The disease of YF is due to direct viral injury to the liver and lymph nodes not immunopathologic mechanisms. Recovery from YF is associated with the development of life-long immunity. Thanks to the work of the US Yellow Fever Study Group, there is an excellent vaccine for YF derived from one of the first strains of YF isolated from a patient. The preparation of this vaccine led to the realization that hepatitis could be transmitted by serum. The virus is not as hepatotropic as the YF virus.
Some patients develop pleural effusions, hemorrhage, and die of shock.
This later syndrome occurs in a specific subset of patients. This phenomenon was analyzed during a Cuban epidemic of DSS in 1981. There was no dengue virus in Cuba from the end of WWII until 1977. There are 4 strains of Dengue virus and the 77-78 outbreak was caused by Dengue type 1. In 1981 there was an epidemic of type 2 Dengue infection.