INVESTIGATION OF FOOD BORNE DISEASE OUTBREAKS

1. INVESTIGATION OF FOOD BORNE DISEASE OUTBREAKS

2. FOOD BORNE DISEASES • Food borne diseases include those resulting from consumption of any solid food or milk, water or other beverages. • Foodborne illness usually arises from improper handling, preparation, or food storage. • Good hygiene practices before, during, and after food preparation can reduce the chances of contracting an illness.

3. All foodborne microbes and toxins enter the body through the gastrointestinal tract and often causes the first symptoms there. • Nausea, vomiting, abdominal cramps and diarrhea are frequent in foodborne diseases. • For example, infections with Escherichia colican be acquired through contaminated food, contaminated drinking water, contaminated swimming water,

4. OBJECTIVES OF INVESTIGATION • To determine how the food stuff became contaminated • If a growth of a toxigenic or infectious organism was involved ,to find how such growth could take place measures can be taken to prevent a repetition of the same set of conditions. this requires: • The location and idenification of the causative agent • Establishment of the means of transmission • Demonstation of the oppurtunity for growth of pathogen • Proof that pathogens has infected the victims

5. MATERIALS AND EQUIPMENTS REQUIRED • The equipment and supplies needed to equip a field kit to take food samples and transmit them to laboratory .they include: • Sterile containers • Sampling devices for sampling • A thermometer • An alcohol lamp • Sterile swabs in diluent • Sterile wrapping paper • Tape for sealing samples • Sterile paper towels • ice

6. The laboratory should be prepared to conduct the necessary microbiological and chemical tests. Prepared materails would include: • Sterile glassware • Water blanks • Appropriate culture media • Test solutions • Serological materials • Hydodemic syringes and needles as well as experimental animals

7. THE FIELD OF INVESTIGATION • Prompt reporting of an outbreak to the health department is the most important if the investigation is to be done successful • Reports usually come from physicians,hospitals,news,agencies. • Promptness in initiating the investigation also important because samples or specimens may be available for only a short time,information obtained promptly is usually more relaibletha delayed reports

8. GATHERING INFORMATION • a complete investigation is made immediately of the place or the places where the suspected meals or beverages were prepared and consumed • Information sought includes: • The menu for the meals • The source and method of preparation for each item of food on the menu • Methods of storage perishable foods • Sources of purchase of food serves • Observations are made on infections on exposed surfaces of the bodies of employees and on the sanitary condition of establishment

9. Geidt (1957) has suggested that outbreaks where not more than 20 persons are involved ,an attempt should be made to questions all of them • If about 50 persons were involved, about half of them should be questioned • The information obtained from them may be recorded on a form such as that entitled”case history questionnaire” • The case history should mentioned the column where there is a place to record age and sex,whether he or she became ill and if so the incubation time and symptoms,and which of the list of foods and beverages served were consumedd

10. COLLECTION OF FOOD SAMPLES • Samples of all left over foods and beverages hould be taken aseptically • Samples of perishable foods should be refrigerated immediately • Samples should be aspeticallytrnasfer to sterile containers • Label each sample to give information as to the type of food,the place and time of sampling • Each sample must be sealed,both inner and outer container with the date and time of sealing

11. Sometimes food samples sought often no longer such as food scraps from plates on which food was served,then collector could collect samples from: • Rinsing • Garbage • If canned food is involved then part of the used can of food is the first choice. • Food samples should be taken,labelled and sealed in the presence of witness if legal action is likely

12. COLLECTION OF SPECIMENS FROM THE HUMAN SOURCES • Specimens may obtain for the purpose of finding the causative organsim of the outbreak.it can be obtain from: • Pateints with food illness • From food handlers • Type of specimen to be taken depend on the illness concerned

13. Cultures from the nose or throat of food handlers are made to test for staphylococci able to produce enterotoxin • Faecal samples are used to test for organism :eg-salmonella and shigella • Blood specimens used for serological tests for indentification of certain pathogens • Vomitus may be tested when chemical poisoning is suspected

14. LABORATORY TESTING • the procedure in testing of samples of food or specimens from human sources depends upon the type of food and information available about the outbreak • The microscopic examination may give a clue to the causative organsim and it also indicate the numvers in the original food

15. INTERPRETATION AND APPLICATION OF RESULTS • The result of the field and laboratory investigation leads to incrimination of the guilty food ,location and elimination of the ultimate source of the cause of the food borne disease outbreak • When an outbreak is small, as within a family, the location of the food responsible for the illness • When the number of persons involved in an outbreak is fairly large,it is difficult to obtain complete and accurate data

16. Sometimes not all the persons may be available for interviewing,not all persons are equally susceptible to food illness,people are forgetful about just what they ate.

17. PREVENTIVE MEASURES • To keep foods as free as possible from contamination with pathogenic agents : • by selection of uncontaminated foods • By adequate pasteurization • By heat processing • By keeping away pathogen-bearing vermin • By avoiding contamination from infected food handlers or carriers • By generally good sanitary practice through out the handling ,preparation andserving of foods

18. To eliminate oppurtunities of growth of pathogens,toxigenic or infection in food • Keeping foods warm for long periods should be avoided • Reject suspected foods • To educate the public better concerning the cause and prevention of food borne illness and dangers involved