|
 Chief among their concerns is whether Zika, unlike similar
mosquito-borne viruses, can be transmitted sexually, or remain
latent in the body - possibly presenting a risk for women who become
pregnant after the Olympics have ended.
More than a dozen disease experts, in interviews with Reuters, said
there is no evidence at this point of long-term risk for future
pregnancies. But, given the surprises seen with the virus so far,
they said people should remain cautious until studies give
scientists a better picture of how the virus works. They said it
would take months or even years of study for definitive answers to
questions about Zika's risks.
Public health agencies have urged pregnant women to avoid travel to
Zika outbreak areas but have given little guidance for couples
planning to start a family.
Dr. Claire Panosian, of the University of California, Los Angeles,
division of infectious diseases, said that for years she has advised
couples to wait several months after traveling to exotic locales
before trying to conceive because of the risk of birth defects from
diseases like toxoplasmosis.
Zika should be no different, she said: "Women of child-bearing age
should be very scrupulous - wait several months."
The virus, which is spreading rapidly through the Americas, has been
linked to a spike in microcephaly, a rare birth defect, in Brazil.
The condition is defined by unusually small heads in newborns and
can cause brain damage.
Zika has not been proven to cause microcephaly, but evidence of an
association led the World Health Organization to declare the
outbreak a global health emergency.
The U.S. Centers for Disease Control and Prevention says pregnant
women should consider skipping the 2016 Olympics because of the risk
of Zika infection. For women who are considering becoming pregnant -
and their male partners - the agency recommends consulting their
physicians in deciding whether to go to the Games.
The U.S. Food and Drug Administration, however, has suggested a more
detailed time frame. It called this week for a six-month delay in
all human cell or tissue donations, including of semen and eggs,
from people who have had Zika infections or traveled to an outbreak
area.
Canada's national health agency on Wednesday advised women who want
to get pregnant to wait at least two months after traveling to
countries affected by the Zika outbreak.
Eighteen women have competed in modern Olympics while pregnant
according to a group of Olympic historians who publish their
statistics at Sports-Reference.com. The number includes U.S. beach
volleyball gold medalist Kerri Walsh, who was not yet aware she was
pregnant when competing in London in 2012.
Some current Olympic hopefuls say they might think twice about the
Rio Games if Zika could threaten future pregnancies, and they are
hoping for some better answers before the competition begins.
"If things stood as they are right now, I probably would not go,"
renowned U.S. soccer goalkeeper Hope Solo told CBS last week. "At
some point I do want to start a family, and I don't want to be
worried."
Solo has spoken out about feeling conflicted over her two great
ambitions – winning Olympic gold and becoming a mother in the
future. "It's scary, and I have a lot of reservations about going to
the Olympics," she said.
DeeDee Trotter, a 33-year-old Olympic sprinter and medalist who aims
to make the U.S. team again this year, said in an interview she
wasn't worried "if the only danger is to women who are pregnant."
That sentiment could change if a prior Zika infection is shown to
pose a risk later "when I do decide to have children," she said.
The U.S. Olympic Committee has told athletes that babies may be at
risk if the mother is infected with Zika while pregnant, or if she
becomes pregnant within an unknown time frame after being infected.
[to top of second column] |
"We have worked to ensure that all potential Olympic and Paralympic
athletes are aware of the CDC's recommendations, and we will
continue to do so," USOC spokesman Mark Jones said in an emailed
statement. "They are the experts."
THE IMMUNITY QUESTION
The CDC says experiencing a Zika infection once likely protects a
person from future infection, although that immunity - like so many
aspects of Zika - is not yet proven.
"It is likely that, following infection, people are immune, but what
percentage of convalesced patients and for how long will not be
clear for some time," said Dr. Leslie Lobel, chair of the department
of virology and developmental genetics at Israel's Ben-Gurion
University of the Negev who has been working with Ugandan and
Brazilian scientists to investigate Zika.
Whether the virus can remain in the body and cause a recurrence also
is not known. In one case, Zika virus was detected in semen 62 days
after the man was infected, but it was not clear whether it was
capable of infecting someone else.
Separately, the CDC is investigating at least 14 cases of possible
sexual transmission.
Zika was first identified in 1947 in Uganda and previously linked to
smaller outbreaks. Many people who are infected show no symptoms,
while those who become ill report relatively mild effects of rash or
fever. There is no vaccine or treatment for the virus, which is in
the same family as dengue, West Nile virus and yellow fever.
Ann Powers, acting chief of the arboviral disease branch at the
CDC's Division of Vector-Borne Diseases, said other viruses similar
to Zika do not remain latent in the body. But she said it will take
months or years to know for certain whether Zika behaves similarly.
Viral infections provoke the human immune system to eliminate the
invader, leaving behind "memory cells" to fight future incursions by
the same virus. But some viruses, like HIV or herpes, can stay in
the body, leaving a person vulnerable to repeat flare ups. Others,
like dengue, can infect multiple times because they have several
strains.
"My feeling is that Zika is very close to dengue virus," said Jae
Jung, director of the University of Southern California Institute
for Emerging Pathogens and Immune Diseases. "There is probably a
very, very low chance of latency" - or a propensity for recurrence.
Other experts caution that Zika's apparently unique behavior on many
fronts means that nothing should be taken for granted.
The deadly Ebola virus, from a different family, has not provided
immunity to all patients who survived infection. In several cases,
including a Scottish nurse, the virus appears to have been
reactivated many months after recovery.
"We cannot assume based upon yellow fever and dengue what's going to
happen with Zika. This one's different," said Dr. Joseph Vinetz, a
tropical disease clinician and professor at the University of
California, San Diego School of Medicine.
(Reporting by Deena Beasley; Editing by Michele Gershberg and Lisa
Girion)
[© 2016 Thomson Reuters. All rights
reserved.] Copyright 2016 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
 |
