Tungiasis in East-Africa - an interdisciplinary approach to understand the interactions between parasite and host - Project Phase II

• Applicant: Privatdozent Dr. Jürgen Krücken
• Subject Area: Parasitology and Biology of Tropical Infectious Disease Pathogens ; Clinical Infectiology and Tropical Medicine
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 405027164

Tungiasis is a zoonotic disease caused by female sand fleas (Tunga penetrans) penetrating the skin of their hosts causing severe inflammation. Resource-poor communities in East Africa are particularly affected. Current knowledge regarding flea ecology and impact of tungiasis on socio-economic parameters and child development is limited. We have shown that there is severe morbidity due to tungiasis that was even worse during school lock-downs due to COVID-19. Our inter-connected scientific objectives are (1) Investigating environmental and behavioural determinants for the heterogeneous distribution of tungiasis in space and time; (2) Investigate host-seeking behaviour of T. penetrans; (3) Assess risk factors of chronic disease; (4) Assess mechanisms of cognitive impacts; (5) Assess impact on animal production; (6) Assess effect of stress and exposure to insect growth regulators (IGRs) on gene expression in T penetrans. Based on recently developed methods to rear T. penetrans larvae to imagines under laboratory conditions, we will determine environmental parameters required for successful development and cues that attract adult fleas to their hosts. Seasonality will be investigated using cross sectional surveys, spatial mapping of flea distribution (in- and outdoor) and human behaviour in wet and dry seasons. Effects of tungiasis on child development and cognitive functions were detected in a previous cross-sectional study and will be confirmed using a longitudinal cohort study to analyse neurocognitive and neurophysiological parameters for attention and sleep disorders. Effects of disability on infection prevalence, intensity and morbidity observed in individual cases will be systematically evaluated in a cross-sectional study. We will quantify effects of tungiasis on pig health and weight gain and thus household economy and use interview data to determine effects on marketability of pigs. Neem and the IGR pyriproxifen were shown to disrupt larval development. The effects of environmental stress, pyriproxifen and neem on T. penetrans gene expression of larval and adult fleas will be investigated using RNA next-generation-sequencing. These activities together with capacity building approaches will strongly increase tungiasis-related knowledge in East Africa regarding flea ecology, physiology and developmental biology as well as impact on human wellbeing and psychological and economic development.

• DFG Programme: Research Grants
• International Connection: Kenya, Uganda
• International Co-Applicants: Professorin Dr. Amina Abubakar; Dr. Ulrike Fillinger; Dr. Francis Mutebi, Ph.D.