In an unprecedented move, the U.S. Centers for Disease Control and Prevention has told pregnant women that they should not travel to the trendy Wynwood neighbourhood in Miami, and that women living there should avoid becoming pregnant because of the risk of contracting Zika virus.
But these carefully crafted public-health messages should provide more reassurance than concern because they are a reminder that a) Zika is a serious health concern only to a subset of the population; b) the high-risk group, pregnant women, can protect themselves; and c) Zika outbreaks tend to be a local threat, not an epidemic threat, at least in North America.
Stated briefly: Women of child-bearing age travelling to a Zika-infected area (be it a one-square-mile section of Miami or to the Olympics in Brazil or to parts of any of the 67 countries that have reported Zika) should take precautions to avoid becoming pregnant, either using contraceptives or practising abstinence. In addition, they and others should take precautions to minimize mosquito bites, such as using repellent (containing DEET or picaridin), and wearing long-sleeved shirts and long pants.
We also need to keep the risk of Zika in perspective. About 80 per cent of people infected have no symptoms and, in others, the symptoms tend to be minor – fever, rash, joint pain and pink eye. However, when a fetus is infected with Zika, it can cause a serious birth defect, microcephaly. Still, even when a pregnant woman is infected, the risk of passing on the virus to her baby is estimated at about one in 100.
More importantly, travellers should bear in mind that Zika is only one of many risks they will face, especially in tropical countries where infectious illnesses are more common. Unlike Canada, childhood illnesses like measles and rubella circulate in some countries. Gastrointestinal infections that can come from unclean food and water also transmit pathogens like E. coli and norovirus.
Not to mention that the single biggest danger to international travellers is not infectious disease, but motor-vehicle crashes. (And, in the United States and some other countries, gun violence.)
In Brazil, where it's winter, it's flu season, and that's a much bigger threat than Zika for travellers. "The one thing I make sure is that all my travel patients have the influenza vaccine," said Dr. Jay Keystone, director of the Medisys clinic in Toronto.
He said travellers to the Olympics should be aware but not overly concerned because the risk of infection from flaviviruses like Zika – which are transmitted by the Aedes aegypti mosquito – is lower in winter, and there will be extensive spraying.
Dr. Keystone said that, while it is difficult to predict, the hope is that Zika will follow the pattern of chikungunya, a similar virus that tore through the Caribbean, infecting more than one million people, before virtually disappearing as immunity developed. Florida has also dealt with a large outbreak of another serious mosquito-borne illness, dengue, and that shows it will likely contain Zika effectively.
The infectious-disease specialist said there is little chance of Zika spreading to Canada, or too far afield in the U.S., because there are no Aedes aegypti mosquitoes in cold climates. (To date, Canada has reported 170 cases of Zika, 168 of them travel-related, one case of sexual transmission and one case of mother-to-child transmission, but no cases of microcephaly.)
"The biggest problem with Zika right now is that people are freaking out," Dr. Keystone said. "The fear is out of proportion with the risk."