Foodborne diseases-

Diseases usually either infectious or toxic in nature, caused by agents that enter the body through the ingestion of food.

Classified in 3 types:1)Food infection- ingestion of viable

pathogens along with food. Eg- typhoid2)Food intoxication- ingestion of preformed

toxins Eg- botulism, stapylococcal poisoning3)Toxi-infection- organisms produce toxins

insitu when ingested along with food Eg- B.cereus poisoning

Sources of pathogenic organisms:- Dairy animals- Brucellosis, Q fever, Salmonellosis Handlers- TB, Scarlet fever, Septic sore throat Environment- Anthrax spores, Corynebacterial inf

Milk borne infections-Salmonellosis - S.typhi- typhoid S.paratyphi- paratyphoid S.enteritidis, S.weltiverdin-FP Sources- water, handlers, flies, infected animals Symptoms- fever, enteritis, ulcers, chills,

vomiting,characteristic rose spot eruptions on the abdomen, toxaemia

Paratyphoid- similar to typhoid but milder Salmonellosis- nausea, vomiting, diarrhoea,

abdominal cramps, chills, moderate fever Diagnosis- microscopic, cultural,

fermentative, serological tests for detecting org in faeces, urine

Specific test for typhoid- Widal testBacillary dysentery- S.dysentriae,

S.sonnei, S.flexneri Sources- water, utensils, flies, handlers Disease in humans- S.dysentriae-most

severe, produces enterotoxin Symptoms- Acute shigellosis, diarrhoea with

blood, pus, mucus, vomiting, abdominal cramps

Diagnosis- isolating org from rectal swab and plating on desoxycholate citrate agar

Streptococcal infections- humans & animals responsible for contaminating milk

S.pyogenes- scarlet fever,septic sore throat S.agalactiae- mastitis Group D (Enterococci)- food poisoning Sources- infected animals, faecal

contamination of milk and its products, milking machines,carriers

Symptoms- Septic sore throat- sudden & irregular fever,

inflammation & swelling of lymph glands of throat,abscesses in cervical lymph glands

Scarlet fever- acute febrile disease of throat accompanied by scarlet rash, infection of middle ear, kidney

Food poisoning- similar to Staph food poisoning Diagnosis- throat swabs for presence of

hemolytic streptococci in septic sore throat Scarlet fever- clinical symptoms, isolation of

org Dick test in humans

Milk borne intoxications- Staphylococcal poisoning- S.aureus Causes gastroenteritis due to enterotoxins Capable of producing enterotoxins in raw milk

at conc of 106 org/ml

Sources- handlers, milch animals Symptoms- nausea, vomiting, abdominal

cramps, diarrhoea, sweating, prostation Diagnosis- Biological method, Serological

method, Coagulase test, Thermonuclease test Botulism- Cl.botulinum severest of all FP, affects NS. mainly prevalent in improperly canned

products leading to bloating of cans Toxins are lethal in small doses, 0.1μg of toxin

may cause death of an individual and 1mg of purified toxin is sufficient to kill 1 million people

Sources- soil, water (serotype E )

Symptoms:- Botulism syndrome- nausea, vomiting,

dryness of skin,mouth &throat, inability to swallow, double vision, progressive paralysis and suffocation; often fatal

Diagnosis- microscopic examination, animal inoculation, cultural identification

E.coli poisoning- causes traveller’s diarrhoea and FP produces 2 types of toxins- LT and ST min of 105 -107 cells/g- cause FP Sources- water, handlers, infected animals

Symptoms- LT toxin- massive watery diarrhoea ST toxin- diarrhoea with or without vomition,

fever Cholera- Vibrio cholerae Unhygienic practices responsible for outbreaks Sources- unclean water, carriers, adulteration

of milk with contaminated water Symptoms- diarrhoea in mild cases In severe cases- diarrhoea, vomiting, rice

water stools, abdominal pain, dehydration, death

Diagnosis- isolation of org from faeces i/p inoculation of g.pigs with pure culture

results in death of the animal within 24 hours

Fungal intoxications- Aflatoxicosis- A.flavus, A.parasiticus Animals fed with aflatoxin containing feed

excrete toxins M1,M2 in milk Recommended upper permissible limit –

90ppm Sources- environment, soil and contaminated

food, poor storage conditions Disease in humans- Acute aflatoxicosis Symptoms- liver hyperplasia, tissue

hemorrhage, anorexia, hepatitis organs like kidney, spleen, pancreas may also

get affected

Milk borne toxi infections-Clostridial perfringes (Cl.welchii)

cause-ingestion of contaminated milk/canned product

Causes gas gangrene

Sources- soil, faeces of man & animals, spores are present in cowshed; water supplies

Disease in humans- severe gastroenteritis; toxins are resistant to intestinal juices.

Bacillus cereus poisoning-

aerobic spore former, seen in heat treated milk

Sources- mastitis milk, environment, soil Toxins- Hemolysin, Lecithinase, enterotoxin Disease in man- 2 types of poisoning a) Diarrhoeal type b) Vomiting type Symptoms- nausea, diarrhoea, abdominal pain Pseudomonas infection- Ps.putrifaciens,

Ps.viscosa, Ps.fragi, Ps.aeruginosa

Sources- water, utensils,udder, teat, cowshed environment

Disease in humans- causes UT infections, eye and ear infections, abscesses, meningitis, enteritis, septicemia, gastrointestinal disturbances

New emerging pathogens

i) Listeriosis- L.monocytogenes mesophilic,psychrotrophic, produces

hemolysins Sources- infected animals, handlers,

unhygienic practices, faecal contamination of milk & water

Survives pasteurization as gets hide in leucocytes

In humans- Listeriosis; In animals- mastitis, keratitis, meningeoencephalitis

Symptoms- acute meningitis with or without septicemia, fever, headache, nausea, vomition, coma resulting in death

Campylobacteriosis- (C.jejuni) Sources- faecal matter, polluted water,

infected animal- causes gastroenteritis in man and mastitis in animals

Symptoms- abdominal pain, diarrhoea Yersiniosis- (Y.enterocolitica) Source-faecal contamination,unhygienic

practices Disease in man- Acute syndrome with

appendicitis

Symptoms-fever,abdominalpain,diarrhoea,vomition

Vibriosis- (V.parahemolytica) Causes gastroenteritis Source- Aquatic foods (fish, crabs and

canned sea foods) Symptoms- diarrhoea, abdominal cramps,

nausea, vomition, chills, fever Other milk borne diseases-a) Bacterial diseases: Tuberculosis- M.tuberculosis 2 types- Pulmonary TB- caused by M.tuberculosis Non pulmonary TB- caused by M.bovis Source-milch animals, handlers,

environment,feed

Symptoms- pleurisy, cough, fever, fatigue, wt loss Diagnosis-examination of sputum, faeces, serum

for the presence of bacilli using Ziel neelson’s staining

Brucellosis- B.melitensis, B.abortus, B.suis Source-environment, persons, diseased animals Disease in man-Malta fever, undulent fever Symptoms-headache, sweating, chills, joint &

muscle pain Diagnosis- blood culture, CFT, agglutination Diptheria- C.diptheriae Source- handlers, animals, environment produces extracellular toxin in resp tract Symptoms-febrile infection of nose, throat, tonsils

Diagnosis-isolating org from throat swab on Loeffler’s medium, staining with MB

Source-infected animals, environment Anthrax- B.anthracis Disease in man- 2 forms Cutaneous anthrax- direct inoculation

through skin, small fruncles, malignant carbuncle of skin

Pulmonary anthrax- inhalation of spores, pneumonia is the chief symptom

Diagnosis-spore staining, biological test Rickettsial disease- Q fever- Coxiella burnetti can survive pasteurization & freezing temp

Symptoms- high fever,headache,malaise,severe sweating,pneumonia,weakness,mastitis in animals

ii) Viral diseases- a)Enterovirus causes summer diarrhoea in children b)Infectious hepatitis- hepatitis A Symptoms- nausea, vomiting, abdominal

pain,fever, chills, anorexia, sore throat, bile in urine, jaundice

c) Tick borne encephalitis- Group B arbovirus Source-contaminated milk, ticks, mites Symptom-biphasic meningeoencephalitis d)FMD-infected dairy products & animals-source Symptoms-fever, difficulty in swallowing, dryness

of mouth, blisters in mouth

Control of milk borne diseases Strict hygienic measures during

production, processing, storage & distribution

Proper pasteurization of the milk Education to public Infected personals should not be allowed

to handle milk and milk products Rigid sanitary discipline should be

followed Detoxification of aflatoxins by physical,

chemical or biological agents Vaccination of the herd

Meat borne infections- i) Bacterial diseases- a)Salmonellosis- S.typhi, S.paratyphi,

S.typhimurium Sources- red meats, raw poultry, infected eggs Symptoms-same as that in milk b)Clostridial illness- 2 types Cl.perfringes-found in soil and faeces of all

animals Source-improper storage of the food Causes 2 types of poisoning Type A- mild form –nausea, abd pain, diarrhoea Type C- severe form, mainly due to β-toxin -

necrotic enteritis, severe abdominal pain

Cl.Botulinum- canned foods, partly processed uneviscerated fish are the sources

Symptoms- similar as that in milk Staphylococcus aureus- raw meat, improper

storage of meat after cooking are the sources

Symptoms- same as in milk Escherichia coli- E.coli (O157:H7) produces shiga like toxin Source- poultry meat Diarrhoeagenic strains of E.coli- Enteropathogenic – infantile diarrhoea Enterotoxigenic-watery stools,vomiting Enteroinvasive-bloody, mucoid stools,

tenesmus, fever

Enterohaemorrhagic- most pathogenic, produces haemorrhagic colitis and haemolytic uraemic syndrome

c) Bacillus poisoning- B.cereus Source-fresh meat and meat products, usually

reflect the carcass contamination with soil, water

Symptoms- same as in milk d)Listeriosis- L.monocytogenes Source- cooked and ready-to-eat meat

products It is a psychrotrophic organism Symptoms-in pregnant women it causes

abortion or still birth

e)Campylobacter jejuni- Source- poultry meat, red meat and offals Symptom-enteritis in adults, abdominal pain-

major feature f)Yersinia enterocolitica- Emerging pathogen,psychrotroph (0-2ºC) Symptom-same as in milk ii) Viral diseases- Small gastroenteritis virus- include rotavirus,

calcivirus Symptoms- diarrhoea, vomition, abdominal

pain, pyrexia, nausea, malaise

Enteroviruses- includes hepatitis A virus (main), polio virus, echovirus and coxsachie virus

Symptoms- similar to that in milk iii) Parasitic diseasesiii) Parasitic diseases a)Cryptosporidiosis- raw or undercooked meat,offal symptom- diarrhoea, abdominal pain b)Sarcocystosis- Sarcocyst occurs in skeletal and

heart muscles of mammals Source- consumption of food contaminated by

carnivore excreta containing sarcocyst ova c)Taeniasis- T.saginata, T.solium Source- consumption of raw and undercooked meat,

unhygienic conditions Symptoms- nervousness, anorexia, weight loss,

abdominal pain, digestive disturbances

d) Trichinosis- Trichinella spiralis

Source- raw and undercooked pork and pork products

Symptoms- diarrhoea, abdominal pain,influenza $ typhoid like fever

e) Toxoplasmosis- Toxoplasma gondii Source- meat and organs containing tissue cysts,

infected meat eaten raw or undercooked Symptoms- transplacental transmission leading to

congenital nervous and ocular lesions f) Hydatidosis- Source- ingestion of gravid segments of

Echinococcus granulosus of dog Cysts get localized in organs like liver,heart muscle

Control of meat borne diseases Strict ante mortem & post mortem

inspection Slaughter hygiene Decontamination of meat End product handling Margin of safety Proper treatment of meat viz freezing or

heating at high temperatures or salting Personal hygiene Proper disposal of affected meat/offal Public education for prevention of eating

raw flesh

Investigation and reporting of outbreaks

Detailed description of cases should be made

Record should be made of food eaten and a common source of infection should be identified

History of previous illness of the personnel handling milk, meat and their products should be found out

Evidence of enteric disorders, scratches, wounds, source of pyogenic infection or evidence of sepsis should be looked for and where indicated, swabs should be taken

Sanitary facilities and practices used in the plants or shops should be recorded

If a particular farm is suspected a detailed veterinary record of the animals should be obtained with particular attention to recent cases of mastitis

Pooled milk samples from 1 or several animals should be taken aseptically, immediately cooled and held cool until delivered to the laboratory for examination

After identification of suspected animals carrying the causative organism, the individual sample should be obtained

All suspected specimens should be collected for investigation of outbreak