Zika's symptoms are mild, but in the letter the experts say it causes babies to be born with abnormally small heads and may also cause a rare and sometimes fatal neurological syndrome in adults.
"An unnecessary risk is posed when 500,000 foreign tourists from all countries attend the Games, potentially acquire that strain, and return home to places where it can become endemic," the letter says.
The biggest risk, it adds, is if athletes contracted the virus and returned home to poor countries that had not yet suffered a Zika outbreak.
http://www.bbc.co.uk/news/world-latin-america-36401150
maybe it will go back to London again
