Bulletin No. 5
April 28, 1989
Shigellosis at Airline In-Flight Catering Kitchens, Anchorage
Five cases of shigellosis (all caused by Shigella flexneri) in Anchorage sparked an intensive epidemiologic investigation. Although none of the case-patients knew each other, we identified four airline in-flight catering kitchens in Anchorage where either a case or a family member worked (Table). Interviews failed to identify any other common exposures.
Together the four kitchens had 300-400 employees and supplied meals for 11 air carriers. Although three of the kitchens prepared employee meals on-site, employees sometimes brought home cooked foods to work to share with co-workers.
The Anchorage Department of Health and Human Services and the Food Sanitation Section of the Alaska Department of Environmental Conservation participated with the Section of Epidemiology in the investigation. Supervisors at each kitchen were contacted (either by telephone or in person) but no evidence of additional diarrheal illness was found.
On February 22, the Section of Epidemiology was notified of a sixth case of shigellosis - a foodhandler at one of the in-flight kitchens. In order to determine if other foodhandlers were infected, we interviewed and obtained stool specimens from kitchen employees. All 52 employees who primarily handled food agreed to participate. Although 10 (19.2%) had diarrhea (defined as >3 loose or watery stools in any 24-hour period) between January 1, 1989 and the third week of February, all 51 stool specimens were negative for Shigella (one specimen was lost).
Between 1972 and 1985 in Anchorage, there was approximately one case of shigellosis reported per month. Therefore, six reports in Anchorage during a two-month interval is clearly an excess. Five of the six patients were linked to airline in-flight catering kitchens. Illness onsets were generally separated by days or weeks and more suggestive of person-to-person spread rather than a common source outbreak. Although many of the 52 foodhandlers who were tested had consumed home-prepared foods brought to the worksite, the role of these foods in the outbreak is unclear.
The Section of Epidemiology recommends that any person with diarrheal illness be excluded from foodhandling. Persons diagnosed with shigellosis should not prepare or handle commercial foods until they have had two successive negative stool cultures collected 24 or more hours apart. All food service establishments should establish and enforce strict employee handwashing procedures.
Patients with severe diarrhea should have a stool specimen collected for bacterial culture. Appropriate media and instructions are available from the State Public Health Laboratories (Anchorage - 274-1602; Fairbanks - 474-7017; and Juneau - 586-3586) and testing, when appropriate, can be arranged free of charge. All patients suspected to have or diagnosed with a notifiable enteric disease should be reported promptly to the Section of Epidemiology (561-4406).
Selected characteristics of persons with shigellosis; Anchorage
January - February, 1989
|Foodhandler at Kitchen A; household contact
works at Kitchen D
Father is truck driver at Kitchen B
Son employed at warehouse of Kitchen B
No apparent connection to in-flight kitchens
Truck driver at Kitchen C
Foodhandler at Kitchen D
Acknowledgments: We thank Jan Wills, Mary Lee Cook and Adele Suiter, Municipality of Anchorage; Cory Willis, Department of Environmental Conservation; Rose Tanaka, State Public Health Laboratory-Anchorage; and the management and employees of the catering kitchens for their help with this investigation.
Reported by: Joan Rogers, RN, Providence Hospital; James Watson, MD.