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Zika Virus and Pregnancy

UPDATE: August 8th, 2016 by David L. Berry, M.D.

According to recent reports in the news and through the United States Centers for Disease Control, the first local mosquito-acquired cases of Zika virus infection have been reported in a very small area of Miami (Dade County), Florida. As of today, there have been 16 confirmed cases of Zika virus from a mosquito-borne vector within the continental United States. This discovery has been considered an inevitability by most epidemiologists based upon the range of the type of mosquito responsible for the virus (Aedes aegypti). The CDC updates their website on a weekly basis, so some of their figures are confirmed cases as of August 3, 2016. Their next update will be at 5:00 AM EST on the morning of August 10, 2016.

Currently, the Zika virus is being transmitted by mosquitoes in 54 countries, most of which are in central and South American countries, the Caribbean, and some south Pacific islands. The CDC updates their affected countries at this website.

As of 8/3/2016, there were 1825 cases of Zika virus in the United States, only 6 of which were acquired by local mosquito bites (all of which were from one neighborhood in Miami, Florida). The remaining ones were either sexually acquired (16 cases) or from a laboratory contamination (one case). Only 5 cases of Guillan-Barre syndrome have been diagnosed as a result of Zika infection in the U.S. Of the 479 known cases of pregnant women diagnosed with Zika infection, only 15 fetuses have been shown to be affected with a birth defect such as microcephaly. Of note to remember, if approximately 500 cases of Zika in pregnancy have been diagnosed and 80% are asymptomatic, we can assume about 2,500 cases are present with only 15 affected fetuses which equates to 0.6% attack rate for a fetus for microcephaly in a woman with proven Zika infection.

Although the actual affected number of fetuses are extremely low, prevention is the only method to address the potential for infection. There are currently three vaccinations being tested in animal models, but these should not be expected to be fully tested and available to the general public for at least one to two more years. Even then, the side-effects in pregnancy will be largely unknown.

In the meantime, the common sense approach to Zika prevention remains the hallmark of the CDC’s and World Health Organization’s recommendations. These include pregnant women avoiding travel to the affected areas. Since Zika can be found in semen for up to 6 months, use of condoms for a partner who travels to these areas for the remainder of pregnancy is recommended. Liberal use of mosquito repellant (Deep Woods Off, Cutter or other DEET products), full body coverage while in an endemic area, and mosquito control efforts such as removal of standing water and commercial yard treatments are appropriate.

Here at Austin Perinatal Associates, we recommend the assessment of all pregnancies in the third trimester (28 - 32 weeks) for signs of fetal microcephaly and rapid testing of all patients at risk based upon travel or known exposures. We have access to a commercial laboratory urine test that can identify Zika-infected individuals in 48 - 72 hours. The test is useful up to 4 weeks after exposure. The out-of-pocket cost is $125.00 and can be charged to a credit card at the time of your visit, but is not covered by insurance.

For further information, call David L. Berry, M.D. or his staff at Austin Perinatal Associates at (512) 206-0101 or visit our website at

UPDATE: May 7th, 2016 by David L. Berry, M.D.

Statistical Update

According to the U.S. Centers for Disease Control, as of May 4, 2016, there have been 472 cases of confirmed Zika virus cases in the United States, of which 0 were locally acquired from mosquitoes. All were acquired via international travel. Of these cases, 44 were pregnant, 10 were sexually transmitted and only 1 has experienced the generalized weakness and complications of Guillain-Barré syndrome. There has been one report of a newborn with microcephaly and a report of a single patient who terminated her pregnancy due to Zika exposure and a severe brain abnormality noted on ultrasound.

In the U.S. Territories of American Samoa, the U.S. Virgin Islands and Puerto Rico, by contrast, 658 of the 661 cases have been identified as mosquito-borne illnesses.

Thirty cases of Zika have been reported in Texas, all of which were acquired by international travel or sexually transmitted from a person in Dallas who had travelled internationally to an affected area.


Zika has been shown to be transmissible via mosquito bite from a specific group of infected mosquitoes, via sexual transmission, via blood transfusion, and from a pregnant woman to her fetus. Breastfeeding does not seem to carry a risk of transmission, and previous infection seems to confer a lifetime immunity.

Currently Affected Countries

The following 44 countries are confirmed to have mosquito-borne Zika infections:

Americas: Aruba, Barbados, Belize, Bolivia, Bonaire, Brazil, Colombia, Costa Rica, Cuba, Curacao, Dominica, Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Mexico, Nicaragua, Panama, Paraguay, Puerto Rico, Lucia, Saint Martin, Saint Vincent and the Grenadines, Sint Maarten, Suriname, Trinidad and Tobago, U.S. Virgin Islands, Venezuela.

Oceana/Pacific Islands: American Samoa, Fiji, Kosrae, Federated States of Micronesia, Marshall Islands, New Caledonia, Papua New Guinea, Samoa, Tonga

Africa: Cape Verde Islands

New Vector of Transmission

Recently released information that a mosquito species other than the Aedes aegypti mosquito endemic to the northern United States has been shown to carry the Zika virus from reports originating from northern Mexico. Aedes albopictus, also known as the Asian tiger mosquito, has been shown to be a potentially dangerous new vector for transmission. This information is important because this new source for infection migrates into states much further north within the U.S. up to the Great Lakes and New England areas, thus expanding the potential range of future Zika infections beyond the lower tier of southern and Gulf states.

Travel Recommendations

The CDC recommends against travel to the affected countries for all pregnant women and women who are planning a pregnancy within 8 weeks. This recommendation includes travel to Brazil for the summer 2016 Olympic Games. Since Zika can be sexually transmitted, the CDC further recommends use of condoms or abstinence from sexual activity for any sexual partners of pregnant patients who have traveled to the affected areas for up to six months (or for the remainder of the pregnancy). Should travel be required by pregnant patients, liberal use of mosquito repellent such as DEET, avoidance of mosquito bites by remaining indoors, within air-conditioned areas or keeping skin well covered is recommended.


We are still unsure as to the attack rate of Zika infection within pregnant women and their fetuses. We are unsure as to the exact percentage of women infected who actually pass it to their unborn baby and what percentage of these babies will end up with severe microcephaly or less severe brain injuries. As with all other viral infections, many people will be exposed, yet have no infection. Others will get infected, yet be asymptomatic. A fraction will get infected and symptomatic and another unknown fraction will pass it to their fetus. A portion of these fetuses will be unaffected depending upon gestational age at infection and viral load. These questions will only be answered over time.


The CDC is the primary diagnostic laboratory. As of May 2, 2016, Quest Laboratories will begin performing viral polymerase-chain reaction (PCR) testing for Zika based upon an emergency use authorization granted by the FDA. Quest becomes the first commercial lab that has been authorized to test for Zika virus.


The Environmental Protection Agency and CDC recommend mosquito repellent with either DEET, picaridin, IR3535, and some oil of lemon eucalyptus and para-menthane-diol. All should be used according to the manufacturer’s recommendations and are safe to use with pregnancy and breastfeeding.


There is currently no treatment for Zika virus. It must run its course. Close monitoring by your physician is recommended, especially with the assistance of a maternal-fetal medicine and ultrasound specialist. Blood tests and amniocentesis can aid in confirming a true diagnosis, but the actual impact of an infected fetus is largely unknown.

UPDATE: February 9th, 2016 by David L. Berry, M.D.

As previously reported the Zika virus has become an international concern based upon an increasing number of cases though out central and South America. Over the past week, there have been nine cases of confirmed Zika virus infections diagnosed in the state of Texas, including one in Travis County. One case in Dallas County was the first to be confirmed as sexually transmitted from a partner that had just returned from international travel. All cases of Zika virus in the United States have been from travelers who were exposed internationally and diagnosed domestically. There have been no cases of Zika virus confirmed in pregnant women in the U.S. and no cases of mosquito-transmitted Zika here.

The origins of the concern for Zika virus-associated fetal birth defects originated in northeastern Brazil. Zika fever is usually a mild and self-limited disease that involves fever, a rash, joint and muscle pain similar to influenza and red eyes (conjunctivitis). About 80% of patients are asymptomatic. In late 2015, during a Zika outbreak in Brazil, there were 37 cases of neonatal microcephaly (small head), two of which were found to be genetic in origin. The remaining 35 patients had mothers that were all exposed to Zika virus-endemic areas. Two of these cases were diagnosed with Zika before delivery by amniocentesis. All of these 35 cases were exposed in the first and second trimester of pregnancy.

The baseline incidence of microcephaly in Brazil has been estimated as 1:20,000. With the 4,000 reported cases of microcephaly recently reported, out of 3 million babies born in Brazil, the incidence of 1 - 3 per 1,000 births in a pandemic outbreak is expected. This translates to 99.7% chance of NOT having a baby with microcephaly, even if you lived in Brazil right now. In a worst-case scenario, and assuming that the association of Zika virus and microcephaly is correct, 50 - 100 new cases of microcephaly would be expected in Austin this year (out of 20,000 deliveries).

Indeed, an international infectious disease outbreak provokes fear in everyone, but especially in the most vulnerable in society, our pregnant women and unborn babies. The World Health Organization has declared an international emergency to open up more doors for rapid research funding, but the truth is that an effective vaccination or treatment for Zika virus will require 2-10 years, according to Niko Vasilakis of the Center for Biodefense and Emerging Infectious Diseases.

Since vaccination and treatment are not available, the only options are 1) mosquito control, and 2) prevention of mosquito bites during the spring and summer months. Personally, the only options and choices for individual patients are avoidance of travel to pandemic areas, coverage of exposed skin when mosquitos are present, liberal mosquito repellant use, and monitoring your pregnancy with your obstetrician and a maternal-fetal specialist.

Please, contact Austin Perinatal Associates for further recommendations.

Video: Dr. Berry speaks to KVUE about the Zika virus.


Original article published 1/17/16, by David L. Berry, M.D.

Zika virus and its potential effect on pregnancy has erupted in the news headlines recently. The concerns for the presumed association between exposure, infection in pregnancy, and neonatal microcephaly has led some countries in central and south America to issue travel and pregnancy warnings.

What we know

  1. Zika virus is a Flavivirus that is similar to Dengue and Chikungunya.
  2. Transmission of the virus is primarily through the bite of an infected Aedes species mosquito. This species of mosquito tends to be fairly aggressive and bites throughout the daytime hours.
  3. 80% of cases of Zika virus are asymptomatic.
  4. Brazil has seen an increase in cases of Zika virus and a 15 – 20 fold increase in cases of microcephaly (very small underdeveloped brains) in newborn babies.
  5. Previous epidemics of Zika virus have not been associated with fetal microcephaly.
  6. Even with just over 4,000 cases of microcephaly reported in Brazil in the past 6 months, this represents only a small fraction of the 3 million births per year in that country (about 1:500 births per year). Therefore, even with this “pandemic”, less than 1% of babies are actually affected.

What we do not know

  1. There is a perception of association, but no proof of cause and effect that Zika virus infection in pregnancy directly causes microcephaly.
  2. We do not know actual incidence, attack rates and true risks of exposed women. Epidemiology looks backwards in time and frequently the fear is greater than the future reality.
  3. There is speculation that there will likely be some presence of the virus in the United States in the next 3 - 6 months due to mosquito migration and the high prevalence of international travel, but this is speculation.
  4. Based upon embryology and other types of congenital fetal infection that would adversely affect the brain may likely happen around the 8th until the 28th week infections, however neither the WHO or CDC has made specific recommendations.

Austin Perinatal Recommendations

  1. Prudence would dictate avoidance of travel to these countries while pregnant (particularly 8 - 28 weeks) and use of DEET containing mosquito repellant in a mosquito-prone area throughout the spring to fall months, especially in warm or tropical climates.
  2. Austin Perinatal Associates does not recommend termination of pregnancy for potential exposures due to the low prevalence of overt fetal microcephaly.
  3. APA does recommend serial ultrasound monitoring and CDC testing for overtly symptomatic patients including blood test and amniocentesis, when indicated.
  4. Consider 28 - 30 week ultrasound for all fetuses until further information can be elucidated about transmission, actual fetal risks, and attack rates in pregnancy.

Click here for the most recent CDC update.

Dr. David L. Berry

A 4th generation physician and Austinite since 1978, Dr. Berry is board certified by the American Board of Obstetrics and Gynecology both in OB/GYN and maternal-fetal medicine.

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