The virus is an influenza A virus, carrying the designation H1N1 and is spreading from person to person.
It contains DNA from avian, swine and human viruses, including elements from European and Asian swine viruses, according to the U.S. Centers for Disease .
Virus samples have been sent to laboratories in Canada for testing, they said.
The government also decided to close all schools in Mexico City and the center of the country to avoid spreading of the virus.
The World Health Organization, which has identified swine influenza as a potential source of a human flu pandemic, has also activated its global epidemic operations center.
The International Classification of Headache Disorders (ICHD) is an in-depth hierarchical classification of headaches .
