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A Healthy Curiosity: Zika virus - what you need to know

October 3rd 2016 / Peta Bee

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It's the virus that's made world news and threatened the Olympics in Rio, but how much should you worry about Zika? Peta Bee investigates

As if going for gold was not enough pressure to bear on their shoulders, members of Team GB and Olympians from other countries had an additional challenge to face in Rio: Zika. The mosquito-borne virus can cause crippling birth defects and neurological disorders in newborns as well as unwanted symptoms in adults. It’s a risk that was taken seriously by the British Olympic Association whose medical experts liaised with researchers at the London School of Hygiene and Tropical Medicine (LSHTM) before deciding Team GB should go to Rio.

However, not everyone was convinced by the protective guidelines that were produced. As many as 14 male golfers, including Team GB’s Rory McIlroy, pulled out of the Rio Olympic Games through fears surrounding Zika and others expressed concern that precautionary measures might not be enough to protect them against the risks. Jessica Ennis-Hill decided not to take her husband Andy and two-year-old son Reggie to Rio because of the Zika scare. Instead, she took her family to Spain where she trained before jetting off to the British training Camp near Rio alone. “Obviously I am concerned and I do think about it,” the heptathlon star said in June. “Certain elements of it worry me, so we’ve decided we’re going to train in Europe.”

Likewise, Susie Verrill, the girlfriend of current Olympic champion long jumper, Greg Rutherford, said the couple made the decision that she should stay at home with their young son rather than risk infection from the virus. “We’re not ones to worry unnecessarily, but after more than 100 medical experts stressed the Games should be moved to prevent the disease from spreading, this was a huge factor in us choosing to stay put,” Verill wrote recently in the online magazine Standard Issue. “We’ve also made the decision to have Greg’s sperm frozen. We’d love to have more children and with research in its infancy, I wouldn’t want to put myself in a situation which could have been prevented.”

What about the rest of us? Should we travel or stay put? Here, we examine the facts with the help of Jimmy Whitworth, Professor of International Public Health at LSHTM.

WHAT IS ZIKA?

“Zika is transmitted by the Aedes aegypti mosquito,” explains Professor Whitworth. Mosquitoes become infected when they feed on a person already infected with the virus, and can then spread the virus to other people through bites.

HOW IS THE VIRUS SPREAD?

Besides via the infected mosquitoes themselves, the virus is transmitted through human-to-human contact, through sexual activity and between mother and child during pregnancy. What’s worrying is that Zika can be transmitted through sex even when a partner shows no symptoms - the virus is contagious both before and after symptoms become apparent. But Professor Whitworth stresses that “the risk of sexual transmission is thought to be very low”. He says that “there have been a small number of suspected cases of transmission via blood transfusion, and blood safety measures are in place in the UK”, but despite a letter to the New England Journal of Medicine in June raising the possibility that it could be transmitted by oral sex - potentially even by kissing - if it is present in saliva, he says “there is currently no evidence of the virus spreading through social contact such as kissing, hugging or handshakes”.

WHAT ARE THE SYMPTOMS?

In adults, symptoms of the virus include low fever, low energy, chills, red eyes and a rash. It has also been linked to Guillain-Barré syndrome, a condition that causes temporary paralysis in adults. However, the infection is normally very mild and it’s been estimated that only around one in five infected people develop symptoms - many might be transmitting it to others, unaware that they’ve been infected.

WHAT IF YOU ARE WORRIED – IS THERE A TEST FOR IT?

British GPs are on heightened alert and ready to prioritise potential cases. “Blood tests can be carried out to check for the virus – these are usually recommended for people who have travelled to an area with Zika and have had Zika-like symptoms,” says Professor Whitworth. Tests are sophisticated and need laboratory diagnosis – there is certainly no accurate high street diagnosis.

WHERE ARE THE RISKIEST PLACES TO VISIT?

Zika had previously been detected in Africa, Asia and the Pacific Islands, with the latest outbreak occurring in the Caribbean as well as parts of North and South America also affected. High population cities are great breeding sites for the mosquito and it is rarely found more than 100m from human habitations. Brazil has the largest-known outbreak but, as summer temperatures rise, the offending mosquito is also to be found in southern states of the USA including Texas, Louisiana and Florida where cases have been confirmed. Public Health England (PHE) has provided a comprehensive list of affected areas (www.gov.uk). “Countries in Southern Europe, including France and Italy, need to be especially vigilant and it’s important that holidaymakers follow public health advice while abroad, including taking all the necessary precautions to avoid getting bitten,” Professor Whitworth says. There have been isolated cases in the UK, but “there is virtually no chance of there being an epidemic here”, he says. “The risk to the UK is very low,” Professor Whitworth explains. “The mosquitos that spread Zika are not found naturally in the UK - our climate is too cold, even in summer.”

HOW LONG DOES THE VIRUS STAY IN YOUR BODY?

Studies are still being conducted to fully understand how long Zika stays in semen and vaginal fluids, but experts believe it may survive in semen longer than other bodily fluids such as saliva and breast milk. “We don’t have definitive evidence on exactly how long it remains, but we do know that it can remain for a few months,” Professor Whitworth says. “Current advice from Public Health England is for a man to practice safe sex for six months following the start of Zika virus symptoms.”

IS THERE A PROVEN LINK THAT ZIKA CAUSES MICROCEPHALY?

In babies born to mothers infected by Zika, the virus has been linked to microcephaly – unusually small heads and brain damage – as well as other congenital problems. In April, scientists at the US Centers for Disease Control and Prevention (CDC) concluded in a report published in the New England Journal of Medicine, that the virus is indeed a cause of these severe foetal brain defects. “There is now a proven link between Zika and microcephaly as well as other birth defects,” says Professor Whitworth “Pregnant women and couples looking to conceive should think twice about travelling to parts of the US and anywhere active Zika transmission could occur.”

IS THERE PREVENTATIVE TREATMENT FOR IT?

There is currently no vaccine against the Zika virus although pharmaceutical companies are making great efforts to produce one. If you are planning a baby or if there is the slightest chance you might get pregnant, the advice is to consult your GP before travelling to any places where the risk of Zika might be high. For all travellers, prevention comes down to fastidious avoidance of mosquito bites by the usual methods. If you are going to a high risk tropical area, make sure the ingredient list includes either DEET (20 to 50 per cent) or PMD. Also cover up with long-sleeve tops and lightweight trousers, preferably treated with insecticide.

ARE YOU IMMUNE ONCE YOU’VE HAD IT?

“People who have recovered from Zika virus infection are thought to have immunity from the virus, but it is not known how long this immunity lasts,” Professor Whitworth says.

IS THERE A SAFE TIME TO TRAVEL DURING PREGNANCY?

In short, no. Doctors initially believed that the first trimester of pregnancy was the riskiest for expectant mothers, but more recent studies have suggested that infection with the virus later in pregnancy can be as risky for the unborn child.

IF YOU ARE NOT PLANNING PREGNANCY, WHAT’S THE RISK?

“It’s important to remember that Zika is generally only a minor health risk to most people,” Professor Whitworth says. “Four in five of those infected experience no illness and, in those that do, symptoms are usually limited to fever and mild joint pain. If you are not pregnant or not thinking of getting pregnant, then Zika is not something to overly worry about.”

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Interested in holiday health? You might like this piece on why mosquitoes are attracted to you and how to fix it

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