Dr. Guzmán et al. Respond to Dr. Vaughn

This paper presents the response of Dr. Maria Guzman and colleagues to the comments made by Dr. David Vaughn regarding their findings on the retrospective seroepidemiologic study conducted on 1997 in Cuba. It is noted that in his commentary Vaughn has identified the alarming implications of naturally attenuated dengue viral strains that produce overt disease in heterotypically immune individuals. This led Guzman and colleagues to extend their discussion to a more comprehensive search for large virgin-soil dengue virus type 2 and dengue virus type 4 outbreaks. Seldom have these been reported. This is because hospitalized cases have been the principal focus of dengue research during the dengue hemorrhagic fever/dengue shock syndrome era. The approach taken by researchers ignores the only available measure of viral virulence the incidence rate of disease to total infections. For secondary infection dengue this means the ratio of clinical disease due to a specific viral strain to total secondary dengue infections with that strain. Although the phenomenon of virulence has been recognized in 1980 and 1995 appropriate genotyping studies on dengue type 1 strains have not been reported.