Figure 16.

Model of the pathogenic mechanism underlying RVFV infection. Following a mosquito bite, the virus is endocytosed by antigen-presenting cells. Suppression of type I IFN production and necrosis of infected macrophages and dendritic cells cause wide dissemination of viruses. This systemic spread leads to necrosis in a variety of tissues and cells together with suppression of both the innate and adaptive immune responses. Apoptosis of lymphocytes might occur through mediator effects and loss of dendritic cell support, exacerbating the failure of the immune response. An excessive pro-inflammatory cytokine and chemokine response follow, resulting in increased microcirculatory dysfunction through the action of inflammatory mediators. Impairment of the coagulation system results in widespread haemorrhages. Fatal outcomes result from multiorgan failure, oedema in many organs (including the lungs and brain), hypotension and circulatory shock. DC, dendritic cell. NO, nitric oxide. (Illustration adapted from Bray M, 2005).