Some of the headlines have focused on the apparent association between Zika infection in pregnant women and the birth of babies with small brains - a condition known as microcephaly. This association is still largely circumstantial, but if true would be extremely alarming. Zika has also apparently changed its behaviour in other ways, spreading faster, spreading sexually, and also lumbering some survivors with the nasty post-viral Guillain-Barré Syndrome which at its worst can lead to partial temporary paralysis.
Based on previous experience, Zika would have seemed an unlikely candidate for the next big global virus scare. Discovered in macaque monkeys in 1947 in Uganda's Zika forest, it was nearly a decade later that the first human case was detected. Spread by mosquito bite, Zika was mild compared to other members of the flavivirus family, which includes the feared yellow fever, dengue fever and West Nile virus. Nobody was known to have died as a result of Zika infection, and clinical interest was so low that scarcely more than a dozen confirmed cases were described in the medical literature. A brief high fever, a rash, some joint pain and in the worst cases a bit of headache and nausea - Zika was barely worse than a dose of flu.
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