Existing immunity against dengue virus is capable of significantly reducing the risk of Zika virus in newborns, claims a new study.

According to the study published in the Journal of Emerging Infectious Diseases, researchers compared genomes of all known dengue viruses in Brazil to investigate interactions between dengue and Zika viruses. "We can now say that people who have had early infections with dengue do not need to worry much about contracting more severe forms of Zika infection due to this," said virologist Prof Felix Drexler.

According to the virologist, it is known for sure that Zika virus infection during pregnancy can potentially affect the unborn fetus in such a way that the child develops microcephaly or malformations of the head and other severe symptoms.

Zika viruses are usually transmitted by mosquitoes, particularly by the Aedes species, but they can also be transmitted sexually. Symptoms of Zika include rashes, headaches, joint pain and muscle pain, conjunctivitis and sometimes fever.
However, these symptoms are considered mild compared to other tropical diseases that are transmitted by mosquitoes.

During pregnancy, the virus can cause microcephaly and other malformations in the unborn child. Scientists consequently began to search for cofactors that have an influence on whether a Zika infection during pregnancy will develop fatal consequences or not.

Dengue viruses, which are widespread in Latin America and caused dengue fever, were suspected to be cofactors.
Initially, the scientists suspected that the antibodies humans produce against the dengue virus contribute to the fetal damage caused in later Zika infection.

"Surprisingly, our study has shown that a previous dengue infection can protect against Zika-associated damage," emphasized Drexler. As an existing immunity against dengue virus significantly reduces the risk of Zika-associated microcephaly in newly borns.

"We can now say that people who have had early infections with dengue do not need to worry much about contracting more severe forms of Zika infection due to this," summarised Drexler.

Felix Drexler and his research group have already developed several novel Zika virus tests. The Zika diagnostics project in Brazil was brought underway by the DZIF in order to act against the threat of emerging infections. It is also being funded by the EU programme Horizon 2020.