Risk of infection very low indeed, despite concerns heightened by first case in Europe of baby affected by the virus
Spain has reported what is said to be the first birth in Europe of a baby with Zika virus-related brain damage, according to the health authority in Catalonia, where the child was born.
The mother, who has not been identified, caught the virus on a trip abroad but authorities have declined to say where. She was infected in Latin America, where the virus is widespread.
News of the birth came as a study from the United States revealed that between just three and 37 people out of a possible 500,000 visiting Brazil for the Rio Olympics would be expected to go home with Zika.
The study, published in the Annals of Internal Medicine, was carried out to assess the risk in the light of calls from 150 academics for the Olympics to be moved from Rio or called off. Researchers from the Yale School of Public Health, however, said the risk was negligible.
The possibility that travellers returning from the Olympics may spread Zika has become a polemic issue that has led to athletes dropping out of the event, and without evidence, undue stigmatisation of Brazil, said Prof Albert Ko, chair of the department of epidemiology of microbial diseases at YSPH.
Ko said: This study provides data, which together with initial findings from Brazilian scientists, show that these concerns may be largely exaggerated.
The Yale team said rather than Olympic athletes and spectators, it is far more likely that other tourists will be bitten by the Aedes aegypti mosquito and become infected with Zika.
If anything, I would say the estimate we have published greatly overestimates the true risk, said the studys lead author, Joseph Lewnard.
The team made the assumption for the paper that the risk of infection for the visitors was the same as for people living in Brazil, but the visitors will be staying in air-conditioned accommodation where every effort has been made to eradicate mosquito populations.
Based on that I would expect it to be far lower than the numbers we present, he said.
Another study predicted that 1.65 million women of childbearing age in central and south America will be infected with the Zika virus during the current outbreak. The paper by academics at the University of Southampton, the University of Notre Dame and the University of Oxford, which is published in Nature Microbiology, was based on modelling the effects of the epidemic in 5km squares across the region.
The World Health Organisation has sought to reassure athletes, their teams and spectators that Zika will not be a threat at the Olympics, but some have pulled out, including a significant number of golfers in the wake of Rory McIlroys decision not to travel.
This study suggests that for spectators and athletes travelling to Rio this summer, the risk of contracting Zika virus is very low indeed. What risk there is can be mitigated further by taking measures to prevent mosquito bites, such as applying a high quality insect repellent regularly, said Prof Mike Turner, the director of science and head of infection and immunobiology at the Wellcome Trust.