food poisoning - a public health perspective

Food poisoningA public health perspective

Dr. Rizwan S AAssistant ProfessorVMCHRI, Madurai

07.09.2015

Objectives of this lecture

• At the end of this lecture you should be able to– Define food poisoning– State types and

differentiate causes of food poisoning

– Describe the public health importance and prevention aspects of food poisoning

Importance of food safety

• Nearly 200 diseases are caused by unsafe food

• Two million deaths occur every year from contaminated food or drinking water

• Unsafe food creates a vicious cycle of disease and malnutrition, particularly affecting infants, young children, elderly and the sick

Definition

• An acute gastro-enteritis

• Caused by ingestion of food or drink

• Contaminated with bacteria or toxins or chemicals or poisons

Types and Causes

• Bacterial– Toxin type

• Staphylococcus • Streptococcus• Cl. Botulinum

– Infection type• Salmonella

• Non-bacterial– Virus

• Enteroviruses– Parasite

• Giardia, entamoeba– Protozoa

• Nematode• Flatworm• tapeworm

– Chemical• As, Hg, Cd, Cu

Types of bacterial food poisoning

Details of some important causes

• Salmonella• Staphylococcus• Cl. botulinum• Cl. perfringens• B. cereus

• S. typhimurium, S. enteritidis

• Farm animals, poultry• Incubation: 12–24 hr• Mech: infection• Fever, vomiting, watery

diarrhea lasting for 2-3 days



• Enterotoxins of Staphylococcus aureus

• Salads, custards, milk products

• Incubation: 1–6 hr• Mech: Preformed toxin• Vomiting, abdominal

cramps, diarrhea



• Exotoxin of Clostridium botulinum type A, B or E

• Fish, cheese, canned vegetables

• Incubation: 12–36 hr• Toxin affects PS system• Dysphagia, diplopia,

dysarthria, muscle weakness, quadriplegia



• Clostridium perfringens• Meat, poultry - cooked and

allowed to cool slowly at room temperature

• Incubation: 6-24 hr• Mech: spore germination• Diarrhoea, cramps, rapid

recovery in 1 day


• Salmonella• Staphylococcus• Cl. Botulinum• Cl. perfringens• B. cereus

• Bacillus cereus• Raw, dried & processed

foods• Incubation: 12-24 hr• Mech: spore germination• Emetic form: upper GI

symptoms (1-6 hr)• Diarrheal form: lower GI

symptoms (12-24 hr)

Review QVomiting occurs in group of children in the night, who had meal at noon. The causative agent for food poisoning is most likely to be:a. Salmonella b. Botulism c. Staphylococcus d. Viral gastroenteritis

True about staphylococcous food poisoning are all except: e. Due to enterotoxin f. IP below 6 hours g. Sudden onset h. Fever is common

Differential diagnosis of bacterial poisoning

How to investigate a food poisoning outbreak as a public health expert? Interview all people

Food eaten during previous

2 days

Place of consumption

Time of onset of symptoms

Order of onset of symptoms

Questionnaires given to

kitchen workers & dining

workers

Lab diagnosis

Stool, vomit or remnants of

food

Stool samples of kitchen

employees & food handlers

tested

Blood for antibodies

Environmental studies:

Inspection of kitchens

Findings of an investigation

Review Q

Food poisoning is caused by all except

a. Staphylococcus aureus b. Clostridium difficile c. Vibrio parahaemolyticusd. Bacillus cereus

Prevention and control

• Food sanitation• Refrigeration• Surveillance

1. Meat inspection2. Personal hygiene3. Healthy food handlers4. Food handling

technique5. Sanitary improvement6. Environ. hygiene7. Health education



• Food should be immediately & rapidly refrigerated if not eaten after cooking (<40 Celsius)

• “Cook and eat the same day”



• Food samples obtained from food establishments periodically and checked.

• Record of foodborne disease outbreaks

Review Q

What is correct temperature for refrigeration of food?

a. <5 degree Cb. 10-20 degree Cc. >60 degree Cd. 5-10 degree C

What are the 5 keys to safe food?

Take home messages

1. Food poisoning is a common outbreak2. It affects vulnerable people like children3. Most important causes are bacterial4. DD is possible by symptoms, food, IP5. All outbreaks sh be investigated

epidemiologically6. Food sanitation is main prevention method

THANK YOUEmail your queries to [email protected]

mailto:[email protected]

food poisoning - a public health perspective

Health & Medicine