FOOD BORNE DISEASES

Dr Gaurij Hood

Food borne Diseases

1.Introduction-Global and Indian ScenarioFood borne infections vs Food Intoxications

2.Pathogenesis and Transmission

3.Some important foodborne pathogens/toxins/chemicals

4.Investigations and Lab diagnosis

5.Treatment

1.Introduction

• Food borne diseases-(intoxications and

infections) covers illnesses acquired through

consumption of contaminated food-i.e food

poisoning• Food borne disease outbreaks-occurrence of

2 or more cases of similar illness resulting from ingestion of common food OR when observed number of paticular disease exceeds expected number

• Most cases-sporadic but need investigations for control

1.Introduction –Burden

• Global burden-high morbidity and mortality

• Infectious diarrhoea-3 to 5 billion cases and 1.8

million deaths annually

• CDC-76 million cases of food borne diseases in US

annually with appx.5000 deaths

• In India-Integrated disease surveillance

Project(IDSP)-Food poisoning outbreak reporting

increased to more than double in 2009 from

2008(120 in 2009 and 50 in 2008)

Food borne infections vs intoxication

• Infections-Bacterial/Viral/parasite

• Invade and or multiply in lining of intestine

• Incubation period-hours to days

• s/s-diarrhoea,nausea,vomitting,abdominal cramps,fever

• Transmission-spreads from person to person

• Factors-inadequate cooking,cross contamination,poor personal hygiene,bare hand contact

• Intoxications-toxins (natural/preformed bacterial/chemical)

• No invasion or multiplication• Incubation period-minutes to

hours• s/s-

vomitting,nausea,diarrhea,diplopia,weaakness,resp.failure,numbness,sensory/motor dysfunction

• Not communicable• Factors-inadequate

cooking,improper handling temperatures

Some important food-borne pathogens,toxins and chemicals

• 1.Bacteria-Bacillus

cereus,brucella,campylobacter,clostridium

sp,e.coli,Salmonella sp,listeria,staph aureus,,vibrio

cholera and parahemolyticus

• 2.viruses-hepatitis a and e,rotavirus,norvovirus,

• 3.protozoa-

cryptosporidium,cyclospora,entamoeba,giardia,t

gondii

• 4.trematodes,cestodes and nematodes

Food borne pathogens-toxins and chemicals

• Toxins-marine biotoxins,tetrodotoxin(pufferfish),pyrrolizidine alka,mushroom toxins,shellfish toxins,mycotoxins,plant toxicants

• Chemicals-pesticides(opp,sb),radionuclides,nitrites(food preservatives),toxic metals-cd,cu,hg,pb,sn,fluoride,MSG

Pathogenesis and Transmission• Infectious agent or contaminant

• Inoculum/size of infective dose-can be as small as 10-100 bacterial cysts for shigella,EHEC,giardia,E.histolytica or 10^ 5-10^ 8 for vibrio cholera,variable for salmonella

• Animals or humans harbouring infectionshed in fecescontaminate water,fruits,vegetablesinadequate cooking/improper storageinfection

• Warm temperature(10-50 degree cent.)-multiplication of pathogens

Some common bacterial food poisons

Incubation period

cause symptoms Common foods

1-6 hours Staph aureus(enterotoxin)

Nausea,vomitting,diarrhea

Milk n milk products,ham,poultry,salads,custards

Bacillus cereus(enterotoxin)

Nausea,vomitting,(emetic form)

Fried rice

Some common bacterial food poisons

•Incubation period

Cause symptoms Common foods

8-16 hours

Clostridium perfringes

(spores)

Abd.cramps,

diarrhea

Nausea and

vomitting-rare

Meat,

poultry,

legumes.

gravies

Bacillus cereus(diarrheal form-preformed n stable toxins)

Diarrhea,abd.pain,nausea,

No vomitting/fever

Some common bacterial food poisons

Incubation period

cause symptoms Common foods

>16 hours Vibrio cholera

Rice watery stools

Water and ice creams,sea food

Salmonella spp

Inflammatory diarrhea

Meat,milk n milk products,poultry

Shigella sp dysentry Potato/raw eggs-salad

Early diagnosis and investigations

• 1.Initial assessment of cases-Detailed clinical

history including time of onset,duration of

illness,symptoms,h/o travel,recent

meals,cooking and refrigeration,details of others

with similar complaints

• 2.Detailed clinical examination-vitals and

degree of dehydration,systemic signs

Lab diagnosis• Main objectives-

• a)To confirm clinical diagnosis by isolation of

causative agent from proper samples,eg-

stool,vomitus/gastric aspirate,food

specimens

• b)Ensure proper identification of disease

• c)Determine causative agent if present in food

sources with relevant epidemiological markers-

eg Biotyping,serotyping,pcr,phage typing etc

Steps of outbreak investigation• Establishing existence of outbreak(detailed baseline

epidemiological information)Co-ordination with key

personnelCollection and transport of clinical specimens

and food samples for lab testingImplementation of

control and preventive measuresdefinition of

cases,population at risk and finding casesDescription of

epidemiologyDevelopment of possible

hypothesesEpidemiological study to evaluate

hypothesesAnalysis of data and

interpretationReporting findings of outbreak

investigation

Prevention in community• Proper handwashing and personal hygiene

• Proper storage(refrigeration)

• Food saftey education –community and food handlers

• Environmental measures-discourage sewage farming for growing fruits and vegetables

Prevention • Hazard Analysis and Critical Control

Point(HACCP)-• Systematic preventive approach to food

saftey• Addresses physical,chemical and biological

hazards as means of prevention rather than finished product inspection

• Food industry-food saftey hazards identified at all stages of food production and preparation processeskey action taken at Critical Control Points(CCPs)

Principles of Hazard Analysis and Critical Control Point(HACCP)

• Analyse hazardsIdentify critical control pointsEstablish preventive measures with critical limits for each CCPEstablish procedures to monitor CCPSEstablish corrective actions when monitoring shows that critical limit has not metEstablish procedures to verify that system is working properlyEstablish effective record keeping for documentation

Treatment

• 1.Initial t/t-Assessment and reversal of dehydration(ORT/IV Fluids)

• 2.Cause specific treatment if any-eg.chelating agents in case of pesticide poisoning

• 3.Use of antibiotics can be considered if bacterial cause is identified

Collection of food samples• Using aseptic technique n appropriate

containerssamples be refrigerated during storage and transportmust arrive lab within 3 days of collection

• Adequate sample-minimum 100 grams

• Containers-not to be filled >75% of capacity

• Proper labelling is utmost importantlabelled specimen be placed in zip lock bag and sealed

• Vaccine carrier with ice packs for transport and cold chain maintenance(avoid freezing)

• The mainstay of treatment is adequate rehydration.

• The treatment of cholera and other dehydrating diarrheal diseases - promotion of oral rehydration solutions, efficacy of which depends on the fact that glucose-facilitated absorption of sodium and water in the small intestine remains intact in the presence of cholera toxin.

• The use of oral rehydration solutions has reduced mortality due to cholera from >50% (in untreated cases) to <1%.

• The World Health Organization recommends a solution containing 3.5 g sodium chloride, 2.5 g sodium bicarbonate, 1.5 g potassium chloride, and 20 g glucose (or 40 g sucrose) per liter of water.

• Oral rehydration solutions containing rice or cereal as the carbohydrate source may be even more effective than glucose-based solutions, and the addition of L-histidine may reduce the frequency and volume of stool output.

• Patients who are severely dehydrated or in whom vomiting precludes the use of oral therapy should receive IV solutions such as Ringer's lactate.

Five keys to Safer food• 1.Keep Clean-Wash hands before handling food

and often during preparation• Wash hands after going to toilet

• Wash n sanitise all surfaces n equipment for food preparation-protect kitchen from

insects,pets• 2.Separate raw and cooked food-Separate raw

meat,poultry n seafood from other foods• Use separate utensils for handling raw foods

• Store food in containers to avoid contact between raw and cooked foods

Five Keys to Safer Food• 3.Cook Thoroughly-esp.Meat,poultry,eggs and

Seafood• Bring soups n stews to boiling(ensure>70degree

temp)• Reheat cooked food thoroughly• 4.Keep food at safe temperature• Dont leave cooked food at room temp.>2 hours• Prompt refrigeration of cooked n perishable food• Keep cooked food piping hot(>60 de.)prior serving• Don’t store food too long even in refrigerator• Don’t thaw frozen food at room temperature

Five keys to safer food• 5.Use safe water and raw materials-

• Use safe water or treat to make it safe

• Select fresh and wholesome fruits

• Choose foods processed for safety-pasteurised

milk

• Wash fruits n vegetables if eaten raw

• Don’t use food beyond expiry date