A theoretical estimate of the risk of microcephaly during pregnancy with Zika virus infection

Hiroshi Nishiura; Kenji Mizumoto; Kat S Rock; Yohei Yasuda; Ryo Kinoshita; Yuichiro Miyamatsu

doi:10.1016/j.epidem.2016.03.001

A theoretical estimate of the risk of microcephaly during pregnancy with Zika virus infection

Epidemics. 2016 Jun:15:66-70. doi: 10.1016/j.epidem.2016.03.001. Epub 2016 Mar 18.

Authors

Hiroshi Nishiura¹, Kenji Mizumoto², Kat S Rock³, Yohei Yasuda⁴, Ryo Kinoshita⁵, Yuichiro Miyamatsu⁵

Affiliations

¹ Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan; CREST, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan; Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo-shi, Hokkaido 060-8638, Japan. Electronic address: nishiurah@gmail.com.
² Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan; Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 1538902, Japan; Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo-shi, Hokkaido 060-8638, Japan.
³ Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan.
⁴ Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan; CREST, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan.
⁵ Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan; CREST, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan; Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo-shi, Hokkaido 060-8638, Japan.

PMID: 27288540
DOI: 10.1016/j.epidem.2016.03.001

Abstract

Objectives: There has been a growing concern over Zika virus (ZIKV) infection, particularly since a probable link between ZIKV infection during pregnancy and microcephaly in the baby was identified. The present study aimed to estimate a theoretical risk of microcephaly during pregnancy with ZIKV infection in Northeastern Brazil in 2015.

Methods: Temporal distributions of microcephaly, reported dengue-like illness and dengue seropositive in Brazil were extracted from secondary data sources. Using an integral equation model and a backcalculation technique, we estimated the risk of microcephaly during pregnancy with Zika virus infection.

Results: If the fraction of Zika virus infections among a total of seronegative dengue-like illness cases is 30%, the risk of microcephaly following infection during the first trimester was estimated at 46.7% (95% CI: 9.1, 84.2), comparable to the risk of congenital rubella syndrome. However, the risk of microcephaly was shown to vary widely from 14.0% to 100%. The mean gestational age at delivery with microcephaly was estimated at 37.5 weeks (95% CI: 36.9, 39.3).

Conclusions: The time interval between peaks of reported dengue-like illness and microcephaly was consistent with cause-outcome relationship. Our modeling framework predicts that the incidence of microcephaly is expected to steadily decline in early 2016, Brazil.

Keywords: Brazil; Gestation; Microcephaly; Statistical estimation; Zika infection.

MeSH terms

Brazil / epidemiology
Female
Humans
Infant, Newborn
Microcephaly / epidemiology*
Microcephaly / virology*
Pregnancy
Pregnancy Complications, Infectious / epidemiology*
Pregnancy Complications, Infectious / virology*
Retrospective Studies
Risk Assessment
Zika Virus Infection / diagnosis
Zika Virus Infection / epidemiology*
Zika Virus Infection / transmission