An outbreak of the Zika virus has prompted countries around the world to release travel warnings to those traveling to countries or territories in Latin America and the Caribbean.

These actions have been prompted after tests found Zika, an illness borne by mosquitos (the same mosquitos that transmit Dengue Fever, Chikunguya and Yellow Fever) in the placenta of women which had given birth to babies with birth defects.

Zika itself isn’t particularly dangerous, and symptoms are mild and can include headaches, a low fever, joint pain and a rash. 80% of those infected have no idea that they have the virus.

Zika has circulated in parts of Asia and Africa for a long time, but suddenly appeared in Brazil in May 2015, with some experts suggesting that tourists visiting for the World Cup may have brought it over with them.

Brazil has 200 million people who have little or no immunity to Zika, and once someone is infected they can pass it onto an uninfected mosquito, meaning that the virus spreads quickly.

Zika Linked to Severe Birth Defects

While Zika isn’t particularly harmful itself, the link between the virus and microcephaly in infants has been found. Microcephaly is a birth defect where babies are born with usually small heads as the cranium and brain fail to grow at a normal rate. This is a severe defect and is potentially deadly, with those affected usually needing care for the rest of their lives.

More than 4000 cases have been reported in Brazil since October, and the virus is sweeping through South and Central America, with experts warning that there many be hundreds of thousands of women infected without realizing it.

US authorities have confirmed that a mother has given birth to a baby with a small head in Hawaii after being infected with the virus while she visited Brazil, and three people from the UK have also been diagnosed with the Zila virus.

The countries and territories currently affected by the virus include:

• Brazil
• El Salvador
• Columbia
• Guatemala
• Haiti,
• French Guiana
• Honduras
• Mexico
• Paraguay
• Panama
• Venezuela
• Suriname
• Puerto Rico
• Martinque
• Barbados
• Cape Verde
• Samoa
• Bolivia
• Guadeloupe
• Ecuador
• Saint Martin

There is no treatment or vaccine for Zika, and authorities in the countries affected are warning women not to become pregnant. Pregnant women are also advised against traveling to these countries,

Thousands of tourists are expected to flock to Brazil in the next few months as the famous Carnival begins in Rio on the 5th of February and the country hosts the Summer Olympics in August leading to fears that tourists may take the virus home with them.

If you’re planning to visit affected countries, wear long clothes that cover your skin as much as possible. Avoid being outside during dusk and dawn when mosquitos are the most active and use plenty of repellent, reapplying through the day. Perhaps most importantly, avoid being bitten by mosquitos for at least the first two weeks when you’re home to avoid spreading the virus to local mosquitos and then more people.