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Prevent Zika STL
Information about the Zika Virus

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Background On Zika

The Zika virus was first discovered in a monkey in the Zika Forest of Uganda in 1947. Before 2007, at least 14 cases of Zika had been documented. However, it is likely there were other cases that were not reported. Zika outbreaks have probably happened in many locations. Because the symptoms of Zika are similar to those of many other diseases, many cases may not have been recognized. Zika is spread by two types of Aedes mosquitos (Ae. aegypti, Ae. albopictus). Both of these mosquitoes are aggressive daytime biters, but they can also bite at night.

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Outbreak Summary

Before 2015, Zika outbreaks took place in areas of Africa, Southeast Asia, and the Pacific Islands. In May of 2015, the Pan American Health Organization (PAHO) issued an alert about the first confirmed Zika infections in Brazil. Since May of 2015, the CDC has been responding to increased reports of Zika and has helped with investigations led by PAHO and the Brazil Ministry of Health. The first regional travel notices for Zika in South America and Mexico were posted in December of 2015. There are now outbreaks are occurring in many countries and territories. On February 1, 2016, the World Health Organization (WHO) declared a Public Health Emergency of International Concern (PHEIC) because of clusters of microcephaly (small head) and other nervous system disorders in some areas affected by Zika.

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Symptoms

  • The most common symptoms of Zika are:
    • Fever
    • Rash
    • Joint Pain
    • Conjunctivitis (Red Eyes)
  • Other symptoms include:
    • Muscle Pain
    • Headache
  • Many people with Zika won’t have any symptoms or will only have mild symptoms.
  • The sickness 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 it is rare for someone to die from Zika.

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Diagnosis

  • To diagnose Zika, your doctor or other healthcare provider will ask you about any recent travel and any signs and symptoms you may have. A blood or urine test can confirm a Zika infection.
  • See your doctor or other healthcare provider if you develop symptoms (fever, rash, joint pain, or red eyes) and you live in or have recently visited an area with Zika. Make sure to tell your doctor that you traveled to an area with Zika.
  • Your doctor or other healthcare provider may order blood tests to look for Zika or other similar viral diseases like dengue or chikungunya.

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Transmission

  • Zika is spread to people mainly through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus).
    • Mosquitoes that spread Zika are aggressive daytime biters, but they can also bite at night.
  • A pregnant woman can pass Zika to her baby during pregnancy or around the time of birth. The CDC is studying how Zika affects pregnancies.
  • There are no reports of babies getting Zika through breastfeeding. Because of the benefits of breastfeeding, mothers are encouraged to breastfeed even in areas where Zika can be found.
  • A man with Zika can pass it to his sex partners.

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Sexual Transmission

What is known:

  • The Zika virus can stay in semen longer than in blood.
  • Not having sex will eliminate your risk of getting Zika from sex.
  • Condoms can reduce the chance of getting Zika from sex. Use condoms correctly from start to finish, every time you have vaginal, anal, or oral (mouth-to-penis) sex. Condoms also help prevent the spread of HIV and other STDs.
  • Only people whose male sex partners have traveled to or live in an area with Zika are known to be at risk for getting Zika from sex.
  • Couples with a pregnant partner should use condoms correctly every time they have vaginal, anal, or oral (mouth-to-penis) sex OR they should not have sex during the pregnancy.
  • In addition to condoms, couples who do not want to get pregnant should also use the most effective birth control methods that they can use correctly and regularly. Talk to your doctor about this.  These should NOT replace the use of condoms.
  • Anyone who lives in or travels to areas with Zika and is not concerned about pregnancy should consider using a condom every time they have vaginal, anal, or oral (mouth-to-penis) sex or they should not have sex.
    • For couples with a male partner who has traveled to an area with Zika:
      • If the male partner has been diagnosed with Zika or has (or had) symptoms, the couple should consider using condoms or not having sex for at least 6 months after symptoms begin.
      • If the male partner does not get symptoms, the couple should consider using condoms or not having sex for at least 8 weeks after the man returns.
    • For couples with a male partner living in an area with Zika:
      • If the male partner has been diagnosed with Zika or has (or had) symptoms, the couple should consider using condoms or not having sex for at least 6 months after symptoms begin.
      • If the male partner has never had symptoms, the couple should consider using condoms or not having sex while there is Zika in the area.
    • For couples with a non-pregnant female partner who lives in or has traveled to an area with Zika:
      • It is not known if a woman can pass Zika to her sex partners.
      • These couples can also consider using condoms or not having sex.
    • Those considering these options should weigh the personal risks and benefits, including:
      • The mild nature of the illness for many people*
      • Any plans for pregnancy (if appropriate)
      • Access to condoms and other birth control
      • The desire for intimacy, including the willingness to use condoms or not have sex
      • The ability to use condoms or not have sex
  • The Saint Louis County Department of Public Health recommends testing for Zika to people who may have been exposed to Zika through sex and who have Zika symptoms.

*In many cases, Zika does not cause any symptoms or causes only mild symptoms lasting several days to a week. It is not common for someone with Zika to need a hospital.

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Blood Transfusion

  • To date, there have been no confirmed blood transfusion-transmission cases in the United States.
  • There is a strong possibility that Zika virus can be spread through blood transfusions.
    • Because many people with Zika don’t have any symptoms, blood donors may not know they have been infected.
  • Zika currently poses a low risk to the blood supply in St. Louis County.
  • On February 16, 2016, the Food and Drug Administration (FDA) released Recommendations for Donor Screening, Deferral and Product Management to Reduce the Risk of Transfusion-Transmission of Zika Virus, which include specific steps for blood collection organizations.
  • In areas with Zika, the FDA recommends that blood either be screened by a laboratory, subjected to pathogen reduction technology (PRT), or brought in from other areas

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Zika Virus Blood Screening

Blood donor screening using only a questionnaire without a laboratory test is not sufficient for identifying Zika-infected donors in areas with active mosquito-borne transmission of Zika due to the high rate of cases without any symptoms.

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Mosquito Information

  • An Aedes species mosquito with Zika can spread it through bites. Not all people who get Zika will have symptoms.
  • There are many species of Aedes mosquitoes. Not all Aedes species can spread Zika. At this time, the CDC doesn’t know if there are other non-Aedes mosquito species that could spread Zika.
  • Zika is mainly spread through the bite of an Aedes aegypti or Aedes albopictus mosquito.
    • Aedes aegypti mosquitoes live in tropical, subtropical, and some temperate climates. They are the primary vector of Zika, dengue, chikungunya, and other arboviral diseases (diseases spread by insects and other arthropods). Because Aedes aegypti mosquitoes live near and prefer to feed on people, they are considered highly efficient at spreading these diseases.
    • Aedes albopictus mosquitoes live in tropical, subtropical, and temperate climates. They have adapted to survive in a broader temperature range and at cooler temperatures than Aedes aegypti. Because these mosquitoes feed on people and animals, they are less likely to spread viruses like Zika, dengue, or chikungunya. The strain of Ae. albopictus in the United States came from northern Japan in 1985 and is capable of living in more temperate climates.
  • To produce eggs, the female mosquito bites people to feed on blood. When feeding, a mosquito will pierce the skin (like a needle) and inject saliva. This allows the disease-causing germ (for example, Zika) to enter.
  • Once a mosquito is has Zika, it will stay infected for the rest of its life. A mosquito lives for up to 30 days. There is no evidence that mosquitos with Zika have shorter lifespans.
  • Changes in the environment from climate change can influence the spread of mosquitoes.
    • These changes can affect:
      • How quickly viruses replicate in mosquitoes
      • The life cycle of mosquitoes
      • The geographic distribution of viruses, mosquitoes, and animal hosts
  • Natural disasters in the continental United States have rarely been accompanied by outbreaks of viruses spread by mosquitoes. Flooding immediately washes away existing mosquito larvae populations.

Following disasters, mosquito eggs hatch and develop and mosquito populations go up. This takes about a week. New adult mosquitoes are not infected with the virus until they bite an infected person or animal.

  • Flies do not spread Zika. Only a small number of fly species bite people. When a fly bites, it creates a wound and laps blood up from the site. When a fly bites, it does not inject saliva directly into the bite site like a mosquito does.

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Mosquito Control

Here’s what you can do to control mosquitoes around your home:

      • Once a week, empty and scrub, turn over, cover, or throw out any items that hold water like tires, buckets, planters, toys, pools, birdbaths, flowerpot saucers, or trash containers.
      • Tightly cover water storage containers (buckets, cisterns, rain barrels) so that mosquitoes can’t get inside to lay eggs.
      • For containers without lids, use wire mesh with holes smaller than an adult mosquito.
      • Use larvicides to kill young mosquitoes in large containers of water that will not be used for drinking and cannot be covered or dumped out.
  • Use an outdoor bug spray made to kill mosquitoes in areas where they rest.
    • Mosquitoes rest in dark, moist areas like under patio furniture, or under the carport or garage.
  • If you have a septic tank, repair cracks or gaps. Cover any open vent or plumbing pipes. Use wire mesh with holes smaller than an adult mosquito.
  • Here’s what you can do to control mosquitoes inside your home:
    • Use screens on all windows and doors. Repair them if there are any holes or gaps. Do not leave doors propped open.
    • Use air conditioning when possible.
    • Once a week, empty and scrub, turn over, cover, or throw out any items that hold water like vases and flowerpot saucers. Mosquitoes lay eggs near water.
    • Kill mosquitoes inside your home. Use an indoor bug fogger* or indoor bug spray* to kill mosquitoes and treat areas where they rest. These products work immediately and may need to be reapplied. When using insecticides, always follow the directions on the label. Using only insecticide will not keep your home free of mosquitoes.
      • Mosquitoes rest in dark, humid places like under the sink, in closets, under furniture, or in the laundry room.

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Risk

  • Anyone who lives in or travels to an area with Zika who has not already been infected can get it from a mosquito bite.
  • A man with Zika can pass it to his sex partners (female and male). Condoms can lower the chance of getting Zika from sex if used correctly from start to finish, every time you have vaginal, anal, or oral (mouth-to-penis) sex.
  • Condoms should always be used by pregnant couples who live in or travel to an area with Zika. This is true even if a man has tested negative for Zika. If a condom can’t be used every time, then the couple should not have sex during the pregnancy. To be effective, condoms must be used correctly from start to finish, every time a couple has sex. This includes vaginal, anal, and oral (mouth-to-penis) sex.

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Prevention

  • There is no vaccine for Zika.
  • The best way to prevent diseases spread by mosquitoes is to avoid mosquito bites:
    • Wear long-sleeved shirts and long pants.
    • Stay in places with air conditioning and window and door screens to keep mosquitoes outside.
    • Treat your clothing and gear with permethrin or buy pre-treated items.
    • Use Environmental Protection Agency (EPA)-registered bug repellents. Always follow the directions on the label.
      • When used as directed, these bug repellents are proven safe and effective even for pregnant and breastfeeding women.
      • Do not use bug repellents on babies younger than 2 months old.
      • Do not use products containing oil of lemon eucalyptus or para-menthane-diol on children younger than 3 years old.
      • Mosquito netting should be used to cover babies younger than 2 months old in carriers, strollers, or cribs to protect them from mosquito bites.
    • Sleep under a mosquito net if air conditioned or screened rooms are not available or if sleeping outdoors.
  • During the first week of infection, the Zika virus can be found in a person’s blood and can pass from an infected person to a mosquito during a mosquito bite. An infected mosquito can then spread Zika to other people.
    • To help prevent others from getting sick, strictly follow steps to prevent mosquito bites during the first week of illness.
  • Even if they do not feel sick, travelers returning to the United States from an area with Zika should take steps to prevent mosquito bites for 3 weeks. These steps will keep them from passing Zika to mosquitoes that could spread the virus to other people.
  • If you have a baby or child:
    • Do not use bug repellent on babies younger than 2 months old.
    • Do not use products containing oil of lemon eucalyptus or para-menthane-diol on children younger than 3 years old.
    • Dress your child in clothing that covers arms and legs.
    • Cover crib, stroller, and baby carriers with mosquito netting.
    • Do not apply bug repellent on a child’s hands, eyes, or mouth, or on cut or irritated skin.
    • Adults: Spray bug repellent on your hands and then apply it to a child’s face.

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Preventing Sexual Transmission and Family Planning Considerations

  • Only people whose male sex partners have traveled to or live in an area with Zika are known to be at risk for getting Zika from sex. The timeframe for using condoms or waiting to have sex will differ based on a couple’s situation and concerns.
  • Not having sex will eliminate your risk of getting Zika from sex.
  • Pregnant couples should take steps to protect their pregnancy. Because Zika can cause birth defects, pregnant couples should
    • Use a condom every time they have sex or not have sex during the pregnancy.
    • Use condoms correctly from start to finish, every time they have vaginal, anal, or oral (mouth-to-penis) sex.
  • Couples that aren’t pregnant but are still worried about getting Zika from sex should consider using a condom every time they have vaginal, anal, or oral (mouth-to-penis) sex or they should not have sex. To be effective, condoms must be used correctly from start to finish, every time during sex.
    • For couples with a male partner who has traveled to an area with Zika:
      • If a male partner has been diagnosed with Zika or has (or had) symptoms, the couple should consider using condoms or not having sex for at least 6 months after symptoms begin.
      • If a male partner does not get symptoms, the couple should consider using condoms or not having sex for at least 8 weeks after the man returns.
    • For couples with a male partner living in an area with Zika
      • If a male partner has been diagnosed with Zika or has (or had) symptoms, the couple should consider using condoms or not having sex for at least 6 months after symptoms begin.
      • If a male partner has never developed symptoms, the couple should consider using condoms or not having sex while there is Zika in the area.
    • For couples with a non-pregnant female partner who lives in or has traveled to an area with Zika:
      • It is not known if a woman can pass Zika to her sex partners.
      • These couples should also consider using condoms or not having sex.
    • Those considering these options should weigh the personal risks and benefits, including
      • The mild nature of the illness for many people*.
      • Any plans for pregnancy (if appropriate).
      • Access to condoms and other contraception.
      • The desire for intimacy, including the willingness to use condoms or not have sex.
      • The ability to use condoms or not have sex.

* In many cases, Zika does not cause any symptoms or causes only mild symptoms lasting several days to a week. It is not common for someone with Zika to need a hospital.

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Bug Repellent

  • The Saint Louis County Department of Public Health recommends using EPA-registered bug repellents with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol. Choosing an EPA-registered repellent means that the EPA has evaluated the product for effectiveness.
  • Bug repellents registered by the EPA also repel the mosquitoes that spread Zika and other viruses.
  • When used as directed, EPA-registered bug repellents are proven safe and effective even for pregnant and breastfeeding women.
  • Always follow the directions on the product label.
  • Reapply bug repellent as directed.
  • Do not spray repellent on the skin under clothing.
  • If you are also using sunscreen, apply the sunscreen before applying bug repellent.
  • Treat clothing and gear with permethrin or buy permethrin-treated items.
    • The EPA has reviewed scientific studies on the use of permethrin-treated clothing. Based on the EPA’s review, there is no evidence of reproductive or developmental effects to mother or child following exposure to permethrin.
    • Treated clothing remains protective after multiple washings. See product information to learn how long the protection will last.
    • If treating items yourself, follow the product instructions carefully.
    • Do NOT use permethrin products directly on the skin. They are intended to treat clothing.
  • The CDC does not know about the safety or effectiveness of non-EPA registered bug repellents, including some natural repellents.
    • Some natural bug repellents, often made with natural oils, have not been tested for effectiveness.

Homemade bug repellents may not protect you from mosquito bites.

  • Some natural products are EPA-registered.
    • These natural products with EPA registration include para-menthane-diol and oil of lemon eucalyptus.
  • Do not use bug repellents on babies younger than 2 months old.
  • Do not use products containing oil of lemon eucalyptus or para-menthane-diol on children younger than 3 years old.
  • To protect your child from mosquito bites:
    • Dress your child in clothing that covers arms and legs.
    • Cover crib, stroller, and baby carriers with mosquito netting.
    • Do not apply bug repellent on a child’s hands, eyes, or mouth, or on cut or irritated skin.
    • Adults: Spray insect repellent on your hands and then apply it to a child’s face.

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Treatment

  • There is no specific medicine or vaccine for Zika.
  • If you get Zika, you have to treat the symptoms:
    • Get plenty of rest.
    • Drink fluids to prevent dehydration.
    • Take medicine such as acetaminophen (Tylenol®) to reduce fever and pain.
    • Do not take aspirin or other non-steroidal anti-inflammatory drugs (NSAIDS) until dengue can be ruled out to reduce the risk of bleeding.
    • If you are taking medicine for another medical condition, talk to your doctor or other healthcare provider before taking additional medication.
  • During the first week of infection, the Zika virus can be found in a person’s blood. The virus can be passed from an infected person to a mosquito through mosquito bites. An infected mosquito can then spread the virus to other people.

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Zika and Pregnancy

  • Because of the potential risks of Zika infection during pregnancy, the Saint Louis County Department of Public Health’s top priority for the Zika response is to protect pregnant women and their babies.
  • Zika can pass from a pregnant woman to her baby during pregnancy or around the time of birth.
  • Zika infection during pregnancy can cause microcephaly (small head) and other severe brain defects.
  • In addition to microcephaly (small head), doctors have found other problems in pregnancies and among babies infected with Zika before birth such as miscarriage, stillbirth, absent or poorly developed brain structures, defects of the eye, hearing deficits, and impaired growth.
  • Pregnant women should talk to a doctor or other healthcare provider if they or their male sex partner(s) recently traveled to an area with Zika, even if they don’t have any symptoms.
  • Pregnant women should see a doctor or other healthcare provider if they develop a fever, rash, joint pain, or red eyes during their trip or within 2 weeks after traveling to an area where Zika has been reported. They should tell the doctor or other healthcare provider where they traveled.
  • Because Zika infection is a cause of microcephaly (small head), pregnant women should strictly follow steps to prevent mosquito bites and to protect against sexual transmission.
  • If a pregnant woman has a male sex partner who lives in or has traveled to an area with Zika, a condom should be used every time she has sex or she should not have sex during the pregnancy. To be effective, condoms must be used correctly from start to finish, every time a person has sex. This includes vaginal, anal, and oral (mouth-to-penis) sex.

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Available Resources

Revised 8/23/2016