3. SEAFOOD-BORNE DISEASE AND ILLNESS

3.1 European Union
3.2 Japan
3.3 Canada
3.4 United States

Responsibility for the collection and recording of data on disease and illness when seafood is implicated on a worldwide basis is spread among a large number of agencies across many countries. Even within countries, multiple agencies or organizations are often involved. In Europe, data on food-borne illnesses is collected and reported by member country participants of the European World Health Organization (WHO) Surveillance Programme for Control of Food-borne Infections and Intoxication's (FAO/WHO 1995, 1992, 1990). The quality and detail of the data are dependent on each reporting member country. For the European Union, all member countries participate, with the most complete data for seafood-borne disease and illness reported by Denmark, Finland, Germany, Netherlands, Spain, Sweden and the United Kingdom. The European Union has also initiated a Rapid Alert System for food. This system is used to notify all member countries of the European Union when any member country detects unsafe food products. The food product, the cause of the danger and the country of origin are reported.

In the United States, the major sources of information on seafood-borne disease and illness are the Centers for Disease Control (CDC) Food-borne Disease Outbreak Surveillance Program and a data base on shellfish-associated food-borne cases maintained by the Food and Drug Administration (FDA) Northeast Technical Support Unit. The CDC data are derived from reports of food-borne outbreaks submitted by state health departments to the CDC. The FDA data come from books, news accounts, CDC reports, city and state health department files, Public Health Service regional files, case histories and archival reports (Ahmed 1991). Seafood-borne illness data for Japan are published annually by the Veterinary Sanitation Division, Environmental Health Bureau, Ministry of Health and Welfare, as part of the annual statistics for all food-borne illnesses. The number of incidents (outbreaks), patients (cases), and deaths are recorded (Japan Ministry of Health and Welfare 1987-1996). Data for Canada are collected by the Fish Inspection Directorate, Canadian Food Inspection Agency, Government of Canada. The data report annually the cause of illness, description of product causing the illness, product type, country of origin and the numbers of incidents and cases.

Seafood-borne disease and illnesses reported by each reporting area or system represent the minimum number of actual seafood-borne cases that occur. It is highly likely that many seafood-borne illnesses (like all food-borne illnesses) are not reported by the patient nor recognized as a food-borne illness. However, these data collection agencies provide the only reliable sets of data available.

3.1 European Union

Available data for the European Union (FAO/WHO 1995, 1992, 1990) for those member countries with more complete data usually report the number of outbreaks when fish and shellfish are implicated as the source of the outbreak⁴. The data reported do not usually attribute the number of cases⁵ of disease and illness resulting from the outbreaks. Disease or illness outbreaks from fish and shellfish between 1983 and 1992 ranged from 1.9 percent of total food-borne outbreaks in United Kingdom (Scotland) to 12.4 percent in Denmark. When the known food source was identified the range of fish and shellfish outbreaks was from 4.4 percent in the United Kingdom (England/Wales) to 16.1 percent in Finland (Table 2).

The Food and Veterinary Office of the European Union has also initiated a Rapid Alert System for food. This system is used to notify all member countries of the European Union when food products are detected that are a source of danger to health. The source of danger and the country of origin are reported. Between 1992 and November 1997, the 71 seafood alerts from this system represented 42.5 percent of all food alerts. Seafood products implicated and the number of the 71 alerts in which each was implicated were: live mussels (14), tuna fish products (9), fish products, oysters, squid, and chilled raw sole (4 each), shrimp, octopus and seafood (3 each), shellfish, crawfish, scallops, cuttlefish, anchovy and frog legs (2 each), and Nile perch, frozen mussels, frozen perch, bivalve molluscs, king prawn, salmon, chilled raw mullet fillets, fish brochettes, canned fish, clams, frozen mussels (1 each).

Table 2. Summary of the total number of food-borne illness outbreaks attributed to fish and shellfish, selected countries of the European Union, 1983 to 1992

Source: Derived from: (FAO/WHO 1995, 1992, 1990)

1. Data too incomplete to report the remaining countries
2. 1983-1989
3. 1983-1989
4. 1983, 1988-1992
5. 1983-1989
6. 1983-1989, 1991
7. 1983-1989
8. 1983-1984, 1986-1991
9. 1983-1984, 1986-1991

Principal sources⁶ of danger to health⁷, and the number of times each was reported were: Salmonella (27), diarrhetic shellfish poisoning (16), paralytic shellfish poisoning (8), Vibrio parahaemolyticus (7), histamine (5), Vibrio cholerae (4), Listeria monocytogenes (3), Staphylococcus and unspecified contamination (2 each), and Bacillus cereus, scombroid toxin, botulism, Clostridium bifermentans, packaging problem (1 each).

Thirty-three different countries were listed as the exporting country of product on which an alert was reported. Each is listed with the number of times a product originating in that country received an alert: India (7), Portugal and Thailand (5 each), Spain and China (4 each), United Kingdom, Senegal, Guinea and Peru (3 each), France, Italy, Morocco, Kenya/Uganda, Turkey, Ivory Coast, Nigeria, Vietnam, China, Mauritania, Albania (2 each), Belize, Greece, Shetland Isles, New Zealand, Sweden, Sri Lanka, Oman, Malaysia, Denmark, Tunisia, Kenya, and Netherlands (1 each).

3.2 Japan

Categories reported by the Japanese data collection system are shellfish, swellfish (puffer fish) and other, and fish paste and other products of fish and shellfish. Ninety-three percent of the seafood-borne illness outbreaks in Japan from 1987 to 1996 are from fish and shellfish, resulting in 87 percent of the cases (29 012) (See Table 3). Thirty-four deaths occurred during the ten-year period. All but two were from swellfish. Total outbreaks from 1987 to 1996 numbered 1 475 resulting in 33 253 cases.

Table 3. Summary of the number of seafood-borne illness outbreaks and cases attributed to fish and shellfish in Japan, 1987 to 1996

Source: Derived from (Japan Ministry of Health and Welfare 1987-1996)

When the cause of the food-borne illness is known, 18 percent of the outbreaks are from all fish and shellfish sources resulting in nine percent of the cases. Twenty-six percent of food-borne illness deaths in Japan are from all fish and shellfish and products of fish and shellfish (See Table 4). For fish and shellfish, most illnesses caused by bacteria are from Vibrio parahaemolyticus at 75 percent of bacterial disease cases. Salmonella, Staphylocococcus aureus, Escherichia coli and Clostridium perfringens are the other major sources of illness. For products of fish and shellfish, these same five bacteria are the leading causes of illness but the distribution of cases among the bacteria is more evenly spread (Table 5). Natural poisons and chemical substances rank six and seven among both fish and shellfish-borne diseases and fish and shellfish product-borne illnesses.

Table 4. Percentage of total food-borne illnesses attributed to seafood-borne illness outbreaks, cases and deaths in Japan, 1987 to 1996

Source: Derived from (Japan Ministry of Health and Welfare 1987-1996)

Table 5. Summary of the number of seafood-borne illness outbreaks and cases by known causative agent in Japan, 1987 to 1996

Source: Derived from (Japan Ministry of Health and Welfare 1987-1996)

3.3 Canada

From 1991 to 1997, a total of 78 seafood-borne illness outbreaks resulting in 169 cases were recorded in Canada. The top three causes for outbreaks were from histamine, fecal coliforms, and decomposed products, which accounted for 62 percent of the cases. The top three reasons for total number of cases were from histamine, decomposed product and paralytic shellfish poisoning, together representing 60 percent of all cases (See Table 6).

Table 6. Summary of the number of seafood-borne illness outbreaks and cases in Canada by causative agent, 1991 to 1997

Source: Derived from (Andruczyk 1998)

A total of 29 different species of fish and shellfish and or seafood products were implicated in seafood-borne illnesses. The top six in number of outbreaks were mussels (13), clams (12), tuna (10), barracuda (5), and marlin (3). These six represented 56 percent of the outbreaks. The top seven in number of cases were tuna (37), mussels (28), clams (20), barracuda (13), lobster tails (12), marlin (9) and oysters (9), representing 76 percent of all outbreaks. All other species or products implicated (one to three outbreaks; one to six cases) were whelk, mahi mahi, mackerel, swordfish, crab meat, salmon, oysters/quahogs, clams and dips, haddock and clams, halibut, sole fillets, sharks, scallops, salmon/shrimp/scallops, pollock, chicken haddie, shrimp, quahogs, kippers and parrotfish/doctorfish.

Seafood products causing illnesses in Canada from 1991 to 1997 came from 13 different countries or groups of countries. The top three countries in products causing outbreaks were Canada (40) and the United States (19), representing 76 percent of the outbreaks. Other countries implicated in one to four outbreaks and/or one to six cases were Singapore, Ecuador, Thailand, China, Canada/United States, Peru, India, Cuba, Fiji, Guyana and Trinidad/Tobago. Four outbreaks (six cases) could not be traced to the product source.

3.4 United States

In the United States, seafood-borne disease or illness reported by the Centers for Disease Control from 1978 to 1987 totaled 558 outbreaks involving 5 980 cases. However, fish and shellfish constituted only 10.5 percent of all outbreaks and 3.6 percent of all cases when food-borne illnesses from all foods are considered. The number of people made ill from beef (4 percent) and turkey (3.7 percent) exceeds the seafood total, whereas pork (2.7 percent) and chicken (2.6 percent) are slightly lower. If fish and shellfish (2.3 percent) and fish (1.2 percent) are considered separately, the number of reported cases from each is lower than for any animal meat product. However, when only muscle foods (red meat, fish, poultry) are consumed, seafood-borne illness represent 56 percent of all outbreaks and 21 percent of all cases when incidents of unknown etiology are included. These data and those following for the United States are available in more detail (Ahmed 1991).

From 1978 to 1987, the CDC reported 38 seafood-associated outbreaks (351 cases) related to finfish and other non-shellfish sources. All but three outbreaks were from infectious agents associated with processing and preparing the seafood. Unknown agents caused another 16 outbreaks (203 cases). Forty shellfish-associated outbreaks (476 cases) were reported from known pathogenic sources. Another 88 outbreaks (3 271 cases) were from unknown sources. Forty-nine percent were due to infectious agents generally associated with fecal pollution, and 46 percent were from infectious agents generally associated with processing and preparation. From 1978 to 1987, the NETSU reported 2 198 cases of shellfish-associated outbreaks. Naturally occurring aquatic agents caused 15 percent of the outbreaks and 85 percent were due to infectious agents generally associated with fecal pollution. An additional 5 098 cases could not be associated with a known agent (Ahmed 1991).

CDC reported shellfish outbreaks (40 when etiology known) were associated with Vibrio parahaemolyticus (15), Hepatitis A. virus (7), Shigella (4), Salmonella (3), Vibrio cholerae O1, other viral, Non-O1 V. cholerae, Clostridium perfringens, Bacillus cereus (2 each) and Staphylococcus (1). Cases (476 when etiology known) were associated with V. parahaemolyticus (176), Salmonella, non-typhi (80), Shigella (77), other viral (42), Hepatitis A. virus (33), Clostridium perfringens (28), V. cholerae O1 (14), Non-O1 V. cholerae (11), Staphylococcus aureaus (9), and Bacillus cereus (6). NETSU cases (2 182 when etiology known) were associated with unspecified hepatitis (1 645), Non-O1 V. cholerae (120), V. vulnificus (100), Shigella (84), Norwalk and related viruses (82), V. parahaemolyticus (52), Hepatitis A. virus (45), Plesiomonas (18), Campylobacter (16), V. cholerae O1 (13), Aeromonas (7), Vibrio mimicus, Vibrio hollisae, Vibrio fluvialis (5 each), Non-A, non-B hepatitis (1).

Finfish and other seafood-associated outbreaks (35 when etiology known) were from Clostridium botulinum (26), Salmonella (non-typhi), Shigella (3 each), hepatitis A. virus (2 each), and Staphylococcus aureus, Clostridium perfringens, Vibrio cholerae O1 and Bacillus cereus (1 each). Cases (312 when etiology known) were from Hepatitis A. virus (92), Salmonella (67), Shigella (60), Clostridium perfringens (46), Clostridium botulinum (38), Bacillus cereus (4), Staphylococcus aureus (3) and Vibrio cholerae O1 (2).

Naturally occurring fish and shellfish poisons that have been problematic in the United States are ciguatera, scombroid poisoning and paralytic shellfish poisoning (PSP). From 1978 to 1987, ciguatera was responsible for 179 outbreaks (179 cases), scombroid poisoning for 157 outbreaks (757 cases) and PSP for 13 outbreaks (137 cases). Most ciguatera outbreaks were in Hawaii, Guam and Puerto Rico with the implicated fish being in order of incident amberjack, snappers, groupers, goatfish, Po'ou, jacks, barracuda, Ulua, wrasse, surgeonfish, moray eel, papio, roi, rabbit fish and parrot fish (Ahmed 1991). Scombroid poisoning resulted from consuming mahi mahi, tuna, bluefish, raw salmon, marlin, mackerel, blue ulua, opelu, and redfish. PSP incidents were the result of consuming mussels, clams, oysters and scallops. More details on these seafood illness implications and other diseases such as those resulting from chemical contamination are available (Ahmed 1991).

For the United States, crabs, shrimp and oysters are the most often implicated sources of pathogens that naturally occur in marine or freshwater environments. Most illnesses from naturally occurring organisms are associated with eating under-cooked or raw shellfish, particularly raw molluscan shellfish (Ahmed 1991). Other seafood problems are normally due to recontamination or cross-contamination of cooked product by raw product, followed by time/temperature abuse.