ATLANTA – Despite the fact that foodborne outbreaks caused by consumption of fish have decreased over the last 15-20 years, prevalence of such outbreaks still remains relatively high, and the risk of future outbreaks therefore is not one to take lightly.
Kelly A. Walsh of the Center for Disease Control and Prevention’s National Center for Emerging and Zoonotic Infectious Diseases, said her study findings show, “while there was an overall decline in the number of fish outbreaks, they appear to be increasing in recent years,” meaning that public health officials and health care providers should be vigilant, as several popularly consumed fish are the most likely to cause disease.
Lynda Banzi
The two most common etiologic agents behind outbreaks over this time span were scombroid toxin (380 outbreaks, 55%) and ciguatoxin (224 outbreaks, 33%). Onset of symptoms caused by scombroid toxin – including facial and lingual swelling, pruritic rash, diarrhea, and vomiting – can begin in a matter of minutes, and it is typically caused by consumption of tuna and mahi mahi, which were the first (36%) and second most-common (11%) cause of outbreaks between 1998 and 2013, respectively. Ciguatoxin is found in fish such as barracuda and grouper, which caused 6% and 9% of all outbreaks during 1998-2013, respectively. Onset of symptoms can occur in 3-30 hours after consumption of fish, and can cause gastrointestinal, cardiac, and neurologic symptoms, such as fatigue or “aberrant temperature perception,” Ms. Walsh said at the International Conference on Emerging Infectious Diseases.
“Seeing tuna come up most commonly with scombroid toxin is no surprise, but what was surprising is that raw or undercooked fish only accounted for 11% of outbreaks,” Ms. Walsh explained. In instances of undercooked fish causing outbreaks, tuna and salmon were the most commonly reported.
Ms. Walsh and her coinvestigators examined data from the CDC’s Foodborne Disease Outbreak Surveillance System collected between 1998 and 2013, looking specifically at the number of outbreaks, illnesses, hospitalizations, and deaths attributed to fish, as well as which etiologic agents were responsible, the associated fish types these agents were identified in, how the fish were prepared and served for consumption, and the states in which these outbreaks occurred.
In total, 764 outbreaks occurred and led to 4,401 illnesses, with a median of 3 illnesses per outbreak and a range between 2 and 425 illnesses. These outbreaks resulted in 322 hospitalizations and three deaths. However, despite finding that fish-based outbreaks dropped from an average of 62 per year during 1998-2004 to 32 per year during 2005-2012, the number of outbreaks in 2013 alone spiked to 50. The largest outbreak that occurred during 1998-2013 happened in 2012, when 425 illnesses were reported in a multistate outbreak caused by consumption of tuna that was found to have traces of Salmonella Nchanga, and Salmonella Bareilly.
Ms. Walsh and her coinvestigators hope their findings will bring to light the need for better control measures on the fish implicated in recent outbreaks, such as proper fish storage and appropriate preparation of fish. “We’re working with our partners at [the Food and Drug Administration] to inform them of the data that we’ve seen [so] we can inform regulations such as HACCP [Hazard Analysis & Critical Control Points].”
Ms. Walsh did not report any relevant financial disclosures.