IQ4: Should Pregnant Travellers to Zika-Endemic Areas Undergo Amniocentesis?
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Rick Harp: Welcome to Infectious Questions, a public health podcast produced by the National Collaborating Centre for Infectious Diseases. At NCCID we help those with infectious disease questions connect to those with answers. Hello, I’m Rick Harp.
Shivoan Balakumar: And I’m Shivoan Balakumar. This episode continues our focus on the Zika virus. Last episode, we looked at the strength of the link between Zika and birth defects. This time around our guest expert addresses a question about amniocentesis and pregnant woman who have recently travelled to Zika-endemic areas.
Harp: It’s just one in a series of questions sent to us by Public Health residents in Saskatchewan. Stay tuned to learn how you can submit yours.
Our guest this week is Dr. Vanessa Poliquin, with the Department of Obstetrics and Gynecology at the University of Manitoba. Doctor, welcome to Infectious Questions.
Dr. Vanessa Poliquin: Well thank you for having me.
Harp: Now, if I may, I’d like to begin with an update of sorts. Since we released our podcast about it back in April, some new Zika-related information concerning pregnant woman and their partners has come to light. What, in your mind, has been most significant for public health?
Poliquin: Okay, well that’s a great question. So, what you’re alluding to is that reports released earlier this year prompted the scientific community to acknowledge the causal relationship between Zika infection during pregnancy and fetal congenital anomalies. And certainly a particular concern to the prenatal care providers is that transmission to the foetus can occur even if a woman has had no symptoms when she was infected with Zika virus.
Also of concern is that fetal consequences are seen with Zika infections reported in all trimesters of pregnancy. There was data out of—or, there is data out of French Polynesia suggesting that the impact of Zika on the fetus is the highest if the infection occurs in the first trimester. But data out of Brazil certainly suggests that it doesn’t seem to be exclusively limited to a particular trimester.
But since the spring, the next most significant development has centered around the issue of sexual transmission of Zika virus. Sexual transmission of Zika virus has now been reported in a number of different scenarios. This spring, there were already numerous reports of symptomatic men, so symptomatic men transmitting the infection to female sexual partners. And the key really seemed to have been the need for the infected man to have been symptomatic.
Now there have been reports from France of male-to-female transmission even when the infected man has been asymptomatic. Also since the summer there have been isolated case reports suggesting that female-to-male transmission may occur as well as the possibility of transmission via anal and oral intercourse.
What’s more is that the time between infection with Zika virus and sexual transmission can be long, with one instance being reported to have occurred 41 days after the onset of symptoms. The long length of time that can occur between infection and sexual transmission is thought to be related to the persistence of Zika virus in semen, and it’s still unclear just how long infectious virus can persist in semen. But certainly there are reports of highly sensitive tests being able to detect fragments of Zika RNA in semen as far out as 180 days.
So given the persistence of detectable virus in semen, as well as the growing number of reports of sexual transmission remote from the onset of symptoms, the World Health Organization updated their guidelines about sexual transmission of Zika earlier this month.
At this point, given the latest WHO guidelines about sexual transmission, for couples in Canada who are returning from a Zika-affected area, it’s advised to use condoms for up to six months upon their return. And for Canadian couples who are planning a pregnancy, it’s advised to wait six months after returning from a Zika-affected area prior to trying to conceive.
Certainly, sexual partners of pregnant women who are coming back from a Zika-affected area are still advised to used condoms or abstain from sex until the end of the pregnancy. That’s what I think is most impactful for Canadians, and especially pregnant women and their partners.
Harp: Let’s turn to the first question now, from those residents of the Public Health and Preventative Medicine Program at the University of Saskatchewan: “Should amniocentesis, basically a test of amniotic fluid, be offered to pregnant women who’ve recently travelled to Zika-endemic areas?”
Poliquin: Yeah, that’s a great question, and somewhat of a complicated question, if you look at all the algorithms that are out there. Certainly all pregnant women returning from Zika-infected areas should be evaluated by a health professional. And depending on the time since their travel to a Zika-affected area, and whether or not they have symptoms of Zika infection, pregnant women should have blood tests performed in accordance with the laboratory criteria in their jurisdiction.
So if these tests are positive, a pregnant woman should be evaluated by a prenatal care provider or a perinatologist with expertise in Zika exposure during pregnancy. And in these cases, serial ultrasounds are definitely recommended.
In some cases, especially if there are ultrasound findings of microcephaly, which is a small head or brain calcifications, an amniocentesis may be appropriate as part of the follow-up investigations. But because amniocentesis carries its own risk its utility has to be considered on a case-by-case basis. Depending on the clinical situation, an amniocentesis may be useful to either rule in or rule out other diagnoses too, but here again, case-by-case evaluation by a perinatologist is of the utmost importance.
Harp: Now, Doctor, you’ve addressed the situation of the fetus and the mother: what about those cases where it wasn’t the mother who went to a Zika-affected area, but her partner did? What test might be recommended there?
Poliquin: So at this point in time in Canada, testing is approved for symptomatic individuals. So, for instance, a man who has symptoms would qualify for testing for Zika virus, or pregnant women who are asymptomatic.
A man who has gone to a Zika-affected country or area has come back and has no symptoms currently does not qualify for blood testing in Canada. And this is largely because the tests… we’re still learning a lot about the test that we have, and the way it has performed in a situation where there are symptoms versus the way that it has performed in what we call a screening situation, where a man might not have symptoms.
We’re not sure whether the performance of the test is reliable enough. We’re not sure of the precise false positives or false negatives that are associated with the test. And until the test parameters are better understood, we can’t undertake routine testing of asymptomatic individuals.
Balakumar: So, theoretically, there might also be a risk where a pregnant woman could be exposed to Zika without travelling herself. That is, it was her partner who travelled while she stayed in Canada. Has this scenario also been factored into the recommended testing algorithms?
Poliquin: At this point in time, if there is a risk for a woman to have been exposed to Zika, it’s case-by-case they should be seen by a prenatal care practitioner who can liaise with the laboratory to make a case. But because there is the theoretical risk of transmission in that case—if there’s been condomless sex—then a case could be made for testing that individual who is pregnant.
Harp: Thank you, Dr. Poliquin.
Poliquin: Thank you so much for having me.
Harp: Thus concludes this episode of Infectious Questions. Next time on the podcast, more questions from U of S Public Health residents, including what health care providers should do to evaluate infants with positive or inconclusive Zika test results.
Balakumar: And, should mothers who contract Zika during pregnancy breastfeed?
If you have a public health question about the Zika virus you’d like addressed, email it to email@example.com. Or, call our new toll-free number: 1-844-847-9698 and record your question there.
Harp: Infectious Questions is a production of the National Collaborating Centre for Infectious Diseases. Production of this podcast has been made possible through a financial contribution from the Public Health Agency of Canada.
Balakumar: Note that the views expressed here do not necessarily represent those of the Agency.
The host organization of the NCCID is the University of Manitoba. Learn more at nccid.ca.