Aedes Aegypti mosquitos, which transmit dengue fever and Zika virus

It’s the faint buzzing sound that flies past our ears and makes us twitchy, the one that makes us slap ourselves, break out the Aerogard and pack up the picnic early. While the mosquitoes in Melbourne might leave you with a small itchy mark for a few days, the ones in South America, Africa and the Pacific are transmitting a virus causing fevers, headaches and birth defects. Crikey has pulled together what you need to know about the Zika virus.

What is it? Where did it come from?

Zika virus is a mosquito-borne tropical disease, like dengue or yellow fever. It was first identified in rhesus monkeys found in the Zika forest (hence the name) in Uganda in 1947, and five years later in humans. Before 2007, very few human cases of the virus had ever been reported, when outbreaks were recorded in Micronesia and French Polynesia, affecting about 75% of the population. It’s suspected to have then hitched a ride to Brazil before the World Canoe Sprint Championships in 2014, and has since spread rapidly to 22 countries throughout the Americas.  

Can I catch it? 

It will depend where you are in the world. If you’re in Australia and you’re not planning on travelling to one of the affected areas, you will most likely not catch it. Doctors and scientists have identified three possible ways you could catch the virus:

  1. Mosquito bites — most likely. Zika is spread when an infected aedes mosquito first bites someone with the virus and then someone without the virus. These mosquitoes breed and lay eggs in pools of water, e.g. bowls, buckets, pots, even as small as bottle caps.
  2. Sexual contact — rare but plausible. There is evidence that men can pass Zika to their sexual partners through their semen, and the virus is present in semen longer than in blood. As of February 3, there have only been three reports of infection this way, so there is still a lot that we don’t know about sexual transmission.
  3. Mother to foetus — rare. An infected mother can pass on Zika to her child around the time of birth, and also during the pregnancy through the amniotic fluid in the placenta.

What happens if I get it?

Zika is a very mild illness, with symptoms such as fever, rash, headaches and conjunctivitis. Symptoms usually present three to seven days after contracting the virus, but some people have no symptoms at all. Opinions on the incubation period in the body varies between health experts, but all are between two and 12 days. If you’re sick, you’ll recover in about a week.

Sexually transmitted Zika has a few more unknowns attached to it, such as: if women can pass it on through sex; if it can be passed through other forms of sex; if blood has to be present; and how long the man stays infectious. In theory, the virus could linger for weeks or even months in a man’s testes because they’re somewhat shielded from the immune system, making it harder to fight away an infection.

For most, the symptoms are mild (if at all) and leave no lasting harm, but doctors have said the virus currently poses a significant threat to pregnant women. The most dangerous time to contract Zika virus is during the first trimester of pregnancy — i.e. the later you are in your pregnancy when you get infected, the better (although not at all seems to be best) due to the associated health risks.

What are the other health risks? And what is the effect on newborn babies?

Generally, Zika virus is not the problem. You could catch it, have flu-like symptoms for a few days and recover swiftly, but it is the danger of serious birth and neurological defects, like microcephaly, that are associated with the virus that pose the major health risks.

Microcephaly has been linked with the Zika virus after Brazilian health authorities noticed an alarming number of babies were born with smaller-than-average heads. Microcephaly is a condition where the skull and brain are underdeveloped when the baby is born, or the head stops growing after birth. The Zika virus is also thought to be connected with the rare but serious neurological disorder called Guillain-Barre syndrome (GBS), which (triggered by infection) causes temporary and long-term paralysis.

Increases in GBS cases were reported in January 2016 in El Salvador, which had 46 reports in one month (three times the average). The increase overlapped with high numbers of Zika infections (3836 cases in one to two months), hence the possible link.

How can I prevent it and/or treat it?

The only to real way to prevent it is to cancel any travel plans to countries in the midst of the outbreak, as well as to avoid being bitten by a mosquito, especially if you’re pregnant or are trying to get pregnant (see above). The official advice is for women to use contraceptive if within the affected countries to delay pregnancy.

Efforts to create a vaccine for the Zika virus have only just begun, so that is potentially years away. The only way to treat it is with “rest, nourishment and other supportive care”, just like your run-of-the-mill cold, and if symptoms get worse, see a doctor.

Can we just get rid of all the mosquitoes?

It might be a tad extreme to wipe out a whole species, but potentially yes. There are about 3500 species of the little blood-suckers (which is relatively small for a family of insects), but the impact they have on human health is disastrous. After the Zika outbreak in Brazil, efforts to cull mosquito numbers are actually already underway. Every day more than 100,000 genetically modified mosquitoes are released carrying a lethal gene, which they will pass on to their offspring. The small tests show that it can reduce mosquito populations by 80%.

Ecologist Sarah Fang, among many others, believes that mosquitoes don’t actually serve any unique or particular ecological purpose that would be missed. There are some migratory birds and Little Forest bats that need them for food, but both could easily adapt.  

There is no great reason to defend them, so slap and spray to your heart’s content.

Get Crikey for $1 a week.

Lockdowns are over and BBQs are back! At last, we get to talk to people in real life. But conversation topics outside COVID are so thin on the ground.

Join Crikey and we’ll give you something to talk about. Get your first 12 weeks for $12 to get stories, analysis and BBQ stoppers you won’t see anywhere else.

Peter Fray
Peter Fray
Editor-in-chief of Crikey
12 weeks for just $12.