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Zika link to microcephaly, other birth defects strengthens
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Zika virus appears to be associated with additional birth defects aside from microcephaly, including fetal death, placental insufficiency, fetal growth restrictions and central nervous system injuries, according to recent research in the New England Journal of Medicine.
“We have found a strong link between Zika and adverse pregnancy outcomes, which haven’t been documented before,” Karin Nielsen‑Saines, MD, professor of clinical pediatrics at the David Geffen UCLA School of Medicine, said in a press release. “We saw problems with the fetus or the pregnancy at eight weeks, 22 weeks, 25 weeks, and we saw problems at 35 weeks. Even if the fetus isn’t affected the virus appears to damage the placenta, which can lead to fetal death.”
The researchers studied pregnant women (n = 88) who presented to an acute febrile illness clinic in Rio de Janeiro with suspected Zika-related rashes from September 2015 to February. Women were tested for Zika virus infection via RT-PCR assays. The researchers also collected demographic, medical and prenatal history data from the patients. Fetal health was examined by ultrasonography at 20 weeks, between 20 and 30 weeks and after 30 weeks’ gestation.
Study results showed that 82% of the patients tested positive for Zika virus. Of these women, 42 underwent ultrasonography. In addition, 16 women who tested negative for Zika also underwent ultrasonography, while another 28 of the remaining participants declined ultrasound due to inconvenience or fear of potential Zika-related abnormalities. Fetal abnormalities were identified in 12 of the Zika-infected women; no abnormalities were detected among women without Zika infection.
Of the fetuses with abnormalities, there were two fetal deaths, five with in utero growth restriction with or without microcephaly, seven with ventricular calcifications or other central nervous system lesions, and seven with abnormal amniotic fluid volume or cerebral or umbilical artery flow.
“Women with suspected or confirmed Zika virus infection should be monitored closely, with serial ultrasonography to evaluate for signs of placental insufficiency, given the risks of fetal death and intrauterine growth restriction,” Nielsen-Saines and colleagues wrote. “The establishment of a scientifically credible link between Zika virus and abnormal congenital findings is of utmost importance for the effective and successful management of this epidemic in Brazil and worldwide.”
Nielsen-Saines and colleagues expressed concern that without an established link between the virus and birth defects, false information suggesting causation via pesticides may exacerbate both the spread of Zika and the potential for fetal abnormalities.
“That is a really bad idea, because you want to enhance vector control to prevent infection and not abandon that approach during an epidemic," Nielsen-Saines said in the release.
Birth defect cluster strengthens link
According to a report in MMWR, the prevalence of microcephaly in areas of Brazil with confirmed Zika virus transmission is drastically higher than in areas without local transmission, strengthening the link between maternal Zika exposure and abnormal birth outcomes.
“The temporal relationship between outbreaks of Zika virus disease and increases in reported prevalence of microcephaly in Brazil, as well as the significant increase in birth prevalence of microcephaly in states with laboratory-confirmed Zika virus transmission suggest a relationship between these two epidemiologic events,” Juan Cortez-Escalante, MD, of the Pan American Health Organization in Brazil, and colleagues wrote. “The reported occurrence of the 2015-2016 microcephaly cases, especially in Pernambuco, highlight the temporal relationship between preceding Zika virus transmission and the abrupt increase in birth prevalence of microcephaly.”
The researchers found that the prevalence rate of microcephaly in 15 Brazilian states with local Zika transmission was 2.8 cases per 10,000 live births, compared with 0.6 per 10,000 births in four states without transmission.
“There is an urgent need for additional research to confirm the link between Zika virus and microcephaly through prospective and retrospective analytic studies, as well as to determine the critical Zika virus exposure period during pregnancy with respect to fetal infection and microcephaly,” Cortez-Escalante and colleagues wrote. – by David Costill
Disclosure: The researchers report no relevant financial disclosures.
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