Noni E MacDonald describes the low risk for Zika infection during the Olympic and Paralympic Games in Brazil and urges visitors and supporters of the Games to help address the Zika epidemic.

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Every four years the world eagerly turns the spotlight on the country hosting Olympic and Paralympic games. In anticipation, there is relentless news coverage on whether the venues will be ready, what world records might fall, and whether doping will be a problem. For the Brazil Games however, concerns about Zika risks have been added to the mix. Some strident voices have loudly called for the Games to be cancelled or moved. Sadly, many of these voices of doom and gloom failed to examine the evidence and weigh up the risk before offering their opinions.

Brazil is one of the countries reporting transmission of Zika virus by mosquitoes. This is the main route of transmission although sexual transmission also occurs and blood transfusion transmission may be possible. Zika appears to have a particular affinity for neural tissue and is now recognized as a significant cause of congenital abnormalities including microcephaly and of Guillian-Barré Syndrome.

Zika infection in pregnancy appears to be most devastating for the fetus if it occurs late in the first trimester and/or early in the second trimester – much like the timing for most damage with rubella infection in pregnancy. Similar to rubella, the severity of illness in the pregnant women does not predict the severity of damage in the fetus. Asymptomatic infection in the mother has been associated with severe microcephaly and/or major brain anomalies without microcephaly.

Guillian-Barré Syndrome is a serious autoimmune disorder that can be triggered by exposure to some bacteria (for example, campylobacter) and some viruses (for example, influenza). Guillian-Barré Syndrome can cause numbness, muscle weakness and paralysis for up to a few months but most cases recover. With intensive support the majority of patients do very well as only rarely are the nerve changes permanent or even fatal. The rate for Guillian-Barré Syndrome with Zika is about 1/4000 of adults infected. This rate is higher than campylobacter, the most common known cause of this Syndrome.

But what is the risk of Zika infection at the 2016 Games? July and August are not mosquito season in Rio. The cooler dryer weather usually seen at this time of year is not hospitable to mosquitoes and fewer mosquitoes means a much lower risk of Zika transmission.

For athletes and visitors, risk can be further lowered by choosing air conditioned accommodation, using effective insect repellents, wearing light coloured long sleeved shirts and slacks, practicing safer sex or abstaining from sex, and avoiding impoverished areas with poor sanitation and open water where mosquitoes can breed. These steps to decreasing mosquito bites should be taken by any visitor to any country where mosquitoes are major vectors for disease transmission such as dengue, chikungunya, West Nile, yellow fever viruses and malaria.

Setting aside for the moment interests in personal safety, how might all of us help to address the health needs of Brazilians affected by Zika?

First, Zika has been devastating for infants infected in utero. What can each of us do to support these mothers and their infants especially as Brazil’s economy is not strong? Local organizations supporting programs for mothers and their infants are much needed. A number of international health charities who support women and children’s needs can help, but they need donations to do this. Have you donated?

Second, pressure must be brought to bear to control areas where mosquitoes breed – especially open water in slum areas where better sanitation and rain water control are needed. This is of critical importance not merely for the benefit of athletes and visitors, but for the benefit of Brazilians.

Third, pressure is needed for the rapid development of a Zika vaccine. Yet, a number of thorny vaccine quandaries remain. Should pregnant women, especially women in early pregnancy living in an area where Zika is rife, be eligible for the vaccine trials? Once developed, who should be at the top of the Zika vaccine allotment list? Production may not keep up with demand and many countries may not be able to afford a publicly financed program. Should women of child bearing age compete for access with all adults given the relatively high risk of Guillian-Barré Syndrome? These are not simple questions.

Additional questions pertain to whether a live attenuated vaccine or an inactive vaccine is developed. Inactivated vaccine might have more limited risks, but attenuated vaccine would be very worrisome for pregnant women until shown to be safe.

The Rio games should go on as the Zika risk (because of the time of year) is relatively low and can be managed. But we must not sit on the side lines watching this Zika epidemic evolve – we can help and our voices and donations matter.

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Noni MacDonald is a Professor in the Department of Pediatrics at Dalhousie University.