Why is second episode of dengue fever fatal? are there any medicines to avoid it?

Its complicated : Dhf in 2nd infs has suggested a role for heterologous antibodies in enhancing viral uptake and replication in certain cells. Also, levels of tnf, cd8 and il2 are higher indicating an activation of cross reactive memory CD4 and cd8 t lymphocytes in response to second infections. Dhf can have a mortality of 50% in 3rd world. Its only 1% in usa. Rx is supportive. Mosquito repellent preventive.