Think for yourself: The Zika virus

As mainstream media outlets rub their hands together in Burns-like anticipation of the next pandemic, critical thinker John Turnbull takes some time to learn about the Zika virus and separate fear mongering from medical reality.

What is the Zika virus?

THE ZIKA VIRUS is an arbovirus, which means that it is primarily transmitted by arthropod vectors, in this case the Aedes aegypti mosquito. Other well-known arboviruses include Dengue fever, Yellow fever and West Nile virus. The Zika virus was first identified in Zika, Uganda in 1947 in rhesus monkeys, followed by detection in humans in Uganda and Tanzania in 1952.

According to the World Health Organisation (WHO), symptoms of the Zika virus include mild fever, skin rash and conjunctivitis, usually lasting between two and seven days. There is no specific vaccine or treatment currently available, and 80 per cent of people who contract the Zika virus will experience sub-clinical symptoms. Believe it or not, this is a lot worse than it sounds.

What are sub-clinical symptoms?

Essentially, you don’t feel like you’re sick. You may experience particularly mild symptoms that may be written off as tiredness but nothing serious enough to force you to go to the doctor or hospital and get tested.

So I get the virus, I don’t feel sick. How is that a bad thing?

If you’re not pregnant, there is a risk that you could spread the virus to vulnerable individuals or communities without even realising. If you are pregnant, however, the risk is far, far worse. While the specific causal relationship is still being established, there is very strong evidence that the Zika virus causes an increase in the incidence of microcephaly in babies.

For those unfamiliar, microcephaly is a serious congenital condition marked by babies having small heads and poor brain development. There is no treatment for microcephaly but early intervention with speech and occupational therapies has shown to improve development.

Australia has confirmed two Zika virus cases, in people who recently visited Haiti https://t.co/ysdMOo7V8g
— New York Times World (@nytimesworld) February 3, 2016

How is Zika transmitted?

The Zika virus is transmitted via blood or fluid transfer with an infected host, most commonly transmitted by mosquito bite but also via blood transfusion and sexual contact. These last two factors have been played down by most media outlets, although there is a sexually transmitted case in Texas that seems to be attracting some attention.

To be fair, you are significantly less likely to catch the virus via transfusion than mosquito bite (particularly considering the protocols observed with blood donation), although if your partner has recently travelled to West Africa, he probably needs to get tested before you try and get pregnant.

You cannot currently catch the Zika virus through casual person to person contact, the way you may catch a cold or the flu. I say currently, of course, as there is a chance that the virus could mutate and become airborne. However, this seems comparatively unlikely as the virus seems to be thriving through its existing vectors.

The best prevention against the Zika virus is not to get bitten by mosquitos. As anyone who has spent time in a tropical climate can attest, this is often easier said than done. The WHO recommend using mosquito repellent and nets, keep windows closed and eliminating any standing water around your house — it doesn’t take much water for mosquitos to breed.

Is Australia at risk?

In a word, yes. But don’t panic yet.

Aedes aegypti mosquitos are prevalent in Far North Queensland but fortunately, they can’t survive outside tropical environments. This means that you are unlikely to get Zika from a mosquito bite if you live in Melbourne but you should double your preventative efforts if you live somewhere like Townsville. On the other hand, if the virus were to spread to another species, such as the aggressive and hardy Aedes albopicus, there is little to stop the virus spreading to the rest of the country.

Outside of Far North Queensland, the biggest worry comes from the same place it has since air travel was invented — people coming in from overseas. As the burgeoning shipping trade originally allowed Aedes aegypti to spread around the world, the massive prevalence of air travel means that the Zika virus can enter Australia undetected at any time — and it’s not as if customs officers can keep an eye out for travellers with a temperature, as 80 per cent of people are asymptomatic.

What about the rest of the world?

On 28 January 2016, the WHO stated that the Zika virus was "spreading explosively" in the Americas, particularly Central and South America. A number of cases have been reported in the continental United States, and Aedes aegypti are present pretty much everywhere below Canada. One of the biggest concerns is the upcoming Olympics — of particular worry as Brazil has been identified as a hotspot for the virus.

I’ve heard it’s all a Big Pharma conspiracy, like Swine Flu

Hey, you could be right. But probably not. The fact that there isn’t a vaccine or a treatment available suggests that someone didn’t tell the pharmaceutical companies about the conspiracy but I’m sure that won’t stop some from claiming that their miracle product can either prevent or cure the Zika virus, or from claiming that microcephaly isn’t caused by Zika at all.

It’s true that Swine Flu, Bird Flu and countless seasonal flus have come and gone with no major death count. On the other hand, the last global flu pandemic killed around 50 million people, so it makes sense to keep an eye on Zika.

Can’t we just get rid of all the mosquitos?

Actually, yes we can.

Eliminating the global mosquito population is a strategy that is under serious consideration in some scientific and political circles. The favoured approach is to release large quantities of sterile male mosquitos into existing populations, which has the effect of decimating entrenched colonies that may then be targeted with pesticides.

Anyone who has been paying attention to human attempts to control species and their unintended consequences (cane toad, anyone?) knows that this approach could generate unforseen downstream effects. Taking this into account, the decision is not being taken lightly and scientists are currently examining factors like how much mosquitos contribute to the global biomass and the specific implications for global fish populations that are already under threat from overfishing, pollution and climate change. This article in Nature discusses the issue in depth and is well worth a read if you’re interested.

So is this the end of the world as we know it?

No, but that is an awesome song, and a strangely appropriate way to conclude considering the fear mongering happening on the nightly news. There is little doubt that this outbreak will get worse before it gets better but if you’re fortunate enough to live in a first world country with decent health care, you probably don’t have too much to worry about.

Think for yourself and if you can avoid it, don’t get bitten by mosquitos in tropical areas.

Thanks to Steven Novella and the Skeptics Guide to the Universe for their excellent coverage of this topic. If you’re not listening to this podcast, I highly recommend that you check it out.

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