Houston Zika Update

The summer months ushered in a new round of Zika concerns as the virus, which has been linked to miscarriages, birth defects, and a rare form of paralysis, continued its spread to new regions, including the first case of transmission within the continental United States. The U.S. Centers for Disease Control and Prevention (CDC) has now documented 3,358 cases in the U.S. including several linked to an outbreak in the Miami-Dade area. As mosquitoes continue to proliferate in Houston’s warm, wet climate, the Zika virus remains a key worry for many pregnant women and those who are planning to get pregnant.

Dengue fever vector, mosquito biting hand.

Dr. Sean Blackwell, Chief of Service for Obstetrics and Gynecology at Children’s Memorial Hermann Hospital and chair of the Department of Obstetrics at McGovern Medical School at UTHealth, answered some commonly asked questions regarding the virus.

Q: Earlier this summer, the CDC documented cases in which Zika virus was acquired in the Miami-Dade region. A man who traveled there later brought it back to El Paso. How likely is it that we will see a case of Zika transmission happen here in Houston?

Dr. Blackwell: I think we’re preparing for that reality. How bad will it be? We don’t know. The rate of infection is still so unknown much like everything else related to the Zika virus. The big concern, obviously, is for pregnant women who run the risk of a miscarriage or having a baby born with a severe birth defect, such as microcephaly, a condition in which a baby is born with a smaller-than-normal head and often smaller brains that haven’t properly developed. However, we don’t yet know what the effects of Zika could be on pregnant women in the United States. It’s clear there seem to be different risks for microcephaly in different areas. The biggest proportion of Zika-related microcephaly cases so far has been in Brazil, but we don’t know if there’s something specifically going on in that region as opposed to some of the other areas where Zika has appeared and we haven’t seen the same frequency of microcephaly. Ideally, we see no cases of Zika transmission in Houston, but realistically we are preparing for that to happen.

Q: Why is Zika creating such an outpouring of concern?

Dr. Blackwell: People are scared, but the fears differ for different groups of people. Some of my patients who aren’t pregnant yet, but are planning to get pregnant or planning a honeymoon in Central or South America, want to know whether they should delay planning a family. Other patients who recently found out they were pregnant after having traveled to an area where Zika is prevalent, are extremely concerned about their risks. Then there’s another group of patients who are already pregnant, but who haven’t traveled to Zika-affected regions, and they want to know what their risks are here locally.The Do's and Donts of Zika-ff

Q: So what do you tell these patients?

Dr. Blackwell: For now, we’re recommending that women who are traveling to areas where Zika is endemic, or women who have developed a Zika infection, wait for a period of time before pursuing pregnancy. The current guidelines recommend waiting at least eight weeks after exposure or at least six months if their spouse was potentially exposed, and that’s even without symptoms. A large percentage of people infected with Zika don’t exhibit clinical symptoms. Unfortunately, there’s a lot we still don’t know. The U.S. Centers for Disease Control and Prevention (CDC) remains the best place to stay informed. But a lot of what we know is actively evolving and so our advice may change as we learn more.

Q: What about women who are planning to get pregnant but aren’t planning to travel to Zika-affected areas?

Dr. Blackwell: For those patients, we aren’t making any suggestions to delay pregnancy at this time. But we are suggesting that pregnant women, as well as those trying to get pregnant, should take steps now to protect themselves from mosquito bites, even if they aren’t planning to travel to a country with Zika

Q: What are the most effective products to protect against mosquito bites?

Dr. Blackwell: Mosquito repellents are highly effective when used correctly and within their guidelines, and products containing DEET are safe for pregnant women. A study found that the products containing DEET are the most effective. It’s best to treat your clothing AND any exposed skin, and to reapply per the manufacturer’s recommendations. We also recommend applying insect repellent after you apply sunscreen so it remains effective. In addition to using mosquito repellents, you should make sure your windows and door screens are closed and repaired. Avoid standing water. Empty any vessels that may be collecting water in your yard. The CDC has a wonderful list of recommendations on its website, but it’s good common sense to thoroughly inspect your yard, get rid of any freestanding water, and wear protective clothing.Tips for Using Mosquito Repellent-f

Q: Zika is obviously a hot topic, but there are other mosquito-borne infectious diseases that are also troublesome. What other diseases should people be aware of?

Dr. Blackwell: The same mosquitoes that carry Zika also transmit the dengue and chikungunya viruses. Those aren’t linked to the same dramatic birth defects associated with Zika, so they aren’t getting as much attention, but they both can cause serious illnesses that affect babies and adults alike. The same prevention strategies can be used as protection against these viruses, as well.

Q: If you are pregnant and concerned that you may be infected with Zika, what should you do?

Dr. Blackwell: Women who are worried that they may have been exposed to the Zika virus should visit with their healthcare provider. There, they will review a check list of questions: How long ago were they exposed? Did they experience any symptoms of Zika? At what point in their pregnancy were they exposed? Depending on their answers to those questions, they may receive a detailed ultrasound to look for any evidence of a fetal infection. Depending on the risk for exposure, the mothers may be offered a test that can confirm whether they were indeed infected. There are three different types of tests: A molecular test called a PCR tests directly for the virus, but it’s not perfect and it usually only shows positive results around the time when the Zika infection is still active. There is another test that looks at maternal antibodies to determine if a woman has been exposed, but interpretation can be challenging since Zika has cross reactivity with other similar viruses. Finally, there is a diagnostic amniocentesis, where a doctor checks fluid directly around the baby, but that test carries a risk of miscarriage. And I don’t recommend testing unless it’s absolutely necessary.

Q: Why aren’t all pregnant woman automatically tested for Zika exposure?

Dr. Blackwell: You have to be careful because these blood tests aren’t perfect. They aren’t always going to give a definitive answer and they can have false positives. If you started testing enough people, a percentage of them will have false positives. That can lead to inappropriate treatment which could have adverse outcomes for mom and baby. It’s also important to remember that even if a mother or fetus tests positive for Zika, there is no active treatment. Just because a test is available, it doesn’t always mean you should have the test done.

For more information about Zika in Houston, please visit the City of Houston websiteHarris County Public Health or Texas Zika.

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Tashika Varma