A new strain of influenza has created an unusual flu season for North Dakota and across the nation.

The H1N1 influenza virus is responsible for an abnormally early flu season in the state. Since Sept. 1, there have been 3,149 reported cases of influenza, compared to five reported cases at the same time last year.

There have been a large number of absences at schools across the state, but so far only Fort Yates schools have been forced to close.

Most of the reported cases are in people 19 years old and younger. Unlike in seasonal influenza, older people appear to be at less risk. Two people over 60 years old have died in the northwestern part of the state from influenza and other underlying medical conditions.

"This time of year, you typically don't see it," said Michelle Feist, the influenza surveillance coordinator for the state health department.

Seasonal influenza tends to peak in February or March in North Dakota. The health department anticipates another peak in cases when seasonal influenza starts to circulate in the state.

Concerns over H1N1 has caused long lines at vaccination clinics, and most providers of seasonal influenza vaccine have been out of stock for about a month.

Questions about the virus prompted the state health department to open a toll-free number to answer questions. The number is 866-207-2880. The line is answered between 8 a.m. and 5 p.m. Monday through Friday.

Today, the Tribune begins a two-part series about influenza. It takes an in-depth look at the H1N1 influenza virus, common questions about influenza, drug treatments for influenza symptoms and products marketed to treat or prevent influenza.

(Reach reporter Sara Kincaid at 250-8251 or sara.kincaid@bismarcktribune.com.)

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