Health officials say a baby born in Hawaii is the first in the US with a birth defect linked to the Zika virus, a tropical illness spreading through Latin America and Caribbean countries. A dozen cases have shown up in the US with all of the patients believed to have been bitten by mosquitoes while abroad.

Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, cautions that this is just the beginning of the Zika virus in the Western Hemisphere.

The greatest danger is to pregnant women because the virus is linked to babies being born with underdeveloped brains. For that reason the Centers for Disease Control and Prevention have issued a travel advisory asking them to avoid 14 countries that are seeing high rates of infection.

Laura Trevelyan spoke to Dr Fauci who said the critical question now is if the virus will spread with new cases in the United States. He urged travellers to avoid mosquitoes while his lab is actively working on a vaccine.