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Physician Weighs In On Zika Risk As Athletes Drop Out Of Rio Olympics06:51Download

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Aedes aegypti mosquitos are seen in a lab at the Fiocruz Institute on June 2, 2016 in Recife, Brazil. Microcephaly is a birth defect linked to the mosquito-borne Zika virus where infants are born with abnormally small heads. (Photo by Mario Tama/Getty Images)MoreCloseclosemore
Aedes aegypti mosquitos are seen in a lab at the Fiocruz Institute on June 2, 2016 in Recife, Brazil. Microcephaly is a birth defect linked to the mosquito-borne Zika virus where infants are born with abnormally small heads. (Photo by Mario Tama/Getty Images)

The world’s top-ranked golfer, Jason Day, has joined a group of athletes, mainly golfers, who have dropped out of the Olympics because of fears over the Zika virus. The group also includes the American cyclist Tejay van Garderen.

The athletes cite family planning concerns as their primary reason for bowing out. The World Heath Organization is advising pregnant women not to travel to countries with Zika outbreaks, but all the athletes canceling their Olympic bids are male. They say they're worried about transmission to partners.

Here & Now's Robin Young talks with Dr. Dean Blumberg, chief of pediatric diseases at UC Davis Children’s Hospital, about the real risks involved for athletes — and spectators — who venture to Rio.

Interview Highlights: Dr. Dean Blumberg

On knowing, or not knowing, if a person has contracted the virus

"There's a lot more that's not known than is known. The issue with Zika is that it it can cause latent infection in privileged sites of infection. So in the male, that might be in the testicles or some other area where the immune system doesn't reach it effectively, so it doesn't eliminate it. We've seen this for example recently with Ebola virus, where people recover from their acute infection and then the males mate transmit it months later.

And so this has happened with Zika virus, where men have had Zika virus, they've had the acute infection, they've recovered, and then they've transmitted it either through vaginal intercourse, anal intercourse or with oral sex. That has happened. The unknown in this is that it’s not known how long it can be carried in the sperm. So a handful of men have been studied in this area, and what they've found is they've detected viable Zika virus up to 62 days after infection."

On the varying risk levels different athletes may face

"You can imagine somebody like a basketball player or a gymnast who flies into the country, they're in a cab, they go to an air-conditioned hotel and then they're practicing and competing indoors, would have much less risk of exposure to a mosquito, and so much less chance of transmission. Whereas somebody who is outdoors would have much higher risk of being exposed."

On whether or not the Olympics could lead to a more rapid spread of Zika

"Well, certainly they can become infected while they’re in country, and then they could return home and if there was a mosquito that was a competent vector, then you could get transmission in the home country. But the issue is there’s already is so much international travel and globalization, that it's probably not going to significantly change the transmission dynamics. And so we've seen this with other infectious diseases — so for example SARS and when H1N1 came out in 2009 — that these travel restrictions have little effect on spread of these diseases."

On uncertainty in detection time

"What's interesting of that is there's a lot of area of uncertainty. So it’s been detected up to 62 days after infection, but that's where they stopped checking. So does that mean it’s still viable 70 days, 80 days, three months, six months later? I don't know the answer to that, there's so much areas of uncertainty."

On the virus' symptoms

"The consequences of infection are really what's most feared because the disease itself is relatively mild. In 80 percent of cases, people who get infected with Zika virus have no symptoms whatsoever, and the other 20 percent, it’s a relatively mild illness lasting less than a week with fever, rash, muscle and joint aches and a form of pink eye.

What the concern is, is that if infection occurs during the first trimester or early in the second trimester during pregnancy, then this can affect the fetus, and what is causes is fetal brain disruption sequence. And then the brain stops developing, and what this causes then is then is the skull to collapse in on itself, and this results in the small head, or microcephaly. Between 1 and 13 percent of fetuses will be affected like this. But, I think that leads into a lot of the unknowns, between 1 and 13 percent is kind of a broad range. I don’t know what the risk of getting Zika virus infection is, and that obviously is going to depend on your activities and using mosquito repellent."

On the possibly of Brazil’s winter lowering the risk

"The Olympics are going to take place during Brazil's winter. What they have seen is a 20 times decrease of transmission of Dengue and Chikungunya which is transmitted by the same mosquito vector as Zika. And so one would expect 20-times decreased transmission of Zika also. These are all expectations in areas of uncertainty, and I think that's why the perception of risk really is in the hearts and minds of the beholder, especially when you're thinking of the devastating impact this can have on the unborn child. The problem with Zika is that we still have a lot of questions and we can't put a lot of numbers on the risk of Zika virus infection."

Guest

Dr. Dean Blumberg, chief of pediatric diseases at UC Davis Children’s Hospital in California and head of infection control at Shriners Hospital for Children. He tweets @DBlumbergPedsID.

This segment aired on June 30, 2016.

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