Etiology of Severe Microcephaly in Infants: A Multinational Surveillance Study

Severe microcephaly, or head circumference at least 3 standard deviations below the mean for age and sex, is a rare condition with diverse etiology, making diagnosis challenging. Following the 2015 to 2016 Zika virus outbreak, surveillance studies in Australia, Canada, New Zealand, and the United Kingdom and Ireland were conducted to monitor severe microcephaly. We describe the etiology, clinical features, and diagnostic investigations of severe microcephaly among children aged younger than 1 year.

Citation:
Farrar DS, Knowles RL, Nunez C, Baynam G, Bitnun A, et al. Etiology of Severe Microcephaly in Infants: A Multinational Surveillance Study. Pediatrics. 2026;157(2).

Keywords:
Epidemiology; microcephaly; magnetic resonance imaging; diagnosis; etiology; zika virus infection

Abstract:
Severe microcephaly, or head circumference at least 3 standard deviations below the mean for age and sex, is a rare condition with diverse etiology, making diagnosis challenging. Following the 2015 to 2016 Zika virus outbreak, surveillance studies in Australia, Canada, New Zealand, and the United Kingdom and Ireland were conducted to monitor severe microcephaly. We describe the etiology, clinical features, and diagnostic investigations of severe microcephaly among children aged younger than 1 year.