The Zika Virus: What you need to know.

What you need to know about the Zika Virus when trying to get pregnant.
A world map showing where Zika has been reported.

By Carolyn Coulam, MD and Nancy Hemenway

Accessible PDF


The Zika Virus has emerged recently as a new international health crisis to pregnant women or those trying to become pregnant. INCIID is getting calls and questions about Zika and the threat for women of reproductive age who are seeking to get pregnant. Many are worried. INCIID has put together a fact sheet to help with understanding the threat and how to protect yourself.

[Note: Update June 28, 2016, call your Senators to ask them to pass a "clean bill" for emergency funding. Some Senators are adding riders to the bill designed to make it harder to pass. According to the Centers for Disease Control (CDC) Zika is her in the US and is an International Crisis]


The Zika virus was discovered almost 70 years ago in the Zika Forest in Uganda. There were sporadic outbreaks in Africa and Southeast Asia in 2007, then another in French Polynesia in 2013. In the 2013 outbreak, authorities noted a contemporaneous association of an increase in cases of Guillain-Barre syndrome. Simultaneously, authorities saw a dramatic increase in microcephaly and a rapid spread of Zika virus through the Americas. This February (2016) The World Health Organization (WHO) declared the outbreak an international public health crisis because of the link to microcephaly as well as other neurologic syndromes.

What is the Zika Virus and how does it spread?

A virus is an infective agent that is too small to be seen by light microscopy, Viruses multiply only within the living cells of a host. Zika is an RNA virus, closely related to flaviviruses. You might remember from your biology classes that Ribonucleic Acid (RNA) is present in all living cells. RNA acts as a messenger carrying instructions from DNA.  Arthropod vectors carry Flaviviruses (in this case mosquitoes) causing serious diseases like Yellow Fever, various types of encephalitis, and hepatitis C)

Scientists working on Zika do not completely understand the pathology. Researchers think the viral replication takes place in dendritic cells after being bitten by a mosquito. Dendritic cells initiate an immune response and the virus spreads to the lymph nodes and throughout the bloodstream. The virus itself can be detected in the blood as early as the day of onset of symptoms.  The virus can also be detected in urine, sperm, and saliva of an infected individual. The period between exposure to the virus and infection and appearance of first symptoms (the incubation period) is most likely between 3 days to 2 weeks. However, approximately 80% of individuals infected with Zika show no symptoms. Only 1 out of 5 patients show symptoms of the Zika virus. When symptoms do occur, they are usually mild and occur within two weeks after exposure (travel). (Sampathkumar, 2016)

Most common symptoms may include:

  •  Maculopapular rash (A rash in which there are discrete macular and papular lesions or a combination of both.) Rash is more common with the Zika virus.
  • Example of a rashNonpurulent (without pus) conjunctivitis
  • Paint in the small joints of hands and feet
  • There may be a headache
  • Pain in the orbit of the eyes

Rarely is the infection severe enough for hospitalization.


Transmission to humans is through the bites of two kinds of carrier mosquitos. Both Aedes aegypti from tropical and subtropical regions and the Aedes albopictus found in more temperate climates inhabit the United States. The later A. albopictus (originally imported from Southeast Asia) is of particular concern because it has a broader range of habitation, and it adapted remarkably well to cooler climates. A. albopictus, an aggressive daytime biter, is well-established in the United States.

Aside from being bitten by a carrier mosquito, sexual transmission is a possibility but ability to become infected through this method is unclear. In 2011 an American researching Zika in Senegal went home to Colorado and experienced Zika symptoms. He transmitted the virus to his wife through sexual intercourse. There are two other confirmed cases thought to be sexually transmitted. Researchers and authorities do not yet know how long the virus persists in sperm. The CDC recommends that pregnant women should avoid unprotected sex with a partner who travels to Zika infected regions for the duration of their pregnancy as a precaution. Data on the sexual transmission is limited. (Sampathkumar, 2016)

The transfusion-related transmission has occurred. Researched also discovered the virus in breast milk. However, the benefits of breastfeeding likely outweigh the risks. Seek information from your obstetrician, maternal-fetal medicine specialist and lactate consultant for risks associated with breastfeeding. No infections due to transmission from breastfeeding reported thus far. Creation of a vaccine is a priority but at present, there is no vaccine for Zika. Equally important is the development of intense measures by public health officials to further understand and stop transmission of Zika. Also important is exploring the roles of interventions such as IVIg and Zika specific immunoglobulins (a class of proteins present in cells of the immune system that function as antibodies). (Barton, 2016)

Pregnancy, Birth Defects, and Zika

All pregnant women should think carefully about traveling to regions where Zika outbreaks occur. When physicians consult with any pregnant woman, she should be asked about travel history. Expectant mothers who traveled to high-risk regions and are asymptomatic should be offered blood testing and screening for Zika. This testing should occur between 2-12 weeks after travel.

Researchers are working and studying the link between Zika during pregnancy and microcephaly. CDC scientists recently announced there is now enough evidence-based science to conclude a Zika virus infection during pregnancy is a cause of microcephaly. (Questions and Answers: Zika Virus Infection, 2016)

Microcephaly infants accompanied by intellectual disabilities and other neurological conditions, present with abnormally small heads based on the circumference of the head. Some examples of other neurological conditions include hearing loss, eye defects, and impaired growth.  Researchers are looking carefully to determine other associated problems that Zika causes during pregnancy. (Note: norms for head circumference vary in different ethnic and geographic populations. Practitioners do not universally define head size.)

Medical researchers find the Zika virus in all pregnancy trimesters through viral RNA testing of fetal tissue. Amniotic fluid testing revealed Zika in on-going pregnancies and in newborn infants as well as in the placenta of pregnant women. Many of the symptoms for Zika overlap with other similar viruses.  For example Zika symptoms resemble those of Dengue and Chikungunya, diseases also spread by the same mosquitoes that transmit Zika. See your doctor if you develop the symptoms and a Zika affects the region.

Understanding the difference between the presence of the virus and the immunological response that produces antibodies is important. Only the presence of the virus causes fetal abnormalities.

After blood testing, the next step in managing patients may include high-resolution ultrasound. In some cases, the doctor may order amniocentesis AFTER 15 weeks gestation to screen for Zika viral RNA. Referral to a maternal-fetal medicine (high-risk OB) or infectious disease specialist may also be indicated to help manage the pregnancy.

Based on the available evidence, the CDC does not think that Zika virus infection in nonpregnant women pose a risk for birth defects in future pregnancies after the virus clears her bloodstream.

From what authorities know of similar infections, once a person develops antibodies to the Zika virus, she is likely protected from a future Zika infection. (Questions and Answers Zika Virus Infection and Pregnancy, 2016)

If a person travels to an affected region and has a blood test that shows positive antibodies to the virus, this means you likely cannot transmit the virus to the fetus AFTER the incubation period (thought to be 3-12 days).

For example, a person travels to South America for Christmas. She comes back in January but doesn’t attempt pregnancy until the end of February the resulting pregnancy (occurring in February) is not at risk.  Only the presence of the virus (through RNA testing) puts a pregnancy at risk. The presence of positive antibodies to the virus likely means she is immune to further infections.

Prevention Precautions

Prevention from exposure is the best way to avoid infection to the Zika virus.  

  • Avoid mosquito bites.
  • Wear clothes covering exposed areas.
  • Use a repellent with “DEET” (a brand of diethyltoluamide, a colorless oily liquid with a mild odor, used as an insect repellent. See CDC Fact Sheet on Deet.
  • Stay indoors with air-conditioning or in screened-in areas.
  • Treat clothes with Permethrin (a synthetic insecticide of the used chiefly against disease-carrying insects). See the National Pesticide Information Center for more Information

A world map showing where Zika has been reported.



Before you plan a trip or travel, we suggest you visit the Centers for Disease Control (travel site) The CDC provides the most up-to-date travel information and reviews the current at-risk locations for Zika.

Hopefully, this information is helpful and reassuring to current and future reproductive plans. Please email Additional Zika Questions or Post to Dr. Coulam here

Dr. Coulam is a reproductive endocrinologist. She is a pioneer in helping families find causes for multiple pregnancy loss and implantation failure

Dr. Coulam is a board-certified reproductive endocrinologist and pioneer helping families identify the cause for multiple pregnancy loss and other reproductive failures. Take a look at this video clip.


Barton, M. S. (2016, April 19). Canadian Medical Association Journal, 188(7), 118-119.

Questions and Answers Zika Virus Infection and Pregnancy. (2016, April 19). Retrieved from Centers for Disease Control and Prevention:

Questions and Answers: Zika Virus Infection. (2016, April 19). Retrieved from Centers for Disease Control and Prevention:

Sampathkumar, P. S. (2016, April). Zika Virus in the Americas: A Review for Clinicians. Mayo Clinic Proceedings, 91(4), 514-521.

Other Zika Resources

Be sure to check with local health departments to see what the risk might be in your area.

Centers for Disease Control and Prevention

New England Journal of Medicine


The Elsevier

The Lancet Zika Collection of Resources

Oxford University Press Zika Collection

PLOS Journal Zika Collection

Emergency Bulletins CDC

Update: Interim Guidelines for Prevention of Sexual Transmission of Zika Virus — the United States, 2016

Zika Virus Emergency Use Authorization

US Department of Health & Human Services
Disaster Information Management Research Center

World Health Organization (Zika Information)

© 2016 INCIID, Inc. All rights reserved

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