Some degree of this is common in all dengue infections. When severe, it can lead to dengue with warning signs (old term DHF), or severe dengue (old term DSS). The mechanisms appear to be:
1. platelet leakage through endothelial gap junctions mediate by TNFa binding to PECAM-1
2. Dengue infection of megakaryocytes in marrow
3. Complement mediated destruction of platelets due to x-reactive antibody to viral NS3.