Zika Virus Disease and Pregnancy Outcomes in Colombia

Abstract

Background: In 2015 and 2016, Colombia had a widespread outbreak of Zika virus. Data from two national population-based surveillance systems for symptomatic Zika virus disease (ZVD) and birth defects provided complementary information on the effect of the Zika virus outbreak on pregnancies and infant outcomes.

Methods: We collected national surveillance data regarding cases of pregnant women with ZVD that were reported during the period from June 2015 through July 2016. The presence of Zika virus RNA was identified in a subgroup of these women on real-time reverse-transcriptase-polymerase-chain-reaction (rRT-PCR) assay. Brain or eye defects in infants and fetuses and other adverse pregnancy outcomes were identified among the women who had laboratory-confirmed ZVD and for whom data were available regarding pregnancy outcomes. We compared the nationwide prevalence of brain and eye defects during the outbreak with the prevalence both before and after the outbreak period.

Results: Of 18,117 pregnant women with ZVD, the presence of Zika virus was confirmed in 5926 (33%) on rRT-PCR. Of the 5673 pregnancies with laboratory-confirmed ZVD for which outcomes had been reported, 93 infants or fetuses (2%) had brain or eye defects. The incidence of brain or eye defects was higher among pregnancies in which the mother had an onset of ZVD symptoms in the first trimester than in those with an onset during the second or third trimester (3% vs. 1%). A total of 172 of 5673 pregnancies (3%) resulted in pregnancy loss; after the exclusion of pregnancies affected by birth defects, 409 of 5426 (8%) resulted in preterm birth and 333 of 5426 (6%) in low birth weight. The prevalence of brain or eye defects during the outbreak was 13 per 10,000 live births, as compared with a prevalence of 8 per 10,000 live births before the outbreak and 11 per 10,000 live births after the outbreak.

Conclusions: In pregnant women with laboratory-confirmed ZVD, brain or eye defects in infants or fetuses were more common during the Zika virus outbreak than during the periods immediately before and after the outbreak. The frequency of such defects was increased among women with a symptom onset early in pregnancy. (Funded by the Colombian Instituto Nacional de Salud and the Centers for Disease Control and Prevention.).

Figure 1.. Pregnant Women with Symptoms of Zika Virus Disease (ZVD) in Colombia, According to the Date of Symptom Onset (June 15, 2015–July 31, 2016).

Shown is the distribution of symptom onset among 18,117 pregnant women who were reported to the Colombian national surveillance system as having ZVD during the most recent outbreak. The numbers of total cases and laboratory-confirmed cases are provided. Laboratory confirmation was determined by the presence of Zika virus RNA on real-time reverse transcriptase–polymerase-chain-reaction (rRT-PCR) assay.

Figure 2.. Analysis of Surveillance Data and Pregnancy Outcomes.

To clarify the outcomes of pregnancies (including one set of twins), data are provided for infants or fetuses rather than pregnant women. The presence of Zika virus infection in infants or fetuses was confirmed on rRT-PCR assay.

Figure 3.. Laboratory-Confirmed ZVD among Pregnant Women and Reported Cases of Brain or Eye Defects among Infants or Fetuses.

Panel A shows the number of pregnant women with laboratory-confirmed ZVD per 100,000 women of childbearing age in Colombia from June 15, 2015, to July 31, 2016, during the most recent outbreak of Zika virus infection. Panel B shows the number of reported cases of brain or eye defects among infants or fetuses in Colombia from September 2015 through April 2017.