Zika: The Expanding and Deepening Threat

Marc Gozlan, MD

Disclosures

November 14, 2016

June 2016

Early June 2016. Until June, cases of sexual transmission were reported only from symptomatic males. On June 7, 2016, French clinicians reported the case of delayed sexual transmission that occurred in a woman between 32 and 41 days after the onset of symptoms in the man.[74] On June 9, 2016, for the first time, French physicians reported a Zika virus sexual transmission in a couple returning from Martinique, wherein both partners were asymptomatic.[75] Their Zika virus infection was found only during systematic virologic testing in the context of a workup for in vitro fertilization.[75]

On June 16, 2016, CDC announced they would begin reporting from US states the poor outcomes of pregnancies with laboratory evidence of possible Zika virus infection in both live-born infants and pregnancy losses with birth defects.[76] The same day, the CDC reported that as of June 9, a total of 234 pregnant women in the US mainland had been diagnosed with Zika infection and 189 infected pregnant women had been reported from Puerto Rico and other US territories.

At that time, three US infants had been born live with Zika-related birth defects, including severe microcephaly in a baby born to a Hawaiian woman who had spent time in Brazil and in a girl born in a New Jersey hospital whose mother had been exposed to the virus in her native Honduras. Thus far, three women infected with Zika virus had had pregnancy losses—miscarriages, stillbirths, and abortions—with birth defects.

Meanwhile, some brief reports indicated the presence of Zika virus, by RT-PCR and culture, in saliva and urine.[77] Among them was a study from Brazilian researchers[78] who initially announced their findings in early February and published the full results on June 24. These scientists described isolation of infectious Zika virus particles from the saliva and urine of acute-phase patients,[78] again raising the concern about the contribution of a person-to-person infection route.

Later June 2016. The risk for Zika virus transmission through blood transfusions was also a concern. On June 17, 2016, a study[79] showed evidence of Zika virus in 1.1% of blood donations in Puerto Rico. It appeared that the incidence of screened blood donations reactive for Zika virus infection had increased steadily since April 2016.

The risk for Zika virus transmission through blood transfusions was also a concern.

Meanwhile, in a country as large as Brazil, microcephaly was even more clearly the major challenge for public health authorities. On June 29, 2016, Brazilian researchers made an important contribution to improving the surveillance system for congenital Zika virus infection at a time when the epidemic was expected to be even more devastating in the following months.[80]

Using data from the Brazilian surveillance system for microcephaly, the study published in the Lancet[80] described the clinical and anthropometric characteristics of the largest case series of suspected Zika virus infection reported to date. According to this long-awaited analysis of the first 1500 suspected cases in Brazil, microcephaly screening for Zika complications in newborns could have missed some birth defects. Indeed, this study[80] showed that some 20% of the definite or probable cases had normal head circumferences, and for one third of them, there was no history of a rash during pregnancy. According to the authors, "among Zika virus-affected pregnancies, some fetuses will have brain abnormalities and microcephaly, others will have abnormalities with normal head sizes, and presumably others will not be affected."

This study provided a sensitivity of 83% and a specificity of 98% for identifying definite or probable cases of microcephaly based on the cut-off for head circumference; this increased slightly to 87% when history of a rash was also considered. On the basis of these results, the authors recommended that screening criteria should not focus simply on microcephaly and rash during pregnancy and needed to be revised to detect all affected newborn babies.[80]

The same day, in the same journal, a study[81] reported the pathologic findings from three fatal cases and two spontaneous abortions associated with Zika virus infection at 11 and 13 weeks' gestation. The Brazilian authors reported brain abnormalities, including microcephaly, lissencephaly, cerebellar hypoplasia, and ventriculomegaly. They also described a broad range of other congenital malformations, including craniofacial malformations and arthrogryposis. This latter condition is characterized by multiple congenital joint contractures, leading to deformities in the arms and the legs (hips and knees). This report highlighted the value of pathology studies to identify the full spectrum of congenital Zika virus infection.[81]

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