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Zika Virus: What You Need To Know

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Written by Sybil Millar, Communications Advisor for the Ross Tilley Burn Centre, Critical Care and Infectious Diseases programs at Sunnybrook Health Sciences Centre.

Zika virus has been getting a lot of attention in Canada this week, after the first sexually transmitted case here was confirmed. What is Zika virus, and do we need to be worried?

"Zika virus comes from the same family of viruses as Dengue fever and West Nile virus. It's predominantly spread by the Aedes mosquito, although it is not circulating here in Canada so there's no risk of contracting Zika by mosquito bite here," says Dr. Andrew Simor, head, Department of Microbiology and Infectious Diseases consultant at Sunnybrook Health Sciences Centre.

There are, however, other ways the virus can be transmitted. And while most people who get Zika will never experience any symptoms, women who are pregnant or trying to get pregnant are at much greater risk.


Here are three things you need to know about Zika virus:

1) Most people don't even know they have it

Only about 20 per cent of people who are infected with Zika actually experience any symptoms. The rest have no idea they were ever infected with it at all. "If you do have symptoms, it will feel like having a mild flu," says Dr. Simor. Fever, rash, nausea, joint and muscle pain, headaches and redness of the eyes are all signs of a Zika infection. The only way to know for sure, though, is by getting a blood test.

"There have been instances of people developing Guillain-Barre syndrome several weeks after a Zika infection, but it is rare," says Dr. Simor. The overwhelming majority of people will fully recover from Zika.

2) Zika can be transmitted through sexual contact

Mosquitos are transmitting the Zika virus in other parts of the world, but not in Canada. So how else can someone get the virus? "The Zika virus stays in the blood for no more than a week, but it may persist in men's semen for much longer -- at least 60 days," says Dr. Simor. The virus can then be transmitted to the man's sexual partners.

So, if a man has traveled to a Zika affected part of the world, is bitten by a Zika-carrying mosquito, and contracts the virus (and he often won't have any symptoms, so he won't know he had Zika), he may transmit it to his sexual partner for months afterward. It is recommended that men who travel to or live in an area with Zika virus transmission and their non-pregnant sex partners should either abstain from (or use condoms during) sex, in order to reduce the risk of Zika virus transmission.

3) Women who are pregnant, or trying to get pregnant, are at highest risk

For healthy adults, contracting Zika is not serious -- most will never even experience symptoms. However, the risk is much greater for women who are pregnant or trying to get pregnant. "There is a confirmed link between a women contracting Zika virus during pregnancy and microcephaly, which means the baby's brain does not fully form, leading to cognitive impairment," says Dr. Simor. It's still unknown how often this happens, or at what point in the pregnancy the risk is highest, but it is important that women who are pregnant or planning to become pregnant take precautions:

  • Avoid travel to Zika affected areas
  • If travel is unavoidable, take measures to avoid mosquito bites, such as using a mosquito repellant with DEET, using mosquito nets at night, and wearing long pants and long sleeved shirts
  • Men from who have traveled from a Zika affected area should either avoid having sex, or use condoms during sex with their pregnant partners, for the duration of the pregnancy

As always, if you have any questions or concerns about Zika virus, discuss them with your doctor.

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