More than 100 health experts have called for the Rio Olympic Games to be postponed or moved because of the threat to public health from Brazil's Zika virus outbreak, according to a public letter published online.

The Zika virus is primarily spread to people through the bite of an infected mosquito. The most common symptoms are fever, rash, joint pain and red eyes. Most people only deal with mild reactions to the virus, according to the CDC.

"Our greater concern is for global health," the letter said. "The Brazilian strain of Zika virus harms health in ways that science has not observed before. 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."

Zika has been linked to numerous cases of the birth defect micocephaly in Brazil, is spreading rapidly in Latin America and the Caribbean.

The letter was signed by 150 people identified as health experts and was sent to the head of the World Health Organization. 

Reuters contributed to this report.