Rome, January 28 - The Zika virus is "spreading explosively," the head of the World Health Organization said Thursday as Italy started taking the first precautions against possible contagion. Authorities in Italy have stopped blood donations from people who have travelled in affected countries. At a special meeting Thursday in Geneva, WHO Director-General Dr. Margaret Chan said that it will hold an emergency meeting of independent experts on Monday to decide if the virus outbreak should be declared an international health emergency. Chan said the virus - which has been linked to birth defects and neurological problems - is becoming more of a threat. She said although there was no definitive proof that the Zika virus was responsible for a spike in the number of babies being born with abnormally small heads in Brazil, "the level of alarm is extremely high." She also noted a possible relationship between Zika infection and Guillain-Barre syndrome, which can cause temporary paralysis.