UNIT 14 FOOD INFECTIONS AND INTOXICATIONS Structure 14.1 Introduction 14.2 Food Infections and Intoxications 14.3 Food poisoning of bacterial origin 14.3.1 Salmonella food poisoning 14.3.2 Staphylococcal food poisoning 14.3.3. Botulism 14.3.4 Clostridiwn perfigens food poisoning 14.3.5 Bacillus cereus food poisoning . 14.4 How to prevent/control food infections and intoxications? 14.5 Food poisoning of non-bacterial origin 14.5.1 Ergotism 14.5.2 Aflatoxicosis 14.5.3 Lathyrism 14.5.4 Argemone toxicity 14.6 Let Us Sum Up 14.7 Glossary 14.8 Answer to Check Your Progress Exercises 14.1 INTRODUCTION Yo11 would have read in newspapers many instances of food poisoning reported from several places sometimes resulting in many deaths. These instances occur due to food infection or food intoxications due to the contamination of food with certain bacteria or their toxins, inorganic chemicals, poisons of animal origin or poisonous substances derived from plant sources. Food infections and intoxications will cause acute symptoms of either vomiting or diarrhoea or both. The characteristic features of this sort of episode will include (a) sudden onset of illness (b) common source of food (c) simultaneous involvements of many persons, and (d) manifestation of same type of complaints by all affected. In this unit, you will learn about food borne diseases which occur due to the consumption of toxic materials in foods (food toxins) and intoxications due to intake of food which contains toxins formed by bacteria. Food infections occurring due to intake of food containing large numbers of microorganisms causing intestinal diseases like salmonella is the second focal point of the unit. i \ Objectives I \ After studying this unit, you will be able lo: list the common food toxins, food infections and intoxications prevalent in our community. 0 identify their causes, symptoms and complications, and desc6be the management, prevention and control of these conditions. \ 14.2 FOOD INFECTIONS AND INTOXICATIONS Food infections and food intoxications are the two categories of food poisoning. What do we mean by food poisoning? Food poisoning refers to the harmful effects of consumirp food contaminated by microorganisms (bacteria, viruses, moulds fungus). You may recall reading about these microorganisms in unit 16, block 4 of course 1. \ Let us now understand how food infection is different from food intoxications? Food Borne Diseases, Food When we consume contaminated food (i.e. microorganisms are already present in the Infeetloas .ad IatoxlcsLloa food), the microorganisms enter the body, begins to grow and produces the disease. This is food infection. Common diseases infections caused as a result of eating contaminated food include dysentery, cholera, typhoid, infectious hepatitis (Viral infection). On the othcr hand, consuming foods which contains toxic substances produced by the microorganism (in the food) leads to food intoxication. Botulism (an illness) is one example of fmd intoxication. The toxin produced by clostridium botulinum (a bacteria) in food, can cause death. Moulds, fungus also produce toxins in foods. Ergot fungus causes ergotism. Food poisoning i.e. food infections and intoxications is therefore of two types : a) Bacterial origin, and b) Non-bacterial origin. The following section presents a detail discussion on the two types. 14.3 FOOD POISONING OF BACTERIAL ORIGIN You have already leamt that food poisoning can occurs due to the contamination of food by living bacteria or by toxins liberated by them. Different bacteria are known to cause the poisoning. Let us now leam what these different bacteria are which can cause food poisoning and how these organisms get into the food. 14.3.1 Salmonella food poisoning Salmonella food poisoning is a very common form of food poisoning. Its increase in incidence in recent years is attributed to increase in communal feeding activities like in marriages and large parties, increased popularity of ready-to-eat foods, especially tinned foods and certain household practices. What is the causative organism? The common organisms (bacterias) belonging to salmonella specie involved in food poisoning are Salmonella typhimurim, Salmonella Cholera-suis and Salmonella- enteritidis. mat is the source of infection? Food gets infected through contaminated meat, milk and milk products, poultry, egg and egg products. Food also can get infected by rats and mice when the food gets contaminated by their urine and faeces. How does the poisoning occur? Contamination of food may occur at the source or by cross-contamination (due to excess of organisms from surroundings or their foods) during processing of food. It can also occur due to contamination by a carrier or fecal contamination by food handler. The conraminant organisms on ingestion multiply in the intestine and give rise to sudden . onset of diarrhoea or vomiting or both. What are the signs and symptoms of salmonellosis? The onset of the episode is usually sudden. accompanied by chills, fever, nausea, vomiting and a profuse watery diarrhoea lasting for 2 to 3 days. Death is reported to occur in about one per cent of cases. Who are susceptible? Generally all are susceptible. Debilitating conditions increase the susceptibility. What is the incubation period? The incubation period varies from 12-24 hours. What is the period of communicability? The period of communicability extends throughout the course of the disease. Undetected c~enare also known. 14.3.2 Staphylococcal food poisoning Food Infections and Intoxlurtlom Staphylococcus is another common form of food poisoning due to bacterial origin. Staphylococcus toxin is the poison developed by the bacteria when it grows in food. Whet is the causative organism? Staphylococcus aureus are the causative organisms for staphylococcal fc~$poisoning. When the enterotoxin liberated by these strains contaminates the food items, the toxicity occurs. Optimal temperature for th~formation of the enterotoxin by the bacteria is observed to be between 35 to 37 C. The toxins formed are relatively heat stable and resist boiling upto 30 minutes. What is the source of infection? Staphylococci are plentiful in nature. They are found on the skin, in the nose and throat of humans and animals. These are the common organisms causing boils and common skin infections. Udder infection by Staphylococci in milch cattle leads to contamination of milk and milk products causing episodes of food poisoning. Cooked ham, or other meat, chopped or ground food, warmed-over food are the other source of infection. \ What is the reservoir of infection? You will find that the most common source of the organism is a food handler who might be suffering from a nose, throat or skin infection (boils, pimples etc.). Another source is milk of a cow with udder infection. If you store food preparations which are thus infected for several hours at room temperature, the bacteria (disease causing organisms) multiply and produce toxins which cause the poisoning. What is the mode of transmission? Consumption of contaminated food products like pastries, custard, salads, sandwiches, sliced meats and meat products. Contamination occurs from the purulent discharges from infected fingers, infected eyes, abscesses, nasal secretions and apparently normal skin of food handlers coming in contact with food items, where the bacteria multiply when allowed to stand for several hours before serving. These bacteria liberate toxins and cause outbreaks of food poisoning. How does the poisoning occur? Food poisoning occurs because of the toxins liberated by the organisms growing in the contaminated food. As you have already learnt that the toxin is heat resistant, it can remain in the food and cause harm even after the actual organisms have died. The effect of poisoning is due to the action of toxin on the gut and nervous system. What are the signs and symptoms? The illness in staphylococcus poisoning is sudden and usually manifests by onset of vomiting, abdominal cramps and loose motions. When the disease is severe, blood and mucus may appear in the stools. One does not get fever and can recover in one to three What is the incubation period? The incubation period in staphylococcal food poisoning is short and is between 1-6 14.3.3 Botulism Botulism is a very serious form of food poisoning but fortunately its occurrence is rare. If it occurs, it can kill upto the extent of two thirds of its victims. What is the causative organism? The organism responsible is Clostridium botulinum and it is the toxin liberated by the organism that causes the food poisoning. 55 Food Borne Diseases, Food What is the source of contamination? lnfectlons and Intoslcatlon The organism that causes poisoning is widely distributed in soil and dust. Toxin produced by Clostridium botulinum is the toxic agent. Toxins are produced in improperly processed foods and umefrigerated foods of low acidity. It is also observed to be present in the intestinal tracts of domestic animals. The organism enters the food as spores. The foods that are commonly affected by botulism poisoning are home preserved foods (pickles, vegetables), home made cheese etc. What is the incubation period? Incubation period for botulism is reported to be from 12 to 36 hours. How does the poisoning occur? Once spores of the organisms enter the food, under favorable anaerobic conditions they grow and liberate the toxin. The toxin thus liberated acts on the nervous system. The effects of the toxin on the gastrointestinal system are minimal. What is the mode of transmission? Consumption of contaminated food usually consisting of inadequately processed canned items used as it is, without adequate cooking, is responsible for the msmission of the disease. Incidence of botulism, as a result, of contamination from the infected wounds also is known. What are the signs and symptoms? The prominent symptoms in botulism include: difficulty in swallowing, blurring of . vision, double vision, closing of the eyelids, painful joints, weakness of the muscles and sometimes even the paralysis of both hands and legs.