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CONTACT: DAVE PEDERSEN
283 Medical Laboratories
Iowa City IA 52242
(319) 335-8032; fax (319) 335-8034
e-mail: david-pedersen@uiowa.edu

Release: Immediate

NOTE TO EDITORS: Updated information on influenza in Iowa can be found on the UI Hygienic Laboratory's Web page (http://www.uhl.uiowa.edu)

Type B influenza identified by researchers at UI Hygienic Lab

IOWA CITY, Iowa -- The first case of Type B influenza in Iowa has been identified by researchers at the University of Iowa Hygienic Laboratory, the state's environmental and public health laboratory.

Hygienic Laboratory virologists isolated the first case of Type B influenza for the 1996-1997 flu season in Iowa Jan. 23. The virus was identified from a specimen collected at the UI Student Health Service. So far, a total of five cases of Type B influenza have been confirmed by researchers at the laboratory. Type A influenza had already been identified in Iowa for the 1996-1997 flu season Oct. 26.

To date, the Hygienic Laboratory has confirmed more than 120 cases of influenza in Iowa, based on nasal wash or throat culture specimens submitted from physicians, hospitals, clinics and local health departments around the state.

"After three months, the medical community in Iowa is now fully aware of Type A influenza out there. They've seen the symptoms in patients, and they know flu is here, so they typically won't request additional lab confirmation," says Dr. Norman Swack, principal virologist at the Hygienic Laboratory. "The problem with the Type B virus being identified, however, is that amantadine and rimantadine -- drugs used to prevent Type A -- won't work on Type B. So it's important that health professionals know which type of flu they're dealing with."

Amantadine and rimantadine are antiviral medications that prevent influenza, but only when taken before an individual is exposed to the virus. They are often given to nursing home residents to prevent flu outbreaks at these facilities.

Influenza is usually prevalent each year from October to March, when cold weather forces people to stay indoors, where they are more likely to come into contact with people with the flu. The results are the familiar symptoms -- chills, fever, fatigue, cough, headache, body ache and inflammation of the nose and throat. Nausea, vomiting and diarrhea can also occur, especially in young children.

There is an influenza Type C, in addition to the Type B and two Type A varieties. Type C, however, is generally less prevalent and does not develop fully enough to produce flu symptoms. However, people who have been sick with the prevailing

influenza Type A virus can catch any of the other strains later in the season. And the Type A virus doesn't necessarily appear first each year, either. Swack says in past years Type B has been the first detected and predominant virus for the flu season.

Many Americans guard against influenza with a flu shot. Each year's influenza vaccine contains two Type A strains and a Type B strain, which are similar to the strains that will likely circulate in the United States during the upcoming winter season.

Swack says researchers at the Hygienic Laboratory had seen only one of the Type A strains in Iowa this season before the recent Type B isolations. "The Type B virus is not more severe," he says, "but it can be more dangerous if people think they're dealing with the A virus. The symptoms are basically the same. The primary way to tell the difference is through laboratory studies."

Each flu season, Hygienic Laboratory researchers track the number of confirmed cases of influenza on a weekly basis. This year's chart shows that Type A influenza increased each week beginning Nov. 22 and peaked on Dec. 13, with 28 confirmed cases during that week alone. In some years, as Type A -- or at least the number of specimens confirmed as Type A -- decreases, Type B is confirmed and rises in prevalence.

"We have no evidence of that yet," Swack says. "The samples are trickling in now, probably because most health professionals think they're still dealing with the Type A virus."

The Hygienic Laboratory is a collaborating site in two influenza surveillance programs. The laboratory is part of a global network coordinated by the Centers for Disease Control and Prevention (CDC) in Atlanta and the World Health Organization in Geneva, Switzerland. The laboratory reports weekly to the Collaborating Center for Influenza at the CDC, providing information on the number of specimens tested and the number and types of flu viruses isolated. In addition, flu virus samples are submitted to the CDC throughout the season to ascertain which virus types are circulating and to determine which flu strains will be used for next year's flu vaccines.

The Hygienic Laboratory also works with the Iowa Department of Public Health's (IDPH) sentinel physician program. Now in its second year, the IDPH program includes physicians across Iowa who collect nasal or throat samples and send them to the Hygienic Lab for influenza testing and confirmation. The results are sent back to the physicians and the IDPH. "We provide the collection kits and do the laboratory work," Swack says. "It's worked really well."

The key, Swack says, is to keep a good number of flu specimens coming in throughout the season. "Once it's announced that flu is here, with the first confirmed case, some health professionals feel it's not as imperative to send specimens to us. And that's too bad, because if we're not receiving specimens on a regular basis, we don't know exactly when, or if, another strain, like Type B, is here."

Access the latest information on influenza in Iowa on the Hygienic Laboratory's World Wide Web page (http://www.uhl.uiowa.edu).

2/19/97