What Is Zika Virus Disease?
A mosquito-borne viral disease that is typically mild in adults but can cause severe birth defects if contracted during pregnancy.
Pathogen: Zika virus (ZIKV, Flavivirus family)
Type: Virus
Transmission
Primarily through the bite of infected Aedes aegypti and Aedes albopictus mosquitoes (same mosquitoes that transmit dengue). Also transmitted sexually, from mother to foetus during pregnancy, and rarely via blood transfusion.
Vector: Aedes aegypti and Aedes albopictus mosquitoes (daytime biters). Also transmitted sexually.
Symptoms
Most infections are asymptomatic or cause only mild illness: low-grade fever, rash (often itchy, maculopapular), conjunctivitis (red eyes), muscle and joint pain, headache, and fatigue. Symptoms are usually mild and self-limiting.
Incubation period: 3 – 14 days
Usually 3-14 days. Many infections (up to 80%) are asymptomatic.
Timeline: Symptoms appear 3-14 days after an infective bite and typically last 2-7 days. The illness is usually mild enough that many people do not realise they are infected.
Case fatality rate: Very low in adults. Zika is rarely fatal. The primary concern is the devastating effect on foetal development when infection occurs during pregnancy.
Diagnosis & Treatment
Diagnosis: Zika virus PCR on blood or urine (most sensitive in first 2 weeks). Zika IgM serology (from day 5, but cross-reacts with dengue and other flaviviruses). Plaque reduction neutralisation test (PRNT) for confirmation.
Treatment: No specific antiviral treatment. Supportive care: rest, fluids, and paracetamol for fever and pain. Avoid aspirin and NSAIDs until dengue is ruled out (as co-circulation is common). Most people recover fully within a week.
Prevention
- DEET-based insect repellent during the day (safe in pregnancy at recommended concentrations)
- Wear long sleeves and pants
- Use air-conditioned or screened accommodation
- Use condoms during and after travel to prevent sexual transmission
- Pregnant women should consider deferring travel to areas with active Zika transmission
- Use permethrin-treated clothing in high-risk areas
💉 Vaccine Status
There is currently no vaccine available for Zika Virus Disease in Australia for travellers. Prevention relies on avoiding exposure.
Post-Exposure
If you are pregnant or planning pregnancy and have travelled to a Zika-endemic area, consult your obstetrician. Testing is recommended even if asymptomatic. Men should use condoms for at least 3 months after return from a Zika-risk area if their partner is or may become pregnant. Women should wait at least 2 months after return before conceiving.
Long-Term Effects
Congenital Zika syndrome: microcephaly, brain abnormalities, eye defects, hearing loss, and limb contractures in babies born to infected mothers. Guillain-Barre syndrome (ascending paralysis) is a rare complication in adults. Post-infectious arthralgia may persist for weeks.
📋 Zika virus infection is a nationally notifiable disease in Australia. Cases are acquired overseas. There is no local mosquito-borne transmission in Australia, though the Aedes aegypti vector is present in Far North Queensland.
Frequently Asked Questions
Is Zika still a risk for travellers?
Yes. While the massive 2015-2016 outbreak in the Americas has subsided, Zika virus continues to circulate at low levels in many tropical countries. The virus is present in Southeast Asia, the Pacific Islands, Central and South America, and parts of Africa. The risk is ongoing, and Zika should be considered in pre-travel planning, especially for pregnant women or those planning pregnancy.
Should I avoid travel to Bali if I'm pregnant?
Zika virus circulates in Indonesia, including Bali. The Australian Department of Health advises pregnant women to consider deferring non-essential travel to areas with Zika transmission. If travel cannot be avoided, rigorous mosquito bite prevention is essential. Discuss your travel plans with your obstetrician before departure.
How long should I wait to conceive after travelling to a Zika area?
The Australian guidelines recommend: women should wait at least 2 months after returning from a Zika-risk area before trying to conceive. Men should wait at least 3 months, as Zika virus can persist in semen for an extended period. Use condoms during this waiting period. These timeframes apply regardless of whether you had symptoms.
Can Zika be sexually transmitted?
Yes. Zika virus can be transmitted through sexual contact. The virus has been detected in semen for up to 6 months after infection, though the period of infectivity is likely shorter. Both male-to-female and female-to-male sexual transmission have been documented. Condom use is recommended during and after travel to Zika-endemic areas.
What is the difference between Zika, dengue, and chikungunya?
All three are transmitted by the same Aedes mosquitoes and often co-circulate. Dengue causes high fever and severe joint/muscle pain ('breakbone fever') and can be life-threatening. Chikungunya causes intense joint pain that can last months. Zika is usually the mildest, with low-grade fever, rash, and conjunctivitis, but poses a serious risk to unborn babies. All three are prevented by the same mosquito bite measures.
Is there a vaccine for Zika?
No. There is no approved vaccine for Zika virus as of 2026. Several candidates are in clinical trials. Prevention relies entirely on mosquito bite avoidance (DEET repellent, protective clothing, screened accommodation) and, for pregnant women, considering deferral of travel to endemic areas.
What is microcephaly and how is it linked to Zika?
Microcephaly is a birth defect where a baby's head is significantly smaller than expected, indicating abnormal brain development. Zika infection during pregnancy, particularly in the first trimester, can cause microcephaly and other severe brain abnormalities (collectively called congenital Zika syndrome). This is why Zika prevention is critically important for pregnant women.
Can I use DEET repellent if I'm pregnant?
Yes. DEET-based repellents at concentrations up to 50% are considered safe for use during pregnancy and breastfeeding when used as directed. The Australian Government recommends DEET as the first-choice repellent for pregnant women in areas with Zika, dengue, or other mosquito-borne diseases. Apply to exposed skin and reapply as directed.
Sources & References
Last updated: April 2026