There were 67 Zika cases in Singapore in 2017, a sharp decline from the 453 cases last year.
Even for the 17 women who were diagnosed with Zika during their pregnancies in 2016, the 14 women who eventually gave birth had babies with no signs of microcephaly, a condition which causes babies to be born with a smaller head due to abnormalities in the development of the brain. Professor Arijit Biswas, a senior consultant at the National University Hospital's Women's Centre, who also works at NUS Medicine’s Department of Obstetrics and Gynaecology, said that although there appears to be a link between Zika and microcephaly in a developing fetus, the small number of pregnant women affected in Singapore also lowers the probability of having a baby with microcephaly. Prof Biswas is also the lead of the Health Ministry's Clinical Advisory Group on Zika and Pregnancy.
Another reason for the lack of microcephaly cases in Singapore could be due to genetic variances in the Zika strains. The Zika virus strains found in the first two locally transmitted cases in Singapore diverged in early 2010, and were not imported from the South American strain. While there is research to suggest a mutation in the strain circulating in South America could have been the reason for the high rates of microcephaly, Prof Biswas cautioned there is insufficient data on the microcephaly rates among different strains.