Study reveals individuals previously infected with dengue, West Nile may carry increased risk of Zika virus complications

According to a recent study conducted by the Icahn School of Medicine at Mount Sinai, individuals previously infected with West Nile virus or dengue fever may carry an increased risk of complications should they become infected with Zika virus.

In recent years, Zika virus has spread increasingly through South America, the Caribbean, Central America and parts of the United States. The virus is typically spread through the bite of Aedes aegypti species mosquitoes, but can also spread through sexual contact. Symptoms of infection include rash, fever, and joint pain. More seriously, the virus has been linked to microcephaly of the fetus in pregnant women and Guillain-Barré syndrome. All three viruses are members of the flavivirus family.

The Icahn School of Medicine’s study is the first to report a large-scale analysis of Zika virus enhancement by antibodies of individuals that previously contracted dengue or West Nile. The researchers were able to identify the enhancement of Zika virus growth in cell cultures by analyzing blood samples taken from individuals infected with either virus.

Dengue and West Nile-infected plasma was then administered to mice engineered to be susceptible to Zika infection, which resulted in increased mortality and viral loads in the spinal cords as testes of the mice upon virus infection.

“We believe the antibody-dependent enhancement may explain the severe disease manifestations associated with recent Zika virus outbreaks, and highlights the need for great caution when designing vaccines for Zika and other flaviviruses,” Jean Lim, co-author of the study, said.

Study co-author Florian Krammer said that the study found that the antibody-dependent enhancement effect was dependent on the dose of plasma administered and that low concentrations of cross-reactive antibodies clearly enhanced the disease.