Parasites make use of multiple strategies to change energy budgeting in their host

Data are presented showing that the schistosome Trichobilharzia ocellata follows different strategies to meet their requirements of energy and space in their snail host Lymnaea stagnalis. They reach their goal by inhibiting reproduction and normal growth of the host, the main energy consuming processes. In an early stage of infection they already inhibit development of the reproductive tract by their excretion/secretion (E/S) products acting at the level of the reproductive target organs. In a later stage they interfere with the neuroendocrine regulation of reproduction and growth in the host by a nonneuronal factor and by changing expression of neuropeptide encoding genes involved in this regulation. Identification of the parasitic E/S factor(s) inducing these effects will not only reveal parasitic strategies but also the mechanisms and molecules involved in regulation of the host's energy budget.