Above: Image © Kirby Hamilton, iStockphoto

In the beginning, the Zika virus didn’t seem like a very big news story. The symptoms seemed mild: slight fevers and occasional rashes. But time revealed just how dangerous the Zika virus can be, causing serious birth defects like microcephaly as it spreads.

The origins of Zika

The Zika virus is transmitted by Aedes mosquitoes to humans. It was discovered in the Zika Forest in Uganda in 1947. Since then, people have contracted Zika in Africa, the Americas, Asia and the Pacific. So far, cases diagnosed in Canada and the United States have mainly involved people who were infected while travelling abroad. However, as of September 2016, a few dozen people have been infected in by mosquitoes Florida.

The disease is spreading mainly because so few people are immune to the virus. This means the virus can’t be killed off by your immune system (your body’s defense system).

Did you know? Normally, microcephaly occurs in every one in 5000 to one in 10,000 births. However, during the peak of the Zika outbreak in Brazil in 2016, microcephaly was affecting nearly one in 100 newborns.

Zika and microcephaly

Recently, researchers have found that pregnant mothers infected by the Zika virus may be more likely to give birth to babies with a neurological (brain) disorder called microcephaly. But this raises an interesting question. If scientists have known about the Zika virus for decades, why did they only notice a link to microcephaly in 2015?

Because more people are getting infected, a link between Zika and microcephaly has become more obvious. Before 2007, outbreaks of the Zika virus were relatively rare. Since then, there have been major outbreaks in places like the Pacific island of Yap (2007), French Polynesia (2013) and South America (2015).

Infants with microcephaly have smaller heads than other infants of their age and gender. Some can grow up normally. However, others will grow up with developmental delays in speech, movement and other areas. These children also are shorter than average, hyperactive and can have coordination difficulties. In extreme cases, children with microcephaly can develop seizures and mental retardation.

It’s not entirely clear on how the Zika virus causes microcephaly. However, studies have shown that the Zika virus can affect fetal brain cells.

The spread of Zika Virus

Researchers do not know exactly why the Zika virus is infecting more and more people. One possibility is that people travel internationally more than they did in the past. Mosquitoes might bite Zika-infected travellers and spread it to other people. Or visitors to a country might get bitten by a mosquito, return home, and transmit it to other humans through sexual contact.

Also, the mosquitoes that transmit the virus tend to live in warmer climates. Many scientists believe that climate change will allow the Zika virus to spread even more. This is because climate change is associated with an increase in global temperatures. However, scientists are still researching this topic.

Did you know? Research has shown that the Zika virus could be linked to the Guillain-Barré syndrome, a neurological disorder that can cause paralysis and death.

A big news story after all

As you can see, the Zika virus is a bigger threat than people once thought. And Zika is spreading.

Vaccines have offered protection against other deadly viruses. Scientists are currently trying to develop a vaccine against Zika. However, this could take a couple of years, so don’t expect a Zika vaccine to be available at your local travel clinic anytime soon!

If you are thinking of visiting a part of the world affected by Zika, be sure to read the recommendations of the Public Health Agency of Canada.

Learn More!

About the Zika virus:

Zika: the origin and spread of a mosquito-borne virus (2016)
M. K. Kindhauser, T. Allen, V. Frank, R. Santhana & C. Dye, Bulletin of the World Health Organization

Zika virus and complications: questions and answers (2016)
World Health Organization

Zika virus: its effects, how it is spread, and the possible threat to women (2016)
J. Glenza, The Guardian

About microcephaly and the Zika Virus:

Association between Zika virus and microcephaly in French Polynesia, 2013–15: a retrospective study (2016)
S. Cauchemez et al., The Lancet 387

CDC concludes Zika causes microcephaly and other birth defects (2016)
US Centers for Disease Control and Prevention

Diseases and conditions microcephaly (2016)
Mayo Clinic

Short answers to hard questions about Zika virus (2016)
D.G. McNeil Jr., C. Saint Louis & N. St. Fleur, The New York Times

Zika virus and birth defects-reviewing the evidence for causality (2016)
S.A. Rasmussen, D.J. Jamieson, M.A. Honein & L.R. Peterson, The New England Journal of Medicine 374

Adrian Kuchtaruk

Originally from Sudbury, ON, currently pursuing an undergraduate at Queen's University. I have actively tutored many of my peers and other students in subjects ranging from chemistry, biology and physics, to calculus and functions. I have a strong interest in evolutionary biology and am looking to further my studies by pursuing a masters degree in the near future. I have been an active volunteer with Let's Talk Science and am looking to further my love of science by volunteering with Curiocity. In my spare time I love to play basketball and going out on the lake during the summer.

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