Canadian tourists infected with Zika virus are showing more severe symptoms than expected, according to a study published Monday in the Canadian Medical Association Journal.
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 an infrequent infection that’s associated with mild, flu-like symptoms and rash.
While most of the infections resulted in mild symptoms, the Canadian study noted Zika infections were as common as dengue fever and symptoms were more severe — including two cases of Guillain-Barré syndrome, a rare neurological disorder that can lead to temporary paralysis.
The study looked at 1,118 travellers who returned from the Americas between October 2015 and September 2016, and then sought medical attention at travel medicine clinics in urban centres across the country. Of these, 3.1 per cent or 41 travellers had Zika, equal to the number who had dengue, and 23 had chikungunya (another viral disease transmitted by infected mosquitoes that causes fever and joint pain).
The study found no severe complications in the dengue cases but travellers with Zika had complications, including Guillain-Barré, meningitis, and other complications.
Of those diagnosed with Zika, 24 were women and 19 were of child-bearing age. Three of those women were pregnant.
According to the study, congenital transmission occurred in two of the three pregnancies.
Mosquito exposure spread the virus to 40 of the travellers with Zika infection, and one got it though sexual transmission.
“Our observations suggest that complications from Zika infection are under-estimated by data arising exclusively from populations where Zika is endemic,” the study’s authors wrote. The frequency and severity of the newly described congenital Zika syndrome dictates that women who are pregnant avoid travel to areas with ongoing transmission of Zika virus, and those planning to conceive should consider deferring travel.”
Zika is a dangerous mosquito-borne disease, like malaria or yellow fever. Unborn babies can suffer severe complications if their pregnant mothers are infected. Infection can cause microcephaly birth malformations where infants are born with unusually small heads and brains, eye defects and other central nervous system problems. It has also been associated with other neurologic conditions in children and adults such as Guillain-Barré.
Infection cases first started showing up in 2015 in Brazil. Since then, about 70 countries and territories have reported Zika virus transmission, according to the World Health Organization.
As there is no vaccine, infection prevention should rely on mosquito-avoidance measures, for example, screens and netting, insecticide-treated clothing, and insect repellents, the authors wrote.
Zika transmission by the numbers
|Travellers who sought medical attention||1,118|
|Of them, how many had Zika diagnosed||41|
|Of them, how many were women||24|
|Of them, how many were child-bearing age||19|
|Of them, how many were pregnant||3|
|Of them, how many passed Zika onto the child||2|