Zika Virus Factsheet - The Basics

This page provides information for the general public on Zika virus. This is a rapidly changing situation. This website will be updated as new information becomes available. Check regularly for the latest information.

Page last updated: 01 December 2016

Zika is a virus that is closely related to dengue. 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 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 outbreaks are ongoing in the Americas and Pacific Islands.

Refer to the Department of Health webpage for the list of Zika affected countries.

There is evidence of small numbers of cases of Zika virus reported in Southeast Asian countries such as Thailand and Indonesia where the virus may have been present at low levels for many years.

Symptoms

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

Approximately one person in five who catches Zika virus is likely to feel sick, and if they do, the disease is generally not severe and lasts only a few days. Symptoms may be similar to those caused by the flu 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, recent outbreaks of Zika virus in the Pacific and the Americas show that Zika virus can be passed from a woman to her unborn baby. This can cause potentially serious consequences for the baby, in particular a condition called microcephaly (a small head and brain) and other birth defects.

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 affected countries. 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 carry 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 caught overseas.

Zika virus can also spread through sexual activity (vaginal, oral, or anal) particularly from a man to a woman, but male to male and female to male tranmission 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 affected by Zika virus are at increased risk of Zika virus infection. Refer to the Department of Health page for a list of Zika virus affected countries.

The risk assessment for Zika virus transmission in countries uses current and historical information from a range of sources to make an assessment of current transmission of Zika virus.

High risk countries are currently experiencing widespread transmission of Zika virus. There is a high risk of travellers getting a Zika virus infection.

Moderate risk countries have sporadic cases of Zika virus infection occurring. Zika virus is present and may be reported in travellers, however it is not widespread, and the risk of travellers getting a Zika virus infection is thought to be lower than countries with widespread Zika virus.

Low risk countries have not recently reported Zika virus but it has been present in the past. There is a possibility of very low levels of Zika virus being present or occurring in the future. The risk is low but not zero.

Pregnant women and their unborn babies are at particular risk of serious consequences of Zika virus infection. Preventing infection is essential. Refer to Preventing infection.

Preventing infection

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 in countries where Zika virus occurs.Safe sex practices are also important in preventing sexual transmission.

Preventing Zika in pregnancy and preventing sexual transmission

Zika virus infection in a pregnant woman may cause severe birth defects. Pregnant women should defer travel to High Risk countries, while for Moderate risk countries, a pregnant woman should consider deferring travel, based on her individual risk assessment. If the woman 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 a male partner who has been to a High or Moderate riskZika virus affected’ country for the duration of the pregnancy, or for 6 months, whichever is longer. Pregnant women should avoid unprotected sex with a female partner who has been to a High or Moderate riskZika virus affected’ country for the duration of the pregnancy, or for 8 weeks, whichever is longer.

Women who are planning pregnancy or at risk of pregnancy should avoid pregnancy during travel to a high or moderate risk ‘Zika-affected’ country. They should also avoid unprotected sex and pregnancy for at least 8 weeks following return. Advice relating to a partner who has travelled also applies.

For men with a partner who is planning or at risk of pregnancy and the man has travelled to a high or moderate risk ‘Zika virus affected’ country or has a diagnosed Zika infection, pregnancy should be deferred for least 6 months after return, or 6 months after the date that Zika virus infection was diagnosed.

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

To minimise the risk of sexual transmission for all other men and women:

  • If a female partner has travelled or been potentially exposed, avoid unprotected sex for at least 8 weeks after the last day in a high or moderate risk ‘Zika virus affected’ country or for 8 weeks after diagnosis.
  • If a male partner has travelled or been potentially exposed, avoid unprotected sex for at  least 6 months after the last day in a high or moderate risk Zika virus affected’ country if no symptoms appear, or at least 6 months from time of diagnosis of infection.

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

Advice to travellers returning from Low Risk countries should be based on an individual risk assessment.

Do not donate sperm for at least 6 months from the time of last exposure or time of diagnosis.

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.

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. 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 pregnant and breastfeeding women and 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 within the last two weeks from travel to a Zika virus affected country and become unwell, you should see a doctor and mention your overseas travel.

All pregnant women who have travelled to a Zika virus affected country should see their doctor. Testing for Zika virus can be discussed depending on your individual risk assessment.

There are also recommendations about sex safe and preventing pregnancy that may be relevant. 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 Zika virus affected country should not donate whole blood for 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 disappeared.

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.

Can I still donate sperm?

Men returning from Zika virus affected countries should wait at least 6 months upon return before donating sperm.

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

Further information

The Australian Government Department of Health website has the following resources that can provide more 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.