Public health authorities in at least 21 countries and territories of Latin America and the Carribbean have reported the recent introduction of Zika virus infection with on-going local transmission. Local transmission means that mosquitoes in the area have been infected with Zika virus and are spreading it to people. Recent local transmission has also been reported in Samoa and Tonga.
On 1 February 2016 the Director-General of the World Health Organization (WHO) declared that the recent cluster of microcephaly cases and other neurological disorders reported in Brazil, following a similar cluster in French Polynesia in 2014, constitutes a Public Health Emergency of International Concern.
Due to the concerns about the possibility of severe outcomes for unborn babies, women who are pregnant or who are planning to become pregnant, should consider delaying their travel to areas with active outbreaks of Zika.
Where else does Zika virus occur?
Zika virus occurs in tropical areas with large mosquito populations and is known to occur in Africa, the Americas, Southern Asia and the Western Pacific. Zika virus was discovered in 1947, but for many years only sporadic human cases were detected in Africa and Southern Asia.
It first appeared in the Pacific in 2007 in 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, Cook Islands, Solomon Islands, Vanuatu, Fiji and Samoa in 2015, and Samoa and Tonga in 2016.
Since 2014 there have been occasional cases of Zika virus notified in NSW in people who haveacquired the infection while travelling overseas in areas with active transmission of the virus. With the explosive spread of Zika virus in the Americas it is expected that more cases of infection will be identified this year in returned travellers.
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 often causes no symptoms but when it does the illness is usually mild and lasts 4-7days. 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.
Recent outbreaks in the Pacific and Central and South America have raised concerns that Zika virus infection might cause birth defects if the mother gets Zika while pregnant, but further studies are required to confirm or exclude this possible link.
During a recent outbreak in the Pacific, the number of people who had the rare condition called Guillain-Barré syndrome (which causes paralysis) increased, but scientists have not proven that Zika causes this.
Who is at risk?
Travellers who go to affected areas in Africa, Asia, the Western Pacific, and now the Americas are at risk of getting Zika virus infection (see US CDC Zika map). 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.
How is it prevented?
Travellers to affected areas should avoid being bitten by mosquitoes. The Aedes aegypti mosquitoes that transmit Zika, dengueand chikungunya prefer to live and bite people indoors, and peak biting activity is during daylight hours. The 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 or picaridin 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.
There is currently no vaccine against Zika virus.
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.
Please click here for further information from NSW Health regarding Zika Virus