EP1207:           Passing Parasites: A Rare Foodborne Giardiasis Outbreak at a Restaurant


Speaker:          Denise Sockwell , MSPH


A shocking foodborne giardiasis outbreak was investigated and linked to 13 mostly asymptomatic, laboratory-positive restaurant employees. Control included the use of a multitude of standard and unprecedented control measures: a risk control plan, employee training, improved hygiene, close regulatory oversight, employee testing, and the exclusion and restriction of Giardia-positive employees. The multidisciplinary Epi-Ready investigative approach, paid employee sick leave, and strong health director support were key in ending disease transmission to the community.  Attend this session to hear about this rare outbreak and learn about tools that you can use for your own investigations in the future.





Over a five-week period in 2010, five individuals diagnosed with giardiasis were reported to the Alexandria (VA) Health Department. Patronage at a specific restaurant between March and August was the only commonality. A review of the foods consumed did not identify any commonalities.


An Epi-Ready-trained multidisciplinary team conducted an investigation to assess possible sources of Giardia lamblia. An EH evaluation of the restaurant was performed, focusing on food sources, backflow prevention and employee hygiene. No food source or backflow prevention problems were identified. Many instances of inadequate hand washing and bare-hand contact with ready-to-eat-foods were observed. The restaurant had an unofficial employee health policy, but many employees were not aware of it.


Steps were taken to identify infected employees through antigen testing of stool specimens. Due to possible intermittent shedding, two specimens were collected from staff. Testing initially focused on kitchen staff, but was expanded following early results to include bartenders and wait staff. In total, 13 (28%) of 46 employees were positive for G. lamblia; only two reported symptoms within the past six months. Four of these employees cooked, the others were wait staff and bartenders.


A meeting with restaurant management established appropriate control measures. To avoid closure, the restaurant agreed to develop a written risk control plan, an employee health policy and to require employee training. The risk control plan included strict hand washing, gloving, restriction of some employees, and paid sick leave for excluded employees. Also, the restaurant paid for lab tests. Treatment of infected food workers was coordinated through the health department.


Frequent EH evaluations and strict control measures were key to controlling this outbreak. These included identification of infected food service workers, restriction or exclusion of positive employees, and hygiene training for restaurant staff.