Zika virus is spread mostly by the bite of an infected Aedes species mosquito (Ae. Aegypti and Ae. Albopictus). Zika can be passed from a pregnant woman to her fetus. Infection during pregnancy can cause certain birth defects including microcephaly, where babies are born with underdeveloped heads and brain damage. Zika has also been linked to Guillain-Barre syndrome, a condition in which the immune system attacks the nerves. It’s mainly spread through mosquitoes, although some cases of sexual transmission have been reported.
Many areas in the United States have the type of mosquitoes that can spread Zika virus. These mosquitoes are aggressive daytime biters and can also bite at night. Also, Zika can be passed through sex from a person who has Zika to his or her sex partners, usually after a person traveled to an area where Zika has broken out, got the virus, and gave the virus to a sex partner who did not travel.
Many people infected with Zika virus won’t have symptoms or will only have mild symptoms. The most common symptoms of Zika are fever, rash, joint pain, and redness in the whites of the eye. Other symptoms include muscle pain and headache.
“Only about 1 in 5 people with the virus will exhibit symptoms,” says Amesh Adalja MD, a spokesman for the Infectious Diseases Society of America. “The vast majority have no symptoms at all.” Symptoms can appear anywhere from 3 to 14 days after a bite from an infected mosquito, according to the CDC.
Zika is usually mild with symptoms lasting for several days to a week. People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realize they have been infected. Symptoms of Zika are similar to other viruses spread through mosquito bites, like dengue and chikungunya.
Zika virus usually remains in the blood of an infected person for about a week. You should see your doctor if you develop symptoms and you live in or have recently traveled to an area where Zika is spreading. Pregnant women who have Zika symptoms at any point during their pregnancy should be tested for Zika.
There is no specific medicine or vaccine for Zika virus, but the symptoms can be treated with over-the-counter medications and in most cases, the disease usually runs its course within a week or so. The CDC recommends infected people get plenty of rest, drink fluids to prevent dehydration, and take acetaminophen for fever and pain. Aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) should not be taken until dengue is ruled out, to reduce bleeding risk, the agency says. There is no vaccine against Zika, but the National Institutes of Health is testing one in humans.