Parasite-Vector Interactions
In the most important protozoan tropical diseases – malaria, leishmaniosis, sleeping sickness and Chagas disease – the parasites are transmitted to humans by specific vectors: the sporozoan Plasmodium spp. by female Anopheles mosquitoes, Leishmania spp. b
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Günter A. Schaub, Patric Vogel, and Carsten Balczun
Abstract
In the most important protozoan tropical diseases – malaria, leishmaniosis, sleeping sickness and Chagas disease – the parasites are transmitted to humans by specific vectors: the sporozoan Plasmodium spp. by female Anopheles mosquitoes, Leishmania spp. by female sandflies, Trypanosoma brucei ssp. by both gender of tsetse flies and Trypanosoma cruzi by all stages of triatomines. In the lumen of the vector´s gut, all parasites are confronted with the digestive enzymes of the insect and its intestinal immune reactions but also to the microbial fauna. If the parasites are transmitted via the saliva, they must also evade the immune reactions during their way to and in the salivary glands. On the molecular base, specific surface components of the parasites and respective receptors of the insect induce an attachment to or an invasion of the respective tissue, the development of infectious stages and/or immune reactions. In refractory vectors, the latter kill the parasites, but in susceptible vectors at least some parasites survive and can be transmitted. Since full genome sequences are available for many vector species and parasites, modern genomic and proteomic analyses will perhaps identify targets for control of parasite development in the vector.
G.A. Schaub (*) • P. Vogel Zoologie/Parasitologie, Ruhr-Universität-Bochum, Universitätsstrasse 150, 44801 Bochum, Germany e-mail: [email protected]; [email protected] C. Balczun Central Institute of the Bundeswehr, Medical Service Koblenz, Koblenz, Germany e-mail: [email protected] © Springer-Verlag Wien 2016 J. Walochnik, M. Duchêne (eds.), Molecular Parasitology, DOI 10.1007/978-3-7091-1416-2_14
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G.A. Schaub et al.
Introductory Remarks
All parasite-vector systems show fascinating aspects of co-adaptations. In the following we will focus on the interactions in the most important protozoan tropical diseases – malaria, leishmaniosis, sleeping sickness, and Chagas disease. The parasites use specific groups of insects to be transmitted to humans, Plasmodium spp. female mosquitoes of the genus Anopheles, Leishmania spp. female sandflies, Trypanosoma brucei ssp. both gender of tsetse flies and only Trypanosoma cruzi non-dipteran insects but reduviid bugs of the subfamily Triatominae. Since dipterans are similar, their peculiarities will be mentioned in this introduction and those of triatomines below (see Sect. 14.5.2). All dipterans are holometabolous insects, thus possessing four developmental stages: egg, larva, pupa, and adult. These larvae develop in other substrates than adults, thereby avoiding food competition. The intestine of adults has some specialized regions. The distensible crop is part of the foregut and especially used to store ingested sugar solutions to kill microbiota. The foregut ends with the proventriculus. In tsetse flies, specialized cells of the proventriculus secrete the peritrophic matrix (PM); in mosquitoes and sandflies midgut epithelial cells pr
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