Ulrike Fillinger

Designing low-cost floors to control tungiasis

Principal Investigator

Ulrike Fillinger

International Centre of Insect Physiology and Ecology (icipe), Human Health Theme, Kenya

Co-investigators

  1. Steve Lindsay

    Department of Biosciences, Durham University, UK

  2. Lynne Elson

  3. Paul Mwitari*

  4. Menale Kassie

International Centre of Insect Physiology and Ecology (icipe), Human Health Theme, Kenya

*and Kenya Industrial Research and Development Institute (KIRDI)

Lay Summary

Sand flea disease (tungiasis), a highly neglected parasitic skin disease, inflicts pain and suffering on millions of people in Sub-Saharan Africa, and yet gets little attention from donors, scientists, governments and health workers. Tungiasis is caused by the penetration of the female sand flea, Tunga penetrans, into the skin, mostly the feet. The disease is affecting the poorest of the poor living in tropical and subtropical conditions, primarily children and elderly people that depend on others for care. Tungiasis is associated with a pattern of debilitating morbidity. Itching, pain, swelling, deep fissures, ulcers and abscess formation are symptoms of an acute inflammatory response to embedded fleas and bacterial superinfection of the lesions. Chronic infections result in chronic pain, disability, disfigurement and mutilation of the feet. Children with tungiasis are often ridiculed by their peers and it has been shown that both physical incapacity and mental strain and distress reduce school performance. There is currently no effective, widely available, safe and simple treatment for tungiasis. Instead affected individuals in their desperation remove the embedded fleas using unsterilized pins and thorns which carry huge risk of secondary infection with bacteria and viruses. In resource-poor communities without optimal medical care and limited ability to pay for expensive medications, prevention is the most valuable control measure. Recent surveys to identify key determinant of the disease including the social and economic environment, the physical environment, and the affected person’s individual characteristics and behaviours, illustrated that the disease risk is directly associated with lowest socio- economic status; namely poor housing, specifically the absence of a cemented floor, lack of hygiene in terms of regularly washing with soap, poor clothing including the absence of shoes. fleas depend for their development during the immature stages (the off-host stages) on loose, sandy soil. Soil sampling to identify the distribution of off-host stages has shown that infestation hotspots are people’s homes, specifically the bedrooms of children. Findings indicate that simple measures could be implemented to prevent the disease. However, in East Africa solid floors are normally created using layers of decreasing grades of ballast sealed with a top layer of concrete or tiling. These floors can cost a minimum of £5.6 /m2 in Kenya. The average house size for a typical family affected by tungiasis is approximately 24 m2, thus a total cost £134, well beyond the reach these families who survive on less than £0.7 a day. We propose to develop an affordable hardened floor that does not allow the off-host stages sand fleas to develop. Our approach is to experiment with combining traditional techniques (cow dung, mud soil mixing and smearing) and locally available materials (coral dust, diatomite, volcanic dust, slaked lime) with state the art soil stabilization technologies to develop a low-cost floor. The project will be conducted by engineers, entomologists, social economists and public health experts working closely together. First, the multidisciplinary team will work together to generate possible floor options. The engineers will then develop and test different floor technologies for durability and water permeability. Once test floors are ready for trial houses, the entomologists will monitor the floors for the off-host stages of sand fleas and the public health experts will monitor the house occupants for newly embedded fleas. The social economist will assess acceptability the new floors and work with the engineers on the costs the floor. Our hypothesis, is that once a family has a solid floor in their home, they will be at a hugely decreased risk infestation. If we can develop a low-cost flooring within reach most families and subsidized or micro-financed for those that cannot afford this, we will reduce the prevalence tungiasis and the suffering it causes. An added benefit these floors will be the increased level hygiene possible for the households, protecting them from other soil-transmitted parasites and bacteria.