What health risk does the Zika virus pose to those planning on going to Rio?

We speak to leading professor in world virology, Dr. Mary Guinan, about the virus and this summer's Olympic Games

Mosquitos

Image: Ricardo Mazalan / AP/Press Association Images

This summer's Olympic Games in Rio have been met with strong resistance by some due to the country's economic and political turmoil, as well as the high levels of poverty that have not been addressed since the World Cup in 2014.

Their socio-economic standing aside, the outbreak of the Zika virus in Brazil in the past 12 months has drawn greater cause for concern to public health.

The virus, which can present no symptoms, has been linked with a birth defects and is massive threat to women who plan on having children.

"The Zika virus is one that has been recognised rather recently and is now causing havoc in Brazil," explains Dr. Mary Guinan, world virology expert and former chief scientific advisor at the Centres for Disease Control, Atlanta Georgia, "The virus is transmitted by mosquitoes, a certain brand of mosquito called Aedes Aegypti.

"Recently it's been found that it can be sexually transmitted, so even if you live in places where there are no mosquitoes to transmit the virus, you can get it through sexual transmission.

"One of the big problems with the Zika virus is that you may not know you have it.  Very often you're infected and you've got no symptoms whatsoever, but then become a carrier of the virus for months after and you don’t know it. For men it’s carried in the semen and they can infect their partners.

"One of the worst outcomes of the Zika virus can be seen in pregnant women. Pregnant women who are infected with the virus often have babies who are very badly affected.

"Their brains are affected, it’s very tragic. It causes something called microcephaly which causes babies to been born with a smaller than average head."

Scientists at the Centers for Disease Control and Prevention (CDC) concluded that the Zika virus is a cause of microcephaly and other severe fetal brain defects.

In a report published in the New England Journal of Medicine, the CDC authors described a rigorous weighing of evidence using established scientific criteria.

"It is now clear that the virus causes microcephaly" said Dr. Tom Frieden, director of the CDC, "We are also launching further studies to determine whether children who have microcephaly born to mothers infected by the Zika virus is the tip of the iceberg of what we could see in damaging effects on the brain and other developmental problems.

The virus is not one which is common in the US, with cases ranging from two in 10,000 to 12 in 10,000, according to Birth Defects Research (Part A): Clinical and Molecular Teratology. (2013;97:S1-S172)

Lara, who is just under 3-months-old and was born with microcephaly, is examined by a neurologist at the Pedro I hospital in Campina Grande in Paraiba state, Brazil. Paraiba and Pernambuco in Brazils impoverished northeast are ground zero for the Zika epidemic. Since Zika was first detected in Brazil, the two states have accounted for almost half of the 6,158 reported cases of babies born with shrunken heads, a rare condition known as microcephaly. (AP Photo/Felipe Dana)

"The virus eats some of the brain cells and destroys the cells causing the head to become small and there’s all sorts of damages that occur to the brain and to the rest of the body of the baby. Often babies die at birth or soon afterwards. It will have a life of great difficulty if it survives," Dr Guinan added.

Some of the impacts of microcephaly can be seizures, developmental delay (learning to walk and even stand) as well as intellectual disability.

Detection of the virus has become a problem because some of those infected may not present symptoms such as fever, rash, joint pain, and conjunctivitis (red eyes).

There is great difficulty also, Dr Guinan says, in detecting the virus while a mother is pregnant and the child in utero.

"There are some ways but it’s not very precise. You can’t really see the damage, you can only see the child and the result of the damage in the brain

"If the child is seen to have a small head, it may not be from the Zika virus. It may be from a family of small heads. But it’s very difficult to assume it is unless it’s below a certain size. If it’s below a certain size you will know that this child has been seriously damaged."

Centers for Disease Control and Prevention Director Dr. Thomas Frieden speaks at the National Press Club in Washington, Thursday, May 26, 2016, on the latest research and forecasts on the Zika virus. (AP Photo/Andrew Harnik)

The virus has been most prominent in, but not limited to, Brazil. Puerto Rico is also currently suffering an outbreak of the virus. She explains why the virus has spread so quickly and how it arrived in South America.

"It seems to have be introduced in Brazil by a group of French Polynesians because that’s where the virus was most recently a problem.

"There was a boating team or a canoe team, some kind of team that came to Brazil for a contest and scientists think that they introduced the virus to Brazil. Then it started taking off and then people often didn’t know they had it so it’s being transmitted from person to person.

"It began to move around and the effects of microcephaly weren't seen quickly because it may take several months for a pregnant woman to be infected and then it would be nine months. It took several months for someone to realise there was a problem.

"All this was incubating without anyone's knowledge because people didn't have symptoms. The children that were damaged indicated that there was something terrible happening and that’s when the virus was then looked at.

"Because it was only a new virus, there was no test for it, so there’s a big rush now to devise proper tests to diagnose people. For example if the Irish Olympic team is going to Brazil and they get infected and don’t know it... they really need to know it.

"I've been recommending that people who go to any of the countries like Brazil or Puerto Rico, or any of the South American countries who have affected by the outbreak, when they get back that they should be tested for the virus."

Aedes aegypti mosquitoes are photographed inside a mosquito cage at the Fiocruz institute where they have been screening for mosquitoes naturally infected with the Zika virus in Rio de Janeiro, Brazil, Monday, May 23, 2016. As opposed to artificially infected mosquito in labs, the institute found Aedes aegypti mosquitoes that were naturally infected, confirming scientists suspicion that the Aedes aegypti is indeed a vector for Zika. (AP Photo/Felipe Dana)

US President Barack Obama scolded lawmakers this month saying they should not recess unless they reconcile their differences over a Zika prevention funding bill and send him public health legislation he is willing to sign. Attitudes from around the globe indicate that this is an imminent crisis that has not been met with serious concern.

Amir Attaran, a professor specialising in public health at the University of Ottawa said in an article published in the Harvard Public Health Review that the outbreak of the mosquito borne virus poses a grave risk to the health of spectators and athletes at this summer's Olympic Games.

In an interview with AP he said: "If the IOC and the World Health Organization do not have the generosity of heart to delay the games to prevent children being born and disabled their whole lives, then they're among the cruelest institutions in the world."

He asked in the Harvard Public Health Review: "But for the games, would anyone recommend sending an extra half a million visitors into Brazil right now?" 

This isn't a sentiment that Dr. Guinan says she fully agrees with.

"I think Brazil should be taking big steps  to prevent unplanned pregnancies. Women have limited access to birth control. One of the ways we’re going to stop babies being born is to get women who don’t want to get pregnant safe and effective birth control. It’s not there but it needs to be."

On February 1, 2016, the World Health Organization (WHO) declared Zika virus a Public Health Emergency of International Concern (PHEIC).

Zika virus was first discovered in 1947 and is named after the Zika Forest in Uganda. In 1952, the first human cases of Zika were detected and since then, outbreaks of Zika have been reported in tropical Africa, Southeast Asia, and the Pacific Islands.