A mosquito-borne virus may cause babies to be born with abnormally small heads. Zika virus, which first appeared in Brazil in May, causes fever, rash, vomiting, red eyes and, in some cases, death. Brazilian health officials believe that a Zika infection during pregnancy harms growing fetuses. Pregnant women hit by the virus may be more likely to give birth to babies with the rare birth defect microcephaly, a congenital condition marked by a small head and abnormal brain development.
Over recent months, Brazilian health officials have noted an unusually high number of babies born with microcephaly. From 2010 to 2014, on average, 156 Brazilian babies were born with the birth defect each year. This year, health officials have already recorded 1,248 suspected cases of microcephaly. On November 28, government health officials reported that Zika virus had been found in tissue from a baby born with microcephaly, a find that links the birth defect to the virus.
Zika virus also has been documented in Africa, Southeast Asia and islands in the Pacific including the Cook Islands, French Polynesia and the Federated States of Micronesia. Because the Aedes mosquitoes that carry the virus live around the world, the virus will probably spread to previously unaffected areas, the U.S. Centers for Disease Control and Prevention warns.