Genetic fragments of Zika have been traced in the eyes and the tears of laboratory mice that have been infected with the virus. Hence, a new pathway to the body seems to have been discovered.
"Our study suggests that the eye could be a reservoir for Zika virus," said Dr. Michael Diamond of Washington University St. Louis. "We need to consider whether people with Zika have infectious virus in their eyes and how long it actually persists."
The team of scientists injected some infections of the Zika virus to adult mice under the skin, simulating mosquito bites. Some live viruses were found in tears a week later. Tests conducted 28 days later showed that the tears of infected mice contained genetic material from the virus, but they were not "infectious virus."
Hence, the possibility is that Zika might be spreading when they come into contact with tears of infected people. However, such cases would need to be proven.
"We are planning studies in people to find out whether infectious virus persists in the cornea or other compartments of the eye, because that would have implications for corneal transplantation," said Dr. Rajendra Apte, a senior author of the study.
He pointed out that blood-borne viruses such as herpes simplex virus have been transmitted via corneal transplants.
Hence, Zika tends to remain persistently in parts of the body where the immune system is weak, such as semen, vaginal fluid, saliva and now, possibly, tears. It explains why Zika spreads so readily, according to Diamond. "Sexual transmission is probably not playing a major role, but it could be some other bodily fluid - saliva, or urine or tears," he said.
The connection between Zika virus and microencephaly in babies was detected and shown in Brazil. It also leads to a rare neurological syndrome known as Guillain-Barre, apart from related neurological disorders.
The study was published in the journal Cell Reports.
