According to a recent study conducted by the University of Toronto and Public Health Ontario, Canadians who reported travel-related illnesses after returning from the Americas were commonly diagnosed with dengue, but actually were infected with cases of Zika virus that were more severe than expected.
Results of the study were published in a recent issue of the Canadian Medical Association Journal.
The study focused on data obtained from 1,118 people who visited Canadian Travel Medicine Network (CanTravNet) centers, a network of infectious disease specialists across the country, over a period lasting from October 2015 to September 2016. Of the travelers examined at CanTravNet centers, 41 had Zika virus, 41 had dengue fever, and 23 had chikungunya, all of which are mosquito-borne viruses transmitted in the Americas and the Caribbean. In total, 60 cases of Zika infection occurred in females, 59 of which were likely obtained through the bite of a mosquito, while one may have been the result of sexual transmission.
Symptoms from at least 80 percent of Zika-infected travelers included rashes and fever during the acute phase, while up to half of travelers reported joint pain and headaches. Approximately one in six travelers with Zika developed pink eye, otherwise known as conjunctivitis.
Two individuals diagnosed with Zika also came with cases of congenital infection, while another two had Guillain-Barré syndrome, totaling 10 percent of all Zika cases coming with severe complications.
“Referral bias to our centers may have contributed to the more severe clinical presentations noted for Zika, though we would have expected the same phenomenon to occur with dengue and chikungunya were this a significant contributing bias,” said Andrea Boggild, clinical director of the Tropical Disease Unit at the University Health Network at the University of Toronto.