By Sarah Ferris - 02/22/16 09:43 AM EST
Federal health officials are launching a large-scale study to determine whether the Zika virus is the cause of hundreds, and possibly thousands, of birth defects in Brazil.
The Centers for Disease Control and Prevention (CDC) will spend four months working with Brazilian health officials to study a potential link between the rapidly spread mosquito-borne virus and a birth defect called microcephaly. The rare condition causes infants to be born with abnormally small heads, which often drastically shortens their lifespans.
The Department of Health and Human Services (HHS) has requested more than $1 billion to fund research into the relatively unknown virus, as well as to boost diagnostic testing. Republican appropriators in Congress told the White House last week that agencies like the CDC should first use leftover funds from the nation’s Ebola response before requesting additional funding, though the White House has argued those funds are already planned for other public health purposes.
Health officials in the U.S. and globally are increasingly confident that pregnant women who contract the virus are more likely to give birth to babies with microcephaly, but official evidence will be crucial as governments look to ramp up their responses.
"Scientists are increasingly confident that Zika is causing microcephaly, but people may have different judgments about how much proof is enough," Dr. Anne Schuchat, a top CDC official, told reporters in Brazil on Friday, according to Reuters.
"The epidemiologic studies ongoing here in Brazil and some being initiated in Colombia should help cement the link," she said.
Until now, global health officials considered the symptoms and effects of the Zika virus to be mild, usually resembling dengue fever.
The results of the study on birth defects are expected by May. That leaves a potentially dangerous four-month stretch in which countries like the U.S. will treat Zika as “guilty until proven innocent” because of the severity of the correlation, and possibly causation, of the virus and the birth defects.
Some believe it is also linked to another rare condition known as Guillain barre syndrome, which can lead to paralysis. The CDC began a study on Zika and Guillain barre syndrome earlier this winter.
The CDC has issued travel alerts for nearly 30 countries for pregnant women and women who may become pregnant, urging them to avoid exposure to the virus until more is known about the risk to unborn babies.