As the eyes of the world turn to Rio de Janeiro, host of this summer’s Olympic Games, a discussion has exploded about the Zika virus and its potential threat to athletes and tourists, as well as the possibility of a global pandemic. To get the facts, we went to Dr. Rodrigo Brindeiro, director of the Biology Institute at the Federal University of Rio de Janeiro—one of the leading research institutions in Brazil. Dr. Brindeiro, a molecular biologist and geneticist, is part of the team at the university’s Laboratory of Molecular Virology that is currently studying both how the Zika virus affects fetal brain development and potential treatment options. We spoke to him at his laboratory. This interview has been edited for clarity.

Can you give a threat assessment of Zika? How widespread is it? How dangerous is it? And who is most at risk?

We are just now gathering all of the information about this global threat. The virus was first identified in 1947 when it was discovered in the Zika forest in Uganda. Very few knew about it. They just knew that it was a mild virus. Then it spread epidemically in the 1970s to West Africa and then Southeast Asia. Various Zika-related syndromes including microcephaly [abnormal smallness of the head, a congenital condition associated with incomplete brain development] were found in fetuses and babies, but reported instances were very low and they thought it was not directly related to the presence of the virus. Only when they made a retrospective kind of analysis did they find that there was this relationship. It must be noted that microcephaly is only one aspect of this syndrome. It includes a whole series of neurological disorders. And that happened in widespread fashion only in Brazil.

There were so many other theories about what was causing high incidence of microcephaly: trying to say that it was not because of the Zika virus, but because of pesticides and insecticides, and things like that. But it’s not that, and we can prove the relationship between Zika and microcephaly because there were cases of pregnant women with twins in the northeast of Brazil. One was absolutely healthy and the other has microcephaly. If it was about chemicals, this would not happen…. In Brazil, as in many other places, it wasn’t required to report cases of microcephaly to public-health officials. ­­Now it is. So when Zika came, we didn’t have the baseline to compare the frequency of microcephaly happening because of Zika or not. For a pregnant woman that is exposed to Zika virus, there is a 30 percent chance that the fetus will develop the disease. There is much we don’t know, for example we know nothing about infants, infected after they were born. But we know that there is possibility of something very severe.

For adults, Zika infection normally gives a rash and a mild fever or the infected will show no symptoms at all and it will just go away in several days. But for 5 percent of those infected, you can have the development of neurological complications like meningitis, encephalitis, or myelitis. And you have some severe cases for example here in the University Hospital with elderly people developing these kinds of neurological disorders.

So why did it take root in Brazil and explode in such a way? You said it was in Uganda. Uganda also has inequality, standing water, poor sewage—all the things that you hear people speak about with regards to the spread of Zika. Why in Brazil has it taken off as it has?

The population of Uganda is not dense and the spread of Zika is a population-density issue. This kind of virus is spread through the mosquito and that happens in densely populated big cities where you don’t have the sanitary control to control the spread of the mosquito. But this mosquito does not go very far. They fly roughly 100 to 200 meters. With the low density of population, it’s harder to have this spread. In [heavily populated] suburban [Rio] areas like Mesquita, Nova Igaçu, Duque de Caxias, you have the problem, because the mosquito can spread it rapidly.

What did you think of the idea that the Olympics should be canceled because of Zika?

I would not say that [the Olympics should be canceled], for many reasons. First of all, if somebody is infected with Zika, they have a 40­ to 60 percent chance of developing the most prevalent outcome of the infection—that is, just a low fever and rash for one or two days. It’s not a big issue. Most of the rest who get Zika will be absolutely asymptomatic. No symptoms at all. But ­5 percent of them could develop more severe neurological disorders. What the government is doing right now is to intensively fumigate all those areas to avoid the presence of the mosquito that is responsible for let’s say, 90 percent of the transmission of this virus

So you don’t think the Olympics would spark a global pandemic?

No. For the athletes, I don’t think there will be anything but a very low ­level risk of contamination, because they will be in [a controlled environment]. The athletes you can control by controlling their area of action. But tourists can come here to watch a game, [then] they can go to the Amazon area and then they will be exposed. But it’s very easy for you to control that if you are using just repellents and wearing the right clothes for that. So I don’t think it’s a big issue.

The best way to fight the spread of Zika virus—tell me if you disagree—would be for the government to aggressively implement better sewage and eliminate standing water in poor communities. Wouldn’t that be the best way to limit its spread?

That’s absolutely right. For a long time in Brazil, and in Rio de Janeiro, there was a big incidence of dengue. All kinds of government official propaganda were issued saying that the main [factor] in the spread of the [dengue] was [standing water] in homes. I’m not saying that it’s not a cause of the spreading of mosquitoes, but come on. If you take the reality right now from Zika, chikungunya, and dengue, what you see is that the poor populations are affected. Why? It’s not because of their plants. This is absolutely easy to understand when you go to places like Mesquita, Nova Igaçu, and Duque de Caxias [areas in the outskirts of Rio de Janeiro] where you see the total lack of government intervention to establish good standards of sanitation. You see big areas of open sewage close to the houses, dirty water canals, and things like that because of the lack of government intervention in the public engineering system and the health system. You don’t go to Ipanema and see that, but if you go to Duque de Caxias you will see lots of these, low-wage families living in bad situations, and that’s where you can see, for example, open waste areas, and lack of sufficient government intervention to put the pipes in the place. There’s a place in Campina Grande [one of epicenters of microcephaly] close to its hospital, actually, where you will see clouds of mosquitoes.

The government approach for dengue was “Let’s wait for the dengue vaccine,” and now we are paying a price for that. A mosquito can carry hundreds of different viruses. So, okay, you can wait for the dengue vaccine, but then, you will need a Zika vaccine, chikungunya vaccine, and Mayaro vaccine, and o’nyong’nyong vaccine, and so many other viruses that will spread. Zika is about mosquitoes. If you don’t deal with that, other viruses that will come. So Zika is a crisis, but also as always, crisis equals opportunity. There is an opportunity for us to finally focus our eyes upon the control of the mosquito. That is most important: something that should be easy to do, but you have to have the political will to do so. That’s the big issue. So we still have to develop vaccines, we still have to develop new medicines, but first we have to control the mosquito.

Do you also accept the argument that August is a month when there aren’t as many mosquitoes in Rio and that decreases the risk dramatically?

The temperature is going down until July, so we really believe that incidents are going to be low. But there are issues like sexual transmission and the forest reservoirs which the lower temperatures won’t affect—i.e., transmission still possible in these ways despite lower temps. Forest reservoirs are a big issue in Rio de Janeiro, ­­as you know. It’s a beautiful city. One of the things that makes the city beautiful is that we have forests inside the city, like Tijuca forest. It’s a city, a metropolis, that is totally a mosaic of urban, rural, and [forested] areas. I would be more concerned about the Olympic tourists than the athletes. You cannot control the movements of the tourists.