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The Food and Drug Administration (FDA) is amending the food additive regulations to provide for the safe use of ionizing radiation for control of Vibrio species and other foodborne pathogens in fresh or frozen molluscan shellfish (e.g., oysters, mussels, clams, etc.). This action is in response to a petition filed by the National Fisheries Institute and the Louisiana Department of Agriculture and Forestry.
In 1988, 3 intrafamilial cases of hepatitis A occurred in a little town in the nearby of Siena: shellfishes were probably responsible for the index case, close contacts for the two secondary cases, characterized by a very long incubation period (above 60 days). An inapparent infection was detected in one household contact. No other cases of hepatitis A have been observed in that area since the intrafamilial outbreak until now. A seroepidemiological survey was carried out in a group of persons living in the same area, and attending the same school or class-room of one of the secondary intrafamilial cases. 210 sera belonging to 105 teenagers were available; an IgG anti A test was performed on a double serum sample (before and after the outbreak): no seroconversion was observed. Our report underlines the hypoendemicity of hepatitis A infection in our country.
Four unusual outbreaks of food poisoning occurring in the Dunedin Health District during the period 1971-1973 are described. These involved a contaminated cordial, a death associated with a Clostridium perfringens outbreak, salmonellosis and infectious hepatitis in persons eating uncooked shellfish and symptoms associated with the ingestion of a normally edible fish--the trumpeter.
Vibrio vulnificus is an extremely invasive gram-negative bacillus that causes bacteremia and shock. It should be suspected in any patient who is immunocompromised or has liver disease or hemochromatosis. Reduced gastric acidity may also increase the risk of infection if a patient presents with a history of ingesting raw shellfish (especially oysters) or trauma in brackish waters and skin lesions. Patients most commonly present with one of three clinical syndromes: primary septicemia, wound infection, or gastroenteritis. Treatment includes aggressive wound debridement, antibiotic therapy, and supportive care. Rapidly diagnosing and promptly initiating therapy are critical because V vulnificus infection is rapidly progressive and mortality approaches 100% if septic shock occurs.
Microscopic animals associated with foods include free-living and saprophytic invertebrates, parasites of hosts other than humans, and parasitic animals specifically designated as food-borne that can infect a human host by the gastrointestinal route. The first general method used to screen for food-borne species was digestion with pepsin and hydrochloric acid at 36 degrees C, based on the "artificial stomach juice" technique for recovering larvae of the nematode Trichinella spiralis from muscle. This method selects for forms capable of surviving a mammalian digestive enzyme at mammalian temperatures. It has been used successfully to recover a variety of food-borne helminths, not only from mammalian flesh but also from fish, shellfish and molluscs, and can be adapted to greatly reduce the "background of living animals" associated with soils and the crops grown in them. However, not all animal forms that survive digestion are food-borne parasites, and all that succumb are not necessarily noninfectious. Methodology to test for food-borne parasites is, in general, not as efficient as that for food-borne bacteria. Recent developments in food parasitology indicate a need to identify not only the parasite, but also its metabolic products and associated symbionts.
The epidemiology and clinical presentation of enteric infections are discussed in this article. These include bacterial, viral, and parasitic illnesses, and are associated with the increasing popularity of drinking unpasteurized milk; eating raw fish and shellfish; consuming undercooked pork, poultry, and eggs; and having contact with pets. Salmonella, Campylobacter jejuni, Vibrio, Yersinia, Aeromonas, Edwardsiella, hepatitis A virus, Norwalk virus, Anisakis, Eustrongylides, Diphyllobothrium, Nanophyetus, Isospora, and Cryptosporidium are included. The importance of preventing these increasingly recognized enteric infections is emphasized.
Consumption of seafood is increasing and physicians should know more about ichthyosarcotoxism, or fish-flesh poisoning. It appears in a variety of forms: poisoning, ciguatera, tetrodotoxin and scombroid poisoning. Ingestion of certain marine turtles and mammals also has been incriminated as the cause of illness. Paralytic shellfish poisoning can be deadly. In addition, red tide may cause respiratory problems.
A recent outbreak of amnesic shellfish poisoning (ASP) in Atlantic Canada was characterized by severe gastrointestinal and central nervous system pathology. We examined the gastrointestinal effects of an acidic extract of blue mussels contaminated with domoic acid, the suspected toxin responsible for the ASP. We also tested the gastric effects pure domoic acid as well as a putative antagonist of neuroexcitant amino acid receptors, kynurenic acid. Mussel extract produced gastric (antral) ulcers, duodenal ulcers, gastric and duodenal hyperemia and bleeding, as well as peritoneal ascites. Kynurenic acid protected significantly against extract-induced gastropathy, particularly when given 60 or 75 minutes after extract. Pure domoic acid resulted in fatalities in all infant mice tested. These animals exhibited gastric bleeding and hemorrhage, especially at the higher doses employed. In otherwise untreated rats, kynurenic acid exerted significant anti-stress ulcer and anti-gastric secretory effects, but was less effective at blocking ethanol-induced gastric lesions. We suggest that there may be both peripheral as well as central effects of kynurenic acid in modulating normal and pathological gastric function.
An investigation of the epidemic of hepatitis A which occurred in early 1988 in Shanghai was conducted at the Shanghai Number 2 Yarn Dyeing and Weaving Mill. In this factory the attack rate between January and April 1988 was 9%. The rate was highest among staff and workers who ate raw clams (18%) but also higher among those who ate cooked clams (7%) than among those who did not eat clams (2%). In addition, independent risk factors for infection were: age below 30 years (relative risk = 3.0, 95% confidence interval: 2.0, 4.5) shift work (relative risk = 3.3, 95% confidence interval: 1.9, 5.8) and eating out (relative risk = 4.7, 95% confidence interval: 2.3, 9.7). The consumption of clams contaminated with hepatitis A virus was the main risk factor in this episode. The study indicates that strengthening surveillance of shellfish hygiene is important to prevent future epidemics of hepatitis A.
The concept of the sea as a source of noxious agents is perhaps not a familiar one to clinical neurologists, judging by the lack of reference to these agents in standard textbooks. Chemical, physiologic, and pharmacologic laboratories are increasingly investigating the properties of marine toxins, finding in them compounds with interesting and novel structures or unusual physiologic effects. Such substances are seen as possible agents for biologic and, more particularly, physiologic research, and as possible sources of new pharmaceuticals. These include hormone-like substances and antiviral or antitumor agents. Despite these specialized developments, which are in large measure a consequence of the technological advances of the present century, the clinician is at times directly concerned with the effects of marine toxic substances. For example, in Japan, puffer fish or tetrodotoxic poisoning is one of the major causes of deaths from food poisoning. Another marine toxin that has caused many explosive outbreaks of food poisoning. with many deaths in various parts of the world, comes from clams or mussels. This toxin, saxitoxin, is produced by species of marine protozoa including Gonyaulax, and is concentrated in filter-feeding molluscs. These two examples were of significant interest in medicine long before the technologic developments of the twentieth century. In the last few decades, entirely new problems of marine intoxication have arisen as a result of marine pollution from the disposal of industrial wastes in the sea. The most striking example of a man-made marine intoxication has been the outbreak of Minamata disease. In Minamata, Japan, the disposal of mercury-contaminated industrial wastes from a plastics factory into an enclosed bay, followed by human consumption of the contaminated fishes, crabs, or shellfish, led to many instances of acute cerebral degeneration. With the increasing exploration of the sea for both pleasure and economic exploitation, which is a feature of the second half of the twentieth century, it may be expected that the frequency and variety of human intoxications by marine creatures will be increased. This chapter reviews the neurologic effects of noxious substances of marine biologic origin. The subject is now developing so rapidly that overall surveys, such as this, of the general animal life of theocens will soon be beyond the scope of a single review. Nevertheless, it is hoped that the references given will enable the interested reader to pursue particular aspects further.
Eight cases of acute gastroenteritis caused by Vibrio parahaemolyticus in humans are described; to our knowledge, they are the first such reported cases in Spain. All cases appeared between August 20th and October 15th, with a frequency of 8.3% regarding the overall adult patients with acute gastroenteritis, and 11.5% regarding the overall patients with positive stool culture for any enteropathogenic organism. The eight strains were Kanagawa positive and in three patients other enteropathogenic organisms were isolated in addition to Vibrio parahaemolyticus, i.e. Aeromonas hydrophila in two and Salmonella serovariety enteritidis in another. In all cases fish or shellfish had been ingested outside the patients' homes; except for one patient, who ate living clams in the seaside of Galicia, all patients ingested them at seaside restaurants from the Barcelona province. The clinical features of acute gastroenteritis were definite in all patients, but no patients had significant electrolyte losses or required hospital admission. Recovery was spontaneous and no antimicrobial agents were required. All strains were sensitive to tetracyclines, aminoglycosides, cefotaxime, ceftazidime and nearly always to co-trimoxazole.
Methylguanidine (MG), a precursor of carcinogenic methylnitrosocyanamide and methylnitrosourea, has long been considered to occur widely in fresh beef and various fish muscles in fairly high concentrations. Agmatine (AG) has been reported to be easily nitrosated to give a potent mutagen under acidic conditions. A survey has been conducted on the MG and AG contents of various fresh and processed foods. The present study reveals that no appreciable amount, or only trace amounts, of MG could be detected in fresh beef, pork, chicken and various fish and shellfish. In addition, almost the same low levels of MG were detected in various processed foods, except in the case of smoked-dried fish products, where the MG values ranged from 18 to 178 mg/kg. Relatively high concentrations of AG, ranging from 40 to 200 mg/kg, could be detected in fresh abalone and top-shell muscles, while fairly high concentrations of AG could be detected in some processed foods. A dried squid product, in particular, was found to contain as high as 650 mg/kg of AG.
After pointing out clinical, biochemical and biological similarities between paralytic shellfish poisoning and ciguaterra fish poisoning, the authors describe their recent discoveries in regard to ciguaterra origin. The causal agent searched without results since many years, might be a dinoflagellate, of the genus Diplopsalis.
Fresh seafoods collected from Seattle area markets were evaluated for the presence and numbers of Clostridium perfringens. In a comparison of the official AOAC Shahidi-Ferguson perfringens and the simple iron milk methods, 29 of 287 samples of fresh fish and shellfish were positive for C. perfringens. All 29 positive samples were detected by the iron milk medium; however, only 7 of the 29 were detected by the AOAC methods. A statistical evaluation of the data showed a significant difference between the 2 methods.
Three researches undertaken in Bari, with the aim of clarifying the epidemiological circles that determine the typhoid and paratyphoid endemia as well as the so-called salmonellosis minor, are reported here. The results obtained confirm the important role that eating shellfishes plays in spreading of typhoid cases in a sea-town like Bari. Furthermore, data obtained showed that the importing mechanism of infected animals, and then the slaughter-houses and the butcheries , are accounting for spreading of exotic Salmonellae in our country.
Both symptomatic and asymptomatic Vibrio infections, caused by V cholerae, V parahaemolyticus and NAG vibrios, occurred in Singapore. V cholerae are introduced into the country from time to time, but the risk of transmission of infection in the community is negligible in the presence of a high standard of environmental sanitation and a well-established system of epidemiological surveillance. As cholera is probably transmitted through contaminated food, shellfish imported from cholera-endemic countries are regularly monitored for the presence of V cholerae. Vigilance has also been stepped up in the laboratory in view of the possibility of introduction of multiple-antibiotic resistant V cholerae strains into the country. V parahaemolyticus is one of the commonest causes of bacterial food poisoning in Singapore because of the preference of the local population to consume raw or partially cooked seafood. 78% of a variety of imported seafood were found to be contaminated with V parahaemolyticus. Infections caused by NAG vibrios are infrequent, and the mode of transmission has not been established.
A total of 80 food samples were purchased from local retail consumer shops and examined for the presence of motile Aeromonas spp. Of the food categories tested, poultry had the highest incidence, with 100% positive. This was followed by lamb samples, with 60% positive. Raw milk and cheese samples had very low incidence (20%). No motile Aeromonas spp. were found in pre-prepared salads. Shellfish, fish, pork and beef samples had incidences of 40%. Most of the strains isolated were Aeromonas hydrophila, and for most of the food categories, no Aeromonas caviae isolates were obtained.
BACKGROUND: Vibrio vulnificus can cause rapidly spreading skin and soft tissue infections with significant associated morbidity and mortality. Patients with underlying chronic illness, such as cirrhosis, diabetes mellitus, or immunosuppression, have been noted to be at high risk for rapid progression of this infection. The importance of early antibiotic therapy has been reported but the role of operative intervention in these patients is less clear. STUDY DESIGN: We report seven patients who were operatively treated from April 28, 1991 to September 22, 1995 for primary skin and soft tissue infections secondary to Vibrio vulnificus. We have also reviewed the recent literature. The impact of several variables including shock, increased white blood cell count, fever, and the timing of operative intervention on the length of hospital stay and intensive care unit stay was analyzed using the Spearman rank correlation. The impact of early compared with late operative intervention was analyzed using the Mann-Whitney U test. All patients had a history of underlying chronic illness and presented with skin infections in association with recent exposure to saltwater and to shellfish. No patient presented earlier than 24 hours from the time of initial infection. All patients underwent operative exploration within 46 hours of admission with thorough operative debridement of all necrotic tissue. Infection was confined to the skin and subcutaneous tissue. RESULTS: There was no mortality among our patients. The presence of perioperative shock, fever, or elevated white blood cell count did not correlate with an increased intensive care unit stay or an increased hospital stay. Earlier operative exploration and debridement correlated with a decrease in the intensive care unit stay (p < 0.02, correlation coefficient = 0.991) and in the hospital stay (p < 0.02, correlation coefficient = 0.929). Patients who underwent debridement within 72 hours from the time of the infection had a significantly shorter intensive care unit stay (p = 0.0323) and total hospital stay (p = 0.0339). CONCLUSIONS: We advocate operative exploration and thorough debridement of all necrotic tissue in high-risk patients with primary Vibrio vulnificus skin and soft tissue infections.