Health Officials Exploring Possible Association Between Zika Virus and Microcephaly

The Centers for Disease Control and Prevention (CDC) says it is aware of reports of increased numbers of babies born with microcephaly (smaller than expected head size) in Brazil. The Ministry of Health (MOH) of Brazil says it is concerned about a possible association between the Zika virus outbreak and increased numbers of babies born with microcephaly.

There are many causes of microcephaly in babies (e.g., infections a mother can get during pregnancy, genetic abnormalities, exposure to toxic substances during pregnancy). Because of this, health officials say it will take time to determine the cause of microcephaly for the cases being reported in Brazil.

Starting in October 2015, the Brazilian MOH received reports of an increase in the number of babies being born with microcephaly. The number of microcephaly cases are roughly 10 times higher than what the country normally sees in a year. Some samples from babies with microcephaly have tested positive for Zika virus infection but several affected babies have also tested negative using the same test.

The CDC says is not aware of any published reports of increased numbers of microcephaly associated with other similar viral (i.e. flaviviral) diseases transmitted by mosquitoes.

Brazil reported its first case of Zika virus disease in May 2015. Since then, the virus has spread and has caused infections in many Brazilian states and other countries in Latin America.

The CDC recommends that all people, especially pregnant women, who are traveling to Brazil and other areas in Latin America, should take precautions to avoid mosquito bites to reduce their risk of infection with Zika virus and other mosquito-borne viruses such as dengue and chikungunya.

On Jan. 4, 2016, the MoH of Brazil provided the Pan American Health Organization (PAHO) and the World Health Organization (WHO) with an epidemiological report regarding the increase of microcephaly cases in the country.

As of Jan. 2, 2016, 3,174 suspected cases of microcephaly, including 38 deaths, had been identified at the national level. The cases are distributed across 684 municipalities of 21 federal units.

Although investigations are ongoing to characterize the relation between Zika virus infection during pregnancy and the observed increase of microcephaly, information is being shared with PAHO/WHO member states to raise awareness of the situation and to alert countries for similar events in their territories.