Zika virus is a mosquito-borne disease which was first identified in 1947 in Uganda, Africa and has since spread to many tropical regions globally. A list of known affected countries can be found on the Australian Department of Health web site - Countries with current or recent active circulation of Zika virus.
Zika virus can be transmitted to humans by bites from infected Aedes mosquitoes primarily Aedes aegypti and Aedes albopictus. These mosquitoes can also transmit other diseases such as dengue fever. They are common in tropical and sub-tropical regions around the world. In Australia, Aedes aegypti mosquitoes are common in northern Queensland towns (with smaller numbers in some areas of central and southern Queensland), but a local outbreak is likely only in areas that have had dengue fever in recent years. That area is eastern coastal towns from Charters Towers, Townsville and Cairns to the Torres Strait islands.
Aedes albopictus is currently only found in the Torres Strait.
Between 2013 and 2015 there were large outbreaks of Zika virus infection in a number of Pacific countries. Local transmission is ongoing in this region. Since 2015 large outbreaks have been occurring in central and southern America and are continuing.
There have been no outbreaks of Zika virus in Australia. However, people infected with Zika virus while overseas who return to an area where Aedes aegypti mosquitoes are found could be the source of a local outbreak if they are bitten by the mosquito while unwell. After several days an infected mosquito can then pass the virus on to others.
Most people do not become very sick when they are infected with Zika virus. Common symptoms can include:
- low grade fever
- headache, sometimes with pain behind the eyes
- muscle and joint pain, especially in the hands and feet
- red rash
The illness is usually mild and short, lasting four to seven days. It can be diagnosed by having a blood test and/or, if not tested early in the illness, additional tests such as a urine test. There is currently no vaccine to protect against Zika virus.
Recent outbreaks in the Pacific and the Americas have raised concerns that Zika virus infection may cause birth defects such as microcephaly if a woman is infected while pregnant.
Currently it is recommended that women who are pregnant or seeking to become pregnant should consider delaying their travel to areas with current outbreaks of Zika.
If you are pregnant or planning a pregnancy and you or your partner have travelled to a Zika virus affected area, whether unwell or not, consult with your health care provider for advice and testing if indicated.
During a recent Zika outbreak in the Pacific, there was an increase in a rare condition that causes muscle weakness and paralysis called Guillain-Barré Syndrome. This may be as a result of Zika virus infection; however this association is yet to be confirmed.
- See your doctor as soon as possible if you or anyone in your family has symptoms of Zika virus infection and
- have travelled to an area which has current or recent circulation of Zika virus particularly in the last two weeks.
- live in areas with known Zika virus transmission or
- live in north Queensland
- If indicated the doctor can order tests to confirm Zika virus infection.
- Rest at home and make sure you have enough to drink, even if you cannot eat.
- Avoid mosquito bites so you don't spread the disease - use plug-in mosquito vaporiser devices containing insecticide and insect repellent inside and mosquito coils and insect repellent while outside. Stay in a screened or air-conditioned room where possible for at least 7 days from the time you became unwell.
- Have someone stay home to look after you if you are very unwell.
- Avoid aspirin, ibuprofen or other anti-inflammatory drugs as these drugs may result in bleeding if you take them while infected with Zika virus.
The primary way that Zika virus is spread is through the bite of an infected mosquito. The Aedes aegypti mosquitoes live and breed in urban environments around houses and other buildings. They are not found in bush land or swamps.
Aedes aegypti usually bite during the day and are found indoors as well as around the yard. After feeding on blood, female Aedes aegypti mosquitoes lay eggs in any artificial container, such as pot plant bases, old tyres, buckets and tarpaulins that may be holding water. The eggs hatch into ‘wrigglers’ or larvae, which develop into adult mosquitoes over a week or two.
Aedes albopictus, which is currently only found in the Torres Strait in Australia, may also transmit Zika virus. This mosquito is also an urban mosquito but does like to rest in bushes and trees around the home as well as in buildings.
A mosquito becomes infected with Zika virus after biting a sick person who has the virus in their blood. Following a short incubation period that mosquito becomes and remains infectious for life and can then pass the virus on to many other people.
Keep your home free from mosquitoes:
- Kill mosquitoes in your home using insect sprays (including automated intermittent spray devices), applying Interior Residual Spray (surface spray) and plug-in mosquito insecticide vaporisers. Note: pyrethroids are safe in pregnancy.
- Mosquitoes develop in anything that holds water such as pot plant bases, buckets, tarpaulins, old tyres, vases, coconut shells, blocked gutters, and even palm fronds. Neglected rainwater tanks, boats, tubs or pools can breed thousands of mosquitoes.
- Check in and around your home and business premise every week. Throw out old containers or store containers in a dry place. Clean out roof gutters and tip out any containers (or empty and scrub them).
- Ensure your rainwater tank is appropriately screened to prevent mosquito entry or egress.
- Wash out pet water bowls regularly.
Travelling to, or living in, a place with Zika - avoid mosquito bites:
- Aedes aegypti mosquitoes mostly bite during the day but may also bite at night. Use mosquito coils in sheltered areas outdoors or plug-in mosquito insecticide vaporisers and insect sprays inside. Screen living and sleeping areas.
- Ensure accommodation is free of mosquitoes by closing screens, doors and windows and using indoor insect spray.
- Where possible, stay in screened or air-conditioned rooms.
- Use insecticide treated bed nets when sleeping, both day and night.
- Wear light coloured clothing including long sleeved shirts, long pants and cover your feet.
- Use permethrin-treated clothing and gear (such as boots, pants, socks and tents).
- Use insect repellent containing DEET (diethyl toluamide) or picaridin and reapply according to the manufacturer’s recommendations. When used as directed on the product label insect repellents containing DEET and picaridin are safe for pregnant and breast feeding women and babies older than 2 months.
- Insect repellent must be applied to all areas of exposed skin for adequate protection. If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent.
- Queensland Health website: Mosquito borne disease in Queensland