麻豆传媒

SAN DIEGO -- Olympic and Paralympic athletes from the U.S. headed to Brazil in 2016 with Zika virus on their minds, but it turns out they might have missed the true mosquito-borne threats, researchers said here.

None of 457 athletes who attended the games in Brazil showed signs of Zika virus, but blood tests revealed that 48 (11%) appeared to have been infected with dengue, chikungunya, and West Nile viruses, according to Krow Ampofo, MD, of the University of Utah School of Medicine in Salt Lake City, and colleagues.

"Everybody's attention was drawn to the Zika virus, and nobody was looking for the others [diseases]," Ampofo said in a presentation at the annual IDWeek meeting, sponsored jointly by the Infectious Diseases Society of America (IDSA), the Pediatric Infectious Diseases Society (PIDS), the Society for Healthcare Epidemiology of America (SHEA), and the HIV Medicine Association (HIVMA).

However, none of the infected athletes suffered severe symptoms, all recovered, and most should have nothing more to worry about, Ampofo told 麻豆传媒.

Still, the findings were surprising and reveal an unseen number of illnesses, he noted.

The spread of Zika virus in Brazil was a major news story before and during the 2016 Summer Olympics in Rio de Janeiro, which was followed a month later by the 2016 Summer Paralympics for disabled athletes. In fact, the Zika outbreak had peaked in February and March of 2016, months before the Olympics and Paralympics events in August and September, Ampofo said.

"The Brazilians didn't comment on what other arboviruses were there," he said. "We know there's dengue in the area, but the focus was on Zika."

The University of Utah, which provided healthcare to U.S. athletes, received blood tests and surveys from 950 athletes before the events. Of those, 457 (48%) provided blood samples weeks after the games.

Four (0.9%) tested positive for Chikungunya, six (1.3%) for dengue, and 39 (9%) for West Nile Fever. Researchers linked 32 of these cases -- three of four Chikungunya cases, two of six dengue cases, and 27 of 39 West Nile Virus cases -- to travel after the initial blood tests were taken before the games.

There weren't significant differences in terms of demographics and exposure between those with travel-related arboviral infection and those without. The median age hovered around 35 in both groups, and while two-thirds of those with infections were male compared to 49% of those without, there wasn't a statistically significant difference.

Surveys showed that those with infections were more likely than the others to have gotten mosquito bites in Brazil, but that wasn't a statistically significant difference either. However, those with infections were less likely to have used insect repellent (58%) than those without infections (84%, P=0.04).

While the infected athletes seem well, dengue fever in particular has a risk of heightened infection the second time around, Ampofo said.

Why did so many athletes seem to already have been exposed to West Nile before they left the country? Ampofo said that could be because it's so endemic in the U.S. "Depending on which state you live in, you could be infected," he said.

Some of the apparent arbovirus cases could be false positives, commented Wes Van Voorhis, MD, PhD, of the University of Washington in Seattle, who moderated the IDWeek session.

Among the returnees who responded to surveys, the level of symptoms of those with arbovirus infection was actually a bit lower than those without infection, Ampofo told 麻豆传媒.

Fortunately, the results suggest that no one was infected by Zika, he said. "There was a guy who banked his sperm" out of fear before going to the Olympics, "and we can at least hope he had a good time," he noted.

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