Health Committee on March 7th, 2016

[Dr. Gregory Taylor]

It depends on what you mean by “strong”. It's getting stronger every day, and more and more evidence comes out in little bits and pieces virtually daily. There was a report last week that came out in terms of infected stem cells with a precursor to neurological tissue. It is changing. It's a tough one to say “strong”, but it's looking more and more like that.

[Don Davies, NDP, Vancouver Kingsway, BC]

Would a better word be “increase”? Increasing data that is—

[Dr. Gregory Taylor]

Yes.

[Don Davies, NDP, Vancouver Kingsway, BC]

—at least tending towards showing a link with Zika.

[Dr. Gregory Taylor]

Yes, definitely.

[Don Davies, NDP, Vancouver Kingsway, BC]

I have in my hand a The New England Journal of Medicine paper from Friday, March 4 that just came out. It's pretty hot off the presses. The conclusion says that, “Despite mild clinical symptoms, ZIKV infection during pregnancy appears to be associated with grave outcomes, including fetal death, placental insufficiency, fetal growth restriction, and CNS injury.” In fact they found that 29% of the Zika-positive women had fetal abnormalities as revealed by ultrasonography and there were none in the control group. It seems to me that there's starting to be some compelling evidence in there.

[Dr. Gregory Taylor]

Yes, it is moving in that direction. As well there was evidence that it is affecting outside the neurological system, other parts, small fetus, etc. It's looking more and more causal, but we're not quite there yet. Is it there, did it cause that problem, or did it just happen to be there? That's something that is the hard part.

[Don Davies, NDP, Vancouver Kingsway, BC]

I was told that there are four causes of microcephaly: genetics, which is rare; intoxication or a chemical exposure during pregnancy—we've seen a little bit of a conspiracy theory about that already—malnutrition; and viral bacterial infection. One of the take-aways I took from our meeting on Friday is that the evidence is trending toward showing that there is an association. That's why I ask.

It also appears that the evidence is starting to show that first trimester exposure is particularly damaging to the fetus. Is that something that you're...?

[Dr. Gregory Taylor]

You would expect that. Typically the first trimester is when the fetus is most susceptible. It happens with other viral infections, exposure to chemicals, exposure to alcohol, or exposure to any sort of thing. That's what you expect, though there is also evidence to suggest it can have an effect in the last trimester as well. We'll see where that one goes.

On your comment about malnutrition, this may be multifactorial, which means you need several things to come together. What's still interesting is that this is from one area of Brazil only and there tends to be a lower socio-economic status in that area, so it may be that the combination is what causes this, and that's what we'll find out.

[Don Davies, NDP, Vancouver Kingsway, BC]

My colleagues have already commented that it's a bit of a paradox. The actual expression of Zika tends to be fairly asymptomatic 80% of the time, you testified, and it's actually mild expression in most cases. The people who talked to me told me that's actually more concerning from a public health point of view because it's not obvious when it's being transmitted. Is that a fair concern?

[Dr. Gregory Taylor]

It's a concern only in pregnant women or only in men who then have sex with someone or get someone pregnant. That's when it's a concern because, you're right; 80% majority don't know they're infected, and if they don't know, why would they think about it? Part of what we've had in terms of the testing is that if a pregnant woman has been travelling to the area and they come back, whether they've had symptoms or not, we advise them to talk to their doctor. If they want to be tested, we do the serology test and we're delighted to do that.

With men, we advise that they use a condom for at least two weeks following, and if they're having sex with a pregnant woman, to avoid it for at least the entire pregnancy. As well, if they're having sex with someone who could get pregnant, they should avoid it for a couple of months. Those are very conservative and they're being extra cautious, but it's for the very reason that they could transmit it and not know it.

[Don Davies, NDP, Vancouver Kingsway, BC]

I tried to fire off an email while you were talking because it may have been my mistake. I wrote down in my notes from this talk that the longest presence of Zika virus in semen has now been found to be 62 days. Is that an error on my part?

[Dr. Gregory Taylor]

I'm not aware of that. The research I've seen is two weeks. If it's 62 days, I'd like to see that.

[Don Davies, NDP, Vancouver Kingsway, BC]

Okay, I'll pass that on if I see it.

We know that Zika could be transmitted by blood transfusion, albeit rare. We know that it could be transmitted sexually. I also understand that the cases are all male to female. So far there are no cases of female to male. Is that correct?

[Dr. Gregory Taylor]

That's correct.

[Don Davies, NDP, Vancouver Kingsway, BC]

We know it crosses the placenta, so it's in utero and can be passed mother to child. I know that the Zika virus has been found in breast milk, but so far, apparently, there's no transmission through breastfeeding.

[Dr. Gregory Taylor]

We have no record of that.

[Don Davies, NDP, Vancouver Kingsway, BC]

What's the state of detection technology? I know that in pregnant women it's not present in blood or urine. It's in amniotic fluid, but the detection method is invasive. Is there any progress on better detection methods, particularly in pregnant women?

[Dr. Gregory Taylor]

I'll let Dr. Gilmour answer that, but on the surface of it, what we do for microcephaly in particular is serial ultrasounds. The Society of Obstetricians and Gynaecologists tells me that's not particularly good, and it doesn't work until later on, so it doesn't help early. We do serology in pregnant women. Those are the two tests so far.

Matt, did you want to comment?

[Matthew Gilmour]

You're right. With the amniotic fluid it's collected through amniocentesis. That's obviously a bit of an invasive procedure, so that's not a specimen that we've been receiving commonly at the NML. Odds on, the vast majority have been blood specimens, so it's people who are interrogating soon after their return from these countries to see if they are viremic, to see if the virus is still circulating within their body, or again, there's the alternative test with the serologic approach.

We actually have a two-pronged approach where we can fairly rapidly see if someone has a particular class of antibody that would be raised against a viral infection. The problem with that test is that it could equally be detecting something like dengue fever, or West Nile virus, or yellow fever. For these other viruses that are in the same class and are transmitted by the same mosquito, this initial test is really just saying, “You've had a past viral infection.” That's where we have to move on to a second round of serologic testing, a confirmatory test, where we're directly interrogating patients' blood to see if they have the antibodies to Zika. That's where the timelines come into play a bit. That, again, is why, very early on, we put the message out about being transparent about some of the test limitations that we have. There's not really a test limitation on Zika. It's just a test limitation for detecting some of these types of viral infections, including dengue, etc.

If someone is worried that they had Zika, but they're well, if they want the test, we can offer it. But again, it may not be an answer that comes quickly, within the same week. It may come weeks down the line because of the multitude of testing approaches that may be required. We're extremely cognizant of the decisions that patients might be making based upon these test results, again to possibly terminate their pregnancy or not. That's why we've been trying to be as transparent as we can with the limitations and the state of the art of the tests that we have right now, so that people can make this informed decision for themselves.

[Don Davies, NDP, Vancouver Kingsway, BC]

Thank you.

[The Chair, Liberal, Bill Casey]

Thank you. I just have one little question here before we go on.

Is it safe to say, for a Canadian woman who is considering getting pregnant, or who is pregnant, the only way they can get Zika virus is through a blood transfusion or through sexual relations with somebody who has Zika virus?

[Dr. Gregory Taylor]

Or by travelling to the country....

[The Chair, Liberal, Bill Casey]

If they're in Canada, then the only way a woman can get it is in those two ways?

[Dr. Gregory Taylor]

Yes, but that's our knowledge currently. That's correct.