Negative Effects Of Zika During Pregnancy More Common Than Realized

The rate of birth defects, disability and brain irregularities in babies exposed to the Zika virus is considerably higher than was previously believed—regardless of the mother’s symptoms or the trimester she had the infection—found a new study.

Since the discovery of the virus’s spread to the Americas in 2015, scientists have been learning increasingly more about the harmful effects of Zika infection on fetuses and newborns exposed to the virus in the womb.

“A troubling aspect of our study is that children were assessed in early infancy, when some subtle neurologic manifestations of disease are difficult to identify,” the authors reported in the New England Journal of Medicine. “On further follow-up, we suspect that additional clinical manifestations of neurologic disease may be identified in infants who were not previously found to have abnormalities.”

Between September 2015 and May 2016, the researchers recruited 345 pregnant women into the study if they came into a specific clinic in the Manguinhos Rio de Janeiro area of Brazil and had developed a rash within the previous five days. Just over half of these, 182 women, tested positive for Zika based on blood and/or urine tests. Of the mothers without Zika, 42% of them had contracted chikungunya, compared to just 3% of the women who also had Zika. None of them had current cytomegalovirus or dengue fever infections, though more than 80% of the women in both groups had previously had a dengue infection.

The women ranged from being 6 weeks to 39 weeks pregnant at the time of their infection, though more than half were in their second trimester. Only just over a quarter of the women (27%) had had a fever, usually low-grade, but 38% reported that another family member had had a similar illness.

The most common symptoms the women experienced outside of the rash were itching—which 90% of the women with Zika reported—and joint pain, found in 62% of the women with Zika and 70% of the women without Zika. Other symptoms experienced by about a quarter to a half of the women in both groups included red or itchy eyes, fatigue, muscle pain, nausea and enlarged lymph nodes. The symptoms that seemed most associated with Zika—and which should therefore raise a red flag for anyone in an area where Zika is circulating—were red, itchy, infected eyes and rash that looked very red with tiny bumps on it, similar to the way a measles rash looks.

The researchers were able to evaluate the outcomes of 125 infants born to mothers with Zika infections and 61 mothers unaffected by Zika. Although 7% of the pregnancies resulted in fetal death in both groups, the rate of poor outcomes overall was 46% in the mothers with a Zika infection, compared to just 11.5% in the mothers without Zika. Five of the women infected with Zika experienced miscarriages in the first trimester. In addition, two had a miscarriage in the second trimester, and two had stillbirths.

Among the women with Zika infections whose babies survived, almost half—42% of 117 newborns born to 116 women—had birth anomalies (birth defects) and/or brain scans that were severely abnormal, such as calcification or deterioration in the brain. Four of these babies had microcephaly, a head and brain substantially smaller than normal which is associated with various disabilities and which was the first major effect noticed among babies affected by Zika.

“Although microcephaly has been widely discussed in relation to ZIKV infection, it is important to note that other findings such as cerebral calcifications and fetal growth restriction were present more frequently,” the researchers reported. “We have observed a variety of neurologic findings, including visual and hearing deficits, seizure activity, hypertonicity, spasticity, hyperreflexia, contractures, dysphagia and feeding difficulties.”

Nine percent of the Zika-exposed babies were reported to be underweight for the week of pregnancy when they were born (small for gestational age), suggesting fetal growth restriction. One of these infants had also been exposed to chikungunya in the womb.

The trimester in which the mother had had the Zika infection did not appear to make a difference in terms of poor outcomes, though somewhat fewer poor outcomes resulted among fetuses exposed in the third trimester compared to the first two. Of babies exposed to Zika in the first trimester, 55% had birth anomalies or irregular brain findings, a similar proportion as the 52% of babies exposed during the second trimester. A little under a third (29%) of babies exposed in the third trimester had these poor outcomes.

The women in both groups did not differ much in terms of where they lived, their socioeconomic status, other demographic factors or their medical history—but they did differ in one significant way. The researchers also found that 83% of the women who tested negative for Zika had used insect repellent, compared to 60% of the women who had the virus, suggesting that use of insect repellent did offer some protection against the virus.

Other ways women can protect themselves in areas where Zika is circulating include staying indoors as much as is possible, especially in air conditioning if it is available, and ensuring that doors and screens are sealed and closed. In the community, getting rid of standing water can help, and wearing protective clothing—long sleeves and pants—can reduce the risk of being bitten by a Zika-carrying mosquito.

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