Surveillance for the 2000-2001 influenza season began the week of October 9, 2000, and continued weekly through April 30, 2001. Surveillance participants included physicians’ offices, clinics, and university health centers. Also, various schools and school districts throughout the state reported the number of students absent per week during the surveillance period.

There were 129 laboratory confirmed cases reported during the 2000-2001 surveillance season, which is an increase over last season’s 96 cases. The first case was reported on October 16, amid concerns over the influenza vaccine shipment delay. It was reported nearly a month earlier than the first reported case during the 1999-2000 season. Influenza activity peaked the week ending January 27, 2001 nearly a month later than the peak last season. Cases continued to be reported through mid-April. Of the 129 cases, 93 were type B and 36 were type A. Five type A cases were further sub-typed by the Utah Public Health Laboratory and four were the H3N2 strain and one was the H1N1 strain. The Utah cases differed from the national trend of predominantly type A, H1N1 strain. Eighty-five of the reported confirmed cases in Utah were under 18 years of age, and only 4 were over 50 years of age. There were two influenza related deaths reported this year, both were pediatric patients with underlying health conditions.

Weekly rates of absenteeism among participating schools were calculated using student enrollment numbers and number of school days per week. A slight increase in absenteeism was seen during the week of the Thanksgiving holiday but the rates remained fairly consistent throughout the rest of the surveillance period. Similar to last season, absenteeism did not have the same increases that were seen in “influenza-like illnesses” reported by physicians.

Surveillance was enhanced this season by a partnership between the Bureau of Epidemiology and graduate students in the Department of Family and Preventive Medicine at the University of Utah. The students used a statistical package called statistical process control limits to analyze data on daily patient loads of clinics located throughout the state. They also provided supplies and arranged for couriers for participating clinics to collect clinical specimens on their patients. In the past, one of the biggest barriers for physicians in testing their patients has been the inability to transport specimens to the Utah Public Health Laboratory. Through the University’s project, even rural surveillance sites successfully submitted specimens. For more information on the University’s project, please contact the Department of Family and Preventive Medicine at (801) 581-7234.

We wish to thank the following participants in the influenza surveillance project:

Drs. Barton Avery and Gary Harris (Summit Clinic)
Utah State University Student Health Center
Dr. Von S. Pratt
Bountiful Instacare
Weecare Pediatrics
Health South Medical Clinic
Medical Mall Instacare
Mountain View Pediatrics
Rose Park Instacare
Hurricane Family Practice
University of Utah Health Network (Park City)
Brigham Young University Student Health Center
Mountainlands Community Health Center
Logan High School
Box Elder Junior High School
South Sanpete School District
Windridge Elementary School
J. A. Taylor Elementary School
West Point Elementary School
Academy Park Elementary School
Lone Peak Elementary School
Viewmont Elementary School
Backman Elementary School
Carbon School District
Washington School District
South Summit Elementary
Provo School District
Wasatch Middle School
Midland Elementary School

In the past two years, the majority of outbreak associated Salmonella cases in Utah have been identified as Salmonella enteritidis (SE). In 1999, there were three separate outbreaks of SE associated with consumption of home made ice cream prepared with raw eggs. Several other outbreaks of SE were also linked to eggs. In addition to the SE outbreaks, Utah has also seen cases of Salmonella muenchen associated with alfalfa sprouts and Salmonella typhimurium associated with unpasteurized orange juice. There have been outbreaks throughout the country of various types of Salmonella including Salmonella kottbus associated with alfalfa sprouts, Salmonella saintpaul associated with mangoes and Salmonella poona associated with cantaloupe.

The month of February 2001 brought the discovery of a type of Salmonella never before seen in the state of Utah. The Bureau of Epidemiology was notified by the State Microbiology Lab of two cases of Salmonella virchow in a two week period. Since this type of Salmonella is new to Utah, the investigation began. Upon initial investigation, there did not appear to be a link since one case was from Salt Lake County and one was from Duchesne County. Upon further investigation, it was discovered that the Duchesne County resident had traveled to Salt Lake and had eaten at one of the same restaurants as the Salt Lake County case. County food inspectors conducted an investigation of the restaurant, which serves fast food including burgers, fries and shakes, and found no major food safety violations. Nearly a month later, a third case of S. virchow appeared on the scene and the same restaurant was reported in the food history.

At this point, county food safety staff returned to the restaurant to conduct further interviews with food handlers and to collect stool samples for testing. Of twenty-eight food handlers who were interviewed and submitted stool samples, one tested positive for S. virchow. Initially it was thought that this could be the source of the outbreak, but the onset date of the food handler was similar to the other cases and there was no history of travel. The food handler’s symptoms cleared within a few days so a physician was not seen. The positive culture was obtained on March 31, 2001, six weeks after the illness and no symptoms were reported at the time of the lab test. After the organism was identified, the food handler was excluded from work until two negative specimens were obtained. One more case of S. virchow has been identified, bringing the total cases in 2001 to five. The fifth case had an onset date of March 31, 2001. Despite persistent efforts by Salt Lake Valley Health Department, no common exposure with the outbreak cases was identified. (Figure 1)

According to FDA, S. virchow is commonly associated with a variety of sources, including tuna, catfish, shrimp, snake heads and frog legs. The Centers for Disease Control and Prevention has record of two outbreaks of S. virchow between 1973 and 1997. A 1973 outbreak in Maryland was associated with a restaurant exposure to beef or veal. Twenty-four illnesses were reported. Missouri reported an outbreak of S. virchow in 1998 involving exposure in a private home to several food sources including BBQ beef, shrimp and crab. Thirty-eight cases reported illness associated with the outbreak. As Salmonella outbreaks from varying sources continue to pose a public health problem, rapid identification and investigation of cases is the key to prevention.

The Epidemiology Newsletter is published monthly by the Utah Department of Health, Division of Epidemiology and Laboratory Services, Bureau of Epidemiology, to disseminate epidemiologic information to the health care professional and the general public.

Send comments to:  The Bureau of Epidemiology, Box 142104, Salt Lake City, UT 84114-2104, or call (801) 538-6191

Approval 8000008:  Appropriation 3705

Rod Betit, Executive Director, Utah Department of Health
Charles Brokopp, Dr.P.H., Division of Epidemiology and Laboratory Services
Craig R Nichols, MPA, Editor, State Epidemiologist, Director Bureau of Epidemiology
Gerrie Dowdle, MSPH, Managing Editor
Connie Dean, Production Assistant