The Ingestion of fish containing high levels of histamine and other biogenic amines can result in scombroid fish poisoning (SFP), also known as histamine fish poisoning, a foodborne illness that is often underdiagnosed [1]. This condition typically occurs when bacteria convert the naturally occurring amino acid histidine into histamine. In certain fish species, this process can occur rapidly when they are exposed to temperatures above 4˚C [2]. The most frequently implicated fish in scombroid poisoning are dark-meat species like mackerel, sardines, tuna, and mahi-mahi [3]. Scombroid fish poisoning (SFP) happens when fish with high histamine levels, produced during inadequate refrigeration or sustained exposure to elevated temperatures, are consumed [4]. The ingested exogenous histamine can overload the body’s natural detoxification systems, such as diamine oxidase (DAO), resulting in symptoms that closely resemble IgE-mediated allergic reactions, including flushing, headache, and rash [4]. The most related symptoms include abdominal discomfort, diarrhoea, palpitations, dermal flushing, pruritus, urticaria, and, in certain cases, bronchospasm or hypotension [5]. Scombroid fish poisoning (SFP) is a non-IgE-mediated pseudo allergic condition activated by the consumption of spoiled fish with high histamine content [5]. Comparing to real food allergies, it can affect individuals regardless of their allergic history, as it does not involve immune sensitization but somewhat histamine overload [6]. Scombroid fish poisoning (SFP) is completely preventable with correct cold chain management and hygienic management, however, it remains a significant public health concern [6]. To protect consumers, the Food and Agriculture Organization (FAO) and World Health Organization (WHO) mention a maximum histamine level of 200 mg/kg in fishery products [7]. Histamine is also used as a key damage indicator in quality control [7]. Despite scombroid fish poisoning (SFP) is preventable, it continues to arise, mostly in tropical and subtropical regions where high ambient temperatures accelerate bacterial histamine production in inadequately stored fish [8]. Scombroid Fish Poisoning (SFP) is an important but likely underreported public health issue worldwide. According to the Centres for Disease Control and Prevention (CDC), it remains one of the most reported foodborne illnesses linked to seafood in the United States, accounting for approximately 30% - 40% of fish-related outbreaks in recent years [9][10]. Global estimates from world health organization (WHO) and regional data from the European Food and Safety (EFSA) similarly underscore the persistent risk of histamine poisoning in fish, particularly in countries with warm climates and high seafood consumptions [11][12]. In September 2014, a food-borne poisoning outbreak in Tainan, southern Taiwan region affected 37 persons and was related to milkfish fish sticks containing high levels of histamine, revealing the risk of histamine formation in inappropriately stored fish products [13]. Similar seasonal trends and risk factors have been documented in Gulf and Mediterranean countries, where susceptible species like mackerel and tuna accumulate histamine due to warm weather, excessive fish consumption, and insufficient refrigeration [14]-[16]. Local research on SFP remains uncommon in Oman, despite the country’s strong dependence on fish as a major dietary component. Initial reports from the DCSD unreliable evidence suggest a clustering of cases between May and August, most frequently associated with consumption of tuna from restaurants local markets. Challenges in maintaining cold chains storage in traditional and outdoor markets, combined with the persistently high ambient temperatures, may be a major contributing factor. The aim of this study is to investigate seasonal patterns the risk factors of scombroid fish poisoning in Muscat Governorate, Oman. It examines 38 reported confirmed or clinically suspected cases to identify possible correlations between improper storage, exposure to temperature changes, and seasonal variations. The findings are expected guide national food safety strategies, public awareness initiatives, and regulatory measures aimed at reducing the incidence of this preventable illness.

Study Design and Setting:

The retrospective descriptive study was conducted in Muscat Governorate, Oman.

It aimed to examine seasonal trends and potential risk factors associated with Scombroid Fish Poisoning (SFP), based on cases reported to Disease Surveillance and Control Department over a defined study period.

Data Source and Population:

Data was received from the database of the Department of Environmental and Occupational Health at the Directorate General of Health Services (DGHS), Muscat. All 38 of confirmed or clinically suspected cases of foodborne disease reported between January 2020, and December 2024 were reviewed. Cases were included only if they were confirmed or clinically suspected scombroid fish poisoning (SFP) based on reported symptoms, recent fish consumption, and confirmation of exposure source.

Case Selection and Variable:

Inclusion criteria required a recorded history of fish consumption prior to onset of symptoms consistent with scombroid poisoning. Cases were excluded if they lacked essential data or involved other foodborne illnesses unrelated to scombroid fish poisoning (SFP). Cases attributed to other seafood toxins such as ciguatera or shellfish poisoning, were also excluded.

For each included case, the following variables were extracted: age, gender, symptoms, fish type, source of the meal (restaurant or home), and date of exposure.

Case Definition and Severity Classification:

A case of scombroid fish poisoning (SFP) was defined as an individual who developed flushing, rash, headache, diarrhoea, or other histamine-related symptoms within 1 - 2 hours of consuming fish, particularly dark-meat species such as tuna. Severity was classified according to clinical presentation:

Mild: Transient symptoms such as rash, flushing, headache, or nausea without systemic involvement.

Moderate: Symptoms including facial swelling, shortness of breath, or hypotension that required medical attention but resolved without hospitalization.

Data Collection Tool:

A structured data extraction form was developed to systematically collect relevant variables. The form included demographic details (age, gender, nationality), time and month of exposure, type of fish consumed, source of fish (restaurant versus home-prepared), clinical symptoms and patient outcomes. Restaurant information and fish type were confirmed via patient interviews and validated by Public Health Inspection Unit, when available. Cross-checking of case investigation forms was performed to minimise exposure misclassification.

Data Analysis:

Data were entered and analysed using Microsoft Excel. Descriptive statistics were used to summarize demographic, clinical and exposure -related characteristics. Seasonal trends and variable distributions were visualized using tables and graphs.

Ethical Considerations:

The study protocol was reviewed and approved by the Research and Ethical Review Committee at Ministry of Health, Oman. As the study involved retrospective analysis of de-identified data, the requirement for informed consent was waived. All Data were handled with confidentiality and privacy were precisely maintained throughout the study process.

This retrospective observational study examined the risk factors and seasonal distribution of scombroid fish poisoning (SFP) in Muscat, Oman. Analysis of 38 cases reported to the Disease Surveillance and Control Department showed that tuna consumption in restaurants was contributing factor in all cases with the majority occurring in August. All patients made a full recovery, and most cases were classified as mild.

Scombroid fish poisoning in Muscat shows a clear seasonal pattern, with a marked increase in August, likely due to elevated temperatures and old-chain failure. All cases were linked to the restaurant-served tuna and were clinically mild to moderate. Strengthening cold-chain practices and enhancing food safety awareness could significantly reduce the burden of this preventable illness.

Public Health Implications

The findings highlight the need for supported cold chain checking in restaurants, particularly during summer months when the risk for histamine formation is highest. Ensuring fish stored at temperature < 4˚C, improving food handlers training, and increasing public awareness about the risks of consuming unrefrigerated fish may significantly reduce scombroid poisoning incidents. Increased surveillance and timely reporting of sea-food related illnesses would further support prevention efforts.

This study provides the first descriptive analysis of scombroid fish poisoning in Muscat using systematically collected surveillance data. However, small sample size (n = 38) and retrospective design limit generalizability. The lack of laboratory confirmed histamine levels and storage temperature data restricted quantitative assessment of cold chain failure. Future studies should incorporate laboratory testing and temperature monitoring to strengthen connective power.

This study was approved by the Ministry of Health Research and Ethical Review Committee, Oman. Data were obtained from the Disease Surveillance and Control Department. All patient data were anonymized, and no identifying information was collected.