Congress activists protest against BMC (Brihanmumbai Municipal Corporation) over Dengue issues in Mumbai, India Hindustan Times / Getty

The Zika virus made headlines in 2015 when it spread to Brazil for the first recorded time, infecting adults and causing birth defects in thousands of children. Though the virus was downgraded from a global health emergency to chronic threat level by the World Health Organisation at the end of 2016, the disease is still a very pressing issue in parts of the world.

Scientists at Florida Gulf Coast University (FGCU) have been looking into the effect of the Dengue virus antibodies and how this may worsen Zika infections. According to the WHO, Dengue is a viral infection transmitted by the bite of an infected female Aedes mosquito, which also spreads Zika. It is a flu-like illness and severe Dengue can be lethal. There is no official vaccine or specific medication to treat the virus.


Professor of Biological Sciences at FGCU, Sharon Isern studies the viruses in the Flavivirus family including Zika and Dengue. Writing for The Conversation, Isern explained the work her and her colleagues carried out when looking into whether having an immunity to Dengue from an earlier infection could make having a Zika infection worse.

Zika: how can it be stopped? Zika Zika: how can it be stopped?

There are four different types of the Dengue virus, called serotypes, writes Isern. Antibodies produced during infection with one Dengue serotype will lead to lifelong immunity against only that kind of the virus, so if someone is infected with a different serotype later in life, they will not have immunity against it.

In the second infection, the antibodies from the first infection will bind to the new virus type, but can’t prevent it from infecting cells. In this instance, the bound antibodies can transport the viruses to immune cells that are not normally infected by Dengue. This can lead the virus to reproduce rapidly in these cells and lead to severe Dengue. This process, says Isern, is called antibody-dependent enhancement (ADE).


As Zika is closely related to Dengue, research has shown that preexisting immunity to Zika can enhance Dengue virus disease severity. Isern and her team studied the Zika virus to find that antibodies from a prior Dengue virus infection can greatly enhance Zika virus production, as a result of ADE. This can make the Zika virus infection much more severe in patients, leading to Guillain-Barré syndrome and a spike in babies being born with microcephaly.

It is possible to become immune to Zika. If a child becomes infected before they reach puberty for instance, they become immune and cannot pass the virus along to their future offspring. In parts of the world such as Africa, where the virus originated and is endemic, people are more likely to have been exposed to Zika and become immune at a young age.

However as Zika has recently been found in the Americas, an area where the virus had never been reported before 2015, it has affected adults who have never before been exposed to it, particularly women.