Zika virus is an infection caused by a mosquito-borne virus that can affect people in tropical and subtropical regions around the world. For most infected people, Zika causes no symptoms or only a mild illness that resolves within several days. However, the infection deserves particular attention because it can cause serious complications during pregnancy and, in uncommon cases, neurological problems in adults and children.
Zika became a major international health concern during the large outbreak in the Americas in 2015 and 2016. Although Zika activity has declined substantially since that epidemic, the virus has not disappeared. The World Health Organization reported in May 2026 that evidence of current or previous local transmission exists in 97 countries and territories.
How Zika Spreads From One Person to Another
An infected mosquito generally acquires Zika after feeding on an infected person. The virus can subsequently be transmitted when that mosquito bites another person.
Mosquito transmission is the main route, but it is not the only one. Zika can also be transmitted through sexual contact. The virus can be present in semen and other body fluids, meaning a person can potentially transmit Zika even when they experienced few or no symptoms.
Another important route is mother-to-fetus transmission during pregnancy. Infection can cross the placenta and affect fetal development. Transmission associated with pregnancy is the reason Zika has particular importance for people who are pregnant or planning a pregnancy.
Blood transfusion and laboratory exposure have also been reported as possible routes, while other transmission routes such as organ or tissue transplantation remain areas of public-health concern.
Why Many People Never Realize They Have Zika
One of the challenging characteristics of Zika is that infection frequently causes no noticeable illness. When symptoms do occur, they are generally mild.
The incubation period is usually estimated at 3 to 14 days. Typical symptoms can include:
- Fever
- A skin rash
- Red or irritated eyes, known as conjunctivitis
- Joint pain
- Muscle pain
- Headache
- Tiredness or general discomfort
Symptoms commonly last around 2 to 7 days and usually disappear without specific treatment. Because these symptoms overlap with other infections, particularly dengue and chikungunya, symptoms alone cannot reliably establish that someone has Zika.
The absence of symptoms does not necessarily mean the infection has no significance. A person who feels completely healthy may still have been infected and may need to consider precautions related to sexual transmission or pregnancy.
Pregnancy Is the Most Important Health Concern
Zika infection can be particularly dangerous when it occurs during pregnancy. The virus can cross from the pregnant person to the developing fetus and interfere with normal development.
The best-known complication is microcephaly, in which a baby's head is substantially smaller than expected because of abnormal brain development. However, congenital Zika infection can involve much more than head size.
The broader group of abnormalities is called congenital Zika syndrome. Possible effects include abnormalities of brain development, eye problems, hearing impairment, limb contractures, abnormal muscle tone and other neurological problems. Pregnancy complications can also include fetal loss, stillbirth and premature birth.
Importantly, congenital complications can occur even when the pregnant person experienced no obvious Zika symptoms. This makes prevention and appropriate medical assessment especially important for people who have been exposed in areas where Zika transmission occurs.
At the same time, a Zika infection during pregnancy does not mean that a baby will necessarily develop a congenital abnormality. WHO estimates that approximately 5% to 15% of infants born to women infected during pregnancy have evidence of Zika-related complications, although the precise risk varies with circumstances and remains an area of ongoing research.
Neurological Complications Can Occur in Zika
Although most Zika infections are mild, the virus has also been associated with neurological complications.
One of the best-known is Guillain-Barré syndrome (GBS), a rare disorder in which the immune system attacks peripheral nerves. It can produce tingling, weakness and progressive muscle paralysis. In severe cases, the muscles involved in breathing can be affected.
Zika has also been associated with other neurological conditions, including neuropathy and myelitis. These complications are uncommon, but their potential seriousness means that unusual neurological symptoms after a possible Zika infection should receive prompt medical attention.
Guillain-Barré syndrome itself has many possible triggers and is not specific to Zika. Nevertheless, WHO recognizes Zika infection as a trigger for GBS in some people.
How Doctors Test for Zika
Zika diagnosis requires more than simply identifying a rash or fever.
Healthcare professionals consider symptoms together with factors such as recent travel, residence in an area with transmission, mosquito exposure and sexual exposure. Laboratory testing can detect viral RNA or antibodies generated by the immune system.
Testing can be complicated because Zika belongs to a group of closely related flaviviruses. Antibody tests may sometimes cross-react with antibodies produced in response to related viruses such as dengue. Consequently, clinicians interpret test results in the context of a person's medical and travel history.
People who are pregnant and may have been exposed to Zika should discuss the situation with their healthcare provider rather than relying on symptoms alone.
There Is No Specific Medicine for Zika
There are no specific FDA-approved antiviral supplements or medicines to treat or cure the Zika virus. Management focuses entirely on supportive care, such as resting and drinking plenty of fluids, along with acetaminophen to manage fever and pain.
While laboratory and animal studies show that certain nutrients or supplements might restrict Zika replication
Vitamin C: Acts as a general antioxidant, though robust clinical trial data for Zika is lacking.
Folic Acid: Shown in animal models to potentially reduce poor pregnancy outcomes linked to Zika, but human efficacy remains unproven.
Vitamin D & A: Noted in cellular studies to modulate immune responses against viral replication.
Omega-3 (DHA): Suggested by animal research to offer neuroprotective effects, but not established as a treatment.
However, an important precaution concerns dengue. Zika and dengue can produce similar symptoms, and dengue can cause serious bleeding. WHO recommends that when dengue has not been ruled out, people avoid nonsteroidal anti-inflammatory drugs until appropriate medical evaluation has occurred. A healthcare professional can recommend appropriate fever and pain management based on the individual's circumstances.
Preventing Zika Starts With Mosquito Protection
Because there is no vaccine, preventing mosquito bites remains one of the most important ways to reduce Zika risk.
People living in or traveling to areas where Zika transmission occurs can reduce exposure by:
- Wearing clothing that covers the arms and legs.
- Using an appropriate insect repellent according to its label.
- Staying in screened or air-conditioned rooms when possible.
- Using mosquito nets where appropriate.
- Removing standing water around homes where mosquitoes can breed.
- Taking precautions during the daytime as well as at night.
The same measures can reduce exposure to dengue and chikungunya because the mosquitoes responsible for Zika can transmit those diseases as well.
Sexual Prevention Is Also Important
Mosquito avoidance alone cannot eliminate the risk of Zika transmission because infected people can transmit the virus sexually.
Condoms or abstinence can reduce the risk of sexual transmission. The recommended duration of precautions can depend on whether the person infected or exposed is male or female, whether symptoms occurred, whether a partner is pregnant, and whether transmission is currently occurring in the relevant region.
WHO currently recommends that people returning from areas with active Zika transmission use safer sex or abstain for three months for men and two months for women when returning to regions without active transmission. For pregnant women, WHO recommends safer sex or abstinence for the duration of pregnancy when there is a relevant risk of sexual exposure.
Because recommendations can change as evidence and local transmission patterns change, travelers should check current guidance from public-health authorities before and after travel.
Special Precautions Before and During Pregnancy
People who are pregnant or planning to become pregnant should take Zika prevention particularly seriously.
Before traveling to an area where Zika transmission is occurring, it is sensible to check current travel-health guidance. A pregnant traveler should discuss potential exposure with a healthcare professional.
After possible exposure, pregnancy care providers can determine whether testing, ultrasound monitoring, or other follow-up is appropriate.
Importantly, people should not make decisions about pregnancy based solely on fear following possible exposure. Medical counseling can help determine the actual level of risk and appropriate next steps.
Is Zika Still a Global Health Concern?
The dramatic Zika epidemic in the Americas has ended, but the virus remains present.
WHO's May 2026 epidemiological update found evidence of current or previous autochthonous transmission in 97 countries and territories. Transmission has declined considerably compared with the 2015–2016 period, but sporadic transmission and outbreaks remain possible in areas where suitable Aedes mosquito populations exist.
This is why Zika should not be viewed solely as a disease associated with a past epidemic. Continued surveillance, mosquito control, laboratory testing and travel-health awareness remain important.
When to Seek Medical Advice
Consider contacting a healthcare professional if you develop a rash, fever, red eyes, joint pain or other symptoms after traveling to or living in an area where Zika transmission occurs.
Medical advice is particularly important if:
- You are pregnant and may have been exposed.
- You are planning a pregnancy and recently traveled to an area with Zika risk.
- Your sexual partner has recently been exposed.
- You develop neurological symptoms such as progressive weakness, tingling or difficulty walking.
- You have symptoms that could also indicate dengue or another mosquito-borne infection.
Prompt assessment can help distinguish Zika from other infections and determine whether additional monitoring or precautions are appropriate.