Between the 1950s and 1970s, only sporadic cases of Zika virus
infection were reported in western and central Africa and south-east
Asia.4 The disease nearly disappeared over two decades until multiple
outbreaks in the Pacific islands marked the eastward movement of the
virus in the 2000s. In 2007, Yap in Micronesia reported the first
outbreak of Zika virus.5 The second outbreak occurred in 2013 in
French Polynesia, with nearly 30 000 people becoming infected.6 From
there, the epidemic gradually spread to the Cook Islands, New
Caledonia and Easter Island in 2014.7 Genetic analyses have shown
that the strains in the French Polynesia outbreak were more closely
related to the Asian strains,8 indicating that the disease may have been
introduced into the Pacific islands from Asia