Zika Virus Factsheet - The Basics

This page provides information for the general public on Zika virus.

Page last updated: 18 December 2020

Zika virus is closely related to Dengue virus. It is spread by mosquitoes. Zika virus was first found in 1947 and in Asia in 1969. However, it may have been in these areas for much longer.

Zika virus infection was first reported outside Africa and Asia in 2007 where it caused an outbreak in Yap State (Federated States of Micronesia). Between 2013 and 2015 there were large outbreaks of Zika virus in the Pacific Islands, and in 2015, Zika virus emerged in South America, with spread to many countries in South and Central America and the Caribbean. Zika virus transmission is ongoing in the Americas and Asia.

Refer to the United States Centers for Disease Control and Prevention (CDC) Zika Travel Information webpage for information on areas of risk for Zika virus.

Symptoms

If someone is infected with Zika virus, it can typically take 3 to 12 days for symptoms to appear.

Approximately one in five people who are infected with Zika virus is likely to feel sick, and if they do feel sick, the disease is generally not severe and lasts only a few days. Symptoms may be similar to those caused by the influenza virus, and can include:

  • fever;
  • a skin rash;
  • pain in the joints;
  • muscle pain;
  • a headache, especially with pain behind the eyes;
  • conjunctivitis (red eyes); and
  • weakness or lack of energy.

Most people experience a very mild infection without any complications. However, it is now known that Zika virus may be passed from a person to their unborn baby. This can cause potentially serious consequences for the baby, in particular a condition called microcephaly (a small head and brain). Microcephaly is just one of the signs and symptoms of congenital Zika virus syndrome (CZVS) that can be present at birth or appear later in infancy such as seizures (fits), irritability, swallowing problems, hearing and sight abnormalities.

There is also strong scientific agreement that Zika virus can cause a rare paralysing condition called Guillain-Barré Syndrome (GBS). This condition has been found in areas where Zika virus outbreaks are occurring and in cases of individual travellers returning from areas of risk. GBS is known to be caused by other viruses and bacteria as well.

How it spreads

Zika virus is spread by the bite of a mosquito that is carrying the virus. Not all types of mosquito can spread it. Some types of Aedes mosquito can spread Zika virus, particularly Aedes aegypti but also possibly Aedes albopictus. Both are daytime biting mosquitoes, with increased activity around sunrise and sunset. Aedes aegypti mosquitoes often live in and around buildings in urban areas.

Most areas of Australia do not have the Aedes aegypti mosquito that can spread the virus. This mosquito is currently found in parts of Northern, Central and Southwest Queensland. Aedes albopictus is found in the Torres Strait Islands. Therefore, in most parts of Australia, there is no risk of Zika virus being spread by mosquitoes. Currently, all cases of Zika virus diagnosed in Australia were acquired overseas.

Zika virus can also spread through sexual activity (vaginal, oral, or anal) particularly from a male to a female, though male- to -male and female- to-male transmission have also been reported. However, the main way that Zika virus spreads is still by mosquitoes.

People at risk

People living in or visiting countries that are Zika virus areas of risk are at increased risk of Zika virus infection.

Refer to the United States CDC Zika Travel Information webpage for information on areas of risk for Zika virus.

Pregnant women and their unborn babies are at particular risk of serious consequences of Zika virus infection. Preventing infection is essential. Refer to the section on preventing infection for further information. A specific fact sheet is available for pregnant women.

Preventing infection

Refer to summary of advice in Department of Health Zika areas of risk.

An individual risk assessment with your doctor is advised for all travellers.

There is no vaccine for Zika virus infection. Prevention relies on avoiding being bitten by mosquitoes while in areas of risk for Zika virus. Safe sex practices are also important in preventing sexual transmission.

Preventing Zika in pregnancy

Zika virus infection during pregnancy may cause severe birth defects. Those who are pregnant should consider deferring travel to areas of risk for Zika virus. An individual risk assessment is advised for pregnant people considering travel to countries where there is the potential for Zika transmission. If a pregnant person does decide to travel, discussion with a doctor about preventing Zika virus transmission from mosquitoes and sexual partners is advised.

Pregnant women should avoid unprotected sex with any one who has been to a Zika area of risk for the duration of the pregnancy.

Preventing Zika when planning a pregnancy

Females who are planning pregnancy, or likely to become pregnant, should consider deferring travel or avoid pregnancy during travel to areas of risk for Zika virus. They should also avoid unprotected sex and pregnancy for at least 8 weeks following return. Advice relating to a sexual partner who has travelled also applies.

For males who have travelled to a Zika area of risk or has a diagnosed Zika infection, and have a sexual partner who is planning or likely to become pregnant, pregnancy should be deferred for least 3 months after return, or 3 months after the date that Zika virus infection was diagnosed.

Anyone planning a pregnancy should be offered advice about the possibility of testing to help exclude Zika virus infection, including if there are concerns about the consequences of delaying pregnancy for the recommended time periods. Testing may be considered in asymptomatic people planning pregnancy, refer to Laboratory testing.

Preventing sexual transmission in females and males

  • If a female partner has travelled or been potentially exposed, avoid unprotected sex for at least 8 weeks after the last day in a Zika area of risk or for 8 weeks after diagnosis.
  • If a male partner has travelled or been potentially exposed, avoid unprotected sex for at least 3 months after the last day in a Zika area of risk if no symptoms appear, or at least 3 months from time of diagnosis of infection.

A reliable method of contraception should be used to avoid pregnancy.

An individual risk assessment completed with your doctor can help you make decisions about what to do if you are unable to practice safe sex for the recommended period after return from a Zika virus affected country, including the need for any laboratory testing.

Please see your doctor for further advice.

How do I protect myself from mosquitoes?

All travellers should follow recommendations to avoid mosquito bites at all times when travelling in overseas countries where there is a risk of mosquito-borne diseases to reduce their risk of catching Zika virus and other mosquito-borne diseases. This is particularly important if you are pregnant or planning a pregnancy.

It is important to be aware that these precautions are necessary in the daytime and night time:

  • Cover as much exposed skin as possible, including wearing light coloured long-sleeved shirts and long pants;
  • Use insect repellents, applied according to the product label. The most effective mosquito repellents contain Diethyl Toluamide (DEET) or Picaridin. Repellents containing oil of lemon eucalyptus (OLE) (also known as Extract of Lemon Eucalyptus) or para menthane diol (PMD) also provide adequate protection. Note that insect repellents containing DEET or Picaridin, are safe for those pregnant or breastfeeding, and for children older than 2 months, when used according to the product label. If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent;
  • Use insecticide-treated (such as Permethrin) clothing and gear (such as boots, pants, socks, and tents); and
  • Stay and sleep in screened-in or air-conditioned rooms. Use bed nets if you cannot keep mosquitoes from coming inside the room.

Seek medical advice, as soon as practicable, if unwell during or soon after travel.

Travellers returning to areas of Queensland with suitable mosquitoes to transmit Zika should avoid mosquito bites for 4 weeks after return.

How Zika virus infection is diagnosed

A blood or urine test can diagnose Zika virus infection.

For further information on testing, please refer to Information on testing for Zika virus infection.

How Zika virus infection is treated

At the moment there is no specific treatment for Zika virus infection, but supportive medical care can be provided if required (e.g. rest, fluids).

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Preventing Zika virus spread in Australia

Health authorities prevent the spread of Zika virus in Australia by:

  • In areas of Queensland where the mosquitoes Aedes aegypti and/or Aedes albopictus are present, health authorities will respond urgently to cases to prevent it from spreading in Australia, as they do for cases of dengue. This will include advising people on avoiding mosquito bites during their illness and may include controlling mosquitoes around the person’s home
  • Continuing to monitor international ports of entry to prevent the mosquitoes that can transmit Zika virus from entering or spreading to new areas
  • Ensuring the safety of the blood supply through restrictions on whole blood donation for travellers coming to Australia from areas where mosquito-borne diseases are occurring

What should I do if I think I might have Zika virus?

If you have returned from recent travel to an area of risk for Zika virus and become unwell, you should see a doctor and mention your overseas travel.

All pregnant people who have travelled to an area of risk for Zika virus should see their doctor. Testing for Zika virus can be discussed depending on your individual risk assessment.

There are recommendations about sex safe and preventing pregnancy that may be relevant if you have a Zika virus infection. Refer to the section Preventing Zika in pregnancy and preventing Sexual transmission.

Travellers returning to areas of Queensland with suitable mosquitoes to transmit Zika should avoid mosquito bites for 4 weeks after return.

Can I still donate blood?

People who have been to an area of risk for Zika virus should not donate whole blood, clinical plasma, or platelets for a minimum of 4 weeks after they have returned if they do not have symptoms of Zika virus infection.

If you are confirmed by a doctor to have Zika virus infection, you should not donate whole blood for 4 months after symptoms have ceased.

If you have had sex with someone who has been diagnosed with Zika virus infection at any time in the last 6 months, you should not donate whole blood for 4 weeks after the last time you had sex with that person.

For the latest information refer to the Australian Red Cross Blood Service website.

Can I still donate sperm?

Do not donate sperm for at least 6 months from the time of last Zika virus exposure, including: residence in, or travel to, an area of risk for Zika virus; or sex with a person who had exposure to, or diagnosis of, Zika virus in the past 6 months.

People who have had a confirmed Zika virus infection should wait 6 months following diagnosis before donating sperm.

Further information

If you have questions that are not answered by the above resources, or are unsure about any of the provided information, please consult your doctor.