What is Zika Virus?
Zika virus is a mosquito-borne viral infection primarily spread through the bite of infected Aedes mosquitoes. The virus belongs to the Flavivirus family, which also includes dengue, yellow fever, and Japanese encephalitis. In addition to mosquito transmission, Zika virus can also spread through sexual contact, from a pregnant person to their foetus during pregnancy, and in rare cases through blood exposure.
Most infections are mild and many people do not develop symptoms. However, Zika infection during pregnancy can cause serious birth defects, including neurological problems and microcephaly, which is when a baby is born with a smaller than normal head due to underdeveloped brain growth. For this reason, the virus remains an important public health concern for travellers visiting regions where transmission occurs.
According to the World Health Organization (WHO), evidence of mosquito-transmitted Zika virus infection has been reported in more than 90 countries and territories worldwide, although surveillance and reporting vary between regions.
FAQs
In which countries is Zika present?
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Zika virus is primarily found in tropical and subtropical regions around the world. Outbreaks occur in parts of Central and South America, the Caribbean, Southeast Asia, the Pacific Islands, and some areas of Africa. The virus is transmitted by daytime-biting Aedes mosquitoes, which thrive in urban and peri-urban environments. Travellers planning to visit these regions should be aware of the risk and take mosquito bite prevention measures, including using repellent, wearing long clothing, and ensuring accommodation has window screens or air conditioning.
Should pregnant travellers avoid destinations with Zika virus transmission?
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Yes. The Australian Department of Health, strongly advises that women who are pregnant, planning pregnancy, or whose partners are pregnant seek medical advice before travelling to areas with active Zika transmission. Zika infection during pregnancy can cause serious birth defects, including microcephaly, which is when a baby is born with a smaller-than-normal head and may experience developmental delays. It can also lead to other neurological complications for the developing baby. Pregnant travellers are generally advised to postpone non-essential travel to affected areas, and if travel is unavoidable, they should strictly follow mosquito bite prevention measures to reduce the risk of infection.
Can Zika virus be spread through sexual contact?
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Yes. Zika virus can be transmitted through sexual contact with an infected person, including vaginal, anal, and oral sex. The virus can persist in semen for several months after infection and in vaginal fluids for shorter periods. The Australian Department of Health recommends that travellers returning from areas with active Zika transmission practise safe sex or abstain from sexual activity for a defined period to reduce the risk of transmitting the virus to partners, especially if the partner is pregnant. Using condoms consistently and correctly is the most effective way to prevent sexual transmission.
Can I get tested for Zika after travel to avoid passing the infection on to my partner?
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In the context of a patient with symptoms of Zika virus infection, serological testing (and occasionally PCR) is a sufficiently accurate way to diagnose infection. For those without symptoms, however, negative tests do not 100% rule out carriage of the virus. So testing can't be used as a substitute for abstaining or using condoms after travel.
What should I do if I develop symptoms of Zika virus after travelling?
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If you experience symptoms such as fever, rash, joint pain, headache, or red eyes within two weeks of returning from a region where Zika virus is present, you should seek medical advice promptly.
Tell your healthcare provider about your recent travel and any potential mosquito exposure. While most cases are mild and resolve on their own within a week, testing may be recommended, particularly for pregnant women or those planning pregnancy, to assess the risk to the developing baby. Supportive care focuses on rest, staying hydrated, and relieving pain or fever with appropriate medications. Additionally, to prevent further spread, individuals with suspected Zika infection should avoid mosquito bites and practise safe sex for the recommended period after returning from an affected area.
What to Know
Zika symptoms
Many individuals infected with Zika virus do not develop any noticeable symptoms. When symptoms do occur, they typically appear within three to fourteen days after being bitten by an infected mosquito, although most cases present within the first week.
Common signs of infection include mild fever, a generalized skin rash, headache, muscle aches, joint pain, and red eyes. While most infections are self-limiting and resolve within a few days, Zika virus has been associated with rare neurological complications, including Guillain-Barré syndrome, a condition in which the body’s immune system attacks the nerves, potentially causing weakness or paralysis.
Of particular concern, Zika infection during pregnancy can lead to serious congenital abnormalities in the developing baby, most notably microcephaly, a condition where the infant’s head is smaller than normal due to incomplete brain development, along with other neurological and developmental issues. The World Health Organization (WHO) reports that thousands of cases of Zika-associated birth defects have been documented in affected regions since the 2015–2016 outbreaks.
Zika diagnosis and treatment
Diagnosing Zika virus infection relies on a combination of clinical evaluation, travel history, and laboratory testing. Consult your doctor if you have any symptoms or concerns, as they consider recent travel to areas where Zika virus is known to circulate, as well as the presence of typical symptoms. Laboratory confirmation is usually done through blood or urine tests that detect the virus’s RNA or specific antibodies. In Australia, testing is recommended for pregnant women who have travelled to affected regions, or for anyone presenting with compatible symptoms after recent travel.
Currently, there is no antiviral treatment or vaccine available for Zika virus infection. Management is supportive, focusing on relieving discomfort. This includes getting adequate rest, drinking plenty of fluids to prevent dehydration, and taking over-the-counter medications such to reduce fever and relieve pain. It is advised to avoid non-steroidal anti-inflammatory drugs like ibuprofen until dengue infection has been ruled out, due to the risk of bleeding complications.
Additionally, individuals with suspected infection should take measures to prevent mosquito bites, as this can help stop the virus from spreading to others.
Zika prevention
The most effective strategy to prevent Zika virus infection is to avoid mosquito bites, particularly from Aedes species mosquitoes, which are active during the day and are also responsible for transmitting dengue and chikungunya.
Travellers are advised to use insect repellents containing DEET, picaridin, or oil of lemon eucalyptus, and to reapply as directed. Wearing long-sleeved clothing, socks and closed-toe shoes, and staying in air-conditioned or well-screened accommodation further reduces exposure. Eliminating standing water in and around living areas is crucial, as Aedes mosquitoes breed in small collections of water such as flower pots, buckets, or discarded containers.
Because Zika virus can also be transmitted sexually, safe sex practices are important for travellers returning from areas where Zika is present. The Australian Department of Health advises that men who may have been exposed to Zika use condoms or abstain from sexual activity for at least three months, and women for at least two months, particularly if planning a pregnancy. Pregnant travellers should take extra precautions to avoid both mosquito bites and sexual transmission, given the significant risk of complications to the developing baby.