Aruba, one of the very few Caribbean countries that had escaped the Zika virus, has joined the list of destinations U.S. health officials warn pregnant women to avoid.

Named in Wednesday's update was also Bonaire, a small island off the coast of Venezuela that was part of the Netherlands Antilles until a few years ago.

The U.S. Centers for Disease Control and Prevention has advised pregnant women to avoid travel to most of Central and South America, along with much of the Caribbean, out of concern the mosquito-borne Zika virus might cause birth defects.

Women who are even contemplating pregnancy should avoid travel to that region as well. And because researchers recently confirmed the Zika virus can survive in semen and in rare cases be transmitted sexually, the CDC says men who travel to the region should use condoms throughout the duration of their partner's pregnancy.

The virus, discovered in Uganda in 1947 but having a limited health impact for decades, surfaced in South America in 2014 after cropping up in islands of the South Pacific. Its arrival in Brazil dovetailed with a sudden spike in infants born with abnormally small brains, an irreversible condition called microcephaly.

In addition, scientists are examining a possible link between Zika and Guillain-Barre syndrome, which results in muscle weakness or even paralysis.

So far there have been no mosquito-borne transmission of the illness on the U.S. mainland, although there have been several dozen cases of travelers who fall ill once they return here. By itself, the virus causes no symptoms at all in 80 percent of the people infected, and the illness itself is quite mild.

The impact on fetal development, however, is suspected of being severe. For that reason, El Salvador last month urged couples to postpone pregnancies til 2018. And on his pilgrimage to Mexico, Pope Francis speculated that contraception might be considered the lesser of two evils given Zika's dire effect.

"Avoiding pregnancy is not an absolute evil," he said.

Kathleen O'Brien may be reached at kobrien@njadvancemedia.com. Follow her on Twitter @OBrienLedger. Find NJ.com on Facebook.