Mapping of lymphatic filariasis and podoconiosis in Ethiopia

Kebede Deribe is a Wellcome Trust Research Training Fellow in Public Health and Tropical Medicine based in Addis Ababa, Ethiopia. Kebede is actively involved in the mapping of podoconiosis and lymphatic filariasis (LF) in Ethiopia, where he supervises field workers in three regions using smartphone technology for data collection, with guidance from the Task Force for Global Health. He writes for the GAHI blog recounting his experience in the field and the importance of integrating mapping of LF and podoconiosis. 

Ethiopia recently launched its National Master Plan (2013-2015) for Neglected Tropical Diseases under the theme, “End the neglect, integrate, scale up and sustain”. An essential prerequisite to achieving the goals of the plan is a clear understanding of the geographical distribution and burden of NTDs. This allows for targeting of priority areas and determining geographical overlaps among NTDs to enable integrated control.

In Ethiopia, podoconiosis and lymphatic filariasis (LF) are two of the eight NTDs prioritized within the Master Plan. There are two principal causes of elephantiasis, or lymphedema, in the tropics.

The most common cause and a significant public health problem is LF. The other main cause is podoconiosis: a form of elephantiasis arising in barefoot subsistence farmers who are in long-term contact with irritant red clay soil of volcanic origins. The disfigurement and disability associated with podoconiosis reduces productivity and results in stigma towards patients. According to a study in Ethiopia, the total direct costs of podoconiosis amounted to the equivalent of US$143 per patient per year and a productivity loss of 45% of total working days per year.

Through a programme of research initiated in 2003 by Dr. Gail Davey, podoconiosis is steadily gaining more attention nationally and globally. In February 2011, the World Health Organization (WHO) included podoconiosis in its list of neglected tropical diseases and in March 2012, the International Podoconiosis Initiative, also known as Footwork, was launched.

Podoconiosis is one of the NTDs with a clear potential for elimination: it is easily preventable if shoes are consistently worn and early stages can be successfully treated. While one million people are estimated to be affected in Ethiopia, control efforts are hampered by a lack of information on geographical distribution. Maps have long been crucial in the planning of disease control. They help in identifying those populations most at risk from NTDs, ensuring they receive treatment, and helping track progress in control.We have already worked to collate historical data on podoconiosis to help determine the environmental factors associated with the wide variation in the distribution of podoconiosis in Ethiopia.

Support for LF elimination in Ethiopia is provided through the Centre for Neglected Tropical Diseases (CNTD) in the Liverpool School of Tropical Medicine. CNTD has been working with the Ethiopian government since 2009 to implement mass drug administration and monitor progress towards LF elimination using funds from the UK Department for International Development (DfID).

Through collaborations between the Ethiopian Health and Nutrition Research Institute (EHNRI), Brighton and Sussex Medical School, the Center for Neglected Tropical Diseases (CNTD) and the Global Atlas of Helminth Infections  (GAHI) at the London School of Hygiene & Tropical Medicine, and supported by DfID, End Fund, and the Wellcome Trust through my Research Training Fellowship in Public Health and Tropical Medicine, we are conducting integrated mapping of LF and podoconiosis in Ethiopia. We are working in 1,384 communities in 692 districts, covering more than 130,000 individuals. Integrated mapping is crucial because the two diseases are identified as priority NTDs in Ethiopia, have similar clinical features, occur in the same target age group (individuals >15 years old) and diagnosis of one requires exclusion of the other. Preliminary analysis of existing data on LF and podoconiosis indicated that there are potential overlaps of the two diseases in some geographical areas.

In June 2013, 136 health providers, including health officers, nurses and laboratory technicians, received four days of training on data collection and diagnostic tools in Debrezeit Management Institute. The training was opened by Dr. Gail Davey from Sussex, Dr. Maria Rebollo from CNTD and Mr Ashenafi Assefa from EHNRI. On the first day, participants were taught the basic background on the two diseases, the objectives of the survey and the study methods.  On subsequent days, training focused on the immunochromatography test (ICT), physical examination, differential diagnosis, disease staging, sample collection, using smartphones for data collection and citing coordinates using smartphones. On the third and fourth days, the participants split up into 34 teams of 4 and conducted pilot mapping in nearby villages. The training was closed by Dr. Amaha Kebede, EHNRI director, and Mr. Oumer Shafi, Ethiopian National Coordinator of NTDs, who emphasized data quality. To collect data we are using electronic data collection to overcome the challenges posed by paper-based surveys. Devices such as mobile phones, using short message service (SMS), have been effectively used for disease surveillance and health information management. Building on these experiences and with the help of Task Force for Global Health, we have adopted smartphones for data collection. These devices offer the additional advantage of having built-in global positioning systems (GPS) to automatically capture geographic coordinates.

The integrated mapping is currently underway with commendable momentum. Nonetheless it is not without challenges; first, accessing some of the districts during the rainy season is difficult; second, attrition of data collectors is an ongoing challenge. However, the well-structured health system, the EHNRI-Ministry of Health’s leadership and increased mobile phone coverage have all contributed to the success of the mapping.

In addition to the mapping of these two diseases in the country, we will work with epidemiologists at the Global Atlas of Helminth Infections to identify the environmental limits of podoconiosis, develop a spatial risk map and determine an optimal mapping approach to estimate the disease burden of podoconiosis in other countries suspected to be endemic.

We would like to thank all our partners involved in the work through funding, technical support and fruitful partnership. We would also like to request continued support from partners for completion of the mapping and achieving our shared goal of an Ethiopia free of NTDs.

Relevant publications

1. Deribe K, Brooker SJ, Pullan RL, Hailu A, Enquselassie F, Reithinger R, Newport M & Davey G (2013). Spatial distribution of podoconiosis in relation to environmental factors in Ethiopia: a historical review. PLoS ONE 8, e68330.
2. Deribe K, Meribo K, Gebre T, Hailu A, Ali A, Aseffa A, Davey G(2012). The burden of neglected tropical diseases in Ethiopia, and opportunities for integrated control and elimination. Parasit Vectors 5:240.
3. Tekola F, Mariam DH, Davey G (2006). Economic costs of endemic non-filarial elephantiasis in Wolaita Zone, Ethiopia.Trop Med Int Health 11(7):1136-44.
4. Davey G, Tekola F, Newport MJ 2007. Podoconiosis: non-infectious geochemical elephantiasis. Trans R Soc Trop Med Hyg 101(12):1175-80.
5. Shiferaw W, Kebede T, Graves PM, Golasa L, Gebre T, Mosher AW, Tadesse A, Sime H, Lambiyo T, Panicker KN, Richards FO, Hailu A (2012). Lymphatic filariasis in western Ethiopia with special emphasis on prevalence of Wuchereria bancrofti antigenaemia in and around onchocerciasis endemic areas. Trans R Soc Trop Med Hyg 106 (2):117-27.