New Data on Outbreaks Linked to Fish

Fish continue to be an important source of foodborne outbreaks, according to a CDC study. “Fish-Associated Foodborne Disease Outbreaks: United States, 1998-2015” was published in Foodborne Pathogens and Disease. The types of fish most often linked to outbreaks are tuna (37%), mahi-mahi (10%), and grouper (9%).

The study reviewed nearly two decades of data on foodborne disease outbreaks. It found that the average number of outbreaks linked to fish decreased from 62 per year between 1998 and 2006 to 34 per year from 2007 to 2015. However, the percentage of outbreaks linked to fish did not change when compared to all foodborne outbreaks (8% from 1998 to 2006 compared to 9% from 2007 to 2015).

The number of fish outbreaks varied greatly by year, and occurred more often in warmer months. Many regulations around fisheries and fish products were implemented during the study period and may be partly responsible for overall decline in fish outbreaks.

2017 Jul 6. doi: 10.1089/fpd.2017.2286. [Epub ahead of print]

Fish-Associated Foodborne Disease Outbreaks: United States, 1998-2015.

Barrett KA1, Nakao JH1, Taylor EV2, Eggers C3, Gould LH1.

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Abstract

Each year in the United States, ∼260,000 people get sick from contaminated fish. Fish is also the most commonly implicated food category in outbreaks. We reviewed the Centers for Disease Control and Prevention Foodborne Disease Outbreak Surveillance System for outbreaks resulting from consumption of fish during the period 1998-2015. We found 857 outbreaks associated with fish, resulting in 4815 illnesses, 359 hospitalizations, and 4 deaths. The median number of illnesses per outbreak was three (range: 2-425). The annual number of fish-associated outbreaks declined from an average of 62 per year during the period 1998-2006 to 34 per year during the period 2007-2015. Hawaii (221 outbreaks [26%]) and Florida (203 [24%]) reported the most outbreaks. Among 637 outbreaks (74%) with a confirmed etiology, scombrotoxin (349 [55%]) and ciguatoxin (227 [36%]) were by far most common. Most outbreak-associated illnesses were caused by scombrotoxin (1299 [34%]), Salmonella (978 [26%]), and ciguatoxin (894 [23%]). Most hospitalizations were caused by Salmonella (97 [31%]) and ciguatoxin (96 [31%]). Norovirus (105 average illnesses; range: [6-380]) and Salmonella (54 [3-425]) caused the largest outbreaks. Fish types implicated most often were tuna (37%), mahi-mahi (10%), and grouper (9%). The etiology-fish pairs responsible for the most outbreaks were scombrotoxin and tuna (223 outbreaks), scombrotoxin and mahi-mahi (64), and ciguatoxin and grouper (54). The pairs responsible for the most illnesses were scombrotoxin and tuna (720 illnesses) and Salmonella and tuna (660). Of the 840 outbreaks (98%) with a single location of food preparation, 52% were associated with fish prepared in a restaurant and 33% with fish prepared in a private home. Upstream control measures targeted to the most common etiologies and controls during processing and preparation could further reduce outbreaks caused by fish.