Understanding the kinetics of host–pathogen relationships and identifying critical pathogenetic processes are important for the rational development of prophylactic and therapeutic countermeasures. For the most part, the specific mechanisms underlying the pathogenesis of HF viral infection have not been clearly explained, although recent progress has been made, particularly on Ebola virus. A paradigm showing the current views on the pathogenesis of the HF viruses is
illustrated in Figure 13-6. A central theme common to all VHFs, with the possible exception of yellow fever, is that lesions are not severe enough to account for terminal shock and death of the host. Yet VHF infections are characterized by a fulminant shock-like syndrome in fatal cases, suggesting that inflammatory mediators may play a determining role in the disease pathogenesis. Fatal HF viral infections are generally characterized by high viremia and immunosuppression. HF
viral infection in humans and nonhuman primates is characterized by deleterious changes in lymphoid