President Felipe Calderon on Sunday called on Mexicans to avoid flu infections and maintain calm while facing the swine flu, which has infected 1,384 and killed 20 in the nation.

"All Mexican should make a special effort to avoid contact with potential virus carriers," he said. "We are facing an epidemic not because of the number of cases but because it is a mutation of the flu virus. This is a new virus that has affected several states, but mostly the Mexico City conurbation," he said.

As many as 374 people are being treated in hospital for the virus and samples of some dead people are being studied to determine if they suffered swine flu, he added.

He also called for health professionals to document cases and inform the Health Ministry.

The Education Ministry has ordered all institutions from nurseries to universities close in the affected areas until May 6,while the city government has ordered to close the largest city parks as well as public entertainment venues.