Children who have previously been exposed to dengue virus appear to be protected from getting sick when infected with Zika virus, according to a study published Jan. 22, 2019 in PLoS Medicine by Aubree Gordon of the University of Michigan and Eva Harris of the University of California, Berkeley.
Prior and recent dengue virus infection was found to be associated with protection from symptomatic Zika virus infection. Children with prior dengue infection had 38% less risk of showing symptoms when infected with Zika than those who were dengue-free. Zika symptoms include fever, rash, conjunctivitis, muscle, joint pain and headache.
These findings support the hypothesis that prior dengue virus immunity might cross-protect against symptomatic Zika. The two already share many similarities: They belong to the same Flavivirusgenus. Both viruses are transmitted by the Aedes aegypti mosquito, which preys on the same populations.
In a patient with previous dengue infection, the second dengue infection may be more severe via antibody-dependent enhancement. But if the second attack occurs within six months of each other it may get nullified.