Zika Virus


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is Zika virus?

Zika is a virus that can cause disease in humans and is spread mostly through bites from Aedes mosquitos, the same group of mosquitos that also carries the yellow fever, chikungunya, and dengue viruses. Although mosquito bites account for most known Zika infections, reports have also been accumulating of transmission of Zika virus through sexual contact and through transfusion of blood products. Most people infected with Zika never even notice it, because they do not get sick. For those who do get sick (about 20 percent of those who get infected), the most common symptom is a rash that usually itches. Many people also experience conjunctivitis (red eyes) — sometimes with eye pain, sometimes with a discharge — and swollen lymph nodes behind the ears. Fever, headache, and pain in the joints and muscles also are fairly common, but the rash is by far the most common symptom for those who get any symptoms at all. The rash and other symptoms develop about 3-15 days after the person is infected and symptoms usually last from 4 to 7 days.

How common is Zika virus during pregnancy?

Zika is a very new disease on the world scene, so information on its occurrence and risks is changing frequently, but geography is a very important factor. Ades mosquitos live only in tropical and subtropical regions, and below a certain altitude, where winter temperatures do not drop below 10° C. This means that transmission of the virus through bites happens only in tropical and subtropical countries. Thus, if you live in London, Toronto, or Seattle, there is no chance that youll catch Zika through a mosquito bite, but it is possible to become infected through sexual contact with somebody who got infected in the tropics. Since more cases of male-to-female transmission have been documented than the other way around, pregnant women are at risk of getting Zika this way, since they tend to have unprotected sex. Given that they are already pregnant and very often are monogamous, it is quite rare for pregnant women to use protection. As for transmission through blood transfusion, the possibility exists, but agencies such as the US Centers for Disease Control and Prevention and the Red Cross are working quickly to put procedures in place for screening donated blood. This, together with the fact that the need for transfusion during pregnancy is rare, makes the scenario of you getting a Zika infection from a blood transfusion while pregnant rather far-fetched, but the point here is that information is changing quickly.

As for the geography of Zika virus, scientists first noticed the virus in tropical Africa in the 1940s, but it was rare as a cause of human disease until 2007, when an outbreak occurred on an island in Micronesia. Subsequently, there was an outbreak in 2013 in French Polynesia, and then a very big outbreak in Brazil beginning in 2015. In the United States, some cases of Zika have been documented in Florida and Texas, and the disease is expected to appear further north in coming years, due to people traveling.

How is Zika virus during pregnancy diagnosed?

Specific procedures for diagnosis of Zika infection are in in flux because of how new the condition is as a public health threat, but there are two basic diagnostic strategies for a person whose travel history and symptoms (or travel history or Zika infection status of her sexual partner) makes Zika possible. One strategy, known as serology testing, looks to see if your immune system has been manufacturing antibodies against Zika, specifically IgM antibodies, whose presence indicate a recent infection. The other strategy, called nucleic acid testing, looks for a molecule called RNA from the virus, using an enzyme that makes DNA sequences from the RNA, and then using methods that amplify the resulting DNA and read its sequence. The usual approach is to conduct these tests on blood samples, but evidence also has been mounting suggesting that tests on urine, and in some cases cerebral spinal fluid (CSF) can be useful under certain circumstances. Because there is a major concern about birth defects from a maternal Zika infection, testing of your developing baby with extra and more detailed ultrasound scans, and possibly tests on amniotic fluid can come into play if you are suspected of having Zika.

If your testing for Zika virus comes out positive, you also will be tested for other diseases that are spread by Aedes mosquito, especially dengue fever.

Does Zika virus cause problems during pregnancy?

For the mother herself, Zika infection can be symptomless 80 percent of Zika-infected people in the non-pregnant population have no symptoms, but only carry the virus. It may give you a rash, and sometimes other symptoms such as conjunctivitis, muscle and joint pains, swollen lymph nodes behind your ears, and possibly a fever. Also, though the connection with Zika is debated, the virus may also lead to a temporary but serious complication called Guillain-Barré syndrome, in which the immune system attacks a persons peripheral nerves, leading to tingling and weakness (sometimes paralysis) in the legs that may spread to the arms, and changes in blood pressure.

Does Zika during pregnancy cause problems for the baby?

Concern about congenital effects is the main reason why Zika virus during pregnancy is getting so much attention. During the Brazilian outbreak, and beginning with the island outbreaks that preceded it, authorities noticed an increase in congenital defects, including microcephaly (undersized brain and head) and other neurological problems in newborns. This was a major international news topic in the months leading to the 2016 Olympic Games in Rio de Janeiro. Although uncertainty still surrounds the question of whether Zika infection in a pregnant woman has a direct influence on the development of microcephaly and other congenital defects, the trend of the study results and expert opinions is that the virus does indeed put the developing baby at serious risk, though many normal infants have been born to mothers with demonstrated Zika infections. Although there arent enough data to know yet, it is suspected that the risk of severe effects on the child is higher if a woman is infected earlier in pregnancy as compared with later.

What to consider about taking medications when you are pregnant or breastfeeding:

  • The risks to yourself and your baby if you do not treat the Zika infection. In this case, treatment is supportive and includes only mild medications such as those given for fever.
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat Zika virus during pregnancy?

There is no specific treatment for Zika virus, such as an antiviral drug. Thus, treatment is supportive, including rest, hydration, and medications to combat pain and fever, such as acetaminophen in the United States and paracetamol in several other countries. These drugs are are considered safe during pregnancy. Supportive treatment also may include fluids.

Who should NOT stop taking medication for Zika virus during pregnancy?

Treatment is mostly supportive, so medications do not play a role, other than combating fever and pain.

What should I know about choosing a medication for my Zika virus during pregnancy?

Until it is confirmed that you do not have dengue fever, you should not take non-steroidal anti-inflammatory drugs (NSAIDs) to combat fever, as these can exacerbate bleeding. Stick with paracetamol or acetaminophen.

You may find Pregistrys expert reports about the individua
l medications used to treat infections here. Additional information can also be found in the sources listed at the end of this report.

What should I know about taking a medication for my Zika virus when I am breastfeeding?

Pain and fever medications, such as acetaminophen and paracetamol, are not thought to be risky for those who are nursing infants. What has concerned mothers in the past is whether insect repellent could affect a nursing infant. The answer to this is that the risk of insect repellent entering breast milk is less than the risk of the virus itself entering breast milk, although the latter is also very unlikely. Thus, there is no strong rational for avoiding medication, or for avoiding breast feeding. On the other hand, the rational for using insect repellent is very strong, since it is an important preventive measure to keep you from getting Zika virus in the first place.

What alternative therapies besides medications can I use to treat my Zika virus during pregnancy?

Treatment for Zika virus is mostly supportive, meaning that you are monitored and given fluids and other support to keep you from getting worse.

What can I do for myself and my baby when I have Zika virus during pregnancy?

Cooperate with health care providers and accept hospitalization if it is recommended for you. Also keep in mind that Zika virus infection is preventable, particularly through the avoidance of insect bites. The best way to do this is to wear long sleeves and long pants and to use insect repellent, if you are in regions where Aedes mosquitos live. Furthermore, if you travel outside at times of the year when Aedes mosquitos are out, it is helpful to seek out locations that practice good mosquito control using nets and chemical measures, including pesticides. Finally, if your sexual partner is infected with Zika virus, use barrier protection (condoms) during sex throughout the pregnancy.

Resources for Zika virus in pregnancy:

For more information about Zika virus during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or check the following link:


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General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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