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: 29 September 2017

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.

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

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

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, it is now known that Zika virus may 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). 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 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 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 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 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 affected by Zika virus are at increased risk of Zika virus infection. The World Health Organization Zika classification table and the resulting list are used to inform Australian advice to travellers.

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 Preventing infection. A specific fact sheet is available for pregnant women (INSERT HYPERLINK WHEN URL AVAILABLE).

Definitions of Zika affected and a potentially Zika affected

Department of Health Zika country classifications

A Zika affected country is a country where Zika is has recently first occurred and is spreading currently (World Health Organization Category 1), or has been present for a longer time, and there may or may not be cases reported but there is no evidence to show that it has gone (based on WHO category 2).

A country with the potential for Zika transmission is a country where the type of mosquitoes that can transmit Zika virus are present. In some of these areas Zika had spread in the past but is no longer present (based on WHO category 3), while in others there has never been any evidence of Zika spreading there (based on WHO category 4).

For more information on Zika country categories, refer to the Department of Health Zika country classifications. Refer to the WHO website for the latest list. The information is updated frequently, so check back for the latest updates.

Note: Most WHO classifications are for the whole country, but if the type of mosquito that can spread Zika is only present in part of the country, then the classifications are only relevant for that area. The European Centre for Disease Prevention and Control provides additional advice on current Zika transmission on their website.

Preventing infection

See summary of advice in Department of Health Zika country classifications.

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 a Zika affected country. Safe sex practices are also important in preventing sexual transmission.

Preventing Zika in pregnancy

Zika virus infection in a pregnant woman may cause severe birth defects. Pregnant women should consider deferring travel to a Zika affected country (WHO Category 1 and Category 2). An individual risk assessment is advised for women considering travel to countries where there is the country where there is the potential for Zika transmission (WHO Category 3 and Category 4). 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 Zika 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 Zika affected country for the duration of the pregnancy, or for 8 weeks, whichever is longer.

Preventing Zika when planning a pregnancy

Women who are planning pregnancy or at risk of pregnancy should consider deferring travel or avoid pregnancy during travel to a 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 Zika 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, including 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.

Preventing sexual transmission in 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 Zika 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 Zika 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.

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, 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 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 from recent travel to a Zika affected country or a country where there is the potential for Zika transmission and become unwell, you should see a doctor and mention your overseas travel.

All pregnant women who have travelled to a Zika affected country or a country where there is the potential for Zika transmission 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 a Zika 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 a 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

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.