A clinical epidemiological onsite study of a massive outbreak of Scombroid fish poisoning after consumption of yellowtail kingfish in northern Chile

Scombroid fish poisoning (SFP) is an acute illness caused by the consumption of poorly preserved fish containing high levels of histamine. Symptoms develop within 1-2 h, with gastrointestinal, dermatologic, and cardiopulmonary manifestations. The diagnosis relies exclusively on the clinical picture. To describe an onsite clinical-epidemiological study of a massive outbreak of SFP occurring in Chile. Descriptive study of an outbreak occurring in a closed Convention Center after lunch with Chilean Palometa or Seriola lalandi (Yellowtail kingfish). An Onsite questionnaire was answered by all attendants within 24 h. Local health officials supervised the place with a second survey and sample recollection of suspected fish. Eighty-three adults attended the event, of which 81 ate fish. Mean age: 58.5 years old, 82.7% women. The symptomatic attack rate of people eating suspected poisoned fish was 79% (64 out of 81 participants). Most common symptoms included: diarrhea (68%); headache (64%); flushing (64%) and diffuse redness (56%). Mean incubation period: 77 min (30-240 min). 98.4% of patients recovered within 10 h. Ten patients were referred to the emergency room, but none were admitted. There was a presumption of loss of refrigeration in the handling of fish, and confirmation of SFP by clinical basis, incubation period and attack rate. Fish was the only food item associated with illness (Odds ratio: 19, p = 0.014; Fisher two tails). This is one of the 5 largest outbreaks of SFP with fresh fish, ever reported in the literature. The clinical picture and rapid onset of symptoms made it possible to suspect SFP allowing timely management of patients. It is relevant to spread the knowledge about this underdiagnosed and underreported syndrome.