Because Zika and dengue viruses are closely related, is it possible that pre-existing dengue virus immunity could also impact the exposure to Zika symptoms and the virus?
Published in PLOS Medicine, according to researchers from University of California, USA, previous infection with dengue virus could protect children from experiencing Zika symptoms.
The world of Zika virus
The infectious disease that is Zika virus, emerged in northeast Brazil in 2015 and quickly spread across the Americas, affecting populations that have been largely exposed to dengue virus. Because Zika and dengue viruses are closely related, it is possible that pre-existing dengue virus immunity may also impact susceptibility to Zika.
But the effect of previous exposure to the dengue virus on outcomes in those infected with the Zika virus remains unclear.
Analysing the epidemic
To study this potential impact, Eva Harris and her team of colleagues from the University of California analysed the large 2016 Zika epidemic in Managua, Nicaragua, focusing particularly on a paediatric cohort with well-characterised dengue virus immune histories.
The long-term, community-based cohort study, currently in its 15th consecutive year, followed approximately 3,700 children aged 2-14 years old.
The researchers found that prior and recent dengue virus infection was associated with protection from symptomatic Zika virus infection in the total cohort population and among those infected with the Zika virus.
However, by contrast, prior or recent dengue virus infection did not affect the rate of total Zika virus infection.
Can we cross protect individuals?
These findings support the idea that prior dengue virus immunity has the potential ability to cross-protect individuals against symptomatic Zika.
Moreover, according to the authors, further research is required to address the possible immunological mechanisms of cross-protection between Zika and dengue viruses and whether the immunity of dengue virus also modulates severe outcomes of Zika virus infection such as neurological or congenital syndromes.