Food-borne Outbreak among Hospital Epidemiology and Infection Control

Background: Food-borne illness is common.  Three days after the October 1, 2009 HEIC Committee meeting, an HEIC staff member attendee complained of a bitter, metallic taste.  Upon investigation, it was determined that three other HEIC staff member attendees experienced the same taste disturbances.   Two staff members who reported taste symptoms also experienced gastrointestinal illness.

Objective: To determine the cause and source of bitter, metallic taste and gastrointestinal illness among HEIC Committee members.

Methods: A case was defined as an individual experiencing taste disturbances, nausea or diarrhea with onset on or after October 1.  A confidential survey was developed and distributed to all 46 HEIC Committee attendees.  Committee members were queried about presence and onset of diarrhea/nausea, vomiting, abdominal cramps, weird/bitter taste on tongue, metallic food taste, fever, URI, headache, items consumed at the HEIC meeting, influenza vaccination status and type of vaccine, use of medications Clarithromycin or Metronidazole.

Results: 36/46 (78%) individuals returned the questionnaire.  Six (13%), including the 4 HEIC staff members, reported experiencing one or more symptoms. All 6 individuals had a taste disturbance that got worse with eating.  Two of 6 individuals also experienced nausea, diarrhea and headache.  One individual reported to Occupational Health and was furloughed 1 day. 

All 6 individuals who reported symptoms ate a salad containing pine nuts (100% attack rate).   No other committee members reported symptoms and none had eaten the salad.   No other factors (food/drink/medications/vaccine) were common among the symptomatic individuals.  The food vendor was contacted and the pine nuts used in the salads were collected and sent to a toxicologist. Literature review revealed a single report of taste disturbance associated with pine nuts from China; evaluation of the implicated pine nuts did not reveal an infectious or chemical etiology of the taste disturbance, although the pine nuts were found to be oxidized. The FDA has received two dozen complaints within the past several months regarding pine nuts and is investigating further. Asian pine nuts appear to be implicated in most of the reported cases whereas European pine nuts have not.  All 6 affected individuals had resolution of symptoms in 5-10 days. 

Conclusions: We report a food-borne outbreak related to pine nuts associated with significant taste disturbances lasting for 5-10 days. Further investigation is required to determine the exact chemical cause of pine-nut associated taste disturbance and the geographical areas from which the implicated pine nuts hail.