WASHINGTON -- The number of confirmed cases of swine flu in the United States jumped Thursday from 3,352 sufferers to more than 4,000 in 47 states plus the District of Columbia, health authorities said.

The (A)H1N1 influenza virus was confirmed in 4,298 people in the United States, said the Centers for Disease Control and Prevention (CDC) in its daily online report.

Only four states have not seen the virus -- Virginia, Mississippi, Wyoming and Alaska.

The northern state of Illinois tops the list with 620 confirmed cases, followed by Wisconsin (510), California (473) and Texas (439).

The virus has spread to two more states -- North Dakota and Arkansas -- since Wednesday, according to the report posted on the CDC website.

Three people have died of the new strain of swine-origin influenza in the United States.

Officials at the CDC have said they firmly believe cases of the new strain of flu will eventually be reported in all 50 states.