Zika virus ‘spreading explosively’ through Americas
Canada considered safe as transmitting mosquitoes have not yet arrived
The mosquito-borne Zika virus is “spreading explosively” in the Americas and will soon be in all but two countries, Canada and Chile, the head of the World Health Organization says.
Canada enjoys a “biological barrier” to widespread transmission of the virus, according to Dave Patrick, a physician and epidemiologist at the University of B.C.
“The particular mosquitoes that are capable of transmitting the virus are not here,” he said. “We’ve got to keep looking out for them and make sure there isn’t a northward migration.”
The Zika virus has been detected in 23 countries in North and South America and has been linked to thousands of cases of babies born with a severe neurological disorder called microcephaly and the rising incidence of Guillain-Barre syndrome, an immune disorder that causes weakening of the muscles.
The possible links, only recently suspected, have rapidly changed the risk profile of Zika from a mild threat to one of alarming proportions. MARGARET CHAN DIRECTOR GENERAL, WORLD HEALTH ORGANIZATION
“The level of alarm is extremely high,” WHO director general Margaret Chan told the organization’s executive board in Geneva on Thursday. One WHO scientist said the Americas could see up to four million cases of Zika in the next year.
Whether Zika virus infection causes birth malformations and neurological syndromes has not yet been established, but is strongly suspected, Chan said.
“The possible links, only recently suspected, have rapidly changed the risk profile of Zika from a mild threat to one of alarming proportions,” she said.
Two cases of Zika have been confirmed in B.C. residents who are believed to have contracted the illness in El Salvador and Colombia. Neither person was pregnant at the time of the illness and both have recovered.
The WHO will convene an emergency committee on Feb. 1 to consider action in affected countries and how to prioritize research.
Women who are pregnant or planning to become pregnant are being warned to avoid regions where the virus is present. There is no vaccine or treatment for the Zika virus.
The virus is spread by the Aedes family of mosquitoes. A denizen of the tropics, Aedes aegypti is a dangerous mode of transmission for Zika and related viruses such as dengue and yellow fevers. Its close relative, Aedes albopictus, may also transmit the virus and its range includes the United States as far north as the Great Lakes and as far west as the Dakotas.
It’s not yet clear whether Aedes albopictus is an important factor in the spread of the virus, Patrick said. While it is possible to transmit Zika through sexual contact, it is extremely rare and does not appear to be an important means of spreading.
The greater concern is the virus is present in a number of popular destinations for Canadian tourists and that the mosquitoes that spread Zika bite all day long.
“This is a reason to be extra cautious about mosquito avoidance, wear long clothing, and use mosquito repellent,” Patrick said. “As a Canadian, you have to change your mindset because we are used to mosquitoes that bite at dawn or dusk.”
The rapid spread of the virus is due in part to the absence of immunity in the Americas, where the virus has only recently appeared. Zika has been present in equatorial Africa and Asia since the 1950s. In 2014, it crossed into Polynesia, and last year it appeared for the first time in Central and South America and the Caribbean, where it is considered a pandemic.
Three of Canada’s largest airlines are allowing passengers to change bookings to destinations in Central and South America and parts of the Caribbean amid concern over the virus.
WestJet says any passenger can change or cancel a booking before travelling to infected areas. No medical notes are required.
Air Canada says it is allowing passengers and companions in their immediate family to change bookings or receive a refund if they cancel flights because of concerns about the outbreak. The company says customers will need to provide a doctor’s note that says they are at risk of contracting the mosquito-borne virus for them to change bookings or get a refund on flights to countries where Zika has been detected.
Air Transat says pregnant women with a medical note can reschedule or change destinations if they were booked to fly to countries that have been listed by the Pan American Health Organization as having the virus.
Meanwhile, Canadian Blood Services will soon refuse blood donations from those who have travelled to countries where the mosquito-borne Zika virus has become widespread.
Chief medical and scientific officer Dana Devine said the blood collection agency will decide in the next few days which travel destinations would be linked to a temporary ban on donating blood.
Devine said the risk of the Zika virus being transmitted through blood transfusion is low, but said Canadian Blood Services doesn’t want to take any chances.