Zika virus is primarily transmitted to people through the bite of infected Aedes species mosquitoes. It can lead to significant health complications, particularly for pregnant individuals and their developing fetuses. This article explores Zika’s status in the United States, its transmission, symptoms, risks, and prevention.
Zika’s Presence in the US
The presence of Zika virus in the continental United States is currently low, with most reported cases being travel-related. These cases involve individuals infected abroad who then returned to the U.S. Local mosquito-borne transmission, where mosquitoes in the U.S. acquire and spread the virus, has been rare and localized.
U.S. territories, such as Puerto Rico, experienced significant outbreaks in the past. The number of reported Zika virus cases globally has declined since 2017, with only a small number identified in U.S. international travelers in recent years.
How Zika is Transmitted
Zika virus primarily spreads through the bite of infected Aedes species mosquitoes, specifically Aedes aegypti and Aedes albopictus. These mosquitoes are active during both day and night and typically lay their eggs in and near standing water in containers around homes. A mosquito becomes infected when it feeds on a person with the virus, then transmits it through subsequent bites.
Beyond mosquito bites, Zika also spreads through sexual contact. The virus can pass from an infected person to their partners through vaginal, anal, or potentially oral sex, even if the infected individual does not show symptoms. Zika virus can persist in semen longer than in other body fluids. Transmission from a pregnant person to their fetus during pregnancy or around the time of birth is a known pathway.
Recognizing Zika Symptoms and Risks
Many people infected with Zika virus experience no symptoms or only mild ones. When symptoms occur, they typically include fever, rash, joint pain, and conjunctivitis (red eyes). Muscle pain and headache are also commonly reported. These symptoms usually last for several days to a week, and severe illness requiring hospitalization is uncommon.
Zika infection poses significant health risks, particularly during pregnancy. Infection during pregnancy can cause severe birth defects, including microcephaly, where a baby is born with a smaller-than-expected head and other brain abnormalities. The first trimester of pregnancy is considered the period of highest risk, though defects can occur at any point. Zika has also been linked to Guillain-Barré Syndrome (GBS), a rare neurological disorder where the body’s immune system attacks its own nerves, leading to muscle weakness and temporary paralysis.
Preventing Zika Infection
Protecting against mosquito bites is an important method for preventing Zika infection. Use EPA-registered insect repellents containing ingredients like DEET or picaridin on exposed skin and clothing. Wearing long-sleeved shirts and long pants can also reduce skin exposure. Eliminate standing water around homes in containers such as buckets, flowerpots, and old tires to reduce mosquito breeding sites.
Preventing sexual transmission is also important, especially for individuals who have traveled to Zika areas or whose partners have. Using condoms during sexual activity (vaginal, anal, or oral) can reduce transmission. Abstinence from sexual activity is another way to avoid sexual transmission. For pregnant individuals, or those planning pregnancy, discuss travel history with a healthcare provider and follow specific guidance regarding sexual activity and travel to Zika-affected areas.