Surveillance Project Measures Flu Incidence, Identifies Viruses in Primary Care

Runny nose. Stuffy head. Sore throat. Cough. Fever.

As winter approaches, flu-like symptoms such as these become a more common complaint in people’s lives—and in primary care clinics—everywhere.

Last year, the incidence of confirmed influenza in four Madison family medicine clinics, however, was only about 0.5 percent, according to data from a surveillance project led by Department of Family Medicine (DFM) Professor Jonathan Temte, MD, MS, PhD, in collaboration with the Wisconsin Division of Public Health (WDPH) and the Wisconsin State Laboratory of Hygiene (WSLH).

The project, which recently completed its second year, is one of 12 sites nationwide that reports weekly to the Centers for Disease Control and Prevention (CDC). It provides the agency—and participating clinicians—with timely, accurate data on the patterns of influenza and other communicable diseases.

Surveillance Methods

Throughout the year, clinicians took specimens from patients who visited participating clinicians at the DFM’s four Madison residency clinics: Verona, Belleville, Wingra, and Northeast.

To be included in the study, patients must have had at least two symptoms of an acute respiratory infection (ARI), and must have come to the clinic within four days of onset.

Each specimen was rapid-tested for influenza at the clinic, and then sent to the WSLH, which according to Dr. Temte, has the “gold standard in testing.” The WSLH tests identified cases of influenza as well as numerous other respiratory viruses.

Each week, Dr. Temte’s team then tallied the lab results in a database and submitted the complete data to the CDC. The team also updated participating clinics with the current prevalence and viral causes of all ARIs, typical symptoms, and the severity of illness.

“These updates gave clinicians a snapshot of what viruses are in circulation, not just influenza,” Dr. Temte explained. “It’s a unique approach that shows what makes people of all ages—infants through the elderly—sick and what brings them into the clinic.”

Identifying Influenza and Other Viruses

From September 2010 through April 2011, approximately 2.1 percent of all patients who visited the four participating clinics met the study criteria for an ARI; 0.5 percent of all patients tested positive for influenza.

Half of all patients with an ARI had some type of virus. Besides influenza, other viruses commonly found included rhinovirus, adenovirus, metapneumovirus, and parainfluenza.

According to Dr. Temte, the surveillance helps raise awareness of the many different types of viruses, their prevalence and symptoms, and how they should be treated—or not treated.

“In our medical culture, we don’t always acknowledge that what we’re seeing is viral, and that can lead to overtreatment with antibiotics,” he explained. “Naming viruses pays off: it helps physicians and patients better understand what they’re dealing with.”

Dr. Temte’s team will present results of last year’s project at the annual meeting of the North American Primary Care Research Group this November.

They are also continuing the surveillance project at the same four clinics this year, though they plan to recruit additional high-volume clinicians, thereby increasing patient sample size.

The Influenza Incidence Surveillance Project is funded by a grant from the Council of State and Territorial Epidemiologists.