It remines unclear as to what specific cytokine networks regulate EC activation in vivo during O. tsutsugamushi infection; however, it is known that endothelium-activating proinflammatory cytokines, such as TNFα and IL-6, are increased in various mouse tissues in late stages of severe infection, as well as in the serum samples of severe scrub typhus patients [35, 51]. This evidence concerns the gene TNF and infection.