The Zika (ZEE'-kuh) virus is a mosquito-borne viral infection that primarily occurs in tropical and subtropical areas of the world. Most people infected with the Zika virus have no signs and symptoms, while others report mild fever, rash and muscle pain. Other signs and symptoms may include headache, red eyes (conjunctivitis) and a general feeling of discomfort. Zika virus is also called Zika or Zika virus disease.
Zika virus infections during pregnancy have been linked to miscarriage and can cause microcephaly, a potentially fatal congenital brain condition. The Zika virus also may cause other neurological disorders such as Guillain-Barre syndrome.
Researchers are working on a Zika virus vaccine. For now the best prevention is to prevent mosquito bites and reduce mosquito habitats.
As many as 4 out of 5 people infected with the Zika virus have no signs or symptoms. When symptoms do occur, they usually begin two to seven days after a person is bitten by an infected mosquito. Signs and symptoms of the Zika virus most commonly include:
- Mild fever
- Joint or muscle pain
Other signs and symptoms may include:
- Red eyes (conjunctivitis)
Most people recover fully, with symptoms resolving in about a week.
When to see a doctor
See your doctor if you think you or a family member may have the Zika virus, especially if you have recently traveled to an area where there's an ongoing outbreak. The Centers for Disease Control and Prevention (CDC) has blood tests to look for the Zika virus or similar diseases such as dengue or chikungunya viruses, which are spread by the same type of mosquitoes.
The Zika virus is transmitted primarily through the bite of an infected aedes species mosquito, which can be found throughout the world. The virus was first identified in the Zika Forest in Uganda in 1947, but outbreaks have since been reported in southeastern and southern Asia, the Pacific Islands and the Americas.
When a mosquito bites a person infected with the Zika virus, the virus enters the mosquito. When the infected mosquito then bites another person, the virus enters that person's bloodstream.
The virus can also spread to the fetus during pregnancy.
Spread of the virus through sexual contact and blood transfusion have been reported.
Factors that put you at greater risk of developing the Zika virus include:
Living or traveling in countries where there have been outbreaks. Being in tropical and subtropical areas increases your risk of exposure to the virus that causes the Zika virus. Especially high-risk areas include several islands of the Pacific region, a number of countries in Central, South and North America, and islands near West Africa. Because the mosquito that carries the Zika virus is found worldwide, it's likely that outbreaks will continue to spread to new regions.
The mosquitoes that carry the Zika virus are found in some parts of the United States. Most cases of the Zika virus infection in the U.S. have been reported in travelers returning to the U.S. But local transmission has been reported in certain areas of the U.S. and in Puerto Rico.
- Having unprotected sex. The Zika virus can spread to another person through sex. If male sex partners or a couple that includes a male and female partner travel to an area with a Zika risk, the CDC suggests using condoms or avoiding sex for three months. If female partners travel to an area with a Zika risk, the CDC suggests using condoms or avoiding sex for at least two months. Also, the CDC advises abstinence from sexual activity during pregnancy or condom use during all sexual contact for a pregnant woman or her partner who have traveled to or lived in an area of active Zika virus transmission.
Zika virus infections during pregnancy have been linked to miscarriage and microcephaly, a potentially fatal congenital brain condition.
The Zika virus may also cause congenital Zika syndrome, which includes these birth defects:
- Severe microcephaly with a partly collapsed skull
- Brain damage and reduced brain tissue
- Eye damage
- Joint problems, including limited motion
- Reduced body movement due to too much muscle tone after birth
The Zika virus also may cause other neurological disorders such as Guillain-Barre syndrome.
There is no vaccine to protect against the Zika virus.
The CDC recommends all pregnant women avoid traveling to areas where there is an outbreak of the Zika virus. If you have a partner who lives in or has traveled to an area where there is an outbreak of the Zika virus, the CDC recommends abstaining from sex during pregnancy or using a condom during sexual contact.
If you are trying to become pregnant, talk to your doctor about any upcoming travel plans and the risk of getting infected with the Zika virus. Your doctor may suggest you and your partner wait to try to conceive for several months.
During sexual contact, use a condom to reduce the risk of getting or spreading the Zika virus if you or your partner lives in or has traveled to an area where there is an outbreak of Zika virus. Or avoid sexual contact.
If you are living or traveling in tropical areas where the Zika virus is known to be, these tips may help reduce your risk of mosquito bites:
- Stay in air-conditioned or well-screened housing. The mosquitoes that carry the Zika virus are most active from dawn to dusk, but they can also bite at night. Consider sleeping under a mosquito bed net, especially if you are outside.
- Wear protective clothing. When you go into mosquito-infested areas, wear a long-sleeved shirt, long pants, socks and shoes.
Use mosquito repellent. Permethrin can be applied to your clothing, shoes, camping gear and bed netting. You also can buy clothing made with permethrin already in it. For your skin, use a repellent containing at least a 10 percent concentration of DEET.
When used as directed, insect repellents that are registered with the Environmental Protection Agency (EPA) are proven safe and effective for pregnant and breast-feeding women.
- Reduce mosquito habitat. The mosquitoes that carry the Zika virus typically live in and around houses, breeding in standing water that can collect in such things as animal dishes, flower pots and used automobile tires. Reduce the breeding habitat to lower mosquito populations.
Zika virus transmitted through blood transfusion
All blood donations are now screened for the Zika virus. To further reduce the risk of transmitting Zika virus through blood transfusion in areas where there are no active Zika virus outbreaks, the Food and Drug Administration recommends not donating blood for four weeks if you:
- Have a history of Zika virus infection
- Traveled or lived in an area with active Zika virus transmission
- Have symptoms that are suggestive of Zika virus infection within two weeks of travel from an area with Zika virus
- Have had sexual contact with a partner who has been diagnosed with Zika virus infection
- Have had sexual contact with a partner who has traveled or lived in an area with active Zika virus transmission in the past three months
Your doctor will likely ask about your medical and travel history. Be sure to describe international trips in detail, including the countries you and your sexual partner have visited and the dates, as well as any contact you may have had with mosquitoes.
Talk to your doctor about which tests for the Zika virus — or similar diseases such as dengue or chikungunya viruses, which are spread by the same type of mosquitoes — are available in your area. Your doctor may do a blood or urine test to diagnose the Zika virus.
If you are pregnant with no symptoms of Zika virus infection with a history of recent travel to an area with active Zika virus transmission can be offered testing two to 12 weeks after her return.
Following positive, inconclusive or negative test results, care providers may:
- Perform an ultrasound to detect microcephaly or other abnormalities of the brain
- Offer to take a sample of amniotic fluid using a hollow needle inserted into the uterus (amniocentesis) to screen for Zika virus
No specific antiviral treatment for the Zika virus exists. Treatment is aimed at relieving symptoms with rest, fluids and medications — such as acetaminophen (Tylenol, others) — to relieve joint pain and fever.
No vaccine exists to prevent the Zika virus. But several vaccines are currently in clinical trials.
You'll likely start by seeing your primary care provider. But you also might be referred to a doctor who specializes in infectious diseases or travel medicine.
Because appointments can be brief, and because there's often a lot to discuss, it's a good idea to be well-prepared for your appointment. Here's some information to help you get ready, and what to expect from your doctor.
What you can do
Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
- Write down key personal information. List your international travel history, with dates and countries visited and medications taken while traveling. Bring a record of your immunizations, including pre-travel vaccinations.
- Make a list of all your medications. Include any vitamins or supplements you take regularly.
- Write down questions to ask your doctor. Preparing a list of questions can help you make the most of your time with your doctor. List your questions from most important to least important in case time runs out.
For Zika virus disease, some basic questions to ask your doctor include:
- What's the most likely cause of my symptoms?
- What kinds of tests do I need?
- What treatments are available?
- How long will it be before I'm feeling better?
- Are there any long-term effects of this illness?
- Do you have any brochures or other printed material that I can take home with me? What websites do you recommend?
What to expect from your doctor
Be prepared to answer questions from your doctor, such as:
- When did your symptoms begin?
- Are you pregnant or trying to become pregnant? Do you use condoms?
- Have your symptoms been continuous or occasional?
- How severe are your symptoms?
- Does anything seem to make your symptoms better or worse?
- Where have you traveled in the past month?
- Were you bitten by mosquitoes while traveling?
- Have you been in contact recently with anyone who was ill?