By Alice Park
As Zika virus infections continue to spread, with cases reported inparts of Florida and southeast Asia, most people are familiar with the virus’s most damaging effects: on the developing fetus during pregnancy. The most common consequence of infection is an underdeveloped brain, or microcephaly.
Not all babies who are exposed to the virus during pregnancy are affected by Zika; scientists currently believe that only about 10% to 20% of babies are.
When they are, however, they can show very different symptoms. In a report published in JAMA Neurology, researchers led by Dr. Amicar Tanuri at Universidade Federal de Rio de Janeiro in Brazil—a country with one of the highest numbers of affected babies born in the past year—say that microcephaly is only one of the many effects of the virus on fetal brains. Among the 11 babies studied, in whom Zika virus was confirmed in amniotic fluid and cord blood, three died within 48 hours after birth. Nine showed microcephaly, but two showed normal or even enlarged head circumference. All of the babies did, however, show signs of neurological abnormalities, including calcium lesions in parts of the brain, restricted growth and underdevelopment of the brain stem and cerebellum, which coordinates muscle movements.