The Zika virus is capable of infecting the eye. In mice, its genetic material persists for nearly a month. This would explain the eye symptoms observed in some patients.
This study will not tell if the mice are crying. However, she evokes a new track of contamination by the Zika virus. Produced by the School of Medicine at the University of Washington (USA), and published in Cell Reports, studies show the presence of the virus in the tears of rodents. It is infectious, therefore potentially capable of being transmitted.
A specific immune system
The authors of this research infected mice with Zika subcutaneously, mimicking the effect of a mosquito bite. In the lacrimal glands and tears of rodents, active virus was detected up to 7 days after infection. Viral genetic material persists even longer. But 28 days after inoculation, it is no longer able to harm. For Jonathan Miner, the first signatory of the study, “the existence of a window during which tears are highly infectious is possible”.
This long persistence of the virus may be linked to the specific environment of the eye. It benefits from a particular immunity: a barrier separates the blood circulation from the retina. The immune system is less active within the organ, so as not to accidentally damage eye tissue. Viruses can therefore persist even though they have been evacuated from the rest of the body. This phenomenon has already occurred in the case of Ebola hemorrhagic fever.
Eye symptoms
The presence of Zika in the eye would therefore explain the particular symptoms that some patients present: conjunctivitis is not uncommon. Exceptional cases of uveitis have been identified. This disease puts you at risk of partial or total vision loss. Babies exposed in utero virus also suffer, in a third of cases, inflammation of the optic nerve, retinal damage or blindness.
Two questions remain: can the virus contained in the eye be transmitted, and how long does it persist in humans? Further work is planned in order to respond to them. The researchers also plan to determine the route taken by the virus to infect the visual organ: the blood / retina barrier, the optic nerve or another route. They specify that, even if the virus is not infectious, this discovery has a major interest: detection tests less invasive than blood samples would be possible.
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