The chance of contracting a Zika infection during the Olympics is the same as winning the lottery
By Claudia Coeço, biologist, trained in ecology and biomathematics, researcher of Fiocruz’s Scientific Computing Programme (PROCC)
Being worried about the Zika virus is normal, as it is a disease that has a great emotional impact due to its effects on babies. Everyone, when leaving home to visit another country or city for example, internally gauges the risk of facing adversities and thus, uses information they get from friends and the media. In order to reduce this excessive worry of contracting a Zika virus infection during the Olympics, in addition to helping people make well founded decisions, the important thing is transparent information. People need to be sure they are receiving correct and updated information. Therefore, I consider every initiative to make data on the epidemiological situation available important, as well as situational analyses. It is worth remembering that even during the peak of Zika transmissions, there were no cases among the seven thousand athletes who took part in the 44 test-events conducted.
Zika’ mains transmission route is the Aedes aegypti mosquito bite. This mosquito’s behaviour is very much studied in Rio de Janeiro, due to the role it plays in the transmission of dengue. We know that in winter, when night time temperatures in Rio drop to below 22 degrees, the mosquitos’ transmission capacity is very much affected. This is because the virus needs around twelve days to cross the mosquito’s digestive system and reach the salivary gland so it can be injected into another person. And at this temperature the mosquitos have a shorter lifespan, bite much less and only a few survive these twelve days. That is why the number of dengue cases are always low in August, only one to seven cases in each 100 thousand people. In addition, some studies show that the Aedes aegypti is not a good Zika transmitter, thus, less cases of this disease are expected.
However, it is important to emphasise that it is not risk free, as at Games time there will be a very small probability (less than 0.00001) of catching a Zika infection. It is the same sort of chance as winning the lottery with just the one ticket. Despite this, it is important to protect yourself, following the recommendations made by Brazil’s Ministry of Health, of tourists’ countries of origin and GPs. To expecting mothers in particular, because of the risks associated to congenital Zika, you should consult with your doctor about the benefits and risks of visiting Brazil, or any other country where the virus is transmitted. Men who end up infected by the Zika should also try to inform themselves about the period when they should avoid sexual relations, in order to avoid transmitting the virus sexually to their partners.
Although the Zika virus had already been circulating for a few years in Micronesian islands, it was in Brazil that it gained scale and its serious effects on babies were recognised for the first time. Therefore, Zika ended up being associated to Brazil, although it had already been present in over 40 countries. The Zika epidemic is not a local problem, belonging to just the one country. It is a global problem and has to been seen as such, so appropriate public health measures are taken. These measures involve identifying places in the world where the disease has a better chance of establishing itself, in order to inform the population about its risks as soon as possible. It is also important to invest in innovative control strategies for the mosquito, as traditional measures like the use of insecticide have lost its efficacy. In addition, it is very important to invest in surveillance and diagnosis capacity, as well as assistance services for cities.
As mentioned above, the chance of contracting a Zika infection during the Olympics is the same as winning the lottery. As no one wants to win this prize, it is important to get information and follow the guidance provided by health agencies. This same effort will also protect from a potential dengue or chikungunya infection. So, it’s three types of protection for the price of one.
I wish you all a good Rio 2016 Olympic and Paralympic Games.