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Putting the risks of Zika virus into perspective for travellers

Mosquito with zika virus
Written by Paul Taylor

QUESTION: My husband and I decided against taking a vacation down south this winter because we were worried about the Zika virus, which can cause horrific birth defects. We don’t have children yet, but we are thinking about starting a family soon. Now we see that the World Health Organization has lifted its Zika emergency.  Should we reconsider our vacation plans?

ANSWER:  As you correctly point out, the World Health Organization (WHO) has declared that Zika no longer represents a public health emergency.

But that doesn’t mean you can let your guard down.  The risk of Zika infection is simply the new normal in large parts of the Caribbean, and Central and South America that are home to the type of mosquitoes that can spread the virus. In other words, Zika “is here to stay,” and long-term measures are needed to deal with the risks posed by the virus, says WHO. The risks, though, need to be kept in perspective.

In 80 percent of infections, there are almost no symptoms. When people do feel ill, they may experience headache, fever, muscle and joint pain, conjunctivitis (pink eye) or a rash lasting two-to-seven days. In very rare cases, a Zika virus infection can trigger Guillain-Barré Syndrome, a form of temporary muscle paralysis.

So, for most people, it’s a relatively benign virus. However, the consequences can be catastrophic when a pregnant woman gets infected. The virus can interfere with the normal development of the fetus causing birth defects such as microcephaly, in which the head and brain are abnormally small.

The risk of developing microcephaly appears to be highest when a woman is infected in the first trimester of pregnancy, says Dr. Andrew Simor, Chief of Microbiology and Infectious Diseases at Sunnybrook Health Sciences Centre.

An infection at any point throughout the pregnancy, may lead to other neurologic abnormalities affecting sight and hearing and possibly cognitive abilities.

But it’s not known how often Zika produces these dramatic birth defects, partly because the virus hasn’t been studied for very long.

It was first discovered in a Macaque monkey in the Zika Forest of Uganda in 1947.  Initially, there were only sporadic human infections in Africa and Southeast Asia.

Then, in 2007, a big outbreak occurred on Yap Island in Micronesia.  Data collected at the time suggested the chance of an infected pregnant woman giving birth to a child with microcephaly was approximately 1 percent, says Dr. Simor.

The virus began to attract worldwide attention in 2015, when doctors in Brazil reported a huge spike in birth defects in the offspring of women infected with Zika.

Some public-health experts feared that the influx of visitors into Brazil for the 2016 Rio Olympic Games would accelerate the spread the virus around the globe.

However, there weren’t reports of Zika among the international visitors and athletes when they returned home. “I think that is perhaps reassuring that all the concerns pre-Olympics were, in fact, unwarranted,” says Dr. Simor.

Furthermore, other South and Central American countries haven’t seen a similar surge in Zika-related birth defects as happened in Brazil. “Other factors that are currently not well understood may be responsible for this regional variation,” says Dr. Simor.

Even if the risk of birth defects is relatively low, “it’s not insubstantial – and one should take appropriate precautions,” say Dr. Simor.

Public health organizations, including WHO, are still urging pregnant women to steer clear of areas where mosquitoes are actively spreading the virus.

The advice is a bit more nuanced for couples planning to have a child in the near future.

The key challenge is that the virus can remain in the body for months without symptoms, explains Dr. Isaac Bogoch, a tropical infectious disease expert at Toronto General Hospital.

If a couple travels to a Zika-affected area, one of them may unknowingly pick up the virus, says Dr. Bogoch.

Months later, the woman could become pregnant and the virus – lurking in her body or her partner’s semen – might then infect the fetus, he adds.

Studies suggest the Zika virus remains for a longer period of time in a man’s semen, compared to a woman’s vaginal secretions. Experts say a man should use condoms or refrain from sex for six months after returning from an area where Zika is present.  A woman should avoid getting pregnant for two months.

When a man and a woman travel together, this essentially means they should postpone plans for having children for half a year.

During the trip, they should take precautions to avoid getting bitten by Zika-spreading mosquitoes, which are active during the day, especially around dawn and dusk.  For instance, use bug repellant and cover up with pants and long-sleeved shirts.

Of course, all travellers should follow this advice. After all, Zika isn’t the only health threat in the tropics. Mosquitoes are also responsible for spreading other serious illnesses, including malaria, dengue fever and chikungunya. It’s worth noting that malaria-transmitting mosquitoes bite at night. For complete protection against bug-borne diseases, it’s best to guard against bites around the clock. Sleeping under mosquito netting is well advised in some areas.

These precautions may seem like a travel turn-off. But it’s still possible to have an enjoyable – and safe – vacation, says Dr. Bogoch. He suggests talking to your health-care provider so that you have all the up-to-date shots and medicines you may need for the place you plan to visit. The website of the U.S. Centers for Disease Control and Prevention is a good source of health information for travellers.

Keep in mind that the threat of infection varies from region to region, and even within countries.  A few months ago, public health officials warned that mosquitoes were spreading Zika in parts of Miami, Fla. Yet outside that relatively small geographic area, the risk dropped to zero.

“As long as you’re making informed health-care decisions and doing things to mitigate your risks, you can have a wonderful trip,” says Dr. Bogoch.

About the author

Paul Taylor

Paul Taylor, Sunnybrook’s Patient Navigation Advisor, provides advice and answers questions from patients and their families, relying heavily on medical and health experts. Email your questions to AskPaul@sunnybrook.ca
and follow me on Twitter @epaultaylor