| | | See DEN-1 and 2 for general antigenic relationships with other Group B viruses and dengue viruses. | | Several viruses isolated in the West Indies and Tahiti are reported as most closely related to type 3 but significant differences have been shown with some of these from the Philippine prototype H-87. Whether these are strain differences or whether new types are involved remains to be determined. | | Type 3 was first isolated, together with type 4 from patients during an outbreak of what was called Philippine hemorrhagic fever ( [1] , [2] ). Since it differed antigenically from the only two previous types recognized and was the etiological agent of a far more serious disease than classical dengue it was considered that the agent differed not only antigenically from types 1 and 2 but also in pathogenic properties. However since type 3 viruses or viruses closely related to the prototype have been found in India [9] , Pakistan [10] , the West Indies ( [10] , [11] , [12] ), and Tahiti, producing mild and classical dengue without serious or obvious hemorrhagic manifestations the pathogenicity and antigenic properties no longer appear related. | | |
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