Zika's passage to India

Kriangsak Ruchusatsawat and colleagues1 reported an observational study of individuals with suspected Zika virus infection in Thailand between January, 2016, and December, 2017. In late 2018, 159 cases of Zika virus infection were reported in Rajasthan5 and 127 in Madhya Pradesh.6 Since most Zika virus infections are mild or asymptomatic, the extent of these outbreaks is probably underestimated, and the consequences could be severe if the pattern continues into 2019. The widespread poverty and large population in India make uncontrolled spread of Zika virus likely.8 Ruchusatsawat and colleagues1 suggested that Zika virus in Thailand has found a so-called middle ground, with transmission levels high enough to maintain the virus but not high enough for widespread immunity to develop; perhaps a similar dynamic has been established in India. 130 pregnant women in Thailand had Zika virus infection between January, 2016, and August, 2018, of whom 119 gave birth, with four babies having microcephaly.1,9 During this period, 285 cases of microcephaly were reported in Thailand with no maternal history of Zika virus infection.