[The standardization of the plaque reduction technic for differentiating a dengue infection from a yellow fever...

The plaque reduction neutralization assay was standardized to differentiate an infection caused by dengue from another infection produced by yellow fever. Serum samples from Cuban donors were used to this end. Information on previous vaccination against yellow fever was available. Samples from Costa Rican patients with a clinical picture of dengue and with no antecedents of vaccination against yellow fever were also utilized. The optimal plaque staining day was the fifth day and the smallest serum dilution capable of differentiating an infection resulting from dengue from another infection caused by yellow fever was of 1/5. According to the high specificity of the standardized technique, risk factor studies of dengue hemorrhagic fever could be made among individuals vaccinated against yellow fever, which is a present and important topic.