IL4 and infection: It is interesting to note that the induction of Th2 cytokines appears to depend on the infection route: In the i.v. infection model of O. tsutsugamushi Karp that allows rapid dissemination to the organs without passing through the lymph node, transcription of il-4 and il-13 mRNA was found suppressed and thus interpreted as an impaired Th2 response (57).