Zika
Zika is a mosquito-borne viral infection that is often mild or silent, but it matters deeply in pregnancy because infection can harm fetal development.
What Zika is
Zika is an infection caused by Zika virus. Many infected people have no symptoms, and many symptomatic cases are mild. The same feature that makes Zika easy to miss also makes surveillance difficult: outbreaks can spread quietly before health systems notice unusual pregnancy outcomes or clusters of mosquito-borne illness.
How it spreads
Zika spreads mainly through bites from infected Aedes mosquitoes. These mosquitoes often bite during the day and can live close to homes, where small containers of standing water provide breeding sites. Zika can also spread from a pregnant person to a fetus, through sex, and in rare circumstances through blood or tissue exposure.
Symptoms
When symptoms occur, they can include fever, rash, headache, joint pain, red eyes, and muscle pain. Illness usually lasts days to about a week. Because Zika symptoms overlap with dengue, chikungunya, and other infections, exposure history and laboratory testing can be important, especially for pregnant people or people with recent travel to risk areas.
Why pregnancy changes the stakes
Zika is best known for its link to congenital Zika syndrome. Infection during pregnancy can affect the developing brain and eyes and is associated with microcephaly, developmental problems, fetal loss, stillbirth, and preterm birth. The risk is not the same for every exposure, but the possible consequences are serious enough that travel and prevention guidance gives pregnancy special attention.
Testing and diagnosis
Testing depends on timing, symptoms, pregnancy status, travel history, and local transmission. Molecular tests can look for viral genetic material during a narrow window, while antibody tests can be harder to interpret because related flaviviruses can cause cross-reactions. Clinicians often weigh results alongside symptoms and where a person may have been exposed.
Care and treatment
There is no specific antiviral medicine for Zika and no widely available vaccine to prevent it. Care usually focuses on rest, fluids, fever control, and monitoring. People who might have dengue are often told to avoid aspirin and other nonsteroidal anti-inflammatory drugs until dengue is ruled out, because dengue can raise bleeding risk.
Prevention
Prevention centers on avoiding mosquito bites and reducing mosquito breeding sites. Repellent, long sleeves, window screens, air conditioning, bed nets when needed, and removing standing water all help. Sexual transmission guidance can matter after travel or exposure, especially when someone is pregnant or planning pregnancy.
Why it matters
Zika showed how a disease that is mild for many adults can still become a major public-health emergency. Its 2015-2016 spread through the Americas connected mosquito control, prenatal care, travel medicine, laboratory capacity, and long-term support for affected children and families.
What researchers still watch
Public-health teams continue to track where Aedes mosquitoes live, how often Zika circulates silently, how immunity from related viruses affects risk, and which vaccine strategies could be safe and useful. Climate, urban growth, travel, and mosquito control all shape the chance of future outbreaks.