Paralytic shellfish poisoning contamination status and dietary exposure assessment in coastal cities of China / 预防医学

@#Paralytic shellfish poisoning contamination is a threat to human health. Based on review of research articles pertaining to paralytic shellfish poisoning contamination in shellfishes and assessment of dietary exposure to paralytic shellfish poisoning in coastal cities of China from 2007 to 2022, the article describes the status of paralytic shellfish poisoning contamination, influencing factors and dietary exposure assessment in different sea areas of China (Bohai Sea, Huanghai Sea, East China Sea and South China Sea), and the relatively high-level contamination of paralytic shellfish poisoning in shellfishes is found to strongly correlate with red tides caused by season and water temperature in the Bohai Sea and South China Sea areas. Acute exposure assessment based on point estimate model is commonly used for assessment of dietary exposure to paralytic shellfish poisoning, and the risk of human dietary exposure to paralytic shellfish poisoning is within the acceptable range in most areas. Intensified monitoring of paralytic shellfish poisoning contamination in shellfishes and full consideration of parameters like processing factor during dietary exposure assessment are required in the future to allow more precise results.

Bacterial community associated with Pyrodinium bahamense var. compressum during late exponential growth phase based on 16S rRNA gene sequence analysis

Aims@#Pyrodinium bahamense var. compressum is one of the principal causal agents of harmful algal blooms (HABs) in the coastal waters of Sabah, Malaysia. Seafood and aquaculture products tainted with lethal concentrations of the principal neurotoxin, saxitoxin, have been implicated in mortality and morbidity. The bacteria-algae association may play a key role in paralytic shellfish toxin (PST) production during a toxic bloom event. The production of PST during a harmful bloom is unclear and research on the bacterial diversity associated with Sabah P. bahamense is scarce. The present study examined the cultivable bacteria diversity associated with P. bahamense through 16S ribosomal RNA (rRNA) gene sequence analysis.@*Methodology and results@#The V3-V4 region of the 16S rRNA gene sequence was amplified and used to identify bacterial populations associated with P. bahamense var. compressum. A total of 62 isolates were successfully isolated, belonging to three different phyla, which were Proteobacteria; 55 (89%), Bacteroidetes; 6 (10%) and Actinobacteria; 1 (1%). Out of 55 Proteobacteria, 27 isolates were gamma-Proteobacteria (Marinobacter salsuginis) and 28 of the isolates were alpha-Proteobacteria; Mameliella atlantica (13), Roseibium denhamense (10) and Roseibium hamelinense (5). The remaining bacteria isolates from the phyla Bacteroidetes and Actinobacteria were identified as Muricauda lutimaris (6) and Micrococcus luteus (1), respectively.@*Conclusion, significance and impact of study@#The analysis of the bacterial 16S rRNA gene revealed multiple bacterial taxa associated with the toxic P. bahamense var. compressum bloom. The findings of the present work will pave the way for further studies aimed at isolating and characterizing genes involved in the saxitoxin biosynthesis in the associated bacteria.

Determination of PSP Toxins in Moroccan Shellfish by MBA, HPLC and RBA Methods: Links to Causative Phytoplankton Alexandrium minutum

Paralytic shellfish poisoning (PSP) toxins are secondary metabolites of the toxic species of phytoplankton. The consumption of shellfish accumulating these toxins can cause neurological symptoms and even death. Within the framework of the surveillance program of seafood safety along the Moroccan littoral environment established by National Institute of Fisheries Research (INRH), a study of PST was conducted from 2004 to 2016 in south Moroccan’s shellfish, mussels from south Agadir region and Razor Shell from Dakhla bay. The surveillance was carried out bi-monthly or weekly using the AOAC official method of analysis (AOAC 959.08) mouse bioassay (MBA). In parallel, monitoring of toxic phytoplankton in water was conducted. With the aim to determine the shellfish toxin profile, ion-pair high-performance liquid chromatography with post-column derivatisation and fluorescence detection (HPLC-FD) was performed. The Receptor Binding Assay (RBA) also was used for determination of total toxicity of PSP toxins in Agadir’s mussels.In both regions, the analysis of seawater revealed the presence of the toxic algae Alexandrium spp during toxics events. Along the coast of Agadir, PSP toxins in shellfish were associated with the presence of Alexandrium cf. minutum in seawater. These toxic events were widely distributed in time and space and mainly detected during the summer and fall seasons. In some samples concentrations exceeded the sanitary threshold (ST) of 800 ?g eq STX /kg. HPLC analysis revealed that Saxitoxin and Gonyautoxins dominated the toxin profile. The comparison between different methods showed a strong uphill (positive) linear relationship, with a coefficient correlation of r=0.79 between MBA and HPLC and r = 0.809 between MBA and RBA

Detection of shellfish toxins from scallops in Guangzhou seafood market

To evaluate scallop safety in the Guangzhou seafood market, contents of shellfish toxins in adductor muscle, mantle skirts, gills and visceral mass of scallops were examined using enzyme-linked immunosorbent assay (ELISA) and mouse unit assay. The results showed that: paralytic shellfish poisoning contents were up to 37.44 µg/100 g by ELISA and 319.99 MU/100 g by mouse unit assay, which did not exceed the limits of national standards (80 µg/100g and 400 MU/100 g); the contents of diarrhetic shellfish poisoning were 142.04 µg/100g and 0.2 MU/100 g, which exceeded the national standard limits (60 µg/100g); neurotoxic shellfish poisoning was undetectable; the contents of amnesic shellfish poisoning reached 220.12 µg/100g (no limit value could be referred to) . In addition, these poisons were present mainly in visceral mass and gills rather than adductor muscle and mantle skirts, suggesting that these toxins accumulate in a tissue-specific manner.(AU)

Paralytic Shellfish Poisoning by Saxitoxin: Two case reports

Paralytic shellfish poisoning results from consumption of mollusks that have fed on dinoflagellates capable of producing neurotoxins such as saxitoxin. The saxitoxin is concentrated in the shellfish and acts by decreasing sodium-channel permeability, thereby blocking neuronal transmission in skeletal muscles. Symptoms including paresthesia, perioral numbness, perioral tingling, nausea, vomiting, extremity numbness, extremity tingling, dizziness, ataxia, dysphagia, and weakness have been reported. In serious cases, respiratory hold may occur up to 6~24 hours after ingestion. Generally, the treatment for paralytic shellfish poisoning is supportive care, but mechanical ventilation is needed in serious cases acompanied by respiratory hold. We experienced two cases of paralytic shellfish poisoning. Respiratory hold was presented in one case and only mild paresthesia in the other case. After supportive management, including mechanical ventilation in former case, both patients were discharged without sequalae.

Toxicity of long-term intake of PSP at low level from shellfish on rats / 中国病理生理杂志

AIM: In order to investigate the possible cumulative and chronic toxicity of paralytic shellfish poisoning (PSP) and provide more information on toxicity of PSP. METHODS: The sub-acute toxicity of PSP was evaluated in the rat. PSP was extracted from the seafood in market, and the toxicity of the extract was determined by mouse bioassay. The extracts in different toxicity were administrated to rats through gastrotube for 35 days. The biochemical and pathological changes in vital tissues in rats were examined by the detections of some function indexes in blood and urine and the observations under optical microscope during both the exposure period and the subsequent 10-day withdrawal term. RESULTS: No biochemical and pathological changes in tissues occurred for the control and low-dose group (4.6 ?g STX/kg), whereas some changes happened for the middle (9.2 ?g STX/kg) and high groups (18.4 ?g STX/kg). In experiment, some renal function indexes changed in the mid-dose group, and some of the cardiac, hepatic and renal functions indexes altered for the high dose group with some changes in weight of the thymus gland and spleen. What is more, the liver and kidney became indistinct with some inflammatory changes, and some muscles had ruptured for the 40% rats in high-dose group. CONCLUSION: These results suggest that long-term intake of PSP at a concentration, which doesn't exceed the threshold of standard, has some toxicity on rats, and that the toxicity of PSP has an accumulative effect. In a word, it is unsafe for us to eat frequently bivalve seafood polluted by PSP toxins.

All about red tide and paralytic shellfish poisoning

In summary, we are presented with a patient who ingested mussel that are suspected to contain toxins that cause paralytic shellfish poisoning or PSP. Upon reaching the stomach, the digestive process accelerates the release of PSP toxins. The toxins are rapidly absorbed in the stomachs acidic medium and starts to work on the cellular Na channels, blocking the movement of Naions thus preventing the progression of the action potential with the absence of the action potential, there is a continued state of depolarization. This explains the feeling of numbness of the lips and fingertips, as seen in our patient, since these are the areas where nerve endings abound, and thus, are the areas most sensitive to these chemical changes. Our patient experienced this whole gamut of neurologic manifestations. He also started experiencing gastrointestinal symptoms such as epigastric pain and vomiting which are initially erroneously diagnosed as a separate problem Hearing hearsay reports on coconut milk being used as antidote for cases like these, the patient tried it too. The coconut milk, being an alkaline substance, must have stabilized some of the toxins, thus explaining the mild relief experienced by the patient prior to hospitalization. Upon reaching the hospitals, NGT was inserted and NaHCO3 lavage was done which further stabilized the toxins that were not yet absorbed, while those that were absorbed were excreted through the kidneys with the help of mannitol. After all these measures, the patient experienced considerable relief of the neurologic symptoms, though still with the intermitent epigastric pain erroneously diagnosed as Acid Peptic Disease and treated with antacids. Improvement of the neurologic complaints eventually lead to the discharge of the patient Our patient is just one of the lucky ones who benefited from immediate medical intervention to save his life. Many others arent so lucky - - - most of them never even know what hit them and thus could only look heavenwards hoping for divine intervention. Others are left to languish in understaffed overcrowded hospitals in far-flung places. Worse, a lot of those who have died of PSP never even get to a hospital Grim scenarios such as these are bound to occur yearly as long as pollution, deforestation, ignorance, and poverty prevail. We physician may not be able to curb these ills of society but we can certainly help, first and foremost by initiating the more crucial preventive measures, then by administering immediate and knowledgeable modes of treatment, and finally, by never losing the family physicians most important therapeutic tool: genuine concern for the patient. Hopefully, in doing so, we family physicians can join the family of man down to the sunset of our lives, enjoying Manila Bay for its red beautiful scape, and not for its red deadly tide.

Preliminary Research on the Methods of Fragmentation of the Cell Wall and the Toxicity of Alexandrium tamarense in Different Growth Phases / 环境与健康杂志

ve To study the growth curve of Alexandrium tamarense and the toxicity of paralytic shelfish poisoning(PSP) selected in different growth phases, as well as to quantitatively analyze the toxins and compare the different efficiency of breaking cell wall and their virtues and defects between freezing-thawing method and supersonic method, and to provide theoretical basis for the selection of the methods for extraction of PSP. Methods Cells were collected by suction filter, cell wall was broken by freezing-thawing method and supersonic method, the toxicities of Alexandrium tamarense among different growth phases were detected and compared. Results The growth of Alexandrium tamarense typically showed three phases which included a lag phase(0~9 days), an exponential growth phase(10~18 days), and a stationary phase(19~22 days) . The maximum toxicity of cells in the stationary phase appeared, especially in day 21 when the population of cells reached to 9.43?10-6 MU/cell, although the cells in the exponential phase grew fastest. Toxicity of the cells in the lag phase broken by freezing-thawing method was more stronger than that by supersonic method, that meant the toxicity of cells was lowered after the supersonic treatment. In additional, the filtering method for collecting cells presented a lower recovery rate of average 69.0% . Conclusion As for the comparing of freezing-thawing method and supersonic method, it was found that, when cells were in the same phase, the supersonic method had remarkable advantages, but it also had the disadvantage of lowering the tox-icity of cells. When in the same condition of growth and method of fragmentation, cells in the lag phase were broken most easily, and cells in the stationary phase were more difficult to be broken than those in the other two phases. Toxicity of cells was larger and larger with the time of incubation. The toxicity of cells in the lag phase had reached a higher intensity, although toxicities of cells in the next two phases would increase a little.