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