A surge in underdeveloped brains in Brazilian infants born to women infected with the mosquito-borne Zika virus has public health authorities and doctors taking note.
The Zika virus is found in Latin America, the Caribbean and Mexico. The infections are mild, but emerging evidence of a link to birth defects is a jaw dropper.
According to a CBS news report today, experts at the U.S. Centers for Disease Control and Prevention found evidence of the virus in the placentas from two women who miscarried and the brains of two newborns who died. The newborns had small heads, a rare condition known as microcephaly.
In Brazil, the incidence of microcephaly increased 20-fold in the past few months compared with last year. Brazil’s Health Ministry says 3,530 babies have been born with microcephaly in the country since October, compared with less than 150 in 2014.
Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases in Bethseda, Md., and his colleague Dr. David Morens wrote a perspective on Zika virus that appeared in Wednesday’s New England Journal of Medicine.
“Despite the lack of definitive proof of any causal relationship, some health authorities in afflicted regions are recommending that pregnant women take meticulous precautions to avoid mosquito bites and even to delay pregnancy. It is critically important to confirm or dispel a causal link between Zika infection of pregnant women and the occurrence of microcephaly by doing intensive investigative research,” they wrote.
There’s been some evidence that suggests Zika virus may be the cause of microcephaly, said Dr. Kamran Khan, an infectious disease physician and scientist at St. Michael’s Hospital in Toronto, who is studying the spread of the virus.
“This is not 100 per cent conclusive, but it is quite concerning and compelling,” Khan said.
To try to prove the link, scientists could infect animals with Zika virus under controlled conditions to see if they give birth to offspring with the birth defect.
Such experiments will take time as health authorities face a rapidly emerging threat.
There are other infectious diseases that can cause problems in pregnant women that are ubiquitous around the world and don’t trigger travel notices, said Dr. Michael Gardam, director of infection prevention and control at Toronto’s University Health Network.
“To my knowledge, this is the first one specifically related to travel has emerged so quickly that has everybody going from not even thinking about Zika virus, because it seems to be quite a mild illness, to oh my goodness, there could be something significant here,” Gardam said.
An estimated 80 per cent of those infected show no symptoms, Khan said.
The rest have mild fever, rash, red eyes and muscle aches for two to seven days after a bite from the Aedes mosquito, which also transmits dengue and chikungya, according to the World Health Organization.
The CBS news report noted that, earlier this week, Canadian health officials said a B.C. resident who recently travelled to El Salvador contracted Zika virus infection.
The Public Health Agency of Canada said the risk to Canadians is low. The agency’s travel health notice for Zika virus notes cases appearing in Central and South America as well as Mexico. Previous outbreaks have been reported in Africa, Asia and the Oceanic Pacific region, such as Easter Island.
“An investigation to better understand the relationship between Zika virus infection and increased risk for microcephaly is ongoing,” the Public Health Agency of Canada’s travel health notice says.
There is no vaccine or specific treatment for Zika virus.