Dr Peter Keiyoro (University of Nairobi, Kenya) & Dr Josephine Ngunjiri (University of Embu, Ken

Dr Peter Keiyoro (University of Nairobi, Kenya)

Dr. Josephine Ngunjiri ( University of Embu, Kenya)

Interview by Marianne Comparet & Kamran Rafiq (ISNTD)

Tungiasis is a debilitating parasitic disease caused by the flea Tunga penetrans burrowing into skin, affecting poor communities in Africa and Latin America disproportionately. Secondary infections from tungiasis lesions can lead to severe bacteremia, tetanus and gangrene, with significant implications in terms of disability. Despite prevalence reaching up to 50% in certain communities, tungiasis is often overlooked as a severe public health concern, even among healthcare staff. In this interview, the ISNTD speaks to Dr. Peter Keiyoro and Dr. Josephine Ngunjiri, from the Universities of Nairobi and Embu in Kenya, who have been working tirelessly in the field to quantify the burden of this disease in Kenya, train healthcare staff to recognise and address this disease appropriately and raise awareness and advocacy globally for this extremely neglected disease.

It's a great pleasure to meet you and welcome you to the ISNTD. Could you give us a brief overview of your training, background and current research?

I am Dr. Peter Keiyoro, currently based at the University of Nairobi, Kenya. I have training in biological sciences, having specialized in zoology and science education. I have a background in teaching biological sciences and research in neglected tropical diseases, with a strong focus on the impact of tungiasis on school age children.

I entered the field of public health when I developed curricular materials for healthcare providers in Kenya pursuing the Postgraduate Diploma in the Management of Sexually Transmitted Infections (including HIV-AIDS) at The University of Nairobi. In more recent times, I have also attended a short training course on Health Metrics and Evaluation in Global Burden of Disease offered by the Institute of Health Metric and Evaluation (IHME) of Washington University, USA, under the guidance of Prof Christopher Murray. This has allowed me to be an active collaborator in data collection and analysis in the Global Burden of Disease and I have also contributed extensively in several publications (NACET) in this field as well as co-published my work in tungiasis.

My recent research focuses on the highly neglected disease: tungiasis. My personal experience as a tungiasis casualty during my childhood and studies about the impact of tungiasis on school age children in Kenya since 2009 has given me great impetus to continue engaging in research projects related to the burden of disease caused by tungiasis. Our first project focused on the health status among ageing populations affected with tungiasis and on soil factors influencing the prevalence of tungiasis in endemic areas.

The second project was geared towards comorbidities related to tungiasis among the infected children aged 5-14 years.The third project will focus on mapping the disease including investigating the burden of the disease, prevalence and incidences in specific areas in Kenya, sub-Saharan Africa and on a global level.

Dr. Josephine Ngunjiri is a co-principal researcher in the above projects. She is trained in both Science Education as well as Applied Parasitology and Tropical and Infectious Diseases from the University of Nairobi. She has also attended the short training on Health Metrics in Global Burden of Disease offered by Institute of Health Metrics and Evaluation of Washington University. Hence she is an active collaborator in data collection on the Global Burden of Disease and has also contributed extensively in several publications in this area as well as in her work in tungiasis.

What is the prevalence of tungiasis worldwide? What are the hot spots, both in terms of countries/regions, but also populations at risk?

Tungiasis mostly occurs in Latin America, the Caribbean and sub-Saharan Africa where it mainly affects the low income communities. In Kenya for example, although mapping of this disease has not been done, it is known to be prevalent in Murang’a, Nyeri, Kwale, Malindi, Kericho, Narok, Emuhaya, Meru and Kakamega counties where it is widespread among resource-poor communities. It has been estimated that 2.7 million people are at risk of being infected with tungiasis in these stable endemic foci in the affected counties in Kenya. Previous studies also indicated that tungiasis had an age-specific peak with the highest prevalence being among the school age children aged 5-15 years and the elderly.

The presence of tungiasis in Africa can be traced back to the 17th century during which T. penetrans is postulated to have been introduced to West Africa from South America. In 1872, ships carrying infested ballast sand from Brazil arrived in Angola where the disease caused severe morbidity and was described as second cause of mortality after small pox in the 19th century. The disease is also thought to have spread in Sub-Saharan Africa through trade and military routes reaching Kenya, Zanzibar and Madagascar.

In other areas in Africa, for example in Western Nigeria, the prevalence of tungiasis among the school age children was as high as 50% in endemic areas in the 21st century. In Kenya, in the years 2008-2009, the ministry of public health fumigated 285,815 jigger flea-infested households and has raised this target to 573,026 households in the year 2009-2010. In the past it has been indicated that tungiasis related complications had caused more than 275 deaths in a few years in Kenya.

What is the long-term burden? What are some of the major coinfections/comorbidities?

We are currently mostly focusing on these two geographic areas since we have only just carried the first study on the disease burden, using a universal metric that can compare the tungiasis burden and the burden from other diseases and causes of loss of health.

The long term burden is evaluated both in terms of loss of health as well as inequality in accessing education. Mild tungiasis caused 0.3 Disability Adjusted Life Years (DALYs) in all the children, which is equivalent to 0.3 Years of Life Lost (YLL) due to premature death. A total of 2.51 DALYs were lost due to severe tungiasis with male children and children aged 5-9 years bearing the highest burden. Therefore, based on our research, severe tungiasis may cause a loss of 2.51 DALYs.

What has been the focus of your research specifically?

The main focus of our studies has been on the factors promoting the prevalence of tungiasis, and the quantification of loss of health using Disability Adjusted Life Years (DALYs) metrics. We have confined our research for now on the Impact of the disease among children aged 5-14 years and aging populations.

What are currently the processes to diagnose tungiasis? What are the gaps in tungiasis diagnostics and which developments would you like to see in this space?

Tungiasis related symptoms include open wounds (lesions), pain, lethargy, itching, insomnia, difficulty in grasping, and difficulty in walking. The magnitude of these symptoms differs with the severity of the disease.

Diagnosis is confirmed via macroscopic examination. The disease is confirmed by the presence of the embedded female Tunga penetrans which is often at various stages of development (Eisele et al., 2003). There are five stages of development: stage 1-penetrating T. penetrans; stage 2-Red brown itching spot; stage 3-white area with central black area; stage 4-black lesion with T. penetrans dying and stage 5-manipulated lesion.

The diagnosis process is labour-intensive and there is a perception even among health providers that it is not a disease in its own right. This complicates the process of diagnosis and hence the management of the disease. There is a distinct lack of expertise and knowledge about tungiasis, even among healthcare staff. There is a need to train community health workers and health providers to enhance their recognition of tungiasis and there also needs a broader effort to push for its classification as a neglected disease.