According to the CDC statement, a total of 279 pregnant women have tested positive for Zika in either the U.S. or its territories. Concern about the rapid spread of the virus has caused USA Swimming to move a scheduled pre-Olympic training from Puerto Rico to Atlanta.
The mosquito-borne virus is typically contracted by travelers abroad in Latin American countries, such as Brazil, but can also be transmitted sexually.
Symptoms are typically mild and include fever, rash, joint pain and red eyes. Those infected typically do not need to seek intensive medical care.
However, there is a greater risk for pregnant women.
The CDC has found that when pregnant women contract the virus, there is a direct correlation to miscarriage and severe prenatal brain abnormalities, such as microcephaly, a defect in fetal neurological development that results in a smaller than average head and brain.
The number of reported cases of the virus in pregnant women has increased dramatically because the CDC started to account for asymptomatic cases.
“The full range of outcomes of asymptomatic and symptomatic Zika virus infection during pregnancy is not yet well understood,” the CDC reported.
Within the U.S., 49 percent of the 157 infected pregnant women reported feeling symptomatic. Of the 122 infected pregnant women in the U.S. territories, 66 percent reported clinical symptoms.
“Monitoring all pregnant women with possible Zika virus infection during pregnancy, whether asymptomatic or symptomatic, will enhance understanding of possible adverse outcomes and allow better estimates of the number of pregnancies at risk for adverse outcomes,” the report said.
While many of the pregnancies’ outcomes remain unknown, the CDC will continue to release weekly reports on its findings.
As of now, no one has been infected with the virus by a mosquito within the U.S. However, the CDC warns that the Zika virus will likely continue to spread to new areas as summer air travel increases.
In addition to the CDC’s report, the World Health Organization announced Friday that the same strain of virus that is currently being spread across the Americas has also infected 7,500 people in Cape Verde, a small island off the coast of West Africa.
“The findings are of concern because it is further proof that the outbreak is spreading beyond South America and is on the doorstep of Africa,” Dr. Matshidiso Moeti, WHO’s regional director for Africa, said.