Parasites Induced Skin Allergy J Clin Med Res • 2010;2(6):247-255 Being placed in the intermediate host brain, the toxoplasma- expressed epigenomic mechanisms may lead to variations in gene expression during the transformation of tachisoites into bradysoite, waiting then for the definitive host. This way, Toxoplasma gondii dispose the ability to manipulate the personality profile of the intermediate host [16, 59]. The toxoplasmosis-infected people are more predisposed to take a risk, or are less watchful for example in the motorways, whereas toxoplasmosis-infected rats can even lose the cat predation risk [16, 61, 66, 67]. Also the loss of predation risk by rats or the loss of watchfulness by humans at least at the prehistoric time before the invention of entombment, after a toxoplasmic infection, led usually to the rip of their bodies from some carnivore and therefore to the transmission of the parasite into its definitive host like felines [16]. The para- site thus manipulates the behavior of its intermediate host to enhance its transmission to the definitive one [66, 67]. In a similar manner, the experimentally Toxocara canis-infected BALB/c mice take significantly longer to drink from a water source compared with control mice [68]. Moreover, infected mice displayed reduced levels of anxiety to aversive and ex- posed areas of the maze, particularly in the case of the mod- erate and high intensity mice [69]. These findings suggest that a toxocara-infected paratenic host can be an easier prey for their predators. During dracunculiasis, the burning effect in patient’s lower limbs during pregnant larvae extrusion is also a host behavior manipulation, because the expelling first-stage larvae can be developed only within copepods of the ponds [58]. Consequently, the patient hurries to immerse the burning limbs in the ponds in order to cool them. The reduction of respiratory allergic symptoms (like wheezing or airway hyperreactivity) in intensive helminth- infected populations is another example of host behavior manipulation and an evolutionary adaptation from the point of view of parasites [16]. This reduction assures those bet- ter chances for their reproduction and development in the environment “host”, because the liberation mammalian ef- forts against these parasites are suppressed. Thus, toxocara, ascaris, trichiuris, and hookworm have a phase of larval mi- gration into the respiratory system or at least, their entrance way (as eggs) in the human body is the nose or the mouth [16, 42]. To assure their penetration into the host and latter their reproduction or development, these parasites need to affront or avoid the reactive (including allergic) response of the host (like the cough, airway obstruction and airway hy- per-responsiveness) due to induction of immuno-modulatory network [13-16, 70]. The manipulation of host reaction is not an exclusive ability of parasites. Common respiratory infective pathogens can manipulate the host behavior. While during incubation Figure 1. Th1 vs. Th2 response during parasitoses and the development of allergic skin symptoms: Although both re- sponses provide antiparasitic effects, the Th1 response seems to be superior to the Th2 one. Maybe the Th2 response is a host-response, chosen by the parasite that is associated with better survival and hostile tissue penetration. The eosinophil chemotaxis and the avoidance of complement-dependent innate mechanisms are targets of parasite-induced host immune modulation in order to improve its development and survival possibilities within hostile organism. Articles © The authors | Journal compilation © J Clin Med Res and Elmer Press™ | www.jocmr.org 251