FOOD BORNE MICROBIAL DISEASE

OUTLINE DEFINITON STATISTICS OF FOOD-BORNE MICROBIAL DISEASE VIRAL DISEASE AND FOODS TOXIGENIC FUNGI IN FOODS

DEFINITION Food-borne illness arises through the consumption of a food contaminated with a pathogenic species. The food ray serve in two capacities in this food-microorganism-man interaction: foods as vectors of patogens foods as substrates for patogenic growth

Foods as vectors of patogens Micro-organisms associated with these cases generally have a low infective dose ie. only a very small number of the pathogen cells (<100) need to be consumed to bring about a consumer response or reaction. These include typhoid (Salmonella typhi), dysentery (Shigella dysenteriae), cholera (Vibrio cholera) and tuberculosis (Mycobacterium).

Foods as substrates for patogenic growth Foods act as substrates for the growth and multiplication of pathogenic Species. Which when developed to high enough numbers, cause ilIness on human consumption. These are the Classical cases of microbial based food Poisoning. Two sub-groupings may be recognized.

Consumer infection: Upon consumption ion the pathogenic species concerned multiplies in the alimentary tract thereby bring about consumer response or reaction. (Salmonella species. Clostridium pefringens. Vibrio parahaemolyticus, enteropathogen Escherichia coli strains and Shigella species). Consumer intoxication: In this case it is the consumption of a toxic product previously produced in the food by microbial growth which brings about a consumer response. (Staphylococcus aureus and Clostridium botulinum).

STATISTICS OF FOOD-BORNE MICROBIAL DISEASE

Food poisoning statistics require the following three pieces of information : The causative food The origin of the causative food, and The nature of the causative organism.

Statistics gathered in the U. K. , U. S. A Statistics gathered in the U.K., U.S.A. and Australia have continually shown that approximately 70% of all food poisoning outbreaks are associated with the consumption of meat and poultry products. Sea foods contribute to another of the outbreaks while egg and dairy products are responsible for around.

Virusal Disease and Foods Viruses, unlike bacteria, cannot reproduce outside a living host cell. Viruses pathogenic to men cannot reproduce in a food so that there can never be more viruses in a food than were introduced at the time of contamination. Offsetting this inability of viruses to multiply to large numbers in the food is their generally low infective dose.

Because of their more simple chemical, physical and biological nature, viruses are quite often more resistant to food processing and storage stresses than bacteria. Consequently, food processing operations designed to eliminate pathogenic bacteria may not necessarily kill viral contaminants. The technology for viral detection in foods is only in the developmental stages and is mainly based upon physical and chemical methods.

Toxigenic Fungi in Foods Moulds have not only served to synthesize antibiotics but also to produce some foods. Moulds also cause food spoilage but this spoilage has usually been considered as unaesthetic rather than being dangerous to consumer health.

. In fact, it is now well established that many fungi, on contamination and growth in food products, produce toxic substances generally termed mycotoxins. A mycotoxin has been defined as fungal metabolite producee in foodstuffs (or feedstuffs) that causes illness or death when ingested by man or animals.

Mycotoxins of Possible Human Health Significance

Control of mycotoxins in foods is best achieved by preventing mould contamination and subsequent mould growth. Not all moulds are known to produce mycotoxins. Mycotoxin presence in foods can be determined by chemical extraxtion from the food followed by identification of the mycotoxin using chromatographic procedures.

Possible Routes for Mycotoxin Contamination of Human Foods