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