Risk Assessment of Histamine Poisoning from Scombridae Fish Consumption in Nghe An, Vietnam

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Histamine poisoning, also known as scombrotoxin poisoning, commonly occurs after consuming scombroid fish species such as mackerel and tuna. However, other fish species, including sardines, salmon, herring, and anchovies, can also accumulate high levels of histamine. Symptoms of histamine poisoning manifest rapidly, typically within 10 minutes to 2 hours post-ingestion, and include erythema, pruritus, dizziness, headache, and throat irritation—closely resembling allergic reactions. According to the Food Safety Authority, the severity of histamine poisoning depends on the total ingested histamine dose. Histamine levels ranging from 8 mg to 40 mg can already trigger symptoms such as excessive salivation and lacrimation.

Figure 1: Metabolic Fate of Histamine

Compared to livestock and poultry meat, fish muscle tissue has lower mechanical integrity and is more susceptible to microbial contamination. Histamine is formed as a result of microbial growth, which produces histidine decarboxylase enzymes that convert histidine into histamine. Notably, histamine is heat-stable and cannot be destroyed through conventional cooking processes. Consequently, fish containing high histamine levels remains hazardous even after being thoroughly cooked.

Clinical Symptoms

Symptoms of histamine poisoning typically arise within one to several hours post-consumption and include:

• Facial flushing and conjunctival injection
• Respiratory distress due to airway edema and bronchoconstriction
• Urticaria, pruritus, and possible cutaneous rash
• Burning sensation in the oral cavity, hypersalivation, gastric acid hypersecretion, nausea, vomiting, and diarrhea
• Tachycardia and hypotension resulting from vasodilation
• Neurological symptoms such as nausea, dizziness, and headache

Figure 2: Symptoms of histamine food poisoning

Reported Cases of Histamine Food Poisoning in Vietnam

In April 2022, the Thua Thien Hue Provincial Food Safety Authority reported a suspected foodborne illness incident involving four construction workers. Within five minutes of consuming a meal, all individuals exhibited symptoms such as facial and body flushing, blurred vision, dizziness, headache, loose stools, and respiratory distress, requiring emergency hospitalization. Laboratory analysis conducted by the National Institute for Food Safety Testing confirmed a histamine concentration of 425 mg/kg in the tuna sample consumed.

In May 2024, the Nghe An Provincial Food Safety Authority documented another mass food poisoning event in a collective dining facility, where 71 out of 1,416 individuals developed symptoms including facial flushing, tachycardia, headache, hypertension, nausea, and scattered rashes. Analytical testing confirmed that the fried short-bodied mackerel contained a histamine level of 739 mg/kg.

As of this year alone, four histamine poisoning outbreaks have been recorded. The first case occurred in Hai Phong, where a communal meal containing frigate mackerel resulted in 112 affected individuals. The second incident in Phu Tho, also linked to frigate mackerel consumption, caused 154 cases of poisoning. The last two outbreaks were reported in Nghe An, where short-bodied mackerel containing excessive histamine levels led to the hospitalization of 156 people. These incidents underscore the urgent need for comprehensive risk assessments of histamine contamination in fish.

Between 2024 and 2025, with support from the Safe Food for Growth (SAFEGRO) Project, the Vietnam Center for Food Safety Risk Assessment (VFSA) under the National Institute for Food Control (NIFC) is conducting a study titled "Risk Assessment of Histamine Poisoning from Consumption of Scombridae Fish in Nghe An, Vietnam." The findings of this study will serve as a scientific reference for regulatory agencies in decision-making processes aimed at mitigating the risk of histamine poisoning from fish consumption. More importantly, this research also lays the groundwork for establishing one of the first risk assessment frameworks in Vietnam, marking a significant milestone in the country's food safety management.