Zika Virus Infection in a Cohort of Pregnant Women with Exanthematic Disease in Manaus, Brazilian Amazon

Abstract

The epidemic transmission of Zika virus (ZIKV) in Brazil has been identified as a cause of microcephaly and other neurological malformations in the babies of ZIKV-infected women. The frequency of adverse outcomes of Zika virus infection (ZIKVi) in pregnancy differs depending on the characteristics of exposure to infection, the time of recruitment of research participants, and the outcomes to be observed. This study provides a descriptive analysis-from the onset of symptoms to delivery-of a cohort registered as having maternal ZIKVi in pregnancy, from November 2015 to December 2016. Suspected cases were registered at a referral center for infectious and tropical diseases in Manaus, in the Amazonian region of Brazil. Of 834 women notified, 762 women with confirmed pregnancies were enrolled. Reverse-transcriptase polymerase chain reaction (RT-PCR) confirmed ZIKVi in 42.3% of the cohort. In 35.2% of the cohort, ZIKV was the sole infection identified. Severe adverse pregnancy outcomes (miscarriage, stillbirth, or microcephaly) were observed in both RT-PCR ZIKV-positive (5.0%) and ZIKV-negative (1.8%) cases (RR 3.1; 95% IC 1.4-7.3; p < 0.05), especially during the first trimester of pregnancy (RR 6.2, 95% IC 2.3-16.5; p < 0.001). Although other infectious rash diseases were observed in the pregnant women in the study, having confirmed maternal ZIKVi was the most important risk factor for serious adverse pregnancy events.

Keywords: Amazonian region; TORCH Syndrome; ZIKV infection; exanthematic disease in pregnancy; low birth weight; microcephaly; miscarriage; preterm delivery; stillbirth.

Figure 1

Recruitment, follow up, and pregnancy outcomes in women registered as having been exposed to Zika virus infection (ZIKVi) in pregnancy. The reported cases are from the Tropical Medicine Foundation Dr Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil. RT-PCR: reverse transcription polymerase chain reaction; +: positive; −: negative; I: indeterminate; UI: under investigation; NT: not tested; PB: Premature birth; LBW: Low birth weight; PB & LBW: Low birth weight cases associated with premature birth; TRIM: trimester of pregnancy at the onset of symptoms; SOP: severe pregnancy outcome; MOP Moderate adverse outcomes in pregnancy; NAOP: No adverse pregnancy outcomes identified.

Figure 2

Distribution of registered cases of suspected or confirmed maternal ZIKVi in pregnancy, during the period lasting from the 47th epidemiological week of 2015 to the 52nd epidemiological week of 2016. Each point indicates the symptom onset time, stratified according to the gestational outcome (Miscarriage, Stillbirth, or live-born baby). The reported cases are from the Tropical Medicine Foundation Dr Heitor Vieira Dourado (FMT-HVD, Manaus, Brazil).

Figure 3

Distribution of serological markers of infections and coinfections in a cohort of women in Manaus who had exanthematic diseases registered as ZIKVi in pregnancy. ChikV: Chikungunya virus; CMV: cytomegalovirus; DengV: Dengue virus; EBV: Epstein–Barr virus; HerpesV: herpes virus; HIV: Human immunodeficiency virus; MayaroV: Mayaro virus; ParvoV: Parvovirus B19; ZIKV: Zika virus. None: no serological marker of infection found.