Study finds microcephaly related to Zika virus in Brazil
Zika virus has been linked to microcephaly, a birth defect where the baby is born with an abnormally small head, due to abnormal brain development. A study entitled “Zika and the Risk of Microcephaly” says that thousands of cases of microcephaly are potentially linked to Zika Virus in Brazil. The researchers analyzed data from Bahia, a state in Brazil.
The researchers found risk of microcephaly due to Zika virus infection to be as high as 13 percent and as low as one percent in a mother’s first trimester of pregnancy. The risk due to infection was negligible in the mother’s second and third trimesters, but this research is preliminary. The estimates are uncertain because of the limited data available in Brazil. However, other populations and carefully designed surveys can help refine those estimates.
Microcephaly is just one of the birth defects due to Zika virus. In one study, researchers found that babies with microcephaly linked to Zika virus had eye problems. They noticed retinal lesions, hemorrhaging and abnormal blood vessel development.
The risk of adverse events may be higher in symptomatic infections than in mild infections, but mild infections are more common, which contribute to the overall picture of the outbreak.
Although not a lot is known about the effects of Zika virus during pregnancy, the NEJM study showed a clear connection between risk of microcephaly and infection during the first trimester of pregnancy.
A cohort of health professionals banded together in a letter asking that the summer’s Olympic Games be moved from Brazil due to the risk of Zika virus. The CDC recommended delaying travel to areas where Zika virus is actively present.
If the situation in Bahia is similar to other outbreaks, then we expect to see many more cases of microcephaly and other adverse events related to Zika. People need to be careful to avoid Zika while pregnant, and health professionals must be prepared to treat adverse outcomes of pregnancy in coming years.