What Is the Prognosis for Zika Virus Infections?
The prognosis, or predicted course of infection and outcome, is generally good for the person infected. Most people fully recover from Zika virus infection after a few days of symptoms and have no further problems.
The prognosis for the fetus or newborn of a woman infected with Zika in pregnancy is not predictable and is actively being investigated. (See Zika Virus Infections During Pregnancy.) Pregnant women themselves do not seem to have more severe disease or be more susceptible to infection. Once the infection has resolved, it does not affect future pregnancies.
Can Zika Virus Infections Be Prevented?
There is no vaccine against Zika virus, and there is no medication known to prevent it. Avoidance of infected mosquitoes and bites in areas where Zika is active is the primary way to prevent Zika virus. Avoiding sexual transmission, especially to women who are or may become pregnant, is also critical. There is no safe period of time during pregnancy where Zika virus does not cause severe birth defects.
The CDC issues travel advisories that recommend avoidance or enhanced precautions for territories where Zika virus has been reported. This information is updated as new information is received and can be found at the CDC (http://www.cdc.gov/zika/index.html).
Until further studies can be done, women who are pregnant should postpone travel until after delivery. (See Zika Virus Infections During Pregnancy.)
The most reliable prevention requires avoidance of areas where Zika virus has been reported. If traveling or staying in these areas cannot be avoided, mosquito-avoidance precautions should be taken.
Mosquito avoidance precautions include the following:
- Avoid mosquito bites throughout the day and night. Aedes mosquitoes are most active during the day, and they bite indoors as well as outdoors.
- Use long-lasting EPA-registered insect repellents that contain DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol. Follow the label directions carefully, and apply the repellent on top of any sunscreen or other product you may be using.
- Wear loose long-sleeve shirts and pants when possible. Treat clothing with permethrin or buy permethrin-treated clothing, because mosquitoes can bite through clothing.
- Sleep in lodgings with screened windows and doors, or air conditioning, or use mosquito netting around the bed at night. If this is not possible, sleep in a screened and zipped-up tent.
- If you are staying a long time or are at home, mosquito control is important in your environment. Even a bottle cap full of water left outside for a week is a perfect place for mosquitoes to breed. Aedes mosquitoes are adapted to humans and prefer to lay eggs in containers. The eggs can also survive drying out for several months, only to hatch with the next rain, so any collection of water will breed mosquitoes.
- Get rid of any possible breeding areas outside. Remove standing water from around the home. Dispose of tires that may be sitting outdoors. They are excellent breeding grounds because they are hard to empty. Think of any objects that may collect water outside and remove them or turn them over. Make sure all drains are free of clogs, including downspouts.
- People who have Zika fever should stay indoors and avoid mosquito bites for three weeks. Infected people become a source of Zika virus when mosquitoes bite them and then go on to bite another person. The disease then continues to spread. These precautions also help to prevent infection with dengue, Chikungunya, and viral encephalitis, which are found in the same areas as Zika virus and the Aedes mosquito. More detailed information on preventing mosquito bites can be found at the CDC, Zika Virus Prevention (http://www.cdc.gov/zika/prevention/index.html).
Blood-to-blood transmission may occur by transfusion, especially in areas of active transmission where blood donations are not screened for Zika virus. Blood transfusion may not be avoidable, so it is important to consider screening for Zika virus in such cases so appropriate precautions can be advised. Avoid blood-to-blood transmission by not sharing needles with someone who has traveled to such areas and is infected with Zika virus; this may include pregnant women who have been infected several weeks earlier.
Both men and women can be infected by a man or woman with active Zika virus infection. Transmission has been documented by anal and vaginal sex, but other types of sexual transmission, such as mouth to penis, have not been ruled out.
For people returning from an area where Zika virus is active, and who do not have symptoms, the CDC advises the following:
- Both men and women should avoid sex for at least eight weeks after return.
- If you have sex during this time, use barriers to protect against infection, every time during vaginal, anal, and oral sex.
- If the partner of a returning traveler, is pregnant, they should avoid sex or use barriers during sex until the end of pregnancy. (Couples planning pregnancy should discuss this with their health professional.)
- Do not share sex toys during this time.
For people returning from an area where Zika virus is active who develop Zika symptoms, the CDC advises the following:
- Men should avoid sex or use barriers for at least six months after symptoms end.
- Women should avoid sex or use barriers for at least eight weeks after symptoms end.
- Do not share sex toys during this time.
For people living in an area of active Zika virus, the CDC advises the following:
- Avoid sex or use barriers until the area is declared Zika-free.
- If planning pregnancy or if pregnancy occurs, see a health professional right away.
- If not taking precautions and symptoms of Zika fever occur,
- men should avoid sex or use barriers for at least six months after symptoms end and
- women should avoid sex or use barriers for at least eight weeks after symptoms end.
It is very important to use barriers properly and every single time to prevent sexual transmission. Barriers that protect against infection include male and female condoms and dental dams. Dental dams are latex or polyurethane sheets used between the mouth and vagina or anus during oral sex. If not used exactly as intended, they will fail. The CDC provides information about "Condom Effectiveness" in order to help the public protect themselves; this includes links to materials to illustrate correct use of different barriers. (This content is graphic and may not be appropriate for all viewers.)
Because there is continually new information arising about Zika virus and areas of active transmission, it is important to check the CDC Zika web site periodically for updates.