After months of dire predictions from abroad about the mosquito-borne Zika virus, some Brazilian fans are doing some stinging of their own: They're booing U.S. athletes and taunting them over the fears that kept some competitors at home.

From the beach volleyball arena to the soccer stadium, boisterous Brazilian fans are having fun with what had been one of the biggest concerns heading into South America's first Olympics.

The mockery began during the first game by the U.S. women's soccer team, when veteran goalkeeper Hope Solo was greeted by chants of "Zika! Zika!" every time she touched the ball. The jeers were heard again Saturday during a 1-0 U.S. victory over France.

Solo, who irked Brazilians before coming to the Olympics by tweeting a photo of herself wearing a hat with mosquito netting and sporting a giant bottle of bug repellent, might seem an easy target.

Lauren Fendrick and Brooke Sweat didn't stir any controversy, or even make any comments about the virus, in the run-up to their match Sunday in women's volleyball. All the same, the two Olympic newcomers got rousing jeers of "Zika" from fans in bright green and yellow Brazilian jerseys every time they served against Poland.

"Solo has a lot of fans in Brazil and made a very derogative post on social media making fun of the country," said Rodrigo Porto, a 37-year-old engineer. "Every time she kicks the ball, the whole stadium will scream back Zika at her."

Porto says he took part in yet another round of Zika-laced taunts Saturday directed toward another American, defending Olympic beach volleyball champion Kerri Walsh Jennings.

"Brazilian fans are loving, but when they are disappointed and want to make fun of someone, they are relentless," he said.

Not every American is getting booed. On Sunday, crowds cheered loudly for gymnast Simone Biles.

It would be hard to blame U.S. athletes or foreign tourists for being worried about Zika, which can cause birth defects in babies born to mothers who have been infected.

In May, 150 health experts from several countries posted a letter to the World Health Organization calling for the games to be postponed or moved until more about the disease is known. That call came despite the fact that the Olympics are taking place in the Southern Hemisphere's winter, which usually decimates the mosquito population.

The WHO has warned for months of a very low risk of Zika spreading during the Rio Olympics. In addition to the low temperatures — August is Rio's second-coldest month with average daytime highs of 79 degrees Fahrenheit (26 degrees Celsius) — many in Rio have developed immunities after living with the virus for about a year.

That stands in contrast to places where the virus is just now arriving. In Miami, at least 15 people are believed to have been infected through mosquito bites in what would be the first such cases in the mainland U.S.

The most recent data compiled by the Pan American Health Organization showed a steady decrease in suspected Zika cases in Brazil since its peak in February, when about 16,000 cases were reported in a single week, and almost no cases of the virus as of late July. At the Copa D'Or hospital in the touristy Copacabana beach neighborhood, doctors were at a loss to remember even a single case of Zika, chikungunya or other mosquito-borne diseases since June.

"I don't know if the risk is zero, but certainly Rio is one of the safest places in the hemisphere right now, arguably even more than Miami," said Dr. Peter Hotez, a tropical medicine expert at the Baylor College of Medicine in Texas.

Lee Igel, one of the authors of the letter, said he's happy that some of the dire warnings didn't pan out. But he stands by the letter's contents and cautions that much more research is required.

He cited new evidence showing Zika can remain in sperm for longer than the previously thought 90 days, and he called that a serious risk as 500,000 tourists descend on Rio, with some likely to have sex with Brazilians who've been previously infected, perhaps unknowingly, with Zika.

"It's a virus that has evolved. We still don't know the long-term consequence, and every day there's new information popping up," said Igel, a sports and medical ethics expert at New York University.

Still, anxiety over Zika has run high for months among some athletes preparing for Rio. Golfers Jason Day and American tennis duo Mike and Bob Bryan pulled out of the games, while basketball player Pau Gasol of Spain said he was considering freezing his sperm because of the virus.

Tourists in Rio have been bombarded with free bottles and cans of mosquito repellant, courtesy of SC Johnson's OFF! Brand, an official sponsor at the games.

South Korea equipped its athletes with mosquito-repellant uniforms and Australia distributed special antiviral condoms to reduce the risk of sexual transmission.

But Brazilians, who have spent their entire lives making peace with mosquitoes, have always viewed the alarm with skepticism. They complain their northern neighbors are frequently uninformed and unwilling to recognize Brazil's quick identification of the virus here and efforts to eradicate it.

And they are not about to let that go unanswered.

"I think it is just pathetic to be afraid of Zika in Rio at this time of the year," said Nathalia Ferreira, a 29-year-old pharmacist. "I expected people to be more informed. I am more afraid of getting some kind of flu from someone who flew here."