Although the parasitology belongs to one of the longest established disciplines, the recent methodical advances led to the substantial broadening of the possibilities for the detection and treatment of parasitic diseases. However, the exact mechanisms involved in the parasite establishment and survival are frequently unclear and only recently uncovered. At the cellular level, the emerging mechanisms, discussed in this journal issue, include the newly recognized role of mast cells in the host defense against bacterial pathogens, and the role of granulocytes in the host defense against helminths. At the protein level, we discuss here the emerging role of protein tyrosine phosphatases as both targets and tools of nonmetazoan pathogens and viruses. At the level of small signaling molecules, we attempt here to highlight the role of reactive oxygen species as molecules involved both in the host defense, but also produced by some human pathogens and commensals. Scientometric analysis of the fields covered by this journal issue is provided.