Increase in Reported Prevalence of Microcephaly in Infants Born to Women Living in Areas with Confirmed Zika Virus Transmission During the First Trimester of Pregnancy — Brazil, 2015

• Published in: MMWR. Morbidity and mortality weekly report Vol. 65; no. 9; pp. 242 - 247
• Main Authors: de Oliveira, Wanderson Kleber, Cortez-Escalante, Juan, De Oliveira, Wanessa Tenório Gonçalves Holanda, Carmo, Greice Madeleine Ikeda do, Henriques, Cláudio Maierovitch Pessanha, Coelho, Giovanini Evelim, de França, Giovanny Vinícius Araújo
• Format: Journal Article Newsletter
• Language: English
• Published: United States Center for Surveillance, Epidemiology, and Laboratory Services, Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Services 11-03-2016; U.S. Government Printing Office
• Subjects: Aedes; Brazil - epidemiology; Female; Humans; Infant; Infant, Newborn; Infants; Male; Microcephaly - epidemiology; Mosquitoes; Pregnancy; Pregnancy Complications, Infectious - epidemiology; Pregnancy Complications, Infectious - virology; Pregnancy Trimester, First; Pregnant women; Prevalence; Prevalence studies (Epidemiology); Residence Characteristics - statistics & numerical data; Statistics; Zika virus; Zika Virus Infection - epidemiology; Zika Virus Infection - transmission; Brazil
• ISSN: 0149-2195; 1545-861X
• DOI: 10.15585/mmwr.mm6509e2

Widespread transmission of Zika virus by Aedes mosquitoes has been recognized in Brazil since late 2014, and in October 2015, an increase in the number of reported cases of microcephaly was reported to the Brazil Ministry of Health.* By January 2016, a total of 3,530 suspected microcephaly cases had been reported, many of which occurred in infants born to women who lived in or had visited areas where Zika virus transmission was occurring. Microcephaly surveillance was enhanced in late 2015 by implementing a more sensitive case definition. Based on the peak number of reported cases of microcephaly, and assuming an average estimated pregnancy duration of 38 weeks in Brazil (1), the first trimester of pregnancy coincided with reports of cases of febrile rash illness compatible with Zika virus disease in pregnant women in Bahia, Paraíba, and Pernambuco states, supporting an association between Zika virus infection during early pregnancy and the occurrence of microcephaly. Pregnant women in areas where Zika virus transmission is occurring should take steps to avoid mosquito bites. Additional studies are needed to further elucidate the relationship between Zika virus infection in pregnancy and microcephaly.