Zika virus can live in eyes and have identified genetic material from the virus in tears, according to a study from Washington University School of Medicine in St. Louis.
The study, published Sept. 6 in Cell Reports, describes the effect of Zika virus infection
in the eyes of mouse fetuses, newborns and adults. The researchers now are planning complementary studies in human patients infected with the virus.
"Our study suggests that the eye could be a reservoir for Zika virus," said Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine and one of the study's senior authors. "We need to consider whether people with Zika have infectious virus in their eyes and how long it actually persists."
Zika virus causes mild disease in most adults but can cause brain damage and death in fetuses. About a third of all babies infected in utero with Zika show eye disease such as inflammation of the optic nerve, retinal damage or blindness after birth. In adults, Zika can cause conjunctivitis - redness and itchiness of the eyes - and, in rare cases, uveitis.
Eye infection raises the possibility that people could acquire Zika infection through contact with tears from infected people. The researchers found that the tears of infected mice contained Zika's RNA - the genetic material from the virus - but not infectious virus when tested 28 days after infection.
"Even though we didn't find live virus in mouse tears, that doesn't mean that it couldn't be infectious in humans," said Jonathan J. Miner, MD, PhD, an instructor in medicine and the study's lead author. "There could be a window of time when tears are highly infectious and people are coming in contact with it and able to spread it."