Brazilian health authorities are sounding the alarm about a mosquito-borne virus that they believe may be the cause of thousands of infants being born with damaged brains.
The pathogen, known as Zika and first discovered in forest monkeys in Africa over 70 years ago, is the new West Nile — a virus that causes mild symptoms in most but can lead to serious neurological complications or even death in others. Brazil’s health ministry said on Nov. 28 that it had found the Zika virus in a baby with microcephaly — a rare condition in which infants are born with shrunken skulls — during an autopsy after the child died. The virus was also found in the amniotic fluid of two mothers whose babies had the condition.
Until a few years ago, human infections with the virus were almost unheard of. Then, for reasons scientists can’t explain but think may have to do with the complicated effects of climate change, it began to pop up in far-flung parts of the world. In 2007, it infected nearly three-quarters of Yap Island’s 11,000 residents. In 2013, Zika showed up in Tahiti and other parts of French Polynesia and was responsible for making an estimated 28,000 people so ill they sought medical care. It arrived in Brazil in May, where tens of thousands have fallen ill.