Zika virus to spread across Americas. Here’s what you need to know

The Zika virus may be linked to severe birth defects. If you're pregnant and planning to travel this year, read this first.

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Masterfile
Photo, Masterfile.

Update Feb. 3, 2016: A patient from Dallas, Tex. has been infected with the Zika virus after having sexual contact with a person who recently returned from Venezuela, where Zika outbreaks are being reported. It is the second reported case of sexually transmitted Zika virus in the United States. (The first was in 2008 when Colorado biologist Brian Foy contracted the virus from mosquitoes while doing research in Senegal–  he transmitted it to his wife through intercourse when he returned to the U.S.) Canadian Blood Services and the American Red Cross are asking blood donors to wait at least 28 days after travelling from areas with Zika outbreaks before donating blood.

Update Feb. 2, 2016: The World Health Organization declared the Zika virus a “public health emergency of international concern” (PHEIC) yesterday. Since the International Health Regulations “emergency committee” was formed in 2007, it has only ever declared a PHEIC (pronounced “fake”) three times — in 2009 with the H1N1 swine flu outbreak, in May 2014 with the polio resurgence and in August 2014 with the Ebola outbreak. An emergency declaration is to call immediate attention to preventing it from spreading internationally. The chair of the emergency committee explained that the Zika virus itself is not a clinically serious infection — its symptoms are mild — it’s the potential link with microcephaly cases in newborn babies that prompted the PHEIC declaration.

Update Jan. 29, 2016: The World Health Organization (WHO) says the Zika virus is ‘spreading explosively’ in the Americas and predicts it could infect as many as 4-million people this year. Cases of the virus have been established on all continents except Antartica. WHO director general Margaret Chan has assembled an international emergency committee for the Zika virus who will meet on Monday to determine whether the outbreak should be declared as an international public health emergency. Health ministers in El Salvador have advised women to avoid getting pregnant until 2018. Authorities in Colombia, Ecuador and Jamaica have also called for delays in pregnancies, while in the UK, Public Health England has asked that men wear condoms while travelling to infected countries and to continue to do so for 28 days after returning home.


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The mosquito-borne Zika virus is spreading in holiday destinations, including Mexico, South America and the Caribbean, and it’s of particular concern to pregnant women. First identified in Brazil in May, the virus may be linked to severe birth defects. In particular, there seems to be a correlation with a condition called microcephaly, where babies are born with smaller-than-average heads and underdeveloped brains, which, in some cases, can be fatal. The World Health Organization is predicting that the virus will spread to all but two countries in the Americas — Canada and Chile, where the species of mosquito known to transmit the virus isn’t found.

Researchers are also investigating whether the virus can be transmitted sexually (the WHO says there is “one case of possible person-to-person sexual transmission,” and currently no evidence of Zika being transmitted to babies through breast milk). While work on a vaccine is ongoing, women in affected areas, including Brazil, Colombia, Ecuador, El Salvador and Jamaica, have been advised to delay pregnancies until more is known about the virus. Research into Zika is new and still emerging, but troubling nonetheless: the BBC reports there have been around 3,500 reported cases of microcephaly in Brazil alone since October, a 30-fold increase.

The Public Health Agency of Canada (PHAC) and the US-based Centers for Disease Control and Prevention (CDC) has issued a travel alert for countries where Zika virus transmission is ongoing: Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela, and the Commonwealth of Puerto Rico. The CDC has also recently added Barbados, Bolivia, Ecuador, Guadeloupe, Saint Martin, Guyana, Cape Verde and Samoa to the Zika virus list.

Both the PHAC and CDC recommend that pregnant women and women trying to become pregnant should consider postponing travel to the areas where Zika virus transmission is ongoing. If travel cannot be postponed, expectant women to should talk to their doctor or other healthcare provider and strictly follow steps to avoid mosquito bites during the trip. What’s more, the CDC advises pregnant women who have travelled to affected areas be tested for the virus if they show two or more symptoms (fever, rash, joint pain or pink eye/eye irritation) during or within two weeks of travel.

We spoke to Isaac Bogoch, a tropical infectious disease specialist at Toronto General Hospital, to add questions about the Zika virus.

Is there a definite link between the Zika virus and microcephaly?
As of today, we do not have a definite causal link between the two. However, there are several arrows pointing to a strong association and this is clearly a major focus of research.

Are there other birth defects, besides microcephaly, considered to be linked to the Zika virus?
You have to remember this is all very new. We are in very early phases and we just don’t have enough information right now. It looks like microcephaly is the predominant birth defect. There might be more.

What’s the actual risk of infection if you’ve vacationed in one of the countries where it is present?
The exact extent of the infection is not entirely known. There were several cases in Brazil in the middle to late part of 2015. Over the last few months the number of cases in Brazil has grown, and we’ve seen cases pop up in 13 other countries, ranging from Brazil all the way north to Mexico. So it’s in South America, Central America, Mexico and some Caribbean countries.

One of the major challenges with this virus is that about 80 percent of people who get infected will have no symptoms or very mild symptoms. People can be infected and not even know it. It’s hard to know the extent of the virus, so we don’t know the likelihood that the mosquito that bit you is carrying the virus.

What are the symptoms?
For those who do have symptoms, they are typically mild: fever, muscle and joint pain, maybe a rash and some people get conjunctivitis (irritation of the eyes). This lasts for two to three days and then they improve and recover. It’s not something that would be severe enough for most people to even see a doctor. But when we talk about who is symptomatic — that’s just the tip of the iceberg. There are probably a lot more people with the virus than we think.

Is there a test for pregnant women who have recently travelled to one of these countries?
A blood test can be done right now in Canada, but would need to be sent to a public health reference laboratory for analysis — the wait time for results varies from province to province. If you do have it, there’s unfortunately not much you can do: There’s no vaccine or treatment for the infection, but this is a very active area of research right now.

[Editor’s note: In its latest statement, the CDC says that expectant women who test positive for the Zika virus should be monitored with regular ultrasounds and referred to a specialist to monitor the development and anatomy of the fetus.]

Has the virus been identified in the US? Should people worry about travelling to Florida for their vacation?
There have been travellers who have gone to Zika-virus endemic areas and have come back to the US with the infection, but it has not been locally acquired in the US. The virus cannot be transmitted from person to person — you need to be bit by an infected mosquito. Florida has the right climate and the right mosquitos to transmit this infection, but as of today, there’s no Zika virus in Florida.

Will the virus come to Canada?
Travellers who go to a Zika-virus affected area can get infected and be sick in Canada, but we don’t have the right mosquitos to transmit the virus, so you cannot acquire the infection in Canada.

[Editor’s note: The PHAC reports that travel-related cases of Zika virus have been reported in Canada in travellers who have returned from affected countries. There have been no reported cases of locally acquired Zika virus in Canada.]

This piece was originally published by Today’s Parent

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