Food born diseases
Instructional Objectives: At the end of the lecture the student would be able to: 1-Demonstrate the main clinical characteristics of food born diseases. 2-Point out the occurrence of the disease. 3-List the causative agent, mode of transmission, incubation period, and period of communicability of food born diseases. 4-List the main preventive measures of food born diseases. 5-Describe the control measures of food born diseases.Terms applied to illnesses acquired by consumption of contaminated food. ( food born intoxicant &food born infections ) 1.Illness caused by toxicants elaborated by bacterial growth before consumption : (Staphylococcus aureus & bacillus cereus) 2. toxins elaborated in intestine (Clostridium perfringens) 3.Illness caused by bacterial infection with short incubation period ( salmonelosis )
Food born disease outbreak : Occurrence of illness within usually short but variable period of time among individuals who have consumed certain foods in common.
Staphylococcus food intoxication An intoxication not infection Abrupt onset Severe nausea , vomiting , cramps , often accompanied by diarrhea Some time subnormal blood pressure & temp. Self limiting disease ,death are rare Most people are susceptible
Dx : Clinical features ,history &incubation period In an outbreak recovery of large no. Of staphylococcus on routine culture media or detection of enterotoxin from an epidemiologically implicated food confirms the DX *Absence of staph. On culture of heated food does not rule out the DX
Mode of transmission: foods involved are particularly those that come in contact with food handlers hands either without subsequent cooking or with inadequate heating or refrigeration: Source : (human)…Purulent discharges of an infected finger ,eye ,abscesses, naso-pharyngeal secretions or apparently normal skin (bovine)…contaminated milk or milk products
Prevention: 1.Education of food handlers in Strict food hygiene Sanitation &cleanliness of kitchens Proper temp. control Hand washing 2. Reduction of food handling time (initial preparation to service) to an absolute minimum 3. Temporarily exclude people with boils, abscesses or other purulent lesions of hands, face or nose from food handling
Salmonellosis
It is bacterial disease commonly manifested by an acute enterocolitis Sudden onset of headache , abdominal pain ,diarrhea ,nausea & some times vomiting Dehydration may be severe especially among infants &elderly Fever is almost always present Anorexia &diarrhea often persist for several days Septicemia or focal infection may develop Deaths are uncommon except in every young ,very old ,debilitated &immunosuperessedInfectious agent: About 2000 serotype : salmonella typhimuruim & S. enteriditis are the most commonly reported Occurrence : World wide Incidence of infection is highest in infants &young children It may occur is small outbreaks About 60-80% of all cases are sporadic
Reservoir : 1.Wide range of domestic &wild animals: Poultry, ,cattle ,rodents, dogs, cats 2.Human i.e patient ,convalescent carriers & mild unrecognized cases 3.Chronic carriers are rare in humans but prevalent in animals &birds
Mode of transmission : By ingestion of organisms in the food derived from infected animals or contaminated by stool of infected animal or person Raw or undercooked eggs &egg products Raw milk &milk products Contaminated water Meat &meat products Poultry &poultry products
Incubation period From 6-72 hrs , usually about 12-36hrs Period of communicability Throughout the course of illness From several days to several weeks
Prevention 1.Education of food handlers the : hand washing Refrigeration Thoroughly cooking of food of animal origin Maintain sanitary kitchen 2.Educate the public to avoid consuming raw or incompletely cooked eggs
3.Exclude individuals with diarrhea from food handling 4.Educate the known carriers on the need for very careful hygiene &hand washing after defecation &prior to food handling 5.Adequately cook or heat-treat animal derived food prepared for consumption to eliminate pathogens
Control: 1.Reporting 2.Isolation a. Wearing gloves and gowns during handling of feces &contaminated bed linen in hospitalized patients b. Exclude patients from food handling c. Release to return to work requires 2 consecutive negative stool culture for salmonella collated not less than 24 hours apart
Note: if antibiotic have been given the initial culture should be taken at least 48 hrs after the last dose 3. Disinfection 4. Investigation of contacts 5. Specific Rx :uncomplicated :none except rehydration Antibiotics of choice: (Ciprofloxacine, Ampicillin, Amoxicillin, TMP-SMX, Chloramphenicol )
Botulism
There are 3 types of botulism 1.Food born (the classic type) 2.Wound 3.Infant The site of the production of the toxin is different for each type ,but all shares in common the flaccid paralysis that results from botulism neurotoxinDX: Demonstration of botulinum toxin in: Serum , stool, gastric levage , and incriminated food Culture of C. botulinum from: gastric aspirate , stool, of clinical case
Infectious agent:Food born…… toxin (heat labile) produced by C. botulinumToxin is produced in:Improperly processed ,canned, low acid or alkaline foodUnpasteurized foods held without refrigeration especially in airtight packaging (Toxin is destroyed by boiling)
Reservoir Spores are present in soil world wide
Incubation period:Food born… 12-36 hrs .some times several days the shorter the incubation period the more severe the disease &the higher the CFRPrevention: 1-Ensure effective control of processing of commercially canned and preserved food 2-Education of those concerned with home canning regarding the: Proper time, pressure, &temp. required to destroy spores Effectiveness of boiling home canned vegetables for at least (10) minutes to destroy the toxin 3- Bulging containers should not be opened &foods with off-odors should not be eaten or even tested 4-Identified source such as honey ,should not be fed to infants
Control Reporting Isolation :not required The implicated food should be detoxified by boiling before discarding Containers &utensils should be sterilized by boiling or chlorine disinfectant Sanitary disposal of stool of infants cases