Key facts

  • Scientific evidence from outbreaks of Zika virus shows that a Zika virus infection in a pregnant woman can be transmitted to the fetus, and can cause certain congenital abnormalities (including microcephaly).
  • Pregnant women should defer travel to high risk countries. Consider deferring travel to Moderate risk countries. If travelling, follow Zika virus travel precautions.

What is the current situation?

On 10 March 2017 WHO reported that, overall, the global risk assessment has not changed. ZIKV continues to spread geographically to areas where competent vectors are present. Although a decline in cases of Zika virus infection has been reported in some countries, or in some parts of countries, vigilance needs to remain high.

WHO have developed a new Zika virus classification scheme to categorize the presence of and potential for vector-borne ZIKV transmission and to inform public health recommendations. Based on the defined criteria and expert review, some countries, territories and subnational areas were reclassified and some were classified for the first time.

For more information see the WHO Zika Situation Reports.

The Commonwealth Department of Health also maintains a list of Zika-affected countries.

What is Zika virus infection?

Zika virus infection is an illness caused by the Zika virus that is spread through the bite of infected mosquitoes. The virus is closely related to dengue virus and can cause a similar illness. The infection causes no symptoms in 80% of people but when it does the illness is usually mild and lasts 4-7 days. Symptoms of Zika virus infection arise 3-12 days after being bitten and may include fever, a rash, headache, red eyes, muscle aches, and joint pains.

There have been extensive epidemiological and laboratory studies of Zika virus complications and there is strong scientific consensus that Zika virus is a cause of microcephaly, GBS and may cause other congenital neurological disorders.

Where does Zika virus occur?

Zika virus occurs in tropical areas with large mosquito populations and is known to occur in Africa, the Americas, Asia and the Western Pacific. Zika virus was discovered in 1947 in the Zika forest of Uganda, but for many years only sporadic human cases were detected in Africa and Southern Asia.

Zika first appeared in the Pacific in 2007 in a large outbreak on the island of Yap (Federated States of Micronesia). It re-emerged in the region with cases reported for the first time in French Polynesia in 2013-14, New Caledonia in 2014, and Cook Islands, Solomon Islands, Vanuatu, Fiji and Samoa in 2015.

The Commonwealth Department of Health also maintains a list of Zika-affected countries.

Who is at risk?

Travellers who go to affected areas in Africa, Asia, the Western Pacific and the Americas are at risk of getting Zika virus infection. The Aedes aegypti mosquito that is the main transmitter of Zika virus can bite during the day and night, both indoors and outdoors, and often lives around buildings in urban areas.

There is now substantial evidence that Zika virus can be transmitted sexually, although this seems to occur rarely. This of particular concern for pregnant women whose partners have returned from areas with local transmission of Zika virus.

How is it prevented?

There is currently no vaccine against Zika virus.

Travellers to affected areas should avoid being bitten by mosquitoes. The Aedes aegypti mosquitoes that are most commonly responsible for transmitting  Zika (as well as dengue and chikungunya) prefer to live and bite people indoors, and peak biting activity is during daylight hours. This mosquito hides under furniture and tends to bite around the feet and ankles. People may not notice they are being bitten.

Travellers to affected areas should stay in accommodation with screened windows and doors, wear loose fitting clothing that covers the arms and legs, and apply insect repellent containing DEET, picaridin, or oil of eucalyptus to exposed skin, especially during daylight hours and in the early evening.

For additional advice on steps to avoid being bitten by mosquitoes see the Mosquitoes are a Health Hazard Factsheet.

How can sexual transmission of Zika virus be prevented?

Pregnant women should avoid unprotected sex with a male partner who has been to a high or moderate-risk ZIKV-affected country for the duration of the pregnancy, or for six months – whichever is longer.

Pregnant women should avoid unprotected sex with a female partner who has been to a high or moderate-risk ZIKV affected country for the duration of the pregnancy, or at least 8 weeks – whichever is longer. If a female partner has travelled or been potentially exposed, she should avoid unprotected sex for at least eight weeks after the last day in a high or moderate-risk ZIKV-affected country, or for eight weeks after diagnosis.

If a male partner has travelled or been potentially exposed, he should avoid unprotected sex for at least six months after the last day in a high or moderate-risk ZIKV-affected country if no symptoms appear, or for at least six months from time of diagnosis. Men should not donate sperm for at least six months from the time of last exposure or time of diagnosis.

For further information on reducing the risk of sexual transmission refer to the Commonwealth Department of Health Zika virus – information for clinicians and public health practitioners and the list of Zika virus affected countries by risk category.

An individual risk assessment completed with your doctor can help you make decisions about what to do after return from a Zika virus affected country.

Will Zika virus spread in NSW?

It is very unlikely that Zika virus will establish local transmission in NSW as the mosquitoes that spread the infection overseas are not found here. There is no evidence that local mosquitoes can transmit the virus between people.

The Aedes aegypti mosquitoes that transmit Zika virus are found in some parts of north Queensland. This is why anyone diagnosed with Zika virus infection in NSW is advised against travel to north Queensland until they have cleared their infection from their bloodstream (usually about a week after their symptoms started).

Zika testing information for medical practitioners

In NSW, nucleic acid testing and serological testing for Zika virus infection is undertaken in certain laboratories. Testing for Zika virus will usually be done concurrently with, or after excluding, other exotic infections with similar presentations - such as dengue, chikungunya, malaria, and measles - depending on travel history.

If Zika virus infection is suspected, clinicians are advised to discuss testing with their local pathology provider for information about appropriate tests, specimens to be collected and information to be provided on the request form (clinical history including date of symptom onset or date of last potential exposure if asymptomatic and travel history).

Further information

Contact your local public health unit on 1300 066 055

Current as at: Thursday 13 May 2021
Contact page owner: Communicable Diseases