Zika Virus and the Risk of Birth Defects
Introduction to the Relationship Between Zika Virus and Fertility Problems
Infection with the Zika virus is a new and alarming concern for couples who are either pregnant or trying to conceive. Although the virus was first discovered in the 1940’s in a monkey living in the Zika forest of Uganda, the recent rapid spread of the virus throughout the Americas has put it firmly on the radar of the fertility community in the United States. And since many couples either live or vacation (and often honeymoon) in tropical or subtropical areas where the risks are highest, this has resulted in quite a bit of anxiety compounded by confusion.
The primary cause of spread of the Zika virus is through a bite by the Aedes mosquito, which is generally found in tropical or subtropical regions. This Aedes mosquito is also known to transmit other diseases such as dengue fever, Yellow fever, and chikungunya. Once infected, person-to-person transmission of the virus can occur through sexual intercourse, blood transfusions, and placental transfer from mother to fetus.
Developmental Risks of the Zika Virus
From a fertility standpoint, the primary concern of the Zika virus is the risk of developmental defects in the fetus of an infected mother. Zika-associated birth defects occur in approximately 10% of lab-confirmed Zika-positive pregnancies (15% if the infection occurs during the first trimester). The most common developmental concern is the risk for microcephaly, in which the head (and brain) of the baby remains abnormally small. This is generally associated with a range of neurologic problems which can include seizures, trouble with feeding, speech, and sitting/crawling/standing. Hearing and vision can be affected as well as overall intellectual development. Infection with the Zika virus during pregnancy can also increase the risk of fetal death and miscarriage.
There is currently no treatment available for fetuses who are infected with the Zika virus, so the best defense is prevention. Transmission to the fetus can occur both before or after a pregnancy has been established, so preventative measures must be taken by women who are either already pregnant and those who are planning a pregnancy in the near future.
Preventing Zika-Related Birth Defects
As discussed above, the two primary ways that women can be infected with the Zika virus (outside rare instances like needing a blood transfusion) is:
1) A bite by an Aedes mosquito
2) Transmission by sexual partner
Transmission by mosquito bite
Most residents of the United States currently do not live in an area where documented transfer of the Zika virus to people by mosquito bites has been detected, so their primary risk is traveling to an area where there is an endemic risk. However, two states (Florida and Texas) have had isolated cases of Zika transmission by mosquito bites.
The CDC has a published a map of the world showing the areas of risk for Zika transmission by mosquito bites.
Within the United States, as mentioned earlier, the risk of contracting Zika by a mosquito bite is currently low, though a few documented cases have occurred in Florida and Texas. This list is certain to grow, as the potential range of the Aedes mosquito within the United States is relatively large. To understand this future risk, one must know that there are two forms of the Aedes mosquito: aegypti and albopictus. The Aedes aegypti prefer to feed on people and therefore are more likely to transfer the Zika virus. The Aedes albopictus mosquito also feeds on animals in addition to humans, and is therefore less likely to transmit harmful viruses to people. Fortunately, the Aedes aegypti has a smaller potential range within the United States, though it is still fairly broad. The following CDC link shows a map with the potential range of each Aedes mosquito for 2016 in the United States. Remember, this is the potential range for the mosquito, but documented Zika transference by mosquito bites has only been reported in Texas and Florida at this time. Another point to consider though, is that this estimated range for the mosquitos is likely to increase with time due to progressive global warming.
Symptoms consistent with possible infection with the Zika virus include:
1) Fever >38 degrees C 2) Malaise 3) Joint pain 4) Headache 5) Conjunctivitis 6) Skin rash
Preventing Transmission of zika virus
Avoiding Travel
The #1 CDC recommendation for pregnant women or women planning on establishing a pregnancy in the near future is to avoid travel to endemic areas if at all possible.
Prevention of Bug Bites
If a woman must travel to an endemic area, taking steps to prevention bug bites is extremely important. The CDC has 3 main recommendations:
1) Use EPA-registered mosquito repellents that contain at least 20% DEET
2) Cover exposed skin
3) Avoid Bugs where you are staying
CDC ZIKA GUIDELINES (Feb 2019)
If only the male partner travels to an area with risk of Zika
The couple should use condoms or not have sex for at least 3 months
After the male partner returns, even if he doesn’t have symptoms, or
From the start of the male partner’s symptoms or the date he was diagnosed with Zika
If only the female partner travels to an area with risk of Zika
The couple should use condoms or not have sex for at least 2 months
After the female partner returns, even if she doesn’t have symptoms, or
From the start of the female partner’s symptoms or the date she was diagnosed with Zika
If both partners travel to an area with risk of Zika
The couple should use condoms or not have sex for at least 3 months
After returning from an area with risk of Zika, even if they don’t have symptoms, or
From the start of the male partner’s symptoms or the date he was diagnosed with Zika
recommendations for men or women living in endemic areas
Recommendations for couples living in endemic Zika areas are less well-formed, and include talking with your health care provider about the risks of attempting reproduction and avoiding exposure to mosquito bites. Obviously even in the highest risk endemic areas, the vast majority of children are born without any Zika-related birth defects. However, since the consequences are so potentially devastating, it is worthwhile to discuss the risks and devise a plan to minimize the chances of contracting Zika during a pregnancy.
Testing for the Zika virus
Testing for the Zika virus has not been standardized and is rapidly evolving, this creating further uncertainty regarding the effectiveness of the ASRM guidelines above. LabCorp currently offers a “Zika Virus Comprehensive Profile” which can be performed on either blood or urine specimens [CPT 87798(x2)]. ICD-10 diagnosis code to use is Z11.5.