Scombrotoxin poisoning in marine fish from Unguja Island, Zanzibar: risks and public health concerns

Khamis O. Haji, School of Aquatic Sciences and Fisheries Technology, University of Dar es Salaam, P. O. Box 60091, Dar es Salaam, TanzaniaFollow
Prosper L. Mfilinge, School of Aquatic Sciences and Fisheries Technology, University of Dar es Salaam, P. O. Box 60091, Dar es Salaam, TanzaniaFollow
Mwita J. Chacha, School of Aquatic Sciences and Fisheries Technology, University of Dar es Salaam, P. O. Box 60091, Dar es Salaam, TanzaniaFollow

Section

Biological Sciences

Abstract

Histamine is the primary cause of Scombrotoxin Fish Poisoning (SFP) worldwide and poses health risks to populations dependent on fish and fish products. This study investigated histamine levels, awareness of SFP among health-care personnel and consumers, and fish preservation practices in Zanzibar. Three species, Auxis thazard, Sardinella gibbosa, and Lethrinus mahsena, were sampled on board (at sea during fishing), at landing sites, and in markets in Malindi and Chwaka. Histamine concentrations were measured using an amperometric enzymatic biosensor (BIOFISH-300 HIS, Biolan). Additionally, 270 consumers and 72 health-care personnel were surveyed using structured questionnaires, while post- harvest handling and preservation practices were assessed through direct observations of 270 fishing boats using a structured field checklist. Of 72 fish specimens collected, 68 contained detectable histamine. The maximum concentration was 27 mg/kg in S. gibbosa (mean ± SE: 5.46 ± 1.18 mg/kg), followed by 23 mg/kg in A. thazard (5.21 ± 1.10 mg/kg) and 10 mg/kg in L. mahsena (3.42 ± 0.67 mg/kg). Histamine concentrations increased significantly along the value chain at Chwaka (F = 5.502, df = 2, 33, p = 0.009), but not at Malindi (F = 2.919, df = 2, 33, p = 0.068). Poor fish-handling and inadequate cold-chain practices were associated with increasing histamine concentrations along the value chain, while awareness of SFP among health-care personnel and consumers was low. These findings indicate weaknesses in cold-chain practices and limited knowledge of SFP among key stakeholders in Zanzibar. Strengthened public education, cold-chain management, and routine histamine surveillance along the fish value chain are therefore recommended.

Recommended Citation

Haji, Khamis O.; Mfilinge, Prosper L.; and Chacha, Mwita J. (2026) "Scombrotoxin poisoning in marine fish from Unguja Island, Zanzibar: risks and public health concerns," Tanzania Journal of Science: Vol. 52: Iss. 3, Article 11.
Available at:https://doi.org/10.65085/2507-7961.1014