The number of pregnant women in the United States infected with Zika virus is suddenly tripling, due to a change in how the government is counting cases.

U.S. president asks Congress for money: 'it is not something we need to panic about but it is something we have to take seriously' 8:19 Previously, officials had reported how many pregnant women had both Zika symptoms and positive blood tests. In a change announced Friday, the Centers for Disease Control and Prevention will count all women who tested positive — regardless of symptoms.

There are now 157 pregnant women infected with Zika in the 50 states, up from 48 last week.

The agency had worried that one type of blood test is too prone to giving a false positive test result if a woman was infected with a different but similar virus.

Elsewhere, the Zika virus blamed for neurological disorders and birth abnormalities in Brazil has been confirmed to be circulating in Africa for the first time after being sequenced from a sample from Cape Verde, the World Health Organization said.

"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," WHO's Africa director Matshidiso Moeti, said Friday.

"This information will help African countries to re-evaluate their level of risk and adapt and increase their levels of preparedness," she said.

She said she would not recommend strict travel restrictions to try to stop the spread of the disease.

As a first step, WHO advised African countries to:

Heighten risk communication to pregnant women to raise awareness of complications associated with the Asian type of Zika virus.

Promote protection steps to avoid mosquito bites.

Take precautions to avoid sexual transmission.

Countries should increase their surveillance for Zika transmission and congenital malformations, such as microcephaly, as well as Guillain-Barré syndrome, which can cause temporary paralysis, sometimes leading to death.



