Zika Can Be Found in Conjunctival Fluid

Researchers are gathering more evidence of the exact effects of Zika virus infection on eye health.

In a new study published online on September 15 by JAMA Ophthalmology, scientists from Guangzhou, China found that the mosquito-borne virus can be detected in the conjunctival fluid, the fluid underneath the eyelid, of those infected with Zika virus. Earlier studies have linked the infection with conjunctivitis and noted that babies born with microcephaly, a birth defect associated with Zika virus, often also have eye damage. Another study, published earlier in September, suggested that the virus could be transmitted via human tears.

In the China study, researchers collected eye swab samples from six Chinese travelers who had been infected with Zika virus in Venezuela within the past several months. They found that virus RNA was detectable in their conjunctival fluid, via real time-PCR, 5 days after Zika virus symptom onset. In one of the study subjects, the virus was detectable in eye swab samples 7 days later.

Study lead author Changwen Ke, PhD, of the Guangdong Provincial Center for Disease Control and Prevention in Guangzhou, did not respond to Contagion’s requests for comment. In their concluding remarks, though, he and his colleagues noted that their findings further highlight the potential role for the use of eye swabs instead of other bodily fluids in the diagnosis of infection with Zika virus. Although Zika virus has been identified in urine, semen, saliva and breast milk, using these fluids in diagnosis has proved, at times, unreliable. However, Dr. Ke and his team also noted that the virus may not remain in eye fluid as long as it does in the urine and saliva of those infected, which may render its use as a diagnostic tool problematic.

They wrote, “Detection of [Zika virus] RNA is a gold standard of confirmation of infection [and] in this study, we described the direct detection and isolation of ZIKV from conjunctival swab samples. These results, though, are not sufficient to recommend the use of conjunctival swabs as alternative samples for [Zika virus] diagnosis because of shorter persisting and shedding time of [Zika virus] in conjunctiva fluid (<7 days) compared with urine and saliva samples (<20 days).”

In addition, the China study also raises the specter that Zika virus could be transmitted via corneal transplants, a fairly common procedure. However, these and other considerations must be confirmed via further study.

Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.