Worries over the worldwide spread of Ebola grew yesterday after three more health workers were quarantined in Spain and North America threw up border controls at main ports of arrival from the plagued African states.

The United States and Canada announced new screening measures at major airport hubs to check travellers for symptoms of the deadly disease, and pressure grew for other nations to follow their lead.

The Madrid hospital treating infected Spanish auxiliary nurse, Teresa Romero, also announced her condition had worsened yesterday.

Romero, the first person known to have been infected with Ebola outside of Africa, has said she may have caught the deadly virus after touching her face with an infected glove.