Since early January, when we first alerted you to the emergence of the Zika virus throughout the Americas, the impact of this mosquito-borne disease has been dynamic—even inducing several governments to advise pregnant women to avoid travel to a growing number of Zika-prone countries.
The reason for singling out pregnant women (or those who might become pregnant) is that the Zika virus has been linked to an extraordinary surge of microcephaly—a fetal deformity resulting in unusually small heads and brains in newborns. The epicenter of this surge, and the region where it has been aggressively researched and documented, is Brazil, where almost 4,000 suspected cases were identified in 2015—30 times more than in any one-year period since 2010.
Were it not for this link to newborn microcephaly, we likely wouldn’t be talking about Zika today, since its other manifestations are relatively mild (fever, rash, headaches, joint paint, and conjunctivitis) and typically occur between three to twelve days after the mosquito bite. Certainly the symptoms are milder and not quite as debilitating as dengue fever or chikungunya—also carried by the same species of mosquito.
This past week, the Pan American Health Association (PAHO), a sector of the WHO, warned that the Zika virus had been detected in at least 21 countries and territories of the Americas, and the mosquito responsible for transmission of the virus, Aedes aegypti, is present in every country of this region except Canada and Chile.
Does this mean you are free and clear? No—not if you travel to any of the countries where this mosquito takes up residence (which includes much of the U.S., especially the southern and coastal areas, and virtually the entire Caribbean basin, Mexico, Central America, and most of South America).
To date, Zika virus transmissions have been detected only in people who have travelled to areas where local transmission has been documented. But researchers in the U.S. believe it is only a matter of time before the first cases of local transmission are detected, probably in warm, humid areas of Florida, Louisiana, Texas, or any tropical or sub-tropical climates throughout the U.S.
It’s important to understand that transmission occurs when a mosquito (Aedes aegypti) bites a host who is already infected and then bites a non-infected recipient. Since Aedes aegypti is not present in Canada, local transmission is unlikely. But should a Quebecer or Manitoban be bitten by a virus-carrying mosquito while visiting Alabama, South Carolina, Jamaica, Costa Rica, or anywhere else, they will be at risk for infection. But the virus will not be transmitted once they return to Canada, thanks to the absence of Aedes aegypti. But if the recipient of the virus is a pregnant woman, then her risk becomes more tangible.
Consequently, The Public Health Agency of Canada recommends that “pregnant women and those considering becoming pregnant discuss their travel plans with their health care provider to assess their risk and consider postponing travel to areas where the Zika virus is circulating in the Americas. If travel cannot be postponed then strict mosquito bite prevention measures should be followed to protect themselves against bites.”
As any vacationer knows, holding mosquitos at bay is tedious work—dressing in long sleeves and pants during warm days and evenings, rubbing dreaded DEET on every exposed inch of one’s body, and clustering about those mosquito-repelling lanterns that don’t work. But you must do it. Do not belittle the skill and intelligence of the lowly mosquito. It kills more people than any other animal.
Heading south? Do not forget your travel insurance.