Zika complications in Canadian travellers surprise researcher

Canadian adults who went to travel medicine clinics sick with the Zika infection show a range of concerns including severe complications, a new study suggests.

The Zika virus is spread by mosquitoes in the Caribbean, South America, Central America and some U.S. states.

A common perception is that Zika is associated with mild symptoms.

But that was not borne out among the 1,118 travellers who visited travel medicine clinics at cities in British Columbia through Quebec from October 2015 to September 2016.  

“We were a little bit surprised that we noted five per cent of cases had a neurologic complication, so that’s Guillain Barre or Guillain Barre-like syndrome, and then five per cent had congenital transmission,” said Dr. Andrea Boggild, clinical director at tropical disease unit at Toronto’s University Health Network.

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Dr. Andrea Boggild wanted to study Zika virus infections among Canadian travellers, a highly mobile population. (CBC)

Most people with Zika won’t have symptoms. But until now, surveillance data on Zika virus in ill returning Canadian travellers hadn’t been analyzed.

The study in Monday’s issue of the Canadian Medical Association Journal showed Zika was diagnosed as often as dengue, a serious infection.

A threat of paralysis

The researchers only looked at people sick enough to see a health-care professional and be referred to a travel health clinic — a small subset that’s likely biased toward more complicated cases, Boggild cautioned.

The study’s authors found that overall, 41 travellers had Zika  and 41 had dengue. The doctors didn’t find any severe complications in the dengue group.

In contrast, severe complications of Zika included Guillain Barre?, a neurological syndrome that can lead to paralysis, as well as meningitis, and congenital transmission or birth defects.

Dr. Shaun Morris, a principal investigator at SickKids Centre for Global Child Health in Toronto, was not involved in this study, but he said it offers important findings about adult Canadian travellers. 

“Zika potentially can cause meaningfully significant disease in the non-pregnant women population as well,” Morris said. He is part of a surveillance program across Canada to identify and track children born with congenital Zika syndrome.

Pregnant? Delay travel

A main concern was that in pregnant women, Zika infection can cause microcephaly, a malformation where babies are born with abnormally small heads with poorly developed fetal brain because neurons die and fail to form properly.  

“One major message for the pregnant traveller is that we are continuing to advise deferral of travel to areas where Zika virus is transmitted because of the devastating consequences to the fetus,” Boggild said. 

Almost 60 per cent, 24 travellers, with Zika were women. Of these, 79 per cent or 19 were of child-bearing age.

In the milder cases, nearly 90 per cent had rash and 80 per cent had fever.

Boggild said the findings remind travellers to take precautions against illnesses spread by mosquitoes, not only Zika but also dengue, chikungunya and malaria:

• Use a repellent containing DEET or Picaridin on the skin and clothing.
• Use barrier precautions against sexual transmission while travelling and upon return.
• If sick after return from the tropics, seek medical assessment to rule out life-threatening infections such as malaria.

‘I like to live in ignorant bliss’

At Toronto Pearson International Airport last week, Zika was not top of mind for two travellers heading south for fun in the sun.

“I like to live in ignorant bliss sometimes,” Donna Allen said of Zika as she prepared to catch a flight to a resort in Cancun, Mexico. She packed mosquito repellent.

So did Anita Husain, who was headed to Jamaica with her young daughter. Safety was her main concern. 

The travel health surveillance is funded by the Public Health Agency of Canada.