Tens of thousands of Mexican primary school children have returned to freshly-scrubbed classrooms following a nationwide shutdown prompted by the H1NI swine flu virus that has now left 56 Mexicans dead.

The move came Monday, four days after Mexican universities and high schools restarted, but in at least six states, schools for younger children remained closed due to further fears about the flu.  

Mexico is attempting to restore a sense of normalcy following the outbreak.  Mexico has been the epicenter of the illness, which is expected to cost the economy at least $2.2 billion.  

The World Health Organization says Mexico is one of 30 countries that have reported cases of the virus.  In addition to the fatalities in Mexico, the United States has reported three deaths, while Canada and Costa Rica each have reported one fatality.

The U.S. Centers for Disease Control and Prevention says there are more than 2,600 confirmed cases in 44 U.S. states.

Cuba reported its first case of the illness Monday.  Official media reported the patient is a student from Mexico.

The Chinese Health Ministry says a 30-year-old Chinese national, who traveled to China from the U.S., is the mainland's first case of the swine flu.

Officials say the man is quarantined in Chengdu, after flying to China from the United States, where he is a student.

In other news, Mexico says it will not participate in a Shanghai trade fair because of what it calls China's unacceptable policies regarding swine flu.

Mexico says China has unfairly quarantined Mexican travelers and canceled direct flights from Mexico.  China denied targeting Mexican nationals with the quarantine measures.

Some information for this report was provided by AFP and Reuters.