Zika calls attention to a common birth-defect virus

A common and much less exotic virus than Zika is killing hundreds of babies and leaving thousands with severe birth defects, including abnormally small heads and brains, hearing loss and cerebral palsy. It is the cytomegalovirus (CMV).

This virus is a much greater global problem than Zika, but receives much less attention.

“Birth defects are not high on the public-health agenda,” says Stanley Plotkin, a vaccine researcher at the University of Pennsylvania in Philadelphia. A global focus on reducing child mortality has meant that severe disabilities in children are a lower public-health priority, says Anita Kar, a specialist in congenital abnormalities at the University of Pune in India. Researchers now hope that Zika would raise the profile of birth defects among research funders and public-health agencies, and accelerate efforts to develop a CMV vaccine. As currently there is no vaccine, precautions — handwashing and avoiding contact with children’s saliva and urine — are the only defence. The US National CMV Foundation is lobbying that public-health authorities produce outreach material, including billboards on sides of buses, and do CMV tests for all infants with hearing difficulties. CMV’s link to birth defects has been known since the 1950s, but a 2012 survey found that only 13% of US women and 7% of men had heard of congenital CMV

CMV infections in adults, children and infants are mostly asymptomatic and harmless, but the virus is much more dangerous — often lethal — to the fetus. Worldwide, around 1 in 100 to 500 babies are born with congenital CMV, and of the 10–20% who show symptoms, about 30% will die. Survivors often have liver, lung or spleen damage, or neurological problems including developmental disability or loss of hearing or sight.

According to the World Health Organization (WHO), annually, more than a quarter of a million babies worldwide die shortly after birth from congenital anomalies, and many more are born with serious defects. Contributors to birth defects include genetic abnormalities as well as many more preventable factors, such as infectious diseases, medications, diet and environmental chemicals. But the causes of almost three-quarters are unknown.