How does Zika virus spread?

Zika virus spreads in several ways:

• Through mosquito bites. This is the most common way Zika spreads.
• By passing it to your baby during pregnancy. This can cause serious problems in your baby, including a birth defect called microcephaly and other brain problems.
• Through sex with an infected person
• Through a blood transfusion with infected blood
• Through laboratory exposure in a healthcare setting

Learn how to protect yourself from Zika at: marchofdimes.org/zika
 

The most common way that the Zika virus is transmitted is through a bite from a mosquito that has the Zika virus. It can also be transmitted less commonly through sexual transmission. The majority of people who get infected with the Zika virus actually experience no symptoms whatsoever. Eighty percent don't have any idea that they got the virus, the rest get very mild symptoms, such as fever, joint pain, a mild rash and conjunctivitis (red eyes).

The Zika virus spreads to people primarily through the bite of an infected Aedes species mosquito. People can also get Zika through sexual activity, and the virus can also be passed from a pregnant woman to her unborn child. 

Zika virus is spread by the female Aedes aegypti mosquito. These are mosquitoes that bite during the day time as opposed to the malaria mosquito, for example, which bites at night. There are other infectious diseases that this particular mosquito has carried, such as dengue fever and chikungunya.

The mosquitoes that transmit Zika exist in the United States, primarily in the southern states, and have been here for a long time. But for a disease to start spreading it's not just the mosquitoes that are necessary. It's also the conditions. Screens on windows, air conditioned buildings, and not having standing water, conditions seen in a very urbanized area, makes a huge difference. Mosquito-transmitted diseases typically spread in places like Brazil, or other countries where these amenities, taken for granted in the United States, don't exist.

It is likely that there will be more cases of Zika in the United States. The majority of them will be from people who have traveled to one of these countries. There will be some localized outbreaks of Zika, like there have been of dengue, but the U.S. will not likely see the numbers they’ve seen in South America.

Zika is primarily transmitted through the bite of infected Aedes mosquitoes. These mosquitoes typically lay eggs in and near standing water in things like buckets, bowls, animal dishes, flower pots and vases. They are aggressive daytime biters, prefer to bite people, and live indoors and outdoors near people. The mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.

The Zika virus can also be transmitted from a pregnant mother to her baby during pregnancy or around the time of birth. It's not known how often this occurs.

Anyone who is living in or traveling to an area where Zika virus is found who has not already been infected with Zika virus is at risk for infection. There is no vaccine to prevent or medicine to treat Zika. Travelers can protect themselves from this disease by taking steps to prevent mosquito bites. When traveling to countries where Zika virus or other viruses spread by mosquitoes have been reported, use insect repellent, wear long sleeves and pants, and stay in places with air conditioning or that use window and door screens.

If you have Zika, avoid mosquito bites for the first week of your illness to avoid spreading the virus to other people. 

Typically, Zika is transmitted in two ways:

• Local transmission: A mosquito bites a person infected with Zika, then bites another person.
• Imported transmission: A person traveling outside his/her country is bitten by a Zika-infected mosquito, develops Zika and then returns home.

The virus is NOT spread from person to person, with these possible exceptions:

• A pregnant woman infected with Zika could pass the virus to her newborn during pregnancy or around the time of birth.
• Through infected blood or sexual contact

Zika is spread by the Aedes mosquito, which have distinctive black and white markings, and which exist in many locales. They are active in the daytime, especially early morning and late evening. The virus can be spread from mother to baby, and also sexually and possibly via transfusion.

The Zika virus is spread by Aedes species of mosquitoes. These mosquitoes can pick up the virus by biting an infected person, and then transmit it to someone else they bite later. The virus doesn’t typically spread from person to person directly, though sexual transmission is possible. In fact, the first case of local transmission in the mainland United States was a person who became infected after having sex with someone who had recently traveled from a country where Zika is present.

The type of mosquito that spreads Zika most often is limited to tropical and subtropical areas. In the U.S., they’re most common in Florida, the Gulf Coast and in Hawaii, but they also go as far north as Georgia and South Carolina. Another species that can carry them can range as far as New York in the summer. Experts think the virus will cause small, localized outbreaks in the U.S.

There is no vaccine to prevent Zika, so the best way to protect yourself is to avoid mosquito bites if you are in an area where Zika is active. The Centers for Disease Control and Prevention recommends that pregnant women avoid travel to countries where outbreaks are occurring, and also that they abstain from sex or use condoms with partners who have recently returned from one of these areas.

The World Health Organization recommends the following.

If you live in or travel to an area where Zika is common:

• Keep skin covered with with long-sleeved shirts, pants and hats.
• Use recommended insect repellants.
• Sleep under mosquito nets in topical areas.

To keep mosquitoes away from your home:

• Avoid allowing water to stand in outdoor containers.
• Put garbage in bags and closed containers.
• Use screens and mosquito nets in your windows and doors.