SAN FRANCISCO, California (AFP) -- Some 2,000 students at Washington State University have reported symptoms of swine flu, university officials said, in one of the largest reported outbreaks of the virus on a US college campus.

Washington state's Whitman County, where the school is located said that tests at a state laboratory late last week "confirmed that the influenza outbreak at Washington State University (WSU) ... is indeed caused by the novel 2009 H1N1 Influenza A."

The west-coast school last week instituted a blog to help provide information to students about the sudden and dramatic spread of the A(H1N1) virus on campus just days into the new school term.

"We estimate that we have been in contact with about 2,000 students with influenza-like illness in the first 10 days of our fall semester," the latest online posting said.

"At this time of year, we would typically only see a handful of patients with influenza-like illness. Health care providers in the local community have also seen WSU students with influenza-like illness, but we have no way of knowing how many.

"We also have no way of estimating how many students are self-caring at home without contacting us," school officials said.

University officials said they had been asked by the county health department "to track numbers in this way to give us a better idea of how many students at WSU actually have influenza-like illness."

The university of about 19,000 students added that it is following guidelines issued by the US Centers for Disease Control and Prevention (CDC) in advising students how to avoid catching and spreading the virus.

CDC's director Thomas Frieden told CNN television Sunday that health officials are reporting an "unusual" number of flu cases so far this school year.

"What we do know is that with schools back in session, particularly in the southeast of the US, but also in many parts of the country, we're seeing a fair amount of influenza. And that's very unusual for this time of the year," he said.