Published 07 March 2019
An international team of scientists led by the University of Pittsburgh Graduate School of Public Health, Yale School of Public Health, and the University of Florida reported in the February issue of Science that the higher a person's immunity to dengue virus, the lower their risk of Zika infection. The study, which followed nearly 1,500 people living in a poor neighborhood at the heart of the 2015 Zika outbreak in Brazil, also provides evidence that Brazil's Zika epidemic has largely petered out because enough people acquired immunity to reduce the efficiency of transmission. "Take that with a grain of salt, though. Our study was in a very small urban area, and it is likely that in other parts of Brazil, even different neighborhoods within the same city, people are still susceptible to Zika infection," said co-senior author Ernesto T.A. Marques, M.D., Ph.D., associate professor in Pitt Public Health's Department of Infectious Diseases and Microbiology and public health researcher at Fundação Oswaldo Cruz in Brazil.
Paradoxically, computational models by co-senior author Derek A.T. Cummings, PhD, professor of biology at the University of Florida, showed that participants who had a very recent dengue infection were actually more susceptible to Zika. Possible explanations include protective antibodies have not developed yet or there is something about the immune systems of these people that increases their risk of contracting Zika; or the mosquitoes that transmit dengue also transmit Zika, so a recent dengue infection could mean they are in a place where Zika transmission is active as well. Additional study is needed to determine how these findings could prove useful to clinicians.