Occurrence and density of vibrio parahaemolyticus in live edible crustaceans from markets in China

Vibrio parahaemolyticus is a marine bacterium causing foodborne disease. Occurrence of the bacterium was investigated in six species of edible crustaceans available from markets in mainland China. The bacterium was detected in 22 of 45 whole-body, shell, and feces samples, including mitten crabs, which are supposed to be produced in freshwater ponds. The mean densities ranged from 2.8 log CFU/g in mitten crabs (Eriocheir sinensis) to 5.1 CFU/g in giant tiger prawns (Penaeus monodon). In hemolymph and muscle samples collected axenically, V. parahaemolyticus was detected in all of the prawns at a mean density of 2.6 log most probable number (MPN)/g, in two of five striped stone crabs (Charybdis feriatus) at a mean density of 1.1 log MPN/ml, and two of five mangrove mud crabs (Scylla serrata) at a mean density of 1.3 log MPN/ml. When six mitten crabs were collected from two freshwater ponds in China and were examined, V. parahaemolyticus was not detected. It seemed that cross-contamination occurred among live crustaceans at the markets. The results suggest that proper handling, storage, and cooking of these crustaceans will be necessary to lessen the risk of foodborne illness from V. parahaemolyticus.     

Salmonella prevalence in seafood imported into Japan

A total of 353 samples of 29 types of seafood were tested for Salmonella prevalence and total microbial population. Salmonella enterica serotype Weltevreden was isolated from 2 of 47 black tiger prawn samples. The contamination levels of Salmonella were in a range of <30 to 40 most probable number per 100 g. In addition, one sample of black tiger prawns and two samples of white shrimp were positive for Salmonella invA gene on PCR assay. Although the mean aerobic bacterial count was greater than 4 log CFU/g in most of the sample types, those in the two Salmonella-isolated samples of black tiger prawn were 7.48 and 5.18 log CFU/g, respectively. These results indicate the possibility that shrimp and prawns contribute to foodborne infections. The improvement of seafood quality is an important issue, and the information on contamination by pathogens should be provided as feedback to the originating country, with the aim of increasing safety.     

A gyrB-based PCR for the detection of Vibrio vulnificus and its application for direct detection of this pathogen in oyster enrichment broths

A polymerase chain reaction (PCR) method based on the gyrB (encoding gyrase B or topoisomerase II) gene sequence was developed for the detection of Vibrio vulnificus in seafood. The gyrB primers detected all laboratory isolates of V. vulnificus and did not cross react with other Vibiro and non-Vibrio species examined in this study. The sensitivity of detection of V. vulnificus by gyrB PCR was 300 CFU/g in artificially seeded oyster homogenate without enrichment while, 30 CFU/g could be detected following 18 h enrichment in alkaline peptone water (APW). The gyrB-specific PCR was employed for the direct detection of V. vulnificus in oyster enrichment broths. The assay detected V. vulnificus in 75% of natural oyster samples after 18 h enrichment in APW. The gyrB-based PCR described here offers a simple and specific one step PCR method for the detection of V. vulnificus in seafood enrichment broths.     

2017年广西壮族自治区5个城市贝类海产品致病性弧菌污染状况分析

目的 了解广西壮族自治区贝类海产品中副溶血性弧菌、创伤弧菌、溶藻弧菌和霍乱弧菌的污染现状,为食源性疾病防控和微生物风险评估提供参考依据。方法 2017年在广西壮族自治区3个沿海和2个内陆城市采集贝类海产品进行定性检测,其中副溶血性弧菌同时进行定量检测和毒力基因检测。结果 5个城市共采集800份贝类海产品,致病性弧菌总阳性率为76.5%(612/800),副溶血性弧菌、创伤弧菌和霍乱弧菌阳性率分别为73.9%(591/800)、18.4%(147/800)、0.1%(1/800),未检出溶藻弧菌。副溶血性弧菌阳性率与采样地区、样品状态和贝类品种有关,沿海地区阳性率高于内陆地区,但含量却低于内陆地区;活产品阳性率和含量均高于鲜/冰鲜海产品;蛏子、泥蚶、牡蛎和蛤/蚬子阳性率较高,均在75.0%以上,扇贝和贻贝阳性率相对较低,但含量较高;1.0%(6/591)的菌株检出致病性毒力基因。创伤弧菌阳性率与样品来源、采样地区和贝类品种有关,沿海地区高于内陆地区,农村高于城市,蛏子和泥蚶阳性率最高,均在35.0%以上。结论 广西壮族自治区贝类海产品中副溶血性弧菌和创伤弧菌污染较严重,需重点加强贝类海产品食品安全卫生宣教,加强沿海农村地区创伤弧菌监测。     

Growth and Survival Differences of Vibrio vulnificus and Vibrio parahaemolyticus Strains during Cold Storage

ABSTRACT:  Vibrio vulnificus  and  Vibrio parahaemolyticus  are the most common  Vibrio  species associated with seafood illness in the United States. Our study was conducted to determine if strain-to-strain differences exist in the growth and survival of 8 different  V. vulnificus  and  V. parahaemolyticus  strains at low temperatures. By day 10,  V. vulnificus  strain 515-4C2 had significantly higher counts ( P  < 0.05) (1.97 log CFU/g) compared with strains 3315, 1007, 29306 at 5 °C, which reached nondetectable levels. At 8 °C, strain 515-4C2 had significantly higher counts ( P  < 0.05) (2.23 log CFU/mL) compared with 1007, 33815, 541(O) 49C, which reached nondetectable levels. At 10 °C, only  V. vulnificus  strain 33815 reached nondetectable levels. At 5 °C,  V. parahaemolyticus  strain 541(O) 57C had the highest counts (5.28 log CFU/g) by day 10 while strain 33847 had significantly lower counts (3.46 log CFU/g). After 10 d at 8 °C,  V. parahaemolyticus  strain M350A had the highest counts (7.97 log CFU/mL) while strain 541(O) 57C had the lowest counts (4.80 log CFU/mL). At 10 °C,  V. parahaemolyticus  strain NY477 had significantly higher counts ( P  < 0.05) with 8.31 log CFU/mL compared with strain 33847, which had the lowest counts (6.77 log CFU/mL). Our research has shown that various  V. vulnificus  and  V. parahaemolyticus  strains vary in their ability to survive and grow at refrigeration temperatures.     

Prevalence and antimicrobial susceptibility of major foodborne pathogens in imported seafood

Seafood is a leading commodity implicated in foodborne disease outbreaks in the United States. Seafood importation rose dramatically in the past 3 decades and now contributes to more than 80% of the total U.S. seafood supply. However, limited data are available on the microbiological safety of imported seafood. In this study, we obtained a total of 171 salmon, shrimp, and tilapia samples imported from 12 countries in three retail stores in Baton Rouge, LA. The total microbial population and the prevalence and antimicrobial susceptibilities of six major foodborne-pathogen genera (Campylobacter, Escherichia coli, Listeria, Salmonella, Shigella, and Vibrio) were determined. The aerobic plate counts (APC) for the 171 samples averaged 4.96 log CFU/g, with samples from Chile carrying the highest mean APC of 6.53 log CFU/g and fresh samples having a significantly higher mean APC than frozen ones (P < 0.0001). There were 27 samples (15.8%) with unacceptable microbiological quality (APC > 7 log CFU/g). By culture, no sample tested positive for Campylobacter coli, Shigella, or Vibrio vulnificus. Campylobacter jejuni and Salmonella enterica serovar Typhimurium were each recovered once from farm-raised tilapia from China. By PCR, 17.5 and 32.2% of the samples were positive for Salmonella and Shigella, respectively. The overall prevalence rates of other target bacteria were low, ranging from 4.1% for Listeria monocytogenes to 9.4% for E. coli. All of the Vibrio parahaemolyticus isolates recovered were from shrimp, and 63.3% showed intermediate resistance to ampicillin. Both C. jejuni isolates possessed a rare resistance to gentamicin, while 75% of L. monocytogenes isolates were resistant to nitrofurantoin. Taken together, these findings suggest potential food safety hazards associated with imported seafood and warrant further large-scale studies.     

Vibrio vulnificus and Vibrio parahaemolyticus in U.S. retail shell oysters: a national survey from June 1998 to July 1999.

From June 1998 to July 1999, 370 lots of oysters in the shell were sampled at 275 different establishments (71%, restaurants or oyster bars; 27%, retail seafood markets: and 2%, wholesale seafood markets) in coastal and inland markets throughout the United States. The oysters were harvested from the Gulf (49%). Pacific (14%), Mid-Atlantic (18%), and North Atlantic (11%) Coasts of the United States and from Canada (8%). Densities of Vibrio vulnificus and Vibrio parahaemolyticus were determined using a modification of the most probable number (MPN) techniques described in the Food and Drug Administration's Bacteriological Analytical Manual. DNA probes and enzyme immunoassay were used to identify suspect isolates and to determine the presence of the thermostable direct hemolysin gene associated with pathogenicity of V. parahaemolyticus. Densities of both V. vulnifcus and V. parahaemolyticus in market oysters from all harvest regions followed a seasonal distribution, with highest densities in the summer. Highest densities of both organisms were observed in oysters harvested from the Gulf Coast, where densities often exceeded 10,000 MPN/g. The majority (78%) of lots harvested in the North Atlantic, Pacific, and Canadian Coasts had V. vulnificus densities below the detectable level of 0.2 MPN/g; none exceeded 100 MPN/g. V. parahaemolyticus densities were greater than those of V. vulnificus in lots from these same areas, with some lots exceeding 1,000 MPN/g for V. parahaemolyticus. Some lots from the Mid-Atlantic states exceeded 10,000 MPN/g for both V. vulnificus and V. parahaemolyicus. Overall, there was a significant correlation between V. vulificus and V. parahaemolyticus densities (r = 0.72, n = 202, P < 0.0001), but neither density correlated with salinity. Storage time significantly affected the V. vulnificus (10% decrease per day) and V. parahaemolyticus (7% decrease per day) densities in market oysters. The thermostable direct hemolysin gene associated with V parahaemolyticus virulence was detected in 9 of 3,429 (0.3%) V. parahaemolyticus cultures and in 8 of 198 (4.0%) lots of oysters. These data can be used to estimate the exposure of raw oyster consumers to V. vulnificus and V. parahaemolyticus.     

L‐Carnitine Contents in Seafoods Commonly Eaten in Middle Eastern Countries

Beta‐hydroxy‐gamma‐trimethyl amino butyric acid (L‐carnitine) content of raw and cooked seafood was determined using high‐performance liquid chromatography method. Thirty‐one different fish species and nine different crustaceans were used to compare L‐carnitine content of raw and cooked seafood. Significant differences in L‐carnitine content were found in some species, regardless of the raw or cooked seafood (P < 0.05). There were also significant differences between some of the raw and cooked species (P < 0.05). The levels of L‐carnitine in raw fish samples ranged from 17.98 mg/kg for big‐scale sand smelt to 73.07 mg/kg for European conger (Conger conger). Squid (Loligo vulgaris) and green tiger prawn (Penaeus semisulcatus) were found as the best sources of L‐carnitine among the tested seafood. Microwave cooking also significantly reduced the L‐carnitine content of some seafoods (P < 0.05). The study showed that seafoods are an important origin of L‐carnitine for covering the daily requirements of humans.     

Detection and Enumeration of Vibrio vulnificus by Direct Colony Immunoblot

ABSTRACT:  A direct colony immunoblot method (DCI) for the enumeration of Vibrio vulnificus was developed. Bacterial colonies were transferred from agar plates to membranes, which were then dried and blocked with bovine serum albumin. Subsequently, the membranes were treated with anti- V. vulnificus H antibodies, washed and incubated with peroxidase-conjugated goat anti-rabbit IgG. After a final wash, the membranes were exposed to a substrate mixture containing H₂O₂ which resulted in the development of a purple color by V. vulnificus colonies. The DCI detected all clinical and environmental V. vulnificus strains tested and did not cross-react with other Vibrio species including V. cholerae , V. parahaemolyticus , or V. fluvialis . The DCI was then compared to the DNA hybridization procedure (DNAH) using V. vulnificus agar plates inoculated with mixed cultures of V. vulnificus and V. parahaemolyticus and V. vulnificus -seeded oyster homogenates. Both DCI and DNAH detected 1 to 2 log colony forming units (CFU)/mL V. vulnificus mixed with 4 log CFU/mL V. parahaemolyticus . Both methods were comparable and demonstrated no significant statistical differences when enumerating V. vulnificus in mixed cultures or in oyster homogenates seeded with levels of V. vulnificus from 2 to 6 log CFU/mL. The DCI demonstrated clearer color development and was less time consuming than the DNAH.     

Low temperature pasteurization to reduce the risk of vibrio infections from raw shell-stock oysters

Vibrio vulnificus and V. parahaemolyticus are natural inhabitants of estuarine environments and may be transmitted to humans by ingestion of raw oysters. This study focused on the use of low temperature pasteurization, to reduce these Vibrio spp. to nondetectable levels, thus reducing the risk of infection associated with raw oyster consumption. Artificially inoculated V. vulnificus and V. parahaemolyticus and naturally-contaminated V. vulnificus in live oysters were pasteurized at 50%deg;C for up to 15min. Samples of processed and unprocessed oysters were enumerated for V. vulnificus, V. parahaemolyticus, and aerobic spoilage bacteria for 0-14 days. Low temperature pasteurization was effective in reducing these pathogens from > 100000 to non-detectable levels in less than 10min of processing. Spoilage bacteria were reduced by 2-3 logs, thus increasing the shelf-life for up to 7 days beyond live unprocessed oysters. Vibrio vulnificus in control oysters was reduced by 102 during ice storage alone. Following pasteurization and during a temperature storage abuse study (24h at 22°C), V. vulnificus was not recovered. During this storage period spoilage bacteria exceeded 1 million/g oyster meat.     

Fate of Staphylococcus aureus, Salmonella enterica serovar typhimurium, and vibrio vulnificus in raw oysters treated with chitosan

The fate of Staphylococcus aureus, Salmonella enterica serovar Typhimurium, and Vibrio vulnificus in oysters treated with chitosan was investigated. Three concentrations (0.5, 1.0, and 2.0%) of chitosan in 0.5% hydrochloric acid were prepared and coated onto raw oysters, which were then stored at 4 degrees C for 12 days. Untreated oysters and oysters coated with 0.5% hydrochloric acid without chitosan were used as controls. S. aureus cells were most sensitive to 2.0% chitosan followed by 0.5 and 1.0%. In general, chitosan treatment of oysters produced a decline in the population of S. aureus by 1 to 4 log CFU/ml compared with the untreated control. Chitosan treatment had no influence on the reduction of Salmonella Typhimurium over the 12-day storage period; inhibition of Salmonella Typhimurium growth was similar in both the control samples and the chitosan-treated samples. However, time of storage had a major effect on the survival of Salmonella Typhimurium on oysters. Neither time nor chitosan concentration had a significant effect on the growth of V. vulnificus during storage. All treatments were similar in inhibiting V. vulnificus growth.     

Isolation and molecular characterization of Vibrio parahaemolyticus from fresh, low-temperature preserved, dried, and salted seafood products in two coastal areas of eastern China

A total of 1293 seafood samples from fishing farm, retail markets, restaurants and cooking rooms of hotels in Jiangsu province and Shanghai city of China were collected and analyzed for the prevalence of Vibrio parahaemolyticus during July to October in 2007. Two hundred and fifty one isolates of V. parahaemolyticus were identified, of which 8 isolates were positive for tdh and 2 were positive for trh gene. Three tdh positive isolates were identified from low-temperature preserved seafood samples and 5 isolates from fresh seafood samples, of these tdh positive isolates, 3 were positive in ORF8-PCR test. The genetic diversity among V. parahaemolyticus isolates was assessed using random amplified polymorphic DNA (RAPD)-PCR and the results showed that there were 33 different genetic patterns that were clustered into nine groups (groups A to I) at 82% similarity level. About 31.9% of the isolates belong to type III9d that were widely distributed in fresh, iced, frozen, dried and salted seafood samples. Seven tdh positive isolates belonged to group A and one belonged to group C, 2 trh positive isolates were type I10d belonging to group F, which was identical to that of reference strains isolated from patients. This study demonstrated genetic variability within V. parahaemolyticus isolates from seafood in Chinese markets and confirmed the presence of toxigenic V. parahaemolyticus not only in fresh but also in iced and frozen seafood products indicating that low-temperature preserved seafood might be also a vehicle for transmitting pathogenic V. parahaemolyticus.     

Variable repeat regions in the genome of Vibrio vulnificus and polymorphism in one of the loci in strains isolated from oysters

Vibrio vulnificus an estuarine bacterium is associated with severe wound infections and fatal septicemia related to consumption of raw shellfish. In this study we screened the two whole genome sequences available for V. vulnificus in GenBank for the presence of variable number of tandem repeat (VNTR) regions. Five potential VNTR loci with unit repeat size ranging from 6-7 nucleotides were identified for V. vulnificus genome. One of the loci designated Vv1 was selected to detect the repeat number present in V. vulnificus strains isolated from oyster samples in India. Twenty six of the thirty samples tested were found to be highly polymorphic for the Vv1 locus. Copy numbers for the hexanucleotide motif ranged from 4-55, giving rise to a total of 17 polymorphic groups. Our analysis, shows that different genotypic variants exist in the environment and the VNTR loci studied can be used as a marker for strain discrimination and in epidemiological study of this organism.     

Effects of electrolyzed oxidizing water treatment on reducing Vibrio parahaemolyticus and Vibrio vulnificus in raw oysters

Contamination of Vibrio parahaemolyticus and Vibrio vulnificus in oysters is a food safety concern. This study investigated effects of electrolyzed oxidizing (EO) water treatment on reducing V. parahaemolyticus and V. vulnificus in laboratory-contaminated oysters. EO water exhibited strong antibacterial activity against V. parahaemolyticus and V. vulnificus in pure cultures. Populations of V. parahaemolyticus (8.74 x 10(7) CFU/ml) and V. vulnificus (8.69 x 10(7) CFU/ml) decreased quickly in EO water containing 0.5% NaCl to nondetectable levels (> 6.6 log reductions) within 15 s. Freshly harvested Pacific oysters were inoculated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus at levels of 10(4) and 10(6) most probable number (MPN)/g and treated with EO water (chlorine, 30 ppm; pH 2.82; oxidation-reduction potential, 1131 mV) containing 1% NaCl at room temperature. Reductions of V. parahaemolyticus and V. vulnificus in oysters were determined at 0 (before treatment), 2, 4, 6, and 8 h of treatment. Holding oysters inoculated with V. parahaemolyticus or V. vulnificus in the EO water containing 1% NaCl for 4 to 6 h resulted in significant (P < 0.05) reductions of V. parahaemolyticus and V. vulnificus by 1.13 and 1.05 log MPN/g, respectively. Extended exposure (> 12 h) of oysters in EO water containing high levels of chlorine (> 30 ppm) was found to be detrimental to oysters. EO water could be used as a postharvest treatment to reduce Vibrio contamination in oysters. However, treatment should be limited to 4 to 6 h to avoid death of oysters. Further studies are needed to determine effects of EO water treatment on sensory characteristics of oysters.     

Characterization of the low-salinity stress in Vibrio vulnificus

Vibrio vulnificus is a marine pathogenic bacterium commonly found in seawater or seafood. This organism encounters low-salinity stress in its natural environment and during food processing. This study was designed to investigate the response of V. vulnificus YJ03 to lethal low salinity (0.04% NaCl) and its adaptation to sublethal salinity (0.12% NaCl with 20 amino acids added). A short period in the nonculturable state was induced by lethal low-salinity stress followed by cell death after 30 min of stress. Addition of 1 mM glycine betaine or 0.5 mM sucrose reduced the damage. Low-salinity adaptation was achieved in the exponential-phase cells but not in the stationary-phase cells. Significant protection against lethal low-salinity stress was attained when the cells were adapted for as little as 1.5 min. The adapted cells were significantly protected against lethal low salinity and 2.4% sodium sorbate but sensitized to the challenge of heat (52 degrees C) and acid (pH 3.2). Nonlethal low-salinity treatment of seafood should be avoided to prevent stress adaptation of V. vulnificus.     

Susceptibility of the heat-, acid-, and bile-adapted Vibrio vulnificus to lethal low-salinity stress

As a marine pathogenic bacterium that inhabits seawater or seafood, Vibrio vulnificus encounters low salinity and other stresses in the natural environment and during food processing. This investigation explores the cross-protective response of sublethal heat-, acid-, or bile-adapted V. vulnificus YJ03 against lethal low-salinity stress. Experimental results reveal that the acid (pH 4.4)- and heat (41 degrees C)-adapted V. vulnificus were not cross-protected against the lethal low-salinity challenge (0.04% NaCl). The bile (0.05%)-adapted exponential- and stationary-phase cells were cross-protected against low salinity, whereas low-salinity (0.12% NaCl)-adapted stationary cells were sensitized against 12% bile stress. Results of this study provide further insight into the interaction between low salinity and other common stresses in V. vulnificus.     

Conditions for a 5-log reduction of Vibrio vulnificus in oysters through high hydrostatic pressure treatment

Vibrio vulnificus is frequently associated with oysters, and since oysters are typically consumed raw on a half shell, they can pose a threat to public health due to ingestion of this pathogenic marine microorganism. Oysters should be processed to reduce the number of this pathogen. High pressure processing is gaining more and more acceptance among oyster processors due to its ability to shuck oysters while keeping the fresh-like characteristics of oysters. Nine strains of V. vulnificus were tested for their sensitivities to high pressure. The most pressure-resistant strain of V. vulnificus, MLT 403, was selected and used in the subsequent experiments to represent a worst case scenario for evaluation of the processing parameters for inactivation of V. vulnificus in oysters. To evaluate the effect of temperature on pressure inactivation of V. vulnificus, oyster meats were inoculated with V. vulnificus MLT 403 and incubated at room temperature for 24 h. Oyster meats were then blended and treated at 150 MPa for 4 min, and 200 MPa for 1 min. Pressure treatments were carried out at -2, 1, 5, 10, 20, 30, 40, and 45 degrees C. Cold temperatures (<20 degrees C) and slightly elevated temperatures (>30 degrees C) substantially increased pressure inactivation of V. vulnificus. For example, a 4-min treatment of 150 MPa at -2 and 40 degrees C reduced the counts of V. vulnificus by 4.7 and 2.8 log, respectively, while at 20 degrees C the same treatment only reduced counts by 0.5 log. Temperatures of -2 and 1 degrees C were used to determine the effect of pressure level, temperature, and treatment time on the inactivation of V. vulnificus infected to live oysters through feeding. To achieve a >5-log reduction in the counts of V. vulnificus in a relatively short treatment time (or=250 MPa at -2 or 1 degrees C.     

NOVEL NONTHERMAL METHODS TO REDUCE VIBRIO VULNIFICUS IN RAW OYSTERS

Vibrio vulnificus is a foodborne pathogen associated with consumption of raw oyster. No scientific data is available on postharvest treatments of oyster by ultrasound, ozone, and organic acids. This study was designed to investigate the effects of these treatments on inactivation of V. vulnificus naturally present in the in-shell or half-shelled oysters. In in-shell oysters, these treatments were not effective in reducing the number of this pathogen. Half-shelled oysters treated with ultrasound, and ozone in 2% saline for 30 min had 1 and 1.5 log less V. vulnificus, respectively (p<0.05). Treatment of half-shelled oysters by 50 and 100% lemon juice, 5% citric acid, 10% citric acid, or vinegar for 30 min resulted in a significant reduction (2–4 log) in the numbers of V. vulnificus (p<0.05). Although these methods significantly reduced the population of V. vulnificus in raw oysters, they were not able to reduce the numbers of this pathogen to acceptable level (<3 MPN/g).     

Persistent perfluorinated acids in seafood collected from two cities of China

As an initial survey of human exposure to perfluorinated acids through food consumption in China, seven types of seafood collected from fish markets in two coastal cities were analyzed. Nine perfluorinated compounds were determined using HPLC coupled with ESI-MS/MS. Perfluorooctane sulfonate (PFOS) was the predominant fluorochemical and was found in all 27 seafood samples, including fish, molluscs, crabs, shrimp, oysters, mussels, and clams. Concentrations of PFOS in seafood samples ranged from 0.3 to 13.9 ng/g wet weight, with the highest concentration in mantis shrimp. The hazard ratios of noncancer risk through seafood consumption based on PFOS and perfluorooctanoic acid concentrations were calculated and were less than unity.     

Prevalence of potentially pathogenic Vibrio species in the seafood marketed in Malaysia

Seafood samples obtained in seafood markets and supermarkets at 11 sites selected from four states in Malaysia were examined for the presence of nine potentially pathogenic species from the genus Vibrio between July 1998 and June 1999. We examined 768 sample sets that included shrimp, squid, crab, cockles, and mussels. We extensively examined shrimp samples from Selangor State to determine seasonal variation of Vibrio populations. Eight potentially pathogenic Vibrio species were detected, with overall incidence in the samples at 4.6% for V. cholerae, 4.7% for V. parahaemolyticus, 6.0% for V. vulnificus, 11% for V. alginolyticus, 9.9% for V. metschnikovii, 1.3% for V. mimicus, 13% for V. damsela, 7.6% for V. fluvialis, and 52% for a combined population of all of the above. As many as eight Vibrio species were detected in shrimp and only four in squid and peel mussels. The overall percent incidence of any of the eight vibrios was highest (82%) in cockles (Anadara granosa) among the seafoods examined and was highest (100%) in Kuching, Sarawak State, and lowest (25%) in Penang, Pulau Penang State, among the sampling sites. Of 97 strains of V. cholerae isolated, one strain belonged to the O1 serotype and 14 to the O139 serotype. The results indicate that the various seafood markets in Malaysia are contaminated with potentially pathogenic Vibrio species regardless of the season and suggest that there is a need for adequate consumer protection measures.