Rio de Janeiro (CNN) Rio's Olympic organizers went on the offensive Tuesday, trying to drown out the voices that insist the Zika virus poses a health risk for the 2016 Summer Games.

At a press conference, organizers put up slides showing that the number of Zika cases has fallen quickly as Rio has moved into the colder winter months. So has the number of other mosquito-borne viruses like Dengue fever and chikungunya.

"We are 110% comfortable that we can protect everybody that expects to see the games," said Mario Andrada, director of communication for Rio 2016.

Last month, 150 scientists and doctors posted an open letter arguing the 2016 Summer Games should be postponed or moved.

"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," they wrote.

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