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03/20/2018 14:35 EDT | Updated 03/20/2018 14:35 EDT

It's Safest To Delay Pregnancy If Your Travels Put You At Risk Of Zika

Because Zika can hang around in the body, it may affect sperm, eggs and early embryos for many months after acute infection.

Zika virus is a serious health concern for pregnant women. A new study just published March 15, 2018 in the prestigious New England Journal of Medicine (NEJM) confirms that Zika virus infection is responsible for devastating birth defects and pregnancy complications.

The study followed 555 fetuses during the height of the Zika epidemic in the French Territories of the Americas (Guadeloupe, Martinique, St. Martin, St. Barthelemy and French Guyana). All of the mothers were confirmed to be infected with Zika using highly specific laboratory testing called reverse-transcriptase PCR.

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Brain and eye abnormalities presumed to be due to Zika infection were observed in seven per cent of the babies. Microcephaly, meaning a small brain and head, is arguably the most well-known birth defect associated with Zika virus; this was seen in 5.8 per cent of cases in the study. The worst time to acquire Zika virus appeared to be during the first 12 weeks of pregnancy, when 12.7 per cent of babies developed birth defects. However, babies were still at risk even if infection occurred during the second (3.6 per cent) and third trimesters (5.3 per cent) of pregnancy.

It is worth noting that these risk estimates are much lower than previously reported in Rio de Janeiro, Brazil. A NEJM study from that region reported that up to 42 per cent of pregnancies affected by Zika resulted in birth defects and other adverse outcomes.

A woman should delay pregnancy for two months after travel to a Zika-infested location.

As a fertility doctor, I advise couples that are planning for a pregnancy to carefully consider their travel plans. Zika virus has been a serious concern in many parts of the world since 2015. Most people know that Zika virus can harm babies, but fewer people know about the risks to couples that are in the planning stages of a pregnancy. Because Zika can hang around in the body, it may affect sperm, eggs and early embryos for many months after acute infection.

According to the Canadian Fertility Andrology Society, a woman should delay pregnancy for two months after travel to a Zika-infested location. If the man is the traveller, the couple must delay pregnancy for six months and he is advised to use condoms to reduce the risk of transmitting Zika through sex. The American Society for Reproductive Medicine has also issued similar guidelines.

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Macro of mosquito (Aedes aegypti) sucking blood.

Patients often ask me if we can just test them for Zika before embarking on fertility treatments. Unfortunately, a lot remains to be known about the sensitivity and specificity of Zika virus testing. Therefore, even with a negative test we cannot be sure that patient did not have Zika. The testing is most accurate when a patient reports having symptoms. However, only about 20 per cent of people who acquire the virus will get the typical symptoms: itchy rash, red eyes, fever, muscle and bone aches.

That means 80 per cent of people with Zika may never know they had it. Furthermore, Zika virus has a variable incubation period of three to 12 days, so you may be home from your trip for almost two weeks before symptoms even start, making it more likely to assume you're sick with the flu rather than Zika.

Zika is most commonly transmitted by the Aedes mosquito. Currently, there is no known risk of Zika infection in Canada. Most of the United States is also unaffected, with the exceptions of Texas and Florida. If you're hoping to conceive on a tropical getaway, the destinations are limited. Most of the Caribbean, South America and Central America are considered Zika-endemic or epidemic. Even lower-lying regions of Mexico have had reports of Zika transmission. The best advice is to check the Centers for Disease Control and Prevention (CDC) world map before booking your travel. If you do travel to a Zika-infested area, take precautions (e.g. long sleeves, pants, DEET) to avoid mosquito bites and follow the recommendations above to prevent sexual transmission when you return.

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