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Zika Virus: Answers to Common Questions

What do you need to know about Zika virus? Here are some facts about the virus.

About Zika

  • Zika is a mosquito-borne virus similar to dengue fever, yellow fever or West Nile virus. Zika infection is primarily spread by Aedes aegypti or albopictus mosquitos.

  • Symptoms of Zika virus are generally mild and include fever, rash, joint pain and headaches. People infected with Zika virus rarely need hospitalization. Only about one in five infected individuals will exhibit any symptoms.

  • Zika virus is primarily spread through the bite of infected mosquitos. If a pregnant woman is bitten by an infected mosquito, the infection can cross the placenta, infecting the fetus. The virus has also been transmitted sexually and through blood transfusion or laboratory exposure. The U.S. Food and Drug Administration has published guidelines to help protect the blood supply.

  • There is evidence that Zika virus can be sexually transmitted from a male to his sexual partners and from a female to her sexual partners, especially if they are symptomatic. If a man or woman has lived in, traveled to or plans to travel to an area affected by Zika virus and is sexually active, using condoms the right way every time he or she has sex can reduce the chance that he or she will sexually transmit Zika virus. However, abstaining from sex for eight weeks after traveling to an affected region if you are a female and three months if you are a male is the best way to ensure transmission does not occur. If a woman who is pregnant or trying to conceive is concerned that her male partner may have had or has Zika, she should talk to her health care provider about her male sex partner’s travel history, including how long he stayed, whether he took steps to prevent getting mosquito bites, if he had symptoms, and if she had sex without a condom since his return.

  • Zika during pregnancy can cause microcephaly and other neurologic abnormalities. For more information on how the Zika virus affects pregnant women, read a Zika virus Q&A from maternal-fetal medicine expert Dr. Jeanne Sheffield.

  • There is currently no evidence to suggest that Zika virus presents a risk of birth defects for future pregnancies after it has cleared from the bloodstream. Zika virus usually remains in the blood of an infected person for about a week but may be present longer in semen and urine. The virus may last longer in the blood of a pregnant woman.

  • Zika virus is diagnosed by a blood test. If you are experiencing fever, rash, joint pain and red eyes, especially after recent travel to an affected country or being bitten by a mosquito, please visit your health care provider, who can determine if a blood test is needed. Urine may also be collected if you have recently had or currently have symptoms.

  • Vaccines and treatment are being investigated, but there currently is no medication available to prevent or treat Zika infection. If you exhibit symptoms, these can be treated with plenty of rest, fluids to prevent dehydration and acetaminophen for fever. If you are pregnant, you will continue to undergo regular monitoring to watch for fetal abnormalities after the symptoms have passed.

  • The best way to protect yourself is to limit your exposure by not traveling to countries affected by Zika outbreaks. When traveling to an affected area, wear long-sleeve shirts and long pants to limit skin exposure, stay indoors in screened-in and/or air-conditioned rooms as much as possible, and use mosquito netting. Pregnant women can safely use Environmental Protection Agency-approved bug spray with DEET or picardin or permethrin-infused clothing. Women who recently traveled to an area affected by Zika virus and who exhibit symptoms should wait eight weeks before trying to get pregnant. Men who have symptoms after traveling to affected areas should wait three months before conceiving.

  • The continental United States does have the strains of mosquitoes that can become infected with and spread Zika virus, including Aedes aegypti and albopictus. Please click here to find a map of the approximate distribution of Aedes mosquitos in the U.S. from the Centers for Disease Control and Prevention. Cases of local transmission of Zika in Florida and Texas had been reported within the continental U.S. There have, however, been no recent cases of local transmission in the United States. Johns Hopkins experts believe that mosquito control efforts and the widespread use of air conditioning in this country slowed the spread of Zika in the continental U.S., but residents should continue to take all recommended measures to prevent mosquito bites.


About Travel Recommendations

What are the current recommendations regarding travel to Zika-affected areas?

The Centers for Disease Control and Prevention keeps an updated map of areas where Zika transmission has occurred. For anyone traveling to these locations, avoiding mosquito bites is the best way to avoid exposure to the Zika virus. Pregnant women should speak to their obstetrician-gynecologist if they must travel to an affected area, as well as take precautions to prevent mosquito bites. Depending on where you travel, what your exposure was and if you had any symptoms, your physician may recommend Zika virus testing.


About Potential Mosquito Carriers

  • Zika virus is carried primarily by Aedes species mosquitos, specifically, Aedes aegypti and Aedes albopictus.

  • The mosquitoes that can carry Zika virus tend to live in warmer environments, including tropical, subtropical and, in some cases, temperate climates. The Aedes aegypti and Aedes albopictus mosquitoes can be found in the U.S. The Centers for Disease Control and Prevention (CDC) has a map of the estimated range of these mosquitoes in the U.S. as well as a map of countries and territories where Zika cases have been found.

  • Mosquitoes become infected when they bite a person actively infected with the virus and take in virus-containing blood. They then spread the virus to other people through subsequent bites. Only female mosquitoes bite people; they need blood to lay eggs. In a female mosquito, the virus travels from the gut to the salivary glands and is injected into the next human victim.

  • To prevent mosquitoes from breeding near your home, consider the following prevention methods:

    • Once a week, empty and scrub, cover, or throw out any items outside that hold water, like tires, buckets, planters, toys, pool covers, birdbaths, flowerpots or trash containers.
    • Tightly cover water storage containers (i.e., buckets, rain barrels, etc.).
    • For water storage containers without lids, use wire mesh with holes smaller than an adult mosquito.
    • Use larvicides to treat large containers of water that will not be used for drinking and cannot be covered or dumped out.
    • Use an outdoor flying insect spray in dark, humid areas where mosquitoes rest, like under patio furniture, or in the carport or garage. When using insecticides, always follow label instructions.
    • If you have a septic tank, repair cracks or gaps. Cover open vent or plumbing pipes using wire mesh with holes smaller than an adult mosquito.
  • If you notice a mosquito bite, you can use over-the-counter cortisone or antihistamine creams. You should generally avoid scratching the bite, as it can tear the skin and, in rare cases, lead to an infection.

    Pregnant women who have traveled to an area with active Zika transmission should consult with their Ob/Gyn upon their return and before using medications.

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