Lynne Elson: Tungiasis, a neglected tropical skin disease
Tungiasis is a neglected tropical skin disease caused by the sand flea Tunga penetrans which burrows into the skin. Limited clinical trials have shown that neem and coconut oils cause the fleas to age prematurely, and that silicon-based oils can kill the fleas effectively. More research is needed to develop interventions to control and treat the disease.
My name is Lynne Elson, I am a research fellow with Oxford University and KEMRI Wellcome Trust in Kenya. I work on tungiasis which is a neglected tropical skin disease caused by a sand flea which is known scientifically as Tunga penetrans. The adult female burrows into the skin, mostly of people’s feet but also their hands. It affects mostly children of school age, the elderly and disabled people. It is found very widely throughout Sub-Saharan Africa as well as Central and South America.
There has been some research on looking at how we can prevent the disease, although there have not been any formal systematic studies done. But we think that we can prevent it by sealing the floors, because mostly it is people who live in a house that does not have a hard floor. Many people in Africa and South America live on the floor that is just soil, and the fleas develop within that soil. We think we can prevent it by trying to help people to have a hard floor, but also by assisting people to wash their feet every day with soap. Many of these communities lack access to water and soap, or as you see these people who are disabled or elderly, they cannot do that themselves. And so, they need people to help them.
For treatment, there is no well-known or well effective treatment available in these communities. And in their desperation, people would cut the fleas out of their feet, using non-sterile instruments like thorns which they just pull off bushes, and of course that causes more problems and more pain for them. In Kenya there is a product which is being used widely; it is a disinfectant, potassium permanganate which is actually a hazardous chemical. It causes a lot of irritation and pain when the children are being treated. And in fact, there has been one clinical trial using it for tungiasis and it only killed about 40% of the fleas. So, there is still no good treatment available.
Last year, I was working on a clinical trial myself, which was using a herbal medicine that I found being used very successfully in a community of people living along the coast in Kenya. The products are mostly using neem and coconut oils, both of which come from trees which grow widely along the coast of Kenya. In that study, we found that although within the one-week trial period it did not kill any more fleas than the potassium permanganate, it actually caused the fleas to rapidly age. We saw a change in their development. We feel that had the study been able to go on for a little bit longer, we would have seen all of those fleas were dead and the products would look much better than the potassium permanganate. But even as it is, it improved pathology and it caused a reduction in pain that the children were feeling. We feel it is a much better product, people can use it themselves. Because it is not toxic, we can give it to families and they can keep using it regularly, whenever they get re-infected.
There are very few people working on tungiasis, it is a very neglected tropical disease and less than 20 people probably work on the disease. Within the last five to ten years, there has only been a few small studies. I think the most important study that has been done, with a couple of clinical trials, is actually based using a silicon oil, there is a product which is sold in the developed world for treating headlice, which is based on silicon oil. It’s called nyda, and that product has been shown in these two trials to be very effective to kill the fleas. We are very excited about that as well, and it has been pursued with the manufacturers to get registered in endemic countries now and then to build up into a very large-scale trial.
This is a very important disease because it causes so much pain and suffering for the people who are affected, and there are very many people infected. Within Kenya alone, the government estimates that there are 2 million people with tungiasis at the moment. But there are still such gaps in the knowledge of what we know about the disease and how to control it. We need funding to be able to do large-scale surveys to map it and find out how many people are affected, where they live and why some people in one village compared to the next-door village have jiggers while others do not. And also, to find out what are the conditions which enable those fleas to develop within the soil.
The research that I do is very applied, it is all targeted on developing and understanding the ways to control the disease and developing interventions to control it. We work very closely with communities right from the start, and we are working with the policy makers so that as we design our studies, they can be very quickly translated into policy to control the disease at the national level.
This interview was recorded in September 2019