Parasite Infections: From Experimental Models To Natural Systems

Eukaryotic parasites (including parasitic protozoans, worms and arthropods) are more complex and heterogeneous organisms than pathogenic bacteria and viruses. This notion implies different evolutionary strategies of host exploitation. Typically, parasites establish long-term infections and induce relatively little mortality, as they can limit pathological changes by modulating host cells and downregulating adverse immune responses. Their pattern of distribution tends to be endemic rather than epidemic. Despite these seemingly benign traits, parasites usually cause substantial chronic morbidity, thus constituting an enormous socioeconomic burden in humans, particularly in resource poor countries, and in livestock worldwide. Parasite-induced fitness costs are an evolutionary force that can shape populations and contribute to species diversity. Therefore, a thorough understanding of parasites and parasitic diseases requires detailed knowledge of the respective biochemical, molecular and immunological aspects as well as of population genetics, epidemiology and ecology.

The Research Topic will bridge disciplines to connect molecular, immunological and wildlife aspects of parasitic infections. The Research Topic puts emphases on four groups of parasites: Plasmodium, Toxoplasma, Giardia and intestinal helminths because: Plasmodium that causes malaria remains one of the most serious parasitic diseases in the poorest countries of the world, with an estimated 0.7 - 1 million annual deaths, primarily in young children; Toxoplasma gondii exemplifies an opportunistic and generalist zoonotic pathogens with a worldwide distribution, infecting more than one third of the human population; Giardia duodenalis is an example of an intestinal protozoan parasite that causes one of the most prevalent enteric parasitic infections worldwide; and, intestinal helminth species because they induce chronic disabling diseases, infect animals and humans alike with billions of infections worldwide. Co-infections will also be covered by the Research Topic because they represent the most common form of parasite infections in wildlife and domestic animal populations.
Within the four types of parasites the following research topics of importance are to be addressed: (I) Molecular approaches dissecting signaling pathways and metabolic regulation.

In particular, signaling and metabolic pathways, stress responses and resistance pathways in operation during and governing protozoan and helminth parasite infections and disease. (II) Cellular interactions of parasites with host immune- and non-immune cells in different body compartments. Here, the identification of mechanisms that either lead to differential immune priming, immune evasion or enhanced protective immunity are of utmost importance. As are signatures of immune cells that point to basic principles of cellular differentiation as well as susceptibility of cells to immunoregulation (III) The impact of parasites on a natural environment, i.e., on wildlife populations. Parasites of wildlife will complement investigations on the molecular and cellular/immunological level and will contribute an organismic perspective on these infections by factors impacting hosts at a population level.

Hence, the Research Topic will cover and illustrate by the means of four main parasitic infections the parasite-host system at the molecular, cellular and organismic level.