Nearly 5,000 new U.S. swine flu cases have been reported in the last week, due partly to its continuing spread in the Northeast.

The number of deaths rose from 27 to 45. That’s according to the Centers for Disease Control and Prevention which released new figures Friday. There are nearly 18,000 probable and confirmed cases now, found in all 50 states, the District of Columbia and Puerto Rico.

[...] cases continue to spread in New England, New York and New Jersey.

The second weave of H1N1 Swine Flu is expected in North America in the fall, especially as the CDC and WHO are not advocating travel restrictions or border crossings.

The World Health Organization says the spread of swine flu has created the first global flu epidemic in 41 years.

The announcement by WHO Director-General Dr. Margaret Chan came Thursday as infections climbed in the United States, Europe, Australia, South America and elsewhere to near 30,000 cases.

Chan said she decided to raise the pandemic alert level from phase 5 to 6, meaning that a global outbreak of swine flu has begun, after an emergency meeting on swine flu with top experts.

Despite this bad news, WHO is cautioning countries that the response to the Pandemic threat level reaching 6 should not be overboard:

“At this early stage, the pandemic can be characterized globally as being moderate in severity,” WHO said in the statement, urging nations not to close borders or restrict travel and trade.