The World Health Organization is studying how great a health risk would be posed by going ahead with the Rio Olympics as scheduled despite concerns about the effect of the zika virus on either athletes or spectators.
The director-general of the U.N. agency, Margaret Chan, says she has asked the agency’s zika emergency committee to evaluate the risk, considering the large numbers of people who will travel to Brazil for summer games in August, an estimated 10,000 athletes from 200 countries and 500,000 spectators.
Dr. Chan said she called on World Health experts in response to a request from a U.S. Senator, Jeanne Shaheen, from the northern state of New Hampshire, who expressed concern about public-health hazards in Rio de Janeiro this year.
“The experts, well-versed in travel medicine, the epidemiology of vector-borne diseases, seasonal patterns of mosquito-borne infections, and risks communications, will meet shortly,” Dr. Chan wrote to Sen. Shaheen. Her letter, sent on Wednesday, said the emergency committee’s assessment would be posted online immediately.
No date has yet been set for the emergency committee’s meeting.
In a global situation report Thursday on zika and associated medical problems, World Health said the virus continues to spread around the world, and vigilance needs to remain high. Overall, 60 countries worldwide have experienced zika outbreaks this year, more than twice as many as last year, the agency said.
World Health has sent teams of senior scientists to Brazil four times to date to gather data on the situation ahead of the games. Even before the U.S. senator’s request, health officials said they were planning for a meeting of experts during June.
About two million Brazilians have contracted Zika since its
outbreak in 2015, and the virus also has spread widely through other parts of Latin America. Medical experts believe Zika is responsible for a surge of serious birth defects, microcephaly, in which babies are born with unusually small heads and brains, and may well also be linked to other diseases.
The mosquito-borne zika virus directly infects the brain progenitor cells destined to become neurons, The University of Texas Southwestern Medical Center researchers reported in a study published online in Cell Reports.
The team of researchers used a strain of zika currently affecting the Americas, and found that the virus infects about 20 percent of cells on average, evades immune system detection and continues to replicate for weeks.
“The cellular system we studied mirrors what pathologists are finding in the brain tissue of affected infants and will be valuable for further understanding how zika causes severe brain-related problems. The system may also serve as a platform for testing new therapies targeting the virus,” said John Schoggins. He is an assistant professor of microbiology at Southwestern and senior author of the study.
The Centers for Disease Control and Prevention Web site lists a series of unanswered questions about the virus. The unanswered questions include when during pregnancy the infection may harm the fetus and how the virus affects individual pregnancies.
“There was a suggestion that the detrimental effects of the virus might be linked to its ability to infect brain cells, specifically the progenitor cells that give rise to neurons,” said Schoggins in a release issued by Southwestern.
“We showed that neural progenitors can be infected by a strain of zika virus that is currently infecting people in the Americas,” Schoggins said. “We found that the virus kills some neural progenitor cells, but not all. Other cells survive the infection, and surprisingly, continue to replicate the virus for many weeks. In addition, it appears that zika virus does not stimulate much of an immune response.”