W.H.O. says Olympics should go ahead in Brazil despite Zika virus

The Olympic Games should go on as planned, theWorld Health Organizationsaid Tuesday, and athletes and spectators, except for pregnant women, should not hesitate to attend so long as they take precautions against infection with the Zika virus.

Pregnant women were advised not to go to Brazil for the event or theParalympics. The W.H.O. previously told them to avoid any area where Zika is circulating.

Some attendees may contract the mosquito-borne infection and even bring it back home, but the risk in August — midwinter in Rio de Janeiro — is relatively low, W.H.O. officials said.

Travel related to the Olympics accounts for only a fraction of the travel already occurring to and from countries with Zika transmission, the officials noted.

Mass gatherings like the World Cup or the Muslim pilgrimage to Mecca “can amplify a disease or can raise the risk that it will spread to other countries,” said Dr. Bruce Aylward, who is leading the W.H.O. response to Zika. “You can’t dismiss that, but the committee felt there should be a much lower risk from the Olympics.”

The W.H.O. was acting on the advice of its emergency committee, but essentially repeated the Olympics-related travel adviceit gave on May 12, which implied that the Games should go on. The agency expects Zika to spread from northern Argentina to the southern United States whether or not the Games take place.

The Aedes aegypti mosquitoes that spread Zika are rare in Europe and in nontropical regions of North America. The virus is believed to be endemic in Africa and Asia, though it is not certain how many people have had it or whether they are immune to the strain circulating in the Americas, a descendant of the Asian strain.

Dr. Karin Nielsen, an infectious disease pediatrician at the University of California, Los Angeles, who is studying Zika infections in Rio de Janeiro with the Oswaldo Cruz Foundation, said the foundation had reported no new cases in nearly eight weeks since the weather began cooling. Mosquito-borne diseases “run a cycle and are not continuously present, so Zika should not be a problem for the Olympics,” she said.

But other experts disagreed.

Amir Attaran, a public health and law professor at the University of Ottawa, called the decision “scientifically ill-considered.”

“The people going to Rio are the elite: the athletes and the global 1 percent who can afford tickets and can take precautions,” he said. “But the people shouldering the risk if this spreads will be the slum-dwellers in Mumbai, Kinshasa and Lagos who aren’t going to be able to take precautions.”

Dr. Attaran has been urging the W.H.O. to advise postponing nonessential travel to affected areas. The agency did not, but said that officials in Brazil should “continue to intensify” mosquito control and that insect repellent,condomsand health advice should be available for all athletes and visitors.

Arthur L. Caplan, a bioethicist at New York University whowrote in Februarythat holding the Olympics in Brazil would be “irresponsible,” said the W.H.O. was “betting on the weather, responsible behavior by visitors, adequate mosquito control and a low sexual-transmission rate by returning visitors. All are gambles.”

Also on Tuesday, the Centers for Disease Control and Prevention released a proposed plan for fighting Zika if it starts spreading in the continental United States.

The agency expects some local mosquito transmission this summer in Florida and along the Gulf Coast to Texas. The plan outlines steps if even one case appears.

Because Aedes aegypti mosquitoes do not fly far, officials can provide “a large margin of safety” by concentrating efforts within a one-mile circle around each known infection, the plan said.

One case, with no further transmission, would require a 45-day effort, the C.D.C. said. But if the infection spreads, the agency will help local officials investigate and warn residents. If needed, it will send emergency teams.

The W.H.O. convened its emergency committee by phone to consider the Olympics because, under regulations adopted in 2007, the declaration of an international public health emergency requires that the committee that recommended it meet every three months to assess the situation.

On Feb. 1, the committee advised the W.H.O. director general, Dr. Margaret Chan, to declare an emergency over the possibility that the Zika virus had causedacluster of birth defectsin large numbers of babies in Brazil.

The W.H.O. and the C.D.C.have concludedthat Zika causesmicrocephaly: abnormally small heads and brain damage in infants.

(THE NEW YORK TIMES)