Zika virus has been misdiagnosed as dengue because of similar clinical symptoms and serologic cross-reactivity with DENVs. In article named "Genetic and Serologic Properties of Zika Virus Associated with an Epidemic, Yap State, Micronesia, 2007", the serologic data indicate that ZIKV-infected patients can be positive in an IgM assay for DENVs, particularly if ZIKV is a secondary flavivirus infection. In contrast to primary flavivirus/ZIKV–infected patients, secondary flavivirus–infected patients showed a high degree of serologic cross-reactivity with other flaviviruses.
IgM antibody response in primary flavivirus/ZIKV–infected patients is specific for ZIKV. PRNT90 results also showed that the neutralizing antibody response among primary flavivirus/ ZIKV–infected patients is highly specific. If ZIKV is the first flavivirus encountered, data indicates that cross-reactivity is minimal.
Levels of viremia among ZIKV-infected patients were relatively low. And, Nucleic acid sequence of ZIKV 2007 showed divergence (11%) from the prototype strain (MR766) isolated in 1947. However, the predicted amino acid sequence is fairly conserved (96%), which is likely the result of the selective pressure maintained on the virus because replication occurs in vertebrate hosts and arthropod vectors.