17.Foodborne.diseasespptx.pdf

Foodborne Diseases Taonga Musonda  Foodborne diseases Foodborne diseases are diseases that are caused by consumption of food contaminated by pathogenic microbes They can also be caused by chemicals or natural toxins They are also known as food poisoning or foodborn...

Foodborne Diseases Taonga Musonda  Foodborne diseases Foodborne diseases are diseases that are caused by consumption of food contaminated by pathogenic microbes They can also be caused by chemicals or natural toxins They are also known as food poisoning or foodborne illnesses These are usually acute and of sudden onset  Foodborne Diseases 3 types: 1. Foodborne infection Ingestion of pathogenic microbes that penetrate the intestinal mucosa and multiply 2. Foodborne intoxication (poisoning) Ingestion of pre-fomed toxins in food 3. Food Toxico-infection Combination of both foodborne infection and foodborne intoxication Microbes produce toxins insitu when ingested along with food, e.g. Bacillus cereus food poisoning Food Infections vs Food Intoxication Properties Food Infections Food Intoxication Invasion and Multiplication Invade and multiply in intestinal No invasion or multiplication mucosa Incubation period Hours to days Minutes to hours Signs and Symptoms Typically diarrhoea; also nausea, Typically Vomiting; also nausea, vomiting abdominal cramps, fever diarrhoea, weakness, respiratory failure, numbness, sensory/motor dysfunction Communicability Communicable – spreads from Non-communicable person to person Enabling Factors Inadequate cooking, cross Inadequate cooking improper contamination, poor personal handling hygiene, bare hand contact Cause Microbial; Bacteria, Viruses, Toxins (Natural, chemical or Parasites/Protozoa microbial preformed toxins)  Salmonella typhirium food poisoning Transmission is via consumption of contaminated food Faecal oral route After being ingested, bacteria binds to intestinal epithelial cells with use of fimbria and invades the mucosa Bacteria multiplies and induces an inflammatory reaction Incubation periord – 8-24 hours  Salmonella Symptoms Abdominal pain Fever Diarrhoea Nausea and vomiting may happen first, but usually do not persist once the pain & diarrhoea begin Recovery is usually within a week and the patient usually does not require antibiotic treatment.  Escherichia coli food poisoning Enterohemorrhagic E.coli ( E.coli O157:H7 serotype) Produces verotoxin identical to shiga toxin Attach to the mucosa of the large intestine Produced toxin has direct effect on intestinal epithelium resulting in diarrhoea  Campylobacter Food borne Disease Genaral characteristics Oxidase positive Non-spore forming They are microaerophilic and thermophilic – growing well at 42OC  Campylobacter Foodborne Disease Transmission: Infections are acquired by consumption of contaminated food - poultry, milk or water. Oral fecal route Incubation period: 2-11 days Virulence factors Flagella Adhesion proteins Serine protease Cytolethal distended toxin  Campylobacter Food borne Disease Pathogenesis Low infectious dose (500-800 organisms) Invades mucosa of the colon Produces a thermo labile enterotoxin ,CDT, which causes cytotoxicity CDT also triggers secretion of IL-8 as an immune response Apoptosis and thus leading to inflammatory diarrhoea (bloody watery)  Campylobacter Foodborne Disease Symptoms Bloody diarrhoea Fever Abdominal cramps Generally self-limiting in 3 - 5 days but may last longer  Clostridia food poisoning 1. Clostridium botulinum Spores resist boiling for long periods; moist heat at 121 OC is required for certain destruction Spores may germinate and grow in food in sufficient anaerobic conditions When they grow, they elaborate a neurotoxin of extraordinary activity Botulinum toxin is one of the most potent toxins with a lethal dose of