In food contamination events, identification of both the contaminated food product and the contaminant itself play critical roles in reducing the incident’s public health impact. Speedy and accurate symptom recognition is critical to identify contaminated products and guide the delivery of appropriate medical countermeasures. These countermeasures can be deployed – and be lifesaving – based on recognition of a patient’s toxidrome, without necessarily identifying the toxic contaminant. However, the most potent countermeasures are often specific to an agent or a class of agents.
The ability to successfully warn the public to avoid exposure to contaminated foods and/or seek medical assistance depends upon identifying the exposure route – that is, the contaminated food product. The exposure route can be identified first from a combination of patient diagnoses and epidemiological investigations, and then confirmed with laboratory investigations of the potentially contaminated food items. For cases in which adverse health effects occur soon after ingestion, the association of symptoms with a particular food item may be readily apparent and even reported in the media. Contamination of products with short shelf-life, made in small batches, or consumed locally is easier to recognize (and thus identify) because affected individuals seek care at the same time and place. For example, the contaminated chicken tenders described in the Prologue were readily attributed as the cause of illness in schoolchildren, as symptom onset was immediate and experienced by dozens of individuals at a single site.9 For cases in which adverse health effects occur well after ingestion (hours later), and for foods with longer shelf-lives, made in larger batches, and consumed regionally or nationally, the association of illness with a particular food item may be more difficult to uncover, and will rely more heavily on the work of investigators. Thus, details surrounding the exposure route can provide some insight into the magnitude of avoidable exposures.
Once the contaminated food product has been identified, the toxic material can be identified through laboratory investigations using patient samples and contaminated food items. Knowing the identity of the toxic material consumed can greatly improve medical care, patient outcomes, and incident management. In some cases, such as cyanide or heavy metal poisoning, immediate administration of medical countermeasures (MCMs) is critical. Although the need for laboratory analyses will generally delay substance identification in food contamination events, response activities that protect public health can proceed as the offending food product can be recalled well before the contaminant itself is known.
Footnotes
9. Dworkin, M.S., Patel, A., Fennell, M., Vollmer, M., Bailey., Bloom, J., R. et al. (2004). An outbreak of ammonia poisoning from chicken tenders served in a school lunch. Journal of Food Protection. 67(6). (pp. 1299-1302).