ANDRZEJ KRAUZEAt the end of October 2015, alarm bells began ringing: hundreds of pregnant women in northeastern Brazil were giving birth to babies with unusually small heads and an unusual pattern of very severe neurological damage. Epidemiologists observed an association of the condition with the mothers’ infection by a mosquito-borne virus called Zika early in pregnancy, and researchers raced to demonstrate a causal relationship. The virus generated such buzz (and fear) that reports were omnipresent throughout 2016, both in the popular media and in the scientific literature. At one point, officials considered canceling the 2016 Olympic Games, which were eventually held in Rio de Janeiro in August with no cases of infection reported.
Last February, as infections continued to mount across Latin America and the Caribbean, the World Health Organization (WHO) declared Zika a “public health emergency of international concern.” After visitors to countries in those regions returned home with infections, researchers confirmed that the virus could be transmitted sexually and was associated with an increased incidence of peripheral nerve damage manifested as muscle weakness and paralysis (Guillain-Barré syndrome). Then, in July, Zika-harboring mosquitoes appeared in the continental United States, with 184 locally acquired cases reported in Florida (at press time. As of 12/28 the number has risen to 210). Vigilant monitoring and heavy insecticide spraying seems to have halted active transmission there, but at the end of November, Texas became the second state to report a locally ...
