Human Food Poisoning (disease control in animals to benefit public health)

What is foodbourne infection?

• Infection with an agent (usually bacterial or viral) that results in often diarrhoeal disease

• Frequently zoonotic

What are some examples of foodbourne infection?

Salmonella, E.coli, Norovirus

What is food poisoning?

Exposure to toxins (microbial or other) that results in disease

What is food poinsoning frequently caused by?

Contamination, poor storage or poor handling

What are some examples of food poisoning?

Staphylococcus toxin, bacillus enterotoxin, afalotoxins from fungi

What is food security

Exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food which meets their dietary needs and food preferences for an active and healthy life.

What are the UK’s major foodbourne diseases?

• Salmonella enterica

• Escherichia coli

• Compylobacter

• Listeria monocytogenes

• Clostridium perfringes

• Hepatitis E

• Norovirus

What is the main cause of human bacterial gastroenteritis?

Campylobacter

caused by c.jejuni & c.coli

What type of bacteria are campylobacter?

Gram negative spiral rods

What are the human symptoms of campylobacteriosis?

• D+ (frequently with blood in faeces)

• Abdo pain

• Fever

• Headache

• Nausea and/or vomitting

Who are at main risk of campylobacteriosis

• Under 5s

• Over 65s

• Bowel cancer patients

• Those taking proton pump inhibitor drugs

What are the main sources of campylobacter?

• Poultry meat

• Red meat

• Water

Why are broiler chickens associated with campylobacter?

• Core temp (41-42 degrees) suits campylobacter

• Ceca supports high levels of growth

• High shedding levels in faecal and caecal droppings

How can production and processing of chicken lead to campylobacter spread?

• biosecurity breakdowns

• transport increases stress = more shedding

• cross contamination on production lines

• low infective dose - can cause disease in low doses

2017 regulations to reduce campylobacter

• Food Standards Agency introduced targets for reducing risk

• Reduce campylobacter levels to less than 1000 Colony Forming Units (CFU)

Is it possible to rear campylobacter-free chickens?

Yes

Would cost £20-£50 per bird though

What is the main pathotype of concern for E.coli?

EHEC - Entero Haemorrhagic (STEC/VTEC)

Where does E.coli live in animal host?

Distal rectum

Even if not shed, bacteria from the GI tract may contaminate meat at time of slaughter

Yersinia & Shigella

Both similar to salmonella and E.coli

Causes human dysyntery

Describe Listeria monocytogenes

• Gram positive rod-shaped intramacrophage pathogen

• May be zoonotic (including foodborne)

What is Literia Monocytogenes associated with?

• Cooked meats

• Pate

• Soft cheese

• Smoked fish

• Pre-prepared sandwiches

• Cook-chill meals

can grow well at low temperatures

What are the human symptoms of listeriosis?

Either gastroenteritis or flu-like symptoms (mild)

Who is at risk of listeriosis?

Pregnant, elderly & immunocompromised

What do enterotoxins usually induce?

• D+

• V+

Bacillus food poisoning is associated with which foods?

Pulses and rice

Why shouldn't you reheat cooked rice?

• Cooking kills vegetative bacteria but not spores

• When left and not chilled more spores form which produce toxins

• When re-heated and consumed, spores are eaten

Which two species of clostridia may cause severe food poisoning?

Clostridium perfringens & Clostridium botulinum

C.botulinum poisoning is associated with which foods?

• Poorly canned or bottled foods

• Honey

less of a problem now

C.perfringens germinates in which conditions?

• Poorly stored meat or reheating meat in mass catering

• Type A toxins is biggest concern

Vibrio parahaemolyticus poisoning is associated with which foods

• Salt

• Undercooked shellfish

The main viral cause of diarrhoea in UK

Norovirus

How is hepatitis A transmitted?

• Through person-to-person contact (poor hygiene)

• Anal intercourse

• Faecal contamination of food & water

What is the main source of foodbourne hepatitis A?

Contaminated shellfish (oysters in particular)

What are symptoms of hepatitis A?

Nausea, D+, V+, jaundice & flu-like illness

What are symptoms of Hepatitis E? In which food products is it commonly found?

• Short lived hepatitis but can be severe & cause death

• Pork and pork products

How can bugs survive on food so well?

• biofilms - attaching to surfaces of food and prep areas

• listeria - resistant to cold and grow well

• salmonella persists well in chilled foods

Why vegetables and other foods may be a source of foodborne infection?

• manure/fertiliser can contain pathogens

• livestock carriers can contaminate the environment

• rodent and wild bird contamination

• continuous, warm system with water re-use = contamination of water