Colombia experienced a fourfold increase in cases of microcephaly following the Zika virus outbreak in 2016, with temporal evidence suggesting that infection in the first months of pregnancy poses the greatest risk to the fetus of microcephaly.
From January 31 through mid-November 2016, there were 476 cases of microcephaly reported in Colombia, four times the rate of cases reported during the same period in 2015. In July 2016, there was a ninefold increase in Colombian microcephaly cases reported, compared with July 2015, according to data published in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.
Based on an average full-term gestation – because the 24-week period from the peak of Colombia’s Zika virus outbreak occurred simultaneously with the peak in reported microcephaly cases – there is a temporal suggestion that the greatest risk for microcephaly is associated with Zika virus infection during the first half of pregnancy, according to the authors of the report. Of the reported cases of microcephaly in 2016, 432 were live-born infants and 44 were pregnancy losses (MMWR. 2016 Dec 9. doi: 10.15585/mmwr.mm6549e1).
Of Colombia’s reported 105,000 cases of Zika virus occurring between August 9, 2015, and November 12, 2016, nearly 20,000 cases were in pregnant women, according to the Instituto Nacional de Salud.
The findings reinforce previous data indicating the correlation between early Zika virus-infection and microcephaly (N Engl J Med. 2016;374:1981-7. doi: 10.1056/NEJMsr1604338), although the report’s authors cautioned there are several confounders to these data, including that the surveillance was passive, not all reported cases of Zika virus infection were confirmed by a laboratory, and not all cases might have been reported.
The authors reported no relevant disclosures.
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