A week ago, you probably had never heard of the Zika virus.

Chances are you now know something about the illness that is spreading rapidly in Latin America. Word of the epidemic also spread rapidly this past week.

It has spurred travel alerts from the U.S. Centers for Disease Control and Prevention (CDC) as well as a $300 million program in Brazil to wipe out the mosquito that carries the disease.

The virus is transmitted by mosquito bite. It’s not known to travel from person to person.

People infected by the Zika virus usually suffer symptoms of fever, rashes, joint pain, and red eyes, according to the CDC.

The symptoms are usually mild for adults and last a few days to a week. However, the disease can cause serious brain damage if it infects an infant still in the womb.

The mosquito responsible for the Zika virus can also transmit dengue fever and chikungunya.

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Travel Advisories Issued

On Friday, CDC officials added eight more countries to its list of those with Zika virus travel alerts.

The countries are Barbados, Bolivia, Ecuador, Guadeloupe, Saint Martin, Guyana, Cape Verde, and Samoa.

On Jan. 15, the CDC listed a Zika travel alert for 14 countries: Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Suriname, and Venezuela.

So far, there are at least seven reports of travelers infected with the illness returning to the United States, according to CBS News.

In the CDC alerts, travelers are told the virus is transmitted by a mosquito that is a voracious daytime biter and prefers to bite people. Travelers infected usually don’t exhibit symptoms until they return from their trip.

The CDC also mentions there is no vaccine or medicine available for the Zika virus.

The alerts contain particular cautions for women who are pregnant or who are trying to get pregnant. The CDC alert says these women should postpone any travel to areas where the Zika virus is active.

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Brazil is the Epicenter

Authorities in Brazil are investigating a link between the virus and a rare syndrome known as Guillain-Barre, according to a story in the Washington Post.

They are also looking into the possibility the virus is linked to a rare birth condition called microcephaly. This causes serious brain damage in newborn infants.

There have been 3,900 suspected cases of microcephaly reported in Brazil since October.

In addition, a baby was recently born in Hawaii with the syndrome. The infant’s mother had lived in Brazil last year and it’s suspected she was infected with Zika while pregnant, according to a story in the New York Times.

Brazil now has a reported 1 million cases of Zika infections. The country has launched a $300 million campaign to battle Zika-carrying mosquitos. The effort includes hundreds of soldiers going door-to-door to eliminate places where the mosquitos can breed, according to the Washington Post story.

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How Zika Evolved

The virus was first discovered in 1947 in monkeys living in the Zika Forest in Uganda, according to a story in the health section of the Washington Post.

Only 14 cases of human infection were reported from 1947 to 2007. That year, however, the virus appeared on Yap Island in the southwestern Pacific Ocean. Within months, about three-fourths of the island’s 11,000 residents were infected.

The virus traveled rapidly from there.

In 2013, it showed up in Tahiti. In 2014, it arrived in the Cook Islands and New Caledonia. In 2015, it made its way to Easter Island and then to Brazil.

Now, it’s cropping up in the United States.