Microcephaly is a rare, but devastating form of birth defect in which the brain does not fully develop, and the head is smaller than usual. Individuals with microcephaly also suffer from several co-morbid conditions, including intellectual disability, poor motor function, dwarfism, abnormal features, speech and language difficulty, and seizures.
Officially, microcephaly is a cephalic disorder, meaning that it affects the head. "Micro," of course, means "small," and "cephalic" comes from the Greek word for "head." There are actually two types of microcephaly. Most often it is present before birth, as a result of chromosomal or genetic traits, or it can be acquired by the fetus due to injury, infection, or drug abuse by the parent, including developing as the result of fetal alcohol syndrome. Postnatal onset can also occur, generally from metabolic errors in the person's genetic structure, environmental toxins, infections such as meningitis, or even malnutrition.
In 2016, the number of global cases of microcephaly saw a rapid increase, due to the Zika virus. Zika was first identified in 1947 in Africa, but spread across the global equatorial region, reaching pandemic levels in 2015 and 2016. Microcephaly is one of the main results of Zika infection in pregnant women, although other effects, including its transmission as an STI which would result in microcephaly in the fetus, are yet to be fully known.