Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Final Activity Report Summary - PARASITE EVOLUTION (Microevolutionary and population dynamic processes in parasitic helminths)

Parasites represent a diverse group of biologically different organisms that are united only by their common lifestyle, which is spent either in or on the host, feeding on the tissues of the latter and causing it harm. Therefore, comparative studies are crucial. Here we apply this comparative approach by concentrating on two parasite groups that are known for their epidemic characteristics: Gyrodactylus salaris causes massive mortality in both wild and farmed salmon populations of Scandinavia while the human parasites Schistosoma mansoni and S. haematobium cause huge epidemics in African and South American countries (an estimated 207 million people worldwide are infected with Schistosoma spp.). Uncovering the transmission dynamics is crucial in studying the epidemiology of Gyrodactylus and Schistosoma spp., and population genetic studies are needed to assess the influence of control programs on the evolution of parasite populations.

During the first year we developed new markers for both parasite groups that enable us to study their population genetic structure. A considerable amount of time and money has been spent on the optimization of these markers and processing of the Schistosoma samples. In the following year we will concentrate on Gyrodactylus. An extensive field campaign was carried out to collect Schistosoma parasites from school children in northern Senegal. These samples have been genotyped with our newly developed protocol. Subsequent data analysis revealed a surprising amount of genetic diversity for Schistosoma mansoni parasites, despite its recent introduction in the area (about 30 years ago). The population genetic analyses also show intense transmission dynamics between villages, most likely due to recent human migrations. This results in a continuous introduction of new parasite genotypes and the creation of new host-parasite combinations, which will have a profound impact on infection patterns and the evolution of disease outcome.

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