Three to 37 athletes, tourists and journalists travelling to Brazil for the Summer Olympics could bring Zika virus back to their home countries in a “worst-case scenario,” Yale University scientists say in a new study calling the mosquito-borne virus’ threat “negligible.”

While handfuls of high-profile sports stars have dropped out of the Summer Games in Rio de Janeiro, Yale School of Public Health doctors say travel to and from the Olympics shouldn’t be a concern when it comes to Zika’s spread.

Their findings align with what the World Health Organization and the U.S. Centers for Disease Control and Prevention had concluded earlier this month: the risk is “low” for Zika’s spread at the global event.

READ MORE: Low risk for Zika to spread following Rio Olympics in all but 4 countries

“It’s important to understand the low degree of risk posed by the Olympics in the scheme of many other factors contributing to international Zika virus spread,” the study’s lead author, Joseph Lewnard, said in a university statement.

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“The possibility that travellers returning from the Olympics may spread Zika has become a polemic that has led to athletes dropping out of the event and, without evidence, undue stigmatization of Brazil. This study provides data, which together with initial findings from Brazilian scientists, show that these concerns may be largely exaggerated,” Dr. Albert Ko, another study co-author, said.

Lewnard, Ko and their team created a mathematical model that factored in Zika’s recent transmission in Rio, weather conditions and travel patterns to come up with their estimates.

READ MORE: Rio Olympics: WHO rejects calls to postpone due to Zika virus

They say that more than half of tourists heading to Rio will return to high-income countries where it’ll be hard for the virus to take hold.

Another 30 per cent will head back to Latin American countries where transmission is already well underway.

Keep in mind, it’s already winter in Rio so mosquito activity has subsided.

The Olympic and Paralympic games are expected to draw an estimated 350,000 to 500,000 international visitors and athletes from 207 countries. But health officials say that travel this year will account for less than one per cent of international travel to Zika outbreak countries.

Last month, the World Health Organization rejected calls by some to cancel the Summer Games, saying there is a “very low risk” the Olympics will accelerate the spread of Zika around the world.

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READ MORE: Is the Zika virus a public health risk or an Olympic-size overreaction?

Like dengue, West Nile and yellow fever, Zika virus is a mosquito-borne tropical disease, meaning mosquitoes transmit the disease to humans.

Health officials in El Salvador, Brazil, Jamaica, Ecuador, Honduras and Colombia told residents to delay pregnancy until doctors better understand if the infection tampers with brain development in infants. So far, it’s been linked to a 20-fold increase in a rare defect called microcephaly in babies, in which infants are born with irregularly small heads and underdeveloped brains.

carmen.chai@globalnews.ca

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