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Table 1 Guidelines for the classification of MLSI entries by exposure for BC site (2010–2012)

From: Using environmental health officers’ opinions to inform the source attribution of enteric disease: further analysis of the “most likely source of infection”

MLSI exposure classification

Definition

Water

Consumption or physical contact with water through activities such as swimming

Food

Any beverage or food item for human consumption

Includes:

Spoiled/contaminated food

Food events in which consumption of food or beverages is assumed, such as at a restaurant or Christmas party

Food items intended to be consumed undercooked (except chicken and raw clams), such as sushi, runny eggs, raw eggs and raw beef

Excludes:

Exposure classified as unpasteurized or water

Contaminated food whereby food safety practices are neglected

Food safety practices

Unsafe food safety practices including issues regarding food handling, food preparation, hand hygiene, cross-contamination, temperature (e.g. undercooking), and thawing meat

Excludes:

Exposures related to work/occupation

Cross-contamination specifically stated from live animal exposure or person-to-person transmission

Hand washing by a caregiver not specifically stated to be food related

Unpasteurized

Consumption of unpasteurized, raw or untreated milk, juice, or cheese

Occupational

Implied or directly stated work/occupational exposure

Excludes:

Specifically stated raw water exposure; this was classified as water

Food consumed at work

Environmental

Exposure from the external physical environment, such as exposure to animal feces, animal remains, pet food, sewage backup, indirect animal contact (including eggs), and farm contact

Includes:

Activities such as camping hiking, playing in the park, or visiting a pumpkin patch

Cross-contamination that does not involve food

Excludes:

Exposure classified as water, food, food safety practices, unpasteurized, occupational, animal or person-to-person

Animal

Potential animal contact

Excludes:

Contact through work/occupational exposure

Farm/barn contact without specifically stated animal contact/exposure; this was classified as environmental

Person-to-person

Implied or directly stated person-to-person transmission

Includes:

Cases born with listeriosis

Acquired through sexual transmission

Acquired through breastfeeding

Excludes:

Contact through work/occupational exposure

Domestic travel

Exposure during travel outside Fraser Health Services Delivery Areas plus areas 38, 161, 162, 163, 164, 165, 166, 44, and 45 [20]

Other

MLSI that did not fit in above eight categories

Includes:

Exposures stated as settings (or contact with) such as household, home, long-term care facility, hospital, day care, support care facility, and short-term stay shelter

 

Chronic/asymptomatic carriers

  1. Adapted from Dumoulin et al. [18].