With news of more birth defects linked to the Zika virus in Brazil prompting the US Centers for Disease Control and Prevention to issue travel advisories for affected countries, here is a primer for travelers.

Since October, the number of babies born with suspected microcephaly -- or abnormally small heads -- in Brazil reached about 3,900, up from 150 in 2014.

Here’s what travelers need to know about the mosquito-borne Zika virus:

-Zika is primarily transmitted through the bite of infected Aedes mosquitoes and can also be transmitted from a pregnant mother to her baby.

-The virus has been reported in 14 countries and territories in Latin America and the Caribbean including: Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela and Puerto Rico.

-There is no vaccine to prevent or medicine to treat Zika.

-One in five people infected with the Zika virus become ill and may develop symptoms such as fever, rash, joint pain, conjunctivitis (red eye), headaches and muscle pain.

-Pregnant women have been advised to consider postponing travel to the affected areas.

-Women trying to get pregnant are also advised to consult with their doctor and follow steps to prevent mosquito bites.

-Try to book a hotel or lodging with air conditioning, or screens on windows and door.
-Bring an insecticide-treated mosquito net treated with permethrin.

-At your hotel or lodging, make sure to empty standing water from containers such as flowerpots and buckets which are breeding grounds for mosquitoes.

-The best prevention is to protect yourself from mosquito bites.

-Wear long sleeves and long pants when possible and treat them with insecticide.

-Brand examples of insect repellents include Off!, Cutter, Sawyer, Ultrathon, Skin So Soft Bug Guard Plus, Autan, and Repel (safe for pregnant women).

-Look for products with ingredients such as DEET, Picaridin or KBR 3023, oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD), or IR3535.

-Apply sunscreen first, then apply repellent.

-Do not use insect repellent on babies younger than two months of age. Instead, cover infants in clothing and cover their baby carrier in mosquito netting.