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Sunday, April 29, 2007

title:{foodborne illnesses in seafood}

Here are the foodborne illness associated with seafood. I have elaborate about the more common ones and those associated with shrimps(shellfish).

These are the bacteria pathogens which can be found in raw and processed seafood.

Listeria monocytogenes

L. monocytogenes has been associated with such foods as raw milk, supposedly pasteurized fluid milk, cheeses (particularly soft-ripened varieties), ice cream, raw vegetables, fermented raw-meat sausages, raw and cooked poultry, raw meats (all types), and raw and smoked fish. Its ability to grow at temperatures as low as 3°C permits multiplication in refrigerated foods.

Salmonella

Raw meats, poultry, eggs, milk and dairy products, fish, shrimp, frog legs, yeast, coconut, sauces and salad dressing, cake mixes, cream-filled desserts and toppings, dried gelatin, peanut butter, cocoa, and chocolate.
Various Salmonella species have long been isolated from the outside of egg shells. The present situation with S. enteritidis is complicated by the presence of the organism inside the egg, in the yolk. This and other information strongly suggest vertical transmission, i.e., deposition of the organism in the yolk by an infected layer hen prior to shell deposition. Foods other than eggs have also caused outbreaks of S. enteritidis disease

Clostridium botulinum

The types of foods involved in botulism vary according to food preservation and eating habits in different regions. Any food that is conducive to outgrowth and toxin production, that when processed allows spore survival, and is not subsequently heated before consumption can be associated with botulism. Almost any type of food that is not very acidic (pH above 4.6) can support growth and toxin production by C. botulinum. Botulinal toxin has been demonstrated in a considerable variety of foods, such as canned corn, peppers, green beans, soups, beets, asparagus, mushrooms, ripe olives, spinach, tuna fish, chicken and chicken livers and liver pate, and luncheon meats, ham, sausage, stuffed eggplant, lobster, and smoked and salted fish.

Vibrio cholerae Serogroup O1

Cholera is generally a disease spread by poor sanitation, resulting in contaminated water supplies. This is clearly the main mechanism for the spread of cholera in poor communities in South America. The excellent sanitation facilities in the U.S. are responsible for the near eradication of epidemic cholera. Sporadic cases occur when shellfish harvested from fecally polluted coastal waters are consumed raw. Cholera may also be transmitted by shellfish harvested from nonpolluted waters since V. cholerae O1 is part of the autochthonous microbiota of these waters.

Vibrio cholerae Serogroup Non-O1

Shellfish harvested from U.S. coastal waters frequently contain V. cholerae serogroup non-Ol. Consumption of raw, improperly cooked or cooked, re-contaminated shellfish may lead to infection.

Vibrio parahaemolyticus

Infections with this organism have been associated with the consumption of raw, improperly cooked, or cooked, recontaminated fish and shellfish. A correlation exists between the probability of infection and warmer months of the year. Improper refrigeration of seafoods contaminated with this organism will allow its proliferation, which increases the possibility of infection.

Vibrio vulnificus

This organism has been isolated from oysters, clams, and crabs. Consumption of these products raw or recontaminated may result in illness.

These are the parasites that can be found in raw seafood

Anisakis simplex and related worms

Seafoods are the principal sources of human infections with these larval worms. The adults of A. simplex are found in the stomachs of whales and dolphins. Fertilized eggs from the female parasite pass out of the host with the host's feces. In seawater, the eggs embryonate, developing into larvae that hatch in sea water. These larvae are infective to copepods (minute crustaceans related to shrimp) and other small invertebrates. The larvae grow in the invertebrate and become infective for the next host, a fish or larger invertebrate host such as a squid. The larvae may penetrate through the digestive tract into the muscle of the second host. Some evidence exists that the nematode larvae move from the viscera to the flesh if the fish hosts are not gutted promptly after catching. The life cycles of all the other anisakid genera implicated in human infections are similar. These parasites are known to occur frequently in the flesh of cod, haddock, fluke, pacific salmon, herring, flounder, and monkfish.

Diphyllobothrium spp.

The larvae of these parasites are sometimes found in the flesh of fish.

Eustrongylides sp.

Fish from fresh, brackish or salt water.

Ascaris lumbricoides and Trichuris trichiura

The eggs of these worms are found in insufficiently treated sewage-fertilizer and in soils where they embryonate (i.e., larvae develop in fertilized eggs). The eggs may contaminate crops grown in soil or fertilized with sewage that has received nonlethal treatment; humans are infected when such produce is consumed raw. Infected foodhandlers may contaminate a wide variety of foods.

Other parasites

· Eustrongylides sp.
· Acanthamoeba and other free-living amoebae

These are the virus that sometimes contaminate seafood

Hepatitis A Virus

HAV is excreted in feces of infected people and can produce clinical disease when susceptible individuals consume contaminated water or foods. Cold cuts and sandwiches, fruits and fruit juices, milk and milk products, vegetables, salads, shellfish, and iced drinks are commonly implicated in outbreaks. Water, shellfish, and salads are the most frequent sources. Contamination of foods by infected workers in food processing plants and restaurants is common.

The Norwalk virus family

Norwalk gastroenteritis is transmitted by the fecal-oral route via contaminated water and foods. Secondary person-to-person transmission has been documented. Water is the most common source of outbreaks and may include water from municipal supplies, well, recreational lakes, swiming pools, and water stored aboard cruise ships.
Shellfish and salad ingredients are the foods most often implicated in Norwalk outbreaks. Ingestion of raw or insufficiently steamed clams and oysters poses a high risk for infection with Norwalk virus. Foods other than shellfish are contaminated by ill food handlers.

Other Gastroenteritis Viruses

Viral gastroenteritis is transmitted by the fecal-oral route via person-to-person contact or ingestion of contaminated foods and water. Ill food handlers may contaminate foods that are not further cooked before consumption. Enteric adenovirus may also be transmitted by the respiratory route. Shellfish have been implicated in illness caused by a parvo-like virus.

Other virus that are associated with seafood
· Hepatitis E virus
· Rotavirus

These are the nature toxins that are found in seafood

Various Shellfish-Associated Toxins

Shellfish poisoning is caused by a group of toxins elaborated by planktonic algae (dinoflagellates, in most cases) upon which the shellfish feed. The toxins are accumulated and sometimes metabolized by the shellfish.

Types pf shellfish poisoning
-Paralytic Shellfish Poisoning
-Diarrheic Shellfish Poisoning
-Neurotoxic Shellfish Poisoning
-Amnesic Shellfish Poisoning

All shellfish (filter-feeding molluscs) are potentially toxic. However, PSP is generally associated with mussels, clams, cockles, and scallops; NSP with shellfish harvested along the Florida coast and the Gulf of Mexico; DSP with mussels, oysters, and scallops, and ASP with mussels.

Other toxins

· Ciguatera poisoning
· Scombroid
· Tetrodotoxin (Pufferfish)

12:23 AM;