WASHINGTON - Outbreaks of the new H1N1 swine flu continue to spread across the United States, with 896 confirmed cases and more to come, the U.S. Centers for Disease Control and Prevention reported on Thursday.

U.S. officials have said they expect the swine influenza virus to spread to all 50 states and to cause many infections ranging from mild to severe.

Acting CDC Director Dr Richard Besser said the actual numbers matter less than the pattern of disease. So far we are not seeing any signs of this petering out, Besser told reporters. We are on the upswing.

And even though Mexican officials said they were over the worst, Besser said there was still significant transmission there, too.

We are reporting 1,823 probable and confirmed cases in 44 states, Besser said. He has said that 99 percent of probable cases later turn out to be the new flu, so this is a good indication of how many true cases there are.

On Wednesday, the CDC had confirmed 642 U.S. cases of H1N1.

Only about 10 percent of confirmed cases have a travel history for Mexico, he said. This suggests the virus is still passing very easily from one person to another.

The new virus looks very much like seasonal flu and it takes two rounds of tests to confirm a patient has the new H1N1 swine variety. Besser said the CDC was sending test kits out as quickly as possible and had filled requests for 78 countries, out of 131 who want them.

So far the influenza strain remains mild, with 5 percent of cases sick enough to be hospitalized and two U.S. deaths. Besser cautioned that the sickest patients are likely to be tested first, which could make an outbreak look more severe than it really is.

CDC scientists are trying to answer many questions about the new strain, including how long a person sheds the virus, meaning how long a patient is infectious after recovering.

Other questions:

-- Does treatment with the antiviral drugs Tamiflu, made by Roche AG, and Relenza, made by GlaxoSmithKline, affect whether a person can spread the virus?

-- Are healthcare workers at risk of infection?

-- How many people have been infected and do not know it?

-- How many cases of regular, seasonal H1N1 flu are still occurring?

Besser said people have several months to prepare for the possibility the virus could come back in the cooler months in a more dangerous form. This time between now and the fall is of critical importance to prepare, Besser said.

This will include planning for extended school closures and possible disruptions to supply, he said.

Mexico Medicine CDC