Assessing the effect of neglected tropical diseases on Plasmodium falciparum transmission in an area of co-endemicity

• Applicant: Professor Dr. Peter Gottfried Kremsner, since 12/2020
• Subject Area: Parasitology and Biology of Tropical Infectious Disease Pathogens ; Immunology
• Term: from 2015 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 271597907

In areas of coendemicity of malaria and helminthiases, coinfection of Plasmodium falciparum and helminths is frequent. Epidemiological studies have shown an effect of helminths on malaria symptoms in coinfected subjects. We and others have found that rate and level of P. falciparum gametocytaemia is significantly and consistently increased in chronic helminthiases. This may lead to an increase in transmission of the malaria parasite. In an exploratory study, we found that individuals who are infected with Schistosoma haematobium have a significant impairment of their humoral response to Pfs48/45, a major gametocyte antigen capable of blocking the development of P. falciparum in the mosquito gut. This could further increase transmission of malaria parasites to mosquitoes and is of particular concern in settings where malaria elimination campaigns are implemented or P. falciparum resistance containment. To date there is no study that has fully elucidated the effect of helminth on malaria transmission. With the first grant given to our project, we started a longitudinal study to assess the effect of S. haematobium on P. falciparum life cycle and transmission in two endemic settings, which are representative for West and Central Africa. In the first phase, a cohort was followed to investigate the effect of chronic S. haematobium infection on i) the reservoir of asexual and sexual P. falciparum parasites in humans, ii) transmission and development of gametocytes in Anopheles mosquitoes, and iii) probability of transmission of sporozoites to humans. The same set of experiments are currently being done in the same population, where those with S. haematobium infection are treated effectively with repeated doses of praziquantel. With such an approach, a complete picture of the interaction between S. haematobium and P. falciparum in regard to its transmission is possible. Additionally, the project will build urgently needed capacity in transmission studies in African research institutions. The project will be accompanied by an intense training program and will seek to develop careers of early and mid-term African scientists. The first, DFG-funded phase of the project is currently ongoing and data are being collected and analysed. From the preliminary findings, we identified a need to extend the project to complement activities and explore further topics: i) the cellular immunologic profile ii) host-vector interactions in Schistosomiasis, iii) Plasmodium diversity and genotyping in mosquito, and iv) insecticide susceptibility of the malaria vector.

• DFG Programme: Research Grants
• International Connection: Gabon, Ghana
• Co-Investigators: Alexander Kwarteng, Ph.D.; Professor Dr. Bertrand Lell; Dr. Denis Dekugmen Yar
• Cooperation Partner: Professor Dr. Jürgen May
• International Co-Applicants: Professor Ayola Akim Adegnika, Ph.D.; Professor Dr. Ellis Owusu-Dabo
• Ehemaliger Antragsteller: Professor Dr. Benjamin G. Mordmüller, until 12/2020