Rio De Janeiro, home to the 2016 Olympic games, is known for its many problems ranging from gangs and pollution to an unstable economy and corruption. Now, it is known for the Zika virus, and hundreds of doctors are calling for the games to be moved.

On Friday, more than 100 doctors and professors called for the games to be postponed or moved to another location, “in the name of public health.” These doctors and professors wrote an open letter to the World Health Organization claiming, “the Brazilian strain of the Zika virus harms health in ways science has not observed before.” Doctors from all over the world, ranging from countries like Norway, the United States and Japan, have signed this open letter.

According to these doctors, the Zika virus has worsened in Brazil despite efforts to curb the spread of the disease and that the virus has, “has more serious medical consequences than previously known.

The Zika virus is spread through mosquitos, and if contracted, it causes fever, rash, joint pain and conjunctivitis. Although many people do not need to be hospitalized for the disease, it can cause crippling birth defects in newborns that primarily effect the brain.

The Olympic games are scheduled to begin August 5, and end August 21, with an estimated 500,000 people expected to travel to Brazil for the games from all over the world. “It’s unethical to run the risk,” the letter says about travel to Brazil.

Doctor Ford Vox, a physician who works in brain injury medicine with the Sheppard Center in Atlanta is just one of the hundreds of doctors who have signed the letter to the world health organization. “In my opinion, non-essential travel to Zika endemic areas should be deferred until the situation improves,” said Vox. “The Olympics are not essential.”

The US Olympic Committee has recently told athletes to skip the games if they are concerned about the health risks of competing in Rio. Just last week, the US swimming team decided to move their practices from Puerto Rico to Atlanta due to the health concerns from the Zika virus.

One of the co-authors of the letter, Lee Igel, wrote in an email to CNN, “If you think that a mega-sports event in the midst of a major virus outbreak in a host city dealing with a turbulent economy, sitting on top of a turbulent political situation, sitting on top of a turbulent social condition doesn’t pose a significant health issue, then sure, on with the Games.”