Zika: The Expanding and Deepening Threat

Marc Gozlan, MD


November 14, 2016

Considering that Zika virus can be transmitted sexually through semen and that the virus can be present in semen for several weeks after a man has recovered from a Zika virus infection, the ECDC recommended that "travellers to Zika-affected areas should be advised that the risk of sexual transmission from an infected man to another person can be reduced by using condoms," adding that "travellers showing symptoms compatible with Zika virus disease within 3 weeks of return from an affected area are advised to contact their healthcare provider and mention their recent travel."[12]

Concerning male travelers returning from areas with local transmission of Zika virus, the ECDC asked them to consider using a condom with a female partner at risk of getting pregnant or who was already pregnant for 28 days after their return if they did not have any symptoms compatible with Zika virus infection and for 6 months after recovery from a laboratory-confirmed Zika virus infection.[12]

At that time, two studies had demonstrated the presence of Zika virus RNA in semen. More precisely, Zika virus RNA on polymerase chain reaction (PCR) assay and replicative Zika virus particles had been detected in the semen of a 44-year-old man in Tahiti 3 weeks after onset of symptoms, although two sequential blood samples tested negative,[7] and Zika virus RNA had been found by PCR in a semen sample 28 days after onset of clinical symptoms of Zika virus infection.[16] But at that point, there were no data on viral concentrations in semen, and again, only two reports of sexual transmission of Zika virus.[1,2]

In the same comprehensive background document on Zika virus issues, the ECDC addressed two other important developments—the potential association with microcephaly and GBS. Indeed, between October 22, 2015, and January 30, 2016, the Brazilian authorities received 4783 notifications of microcephaly or CNS anomalies in newborns.[17] At that time, 404 cases from 156 municipalities in nine Brazilian states were confirmed to have microcephaly or CNS anomalies suggestive of congenital Zika virus infections.

WHO released a risk assessment for Africa,[18] saying that for many years, owing to lack of systematic surveillance mechanisms for Zika virus disease, only sporadic human cases were detected in Africa. Cape Verde had reported an outbreak with more than 7000 cases from October 2015 to January 2016. Although it is possible that populations in Africa have some immunity, the viral strain spreading rapidly in the Americas may be unknown to some African populations, and its importation into this continent could lead to a more acute disease and severe sequelae. Vigilance must be maintained, warned the report on the Zika virus risk assessment in the WHO African region.[18]

February 6-22, 2016. Two confirmed and four probable cases of sexual transmission of Zika virus were reported to the CDC.[19] In all cases where type of sexual contact was documented, the contact included condomless vaginal intercourse and occurred when the male partner was symptomatic or shortly after symptoms resolved. The MMWR report[19] suggested that "sexual transmission of Zika virus might be more common than previously reported."

Sexual transmission of Zika virus might be more common than previously reported.

Meanwhile, severe ocular abnormalities were reported as part of the congenital Zika virus syndrome.[20,21,22] The main ophthalmologic findings in infants with microcephaly associated with presumable intrauterine Zika virus infection included optic nerve abnormalities, focal pigment mottling of the retina, chorioretinal atrophy with a predilection for the macular area, subluxation, and coloboma.[20,22] A high proportion of infants with microcephaly had ophthalmologic lesions.

These findings added to a growing body of clinical information about the impact of congenital Zika virus infection on children's eye development and vision, but it remained unclear whether these eye problems resulted from Zika virus or were complications of microcephaly itself. A few months earlier, ocular abnormalities, including intraocular calcifications, microphthalmia, and cataract, had been briefly reported.[13,23]

February 17, 2016. The Lancet Infectious Diseases published an early online article[23] reporting the detection and sequencing of Zika virus from the amniotic fluid of fetuses with microcephaly in two pregnant women from the state of Paraíba in Brazil. Once again, the findings strengthened the putative association between Zika virus and microcephaly in neonates and suggested that the Zika virus could cross the placental barrier.

Meanwhile, the number of countries in the Americas confirming local Zika virus circulation grew to 29. Furthermore, the link between Zika virus and congenital complications in newborns grew stronger with the February 25, 2016, report of several severe birth defects in a stillborn infected baby.[24] This case concerned a 20-year-old pregnant Brazilian woman whose fetus had developed hydrops fetalis and severe CNS defects, including microcephaly and hydranencephaly. Zika virus RNA was detected in CNS tissues and amniotic fluid.[24]

February 27, 2016. Europe's first case of sexually transmitted Zika virus was recorded in France, when a woman was infected after her partner returned from Brazil.


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