Zika Virus: What you need to know

Zika Virus: What you need to know


zika virus mosquito Aedes aegypti

With Zika disease in the news, we’re getting more questions from clients about what this means to them. Here are some commonly asked questions and answers.

What is Zika Virus disease (Zika)?

Zika is a disease caused by Zika virus that’s spread to people primarily through the bite of an infected Aedes species mosquito.

What are the symptoms of Zika?

About one in five people infected with Zika will get sick with mild symptoms.  Many people might not even realize they’ve been infected.

The most common symptoms are low-grade fever, rash, joint pain, conjunctivitis (red eyes) and generalized symptoms such as muscle pain, physical weakness, lack of energy and headaches.  Symptoms typically begin 3 to 12 days after being bitten by an infected mosquito and last for 2 to 7 days.

How is Zika transmitted?

Zika is primarily transmitted through the bite of infected Aedes mosquitoes, which are daytime biting mosquitos.  It can also be transmitted sexually, and from a pregnant mother to her baby during pregnancy or around the time of birth.

Who is at risk of being infected?

Those at risk include anyone in an area where Zika virus is found and who hasn’t already been infected, including pregnant women.

Which countries have Zika?

The Public Health Agency of Canada has confirmed travel-related cases of Zika virus from Central and South America.  Specific areas where Zika virus transmission is ongoing are often difficult to determine and are likely to change over time.  Please visit the World Health Organization’s website for the list of countries affected.

Is this a new virus?

No.  Zika virus was initially identified in 1947 in the Zika Forest in Uganda in the Rhesus macaque population; the first human cases were reported in 1952.

Until 2007, there were infrequent, sporadic human infection cases.  However, in 2007, Zika caused a large outbreak in Micronesia.  Since then, the virus has spread to French Polynesia and a few Pacific Islands, and subsequently in 2015, to Brazil and other countries in Central and South America, the Caribbean and Cape Verde.

Is there a risk to Canadians?

The risk is low.  Mosquitoes known to transmit the virus are not established in Canada and aren’t well suited to our climate.

Current evidence suggests that Zika virus is likely to persist and spread in the Americas and the South Pacific.  Although the risk in Canada is low, travellers should take precautions to avoid mosquito bites in endemic regions.

What can people do to prevent infection?

There is no vaccine or medications to prevent Zika.  The best way to prevent diseases spread by mosquitoes is to avoid being bitten.  Aedes mosquitoes that transmit Zika are daytime feeders with two peaks of biting activity during the day: the first two to three hours after dawn and the mid-to-late afternoon hours. This pattern changes to all-day activity when indoors or during overcast days.

If travelling to countries affected by Zika, protect yourself by:

  • Wearing long-sleeved shirts and long pants.
  • Staying in places with air conditioning or that use window and door screens.
  • Using insect repellents that contain DEET and Picaridin 20% (PiActive).
  • Treating clothing and gear with permethrin or purchasing permethrin-treated items.

Protect others: During the first week of infection, Zika virus can be found in the blood and passed from an infected person to another mosquito through mosquito bites.  An infected mosquito can then spread the virus to other people.  To prevent the spread, avoid mosquito bites during the first week of illness.

Does Zika virus infection in pregnant women cause birth defects?

There are reports of a serious birth defect of the brain called microcephaly (a condition where a baby’s head is smaller when compared to babies of the same sex and age) and other poor pregnancy outcomes in babies of mothers who were infected with Zika virus while pregnant.

Knowledge of the link between Zika and these outcomes is evolving, but until more is known, the Public Health Agency of Canada recommends special precautions for women who are pregnant (in any trimester) and women who are trying to become pregnant:

  • Consider postponing travel to any area where Zika virus transmission is ongoing.
  • If travel cannot be postponed, then strict mosquito bite prevention measures should be followed to protect themselves against bites.

Does Zika virus infection cause Guillain-Barre syndrome (GBS)?

Guillain-Barre syndrome (GBS) is a rare disorder where a person’s own immune system damages the nerve cells, causing muscle weakness and sometimes paralysis. These symptoms can last a few weeks or several months.  While most people fully recover from GBS, some people have permanent damage.

The Brazil Ministry of Health is reporting an increase in GBS cases that have occurred at the same time as the outbreak of Zika virus, and similar increases in GBS have been reported following past outbreaks of Zika in other countries.  Further studies are needed to determine if any relationship exists between Zika virus infection and Guillain-Barre Syndrome.



  • Canadian travellers visiting areas affected by Zika, should protect themselves by taking measures to prevent mosquito bites, including using insect repellent, protective clothing, screened doors and windows.  There is no vaccine or medication that protects against Zika virus infection.
  • Pregnant women, and those considering becoming pregnant, should discuss their risk with their health care provider.  If travel cannot be postponed, strict mosquito bite prevention measures should be followed due to the possible association between Zika virus infection and increased risk of serious health effects on their unborn baby.
  • If you develop symptoms similar to Zika virus infection when travelling, or after you return, see a health care provider and tell them where you’ve been travelling or living.