients were asked if they had been diagnosed with leprosy and physical examination was conducted to exclude signs of leprosy including sensory loss. Onchocerciasis has clear clinical features which can easily be distinguished from podoconiosis. All lymphoedema cases were examined for signs of onchocerciasis. Systemic causes of lymphoedema were ruled out by examination of other organ systems. Hereditary causes of lymphoedema were excluded since they occur at birth or immediately after birth, whereas podoconiosis requires extended exposure to red clay soil.