MJF College of Veterinary &
Animal Science, Chomu (Jaipur)
Dr. Om Prakash Meena
Assistant Professor
Department of Veterinary
Medicine
• Synonym-
Paratyphoid
• Gram negative
• bacilli
• 1-3 / 0.5 microns,
• Motile by
peritrichous flagella
Salmonellosis
• Salmonellosis is one of the important zoonoses
due to bacterial.
• It is an acute or chronic contagious of all
species of animals, birds and human being
characterized by gastro-enteritis.
• The disease has got economic importance as
this causes heavy mortality and high
morbidity.
• Bacteriology –Typhoid fever
• The Genus Salmonella belong to
Enterobacteriaceae
• Facultative anaerobe
• Gram negative bacilli
• Distinguished from other bacteria by
• Biochemical and antigen structure
• Salmonella
• Antigenic Structure
• H – Flegellar antigens
• O – Somatic antigen,
• Vi – Surface antigen in some species only
• H antigens also called flegellar antigens,
• heat labile protein,
• Boiling destroys antigenicity
• When mixed with Antiserum produces
• agglutination and fluffy clumps are produced
• H antigens are strongly immunogenic Induces antibodies
rapidly
• Aerobic / Facultatively anaerobic
• Grows on simple media – Nutrient agar,
• Temp 15 – 41ºc / 37º c
• Colonies appear as large 2 -3 mm, circular, low
convex,
• On MacConkey medium appear
Colorless ( NLF )
Selective Medium - Wilson Blair Bismuth sulphide
medium. Produce Jet black colonies
H2 S produced by Salmonella typhi
Dr.T.V.Rao MD 8
Cultural Characters
www.cdc.org,2004
Enrichment Medium
Liquid Medium
• Selenite F medium
• Tetrathionate broth
• Above medium are used for
isolation of Salmonella from
contaminated specimens
• Particularly stool specimens.
• Identifying Enteric Organisms
• Isolates which are Non lactose fermenting
• Motile, Indole positive
• Urease negative
• Ferment Glucose,Mannitol,Maltose
• Do not ferment Lactose, Sucrose
• Typhoid bacilli are anaerogenic
• Some of the Paratyphoid form acid and gas
• Further identification done by slide
agglutination tests
Antigens – Salmonella ( cont )
• • O Antigens
• • Forms integral part of Cell wall,
• • Like Endotoxin
• • 0 Antigens unaffected by boiling.
• • When mixed with antiserum produce chalky
• clumps are formed, take more time reaction, at
• high temp 50º – 55º c
• O antigens are less immunogenic. than H antigens
Antigen (Vi) – Salmonella ( contd)
• Vi antigens
• Many strains in S.typhi covers the O antigensprevents
• agglutination.
• Resembles like K antigens
• Destroyed after boiling at 60º c / 1 hour.
• Vi a polysaccharide
• Acts as virulence factor, protects the bacilli
• against Phagocytosis and activity of complement
poorly immunogenic low titer of antibodies are
produced, Not diagnostic
Antigenic Variation in
Salmonella
• May be phenotypic / Genotypic
• H to O = loss of Flagella
• May be phase variation from I to II
• V to W variation
• S to R variation
Animal feces
Contact with infected animals
Fecal-oral transmission
• Resistance of Salmonella
• 55ºC – 1 hour
• 60ºC– 15 MT
• Boiling ,Chlorination,
• Pasteurization Destroy the Bacilli.
• The infection is transmitted horizontally by
direct exposure of the susceptible animals from
the infected population.
• Contaminated water is the important source of
transmission.
• Cattle may acquire the infection from infected
cattle or from infected pig, horse, sheep, dog,
poultry and pigeon.
• Animal may contract the infection from human
sources.
Transmission
• Eggs and meat products are mostly responsible
for outbreak of salmonellosis of human beings.
• It is a serious problem in countries with high
standards of hygiene, where the consumption
of raw or slightly heated products of animal
origin has been popular and where application
of hygiene measures may eliminate bacterial
flora that otherwise might inhibit the growth of
salmonellosis.
• The site of infection is the alimentary tract.
• Very young and very old animals are more
susceptible.
• The colonization of the bacteria in the gut depends
on some factors.
• Environmental stress
• transportation stress
• Starvation for a prolonged period of time
Deficiency of vitamin B complex
Poorly ventilated housing
Access to the sewages.
Pathogenesis
On entry the organisms invade the intestinal
mucosa, proliferate there and cause severe damage
to the mucosa.
It also allow addition bacteria to invade the blood
vessel via the intestinal mucosa.
There is resultant haemorrhage and necrosis of
mucosa.
Organisms on entering the blood vessel set up
septicaemia and foci of infection in the spleen,
liver and lymph nodes.
Clinical findings
• Animal may remain asymptomatic carrier without
exhibiting any clinical manifestations.
• The clinical manifestation may appear the carrier
animal when they are exposed to excessive
environmental stress and strain.
• The disease may appear as acute or chronic one.
• From clinical stand point it has been classified as
enteric form and septicaemic form.
Enteric form
• This form is most commonly observed in
adults characterized by anorexia,
depression, high rise of temperature and
profuse watery faeces.
• Initially animals may pass semisolid faeces
which is followed by diarrhoea with blood
clot and mucus.
• Frequent defaection is accompained by
signs of abdominal pain.
• Extensive haemorrhage may cause anaemia.
Gradually the initial temperature drops to subnormal
level and death occurs.
The course is from 3 to 7 days.
The animal that recover may become carrier and may
show the signs of emaciation and polyarthritis.
Pregnant cow may abort.
Pigs will show the signs of pneumonia along with
diarrhoea.
This form is observed in young animalscharacterized by high rise of temperature,dullness, ataxia and recumbancy.
Faeces are putty coloured and contain bloodstreak.
The animal may die within 1-2 days.
But in some cases there is involvement ofmusculoskeletal system resulting to enlargementof joints.
Signs of pneumonia may appear.
The recovered animal continue to excrete theorganisms throughout its life.
• Piglets may show nervous manifestation like
tremor, convulsion and paraltsis.
• The foal may show both enteric and
septicaemic signs.
• Septicaemic form is characterised by
dyspnoea, arthritis and bloody diarrhoea.
Lesions
Organs changes
Gastric mucosa Haemorrhage and oedema
Intestinal mucosa Hyperaemia, necrosis, ulcer
Caecum Zebra marking
Liver Enlarged with necrotic foci
Spleen Enlarged and pulpy
Mesenteric lymph glands haemorrhage
Lung and pleura Pleural adhesion and abscess
Pericardium Sub pricardial haemorrhage
Skin Discolouration in pigs
Diagnosis
• It can be made based on
– History of animal
– Clinical signs
– Lesions
– Confirmatory diagnosis can be made by
isolation and identification of the organisms
through culture.
Differential diagnosis
Coccidiosis It produces haemorrhagic diarrhoea
which is scanty in nature.
Oocyst of coccidia can be identified
in feaces.
Pasteurellosis It may occasionally produce diarrhoea
but principal manifestation lies with the
involvement of respiratory system.
Liver fluke infestation Signs of jaundice, constipation,
emaciation, anaemia and bottle jaw
condition.
Liver fluke eggs can be recovered
from faeces.
Poisoning Various poisons may produce
diarrhoea.
Collibacillosis
Para tuiberculosis
• Various broad spectrum antibiotics and
chemotherapeutic have been recommended.
• The drugs include chloramphenicol, neomycin,
polymixin-B, trimethoprim-sulphamethoxazole
preparation, nitrofurazone.
• Salmonella antiserum may be provided to affected
animal.
• To check dehydration adequate fluid and
electrolytes are to be given.
• To check diarrhoea astrigent and protectants are
to be used
Control
• Calving should be made in a hygienic place.
• Calves should be allowed to have access to
colostrum following their birth.
• Calves should not be exposed to adverse
weather
• Over crowding of animals should be avoided.
• Animal should be provided with clean
wholesome water.
• Animals should not be allowed to drink water
sewage of pool and pond.
Control
• Other susceptible animals like horse, sheep,
bird should be placed away from cattle shed.
• Affected animals should be brought under
immediate treatment.
To prevent the human infection
• Effective pasteurisation of milk is to be made.
• Proper refrigeration of food is required.
• Sterilization of animal foods which are liable to
contamination.
• High standards of abbatoir hygiene is to be maintained.
• Proper handling of fish and shell fish are to be made
• High standard of personal hygiene is to be maintained
by kitchen workers, caterers and food handlers.
• Active immunity- your body develops to protect you from disease
- Some last a lifetime
- Some only last a short period of time
• Passive immunity- the temporary immunity that an infant acquires from its mother
• No vaccine
Don’t eat raw or undercooked food
Cross-contamination of foods should be avoided
Do not prepare food or pour water if you are infected with the bacteria
Wash hands, kitchen surfaces, and utensils with soap and water after they have come in contact with raw meat or poultry
Wash hands after contact with animal feces
Avoid direct/indirect contact between reptiles and infants
1. Explain to children what germs are and where they are found
2. How to properly wash their hands
3. When to wash their hands