PODOCONIOSIS: BAREFOOT IN ETHIOPIA

Podoconiosis (non-filarial elephantiasis) is a non-communicable, yet entirely preventable disease that is endemic in tropical regions¹. It is a chronic, debilitating disorder that occurs after prolonged barefoot exposure to irritant red clay soils derived from volcanic deposits². Podoconiosis affects some of the world’s poorest populations, its occurrence contributes to economic burden³ and social stigmatisation, and the World Health Organisation recently designated it as a Neglected Tropical Disease.

Podoconiosis is highly prevalent in Ethiopia where it is known to affect up to 1 million people. Our multidisciplinary research team visited the East Gojjam zone, on the Ethiopia plateau, where prevalence estimates have determined high rates of podoconiosis occurrence. Sampling traverses were selected according to both disease distribution and known geological variation, soil (surface) samples and vertical profiles were taken at predetermined intervals governed by altitude and distance. The samples have been fully characterized, to determine their mineralogy, including minor and major elemental composition, crystalline and amorphous components and particle size, to quantify the extent of soil weathering and identify a geological signature that may be typical in the soils where disease is endemic. The samples have been tested in vitro using the preliminary screening assays to indicate potential toxicity.

Our research indicates that clay minerals could play an important role in disease initiation, and our preliminary studies have already challenged the few pre-existing hypotheses regarding podoconiosis etiology. Further analysis of the finer fractions within the soil samples is in progress, including full characterization of the nanoparticles (<100 nm) and targeted cellular toxicity testing, to better understand the processes that could occur once the soil enters into the human body. Our continued study of the geological and environmental characteristics, combined with parallel studies into the genetic susceptibility⁴, will increase both awareness of the disease and the likelihood of prevention.

¹Davey G. Lancet 2007; 369:888-9.

²Price EW. T Roy Soc Trop Med H, 1976; 70:288-95.

³Tekola F et al. Trop Med Int Health, 2006; 11:1136-44.

⁴Tekola Ayele F et al. New Engl J Med, 2012; 366:1200-1208.