Animal
Products and Food borne Illness
Scientific Perspectives - Professor Walter J.
Veith
Food
borne
illness is on the increase worldwide and in most cases animal products
are implicated as the main source of infection.
Reactions: ranging from mild to seriously debilitating to fatal, particularly in elderly people and infants. In the case of the botulism, as little as 0.1 g of food in which this bacterium has grown can be seriously debilitating, and in as many as 20% of cases botulism results in death.
Source of Contamination: micro-organisms or their toxins
Symptoms: diarrhea, vomiting or both, but can also involve other parts of the body as in the case of listeriosis (caused by Listeria) or botulism.
The
bacteria most often implicated with food borne diseases are:
Salmonella, Campylobacter, Listeria, Escherichia,
Staphylococcus and Yersinia.
Salmonella
Infections
Main Source: animals - Most outbreaks of the
disease are associated with animal products such as eggs, cheese
and improperly pasteurized milk. Salmonella outbreaks in the
UK have also been associated with infections in cattle and poultry,
and increases in salmonellosis, since 1985 have been largely
linked to a massive rise in cases caused by S. enteritis attributed
largely to poultry and hens’ eggs.[iii] The eggs do not
only become infected because of cracks in the shell, but they
become contaminated because the ovarian tissue of the fowls is
infected.
Spread: contagious from person to person.
Statistics: In the United States it is estimated that salmonellosis cases range from 790 000 to 3 690 000 per year, with as many as 7 041 deaths resulting from the illness.[i] In the last two decades there has been a steady increase in the number of reported cases, and in industrialized countries a dramatic increase seems to have occurred since the mid 1980’s. In both the United States and Canada there has been a steady increase in salmonellosis and between 1975 and 1988 the incidence of noticeable diseases had more than doubled in these countries.
Prevention: Prevention of contamination requires the co-operation of a wide variety of people from the breeders, veterinarians, epidemiologists, microbiologists and caterers, to every household cook. In view of this complexity it is difficult to control the spread of these diseases, particularly since transport and slaughter of animals increases the number of animals which carry Salmonella. In the UK the proportion of infected calves increases from 0.5% for calves leaving the farm to 36% after the slaughter, whereas a US study found that in the case of pigs 7% are infected when they leave the farm, but 50% are infected after slaughter.
Campylobacter
Infections
Source: poultry and milk
Statistics: Campylobacteriosis is a common cause of sporadic disease associated mainly with poultry and milk. In Canada this micro-organism is responsible for more cases of infectious diarrhea than is Salmonella, and in England and Wales it is the most common cause of this illness, with as many as 30 000 cases reported annually.[iv] In third world countries however the situation is much worse, and in African Populations campylobacteriosis is very common.
Listeria
Infections
Listeria infections are not nearly as common as those caused by Salmonella
or Campylobacter, but in view of the serious nature of the symptoms caused
by these infections, it is imperative that this organism be strictly controlled.
Symptoms: Listeria causes a range of symptoms ranging from mild flu to chronic septicemia. It can result in abortion, stillbirth or the birth of severely affected babies.
Source: Listeriosis is caused by eating contaminated food, and in Canada it has claimed more lives than any other food-borne bacteria. The bacteria have been isolated from a wide range of dairy products such as milk, even pasteurized milk, chicken, and sea foods including fish. The bacteria have also been found in coleslaw and even black pepper. Bacterial contamination is also not uncommon in frozen and even precooked chilled chicken.[v] In Spain, milk contamination by Listeria appeared to be seasonal, with a higher incidence in autumn and winter than in spring or summer and interestingly, the incidence was also lower on mountain farms than in plateau farms.[vi] Soft cheeses and pates are sometimes heavily infected. Listeria is particularly troublesome because it can continue to grow at refrigeration temperature.
Escherichia
Coli Infections
Symptoms: Some strains of E. coli can cause intestinal
infections.
Source: Animal products are again implicated in these infections, and milk and beef are the main sources of infection.[vii]
History: In May 1996, an epidemic of food poisoning rocked Japan, which the World Health Organization declared “unprecedented” in modern history. The outbreak started in Oku, a fishing village 180 km west of Osaka and spread to virtually every prefecture in Japan and effected more than 8000 people. The elderly and small children suffered most, and numerous deaths were reported. The infectious agent proved to be a particularly virulent strain (0157:H7) of E.coli. In this case, animal products were once again implicated. Since 1992 enterohaemorrhagic E.coli have become the most frequent causative agent of hemorrhagic diarrhea in North America, and in Europe infections are also becoming more frequent. Unlike other E.coli, enterohaemorrhagic E.coli possess cytotoxic shiga toxins which previously were known only in cases of Shigella dysenteriae infections.[viii]
Yersinia
Infections
Source: Milk and other animal foods are a source of
Yersinia enterocolitica
Symptoms: acute gastroenteritis.
History: In Belgium, Canada, the Netherlands, Australia and parts of Germany, infections from this organism are as common as Salmonella infections, and children in particular are vulnerable.
Statistics: The organism can grow at temperatures as low as 0 °C and the increase in refrigeration practices may select for this organism.
Further details can
be obtained in the book Diet and
Health by Professor Walter J. Veith available through our web
store.
The information on this web site is not intended to replace the medical profession, but to provide common-sense alternatives for healthy living.
References:
[i] Talami, R., La Vecchia, C., Decartli, A., et al. 1984. Social factors, diet and breast cancer in a northern Italian population. Br.J.Cancer. 49:723-9.
[ii] Todd, E. 1990. Epidemiology of food borne illness: North America. Lancet. 336:788-790.
[iii] Waittes, W.M and Arbuthnott, J.P. 1990. Food borne illness: an overview. Lancet. 336:722-725.
[iv] Cooke, E.M. 1990. Epidemiology of foodborne illness: U.K. Lancet. 336:790-793.
[v] Varabioff, Y. 1990. Incidence and recovery of listeria from chicken with pre enrichment techniques. Journal of Food Protection. 53(7):555-557.
[vi] Gaya, P., Saralegui, C., Medina, M., Nuez, M. 1996. Occurrence of Listeria monocytogenes and other Listeria spp. In raw Caprine milk. J.Dairy Sci.79:1936-1941.
[vii] Smith, H.R., Rowe, B., Gross, R.J., Fry, N.H., Scotland, S.M. 1987. Hemorrhagic colitis and vero-cytoloxin-producing Escherichia coli in England and Wales. Lancet. 1. 1062-65.
[viii] Ärzte Zeitung 1997. Gegen EHEC-Infektionen gibt es noch immer keine spezifische Therapie. Ärzte Zeitung 13. January. 1997.
[ix] Coghlan, A. 1996. Animal antibiotics ‘threaten hospital epidemics’. New Scientist.27 July 1996.
by Professor Walter J. Veith Phd.