With evidence growing that the Zika virus can be transmitted sexually, the World Health Organization on Tuesday recommended that all travelers – male and female, with symptoms or no symptoms – practice safe sex or abstinence for six months after returning from areas where Zika is spreading.
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Zika does cause conjunctivitis and eyes are a so-called immune-privileged site, meaning the immune system is not as active there and can not easily destroy infectious viruses and bacteria.
The researchers now are planning complementary studies in human patients infected with the virus.
“Even though we didn’t find live virus in mouse tears, that doesn’t mean that it couldn’t be infectious in humans”, said Dr. Jonathan Miner of Washington University in St. Louis, who led the study.
Zika in pregnancy is the major concern because the virus can damage the unborn child.
They are surprised at the “explosive” infection rates they have seen as Zika spreads – and tears might be the key to finding out why.
Samples of mouse tears were taken 28 days after infection, according to the researchers. This means infections sometimes persist in the eye after they have been eliminated from the rest of the body, the study authors explained.
Professor Paul Cosford, medical director at Public Health England, said: “Public Health England is monitoring the worldwide situation closely and the risk to the United Kingdom remains very low”. Apte is a professor of ophthalmology and visual science.
The WHO said the update was based on new evidence on Zika transmission from asymptomatic males to their female partners and a symptomatic female to her male partner, as well as evidence that Zika is present in semen for longer than thought.
Also, the eyes of mice could be used to test anti-Zika drugs, the authors suggested.
The Aedes aegypti mosquito is behind the large outbreaks of Zika virus in Latin America and the Caribbean. But it can cause birth defects, including microcephaly, which leads to babies born with abnormally small heads and brains. With Zika circulating in Florida, CDC Director Dr. Tom Frieden said the need for new funding was urgent.
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Many people infected with Zika won’t have symptoms or will only have mild ones – a fever, rash and muscle/joint aches.
