Colibacillosis is caused by pathogenic strains of Escherichia coli. It affects poultry and can cause diseases like colisepticaemia, egg peritonitis, yolk sac infection, and coligranuloma. Colisepticaemia is the most serious form, seen in young broilers as bacteremia. Predisposing factors allow E. coli to enter through the respiratory tract, causing lesions in multiple organs. Clinical signs include depression, breathing difficulties, and mortality rates varying from 5-10% to over 50%.

1. Colibacillosis
• Caused by Escherichia coli
• The species is the normal inhabitant of the
digestive tract of mammals and birds and
most strains are not pathogenic
• There rare 100s of serotypes of E.coli
• These are classified on the basis of various
surface antigens which are

2. • O (somatic) antigen- endotoxin liberated
• K (capsular) antigen- polymeric acid present
on the surface
• H (flagellar antigen)
• F(fimbrial or pilus) antigen- involved in
attachment to cell

3. • Only a few Escherichia coli are true pathogens
• These are associated with enteric disease,
referred as enteropathogenic, enterotoxigenic
or enterotoxic
• They are important cause of diarhoea in
humans, pigs, cattle , sheep and horses

4. Diseases caused by E.coli
• Colisepticaemia
• Egg peritonitis
• Yolk sac infection(Omphalitis)
• Coligranuloma(Hjarre’s disease)
• Collectively grouped under colibacillosis

5. Colisepticaemia
• The disease is usually seen in young growing
chickens especially broilers
• It is most serious form of colibacillosis
• Coccidiosis, viral infections, Ranikhet disease
or infectious bronchitis, infectious bursal
disease(IBD) Mycoplasma gallisepticum
infection and nutritional deficiencies
predispose bird to disease
• Mortality vary from 5-10% occasionally>50%

6. Etiology
• E coli belonging to serogroups 01, 02, 035 and
078 especially strains 078:K80 and 02:K1
• Gram negative bacteria, 3 µ long, motile
• Ability to ferment lactose producing pink
colonies on MacConkey’s agar compare to
Salmonella

7. Spread
• E. coli persist for long periods outside the
body in dry , dusty conditions
• Faecal contamination of the eggs may result in
penetration of E. coli throught the shell and is
most important source of infection
• Ovarian infection or salphingitis
• Associated with heavy mortality during hatch
and may give rise to yolk sac infection

8. Pathogenesis
• E. coli found in digestive tract of poultry
• The infection occurs when pathogenic E.coli
enters through respiratory tract when mucosal
barrier are compromised
• eg damaged from viral, bacterial or parasitic
infections, toxins, ammonia fumes, poor
ventilation, nutritional deficiencies,
overcrowding, immuno suppression, poor litter
condition, extreme temperature cause deciliation
of upper respiratory tract

9. Signs
• Birds of 4-12 weeks of age are usually affected
• First sign is drop in feed consumption,
depression, dyspnoea
• Listless, ruffled feathers and develop laboured
breathing and making sharp sound- snicking
• Morbidity can be uto 50% and mortality vary

10. Lesions
• Airsacculitis, cellulitis, peritonitis, perihepatitis,
and pericarditis
• Air sac membrane become thicker and cloudy in
appearance
• Liver may show a thin covering of fibrinous
exudate
• Pneumonia and pleuropneumonia
• omphalitis, & Salphingitis
• Peritonitis is characterized by acute mortality,
fibrin and free yolk

11. • Liver, spleen, lungs and kidneys are dark and
congested
• The air sacs are thickened, opaque, and with
caseous deposit
• A fibrinous pericarditis with pericardial sac
thickened
• The surface of liver is covered by thin layer of
fibrinous material
• Enteritis often with excessive mucus

12. Collibacillosis

14. Diagnosis
• PM examination- typical lesions
• Isolation and identification of organisms from
lungs, heart, liver and air sacs
• ELISA
• PCR

15. Egg peritonitis
• A number of reproductive disorders of poultry
• Peritonitis, salphingitis(inflammation of oviduct)
• Impaction of oviduct
• Post mortem examination reveal egg debris,
inspissated yolk, caseous material, or milky fluid
in abdominal cavity
• Inflammation and distortion of the ovaries
• Rupture of oviduct wall

16. • Small number of death in layers
• Flock peritonitis may result from vent pecking
and egg peritonitis

17. Yolk sac infection
• Mushy chick disease, omphalitis
• Most common cause of mortality in chicks during
the first week after hatching
• Yolk sac infection associated with inflammed
navel or multiplication of bacteria in hatching
eggs following faecal contamination of the shell
• Other bacteria like Bacillus cereus, Staphylococci,
Pseudomonas, Proteus and Clostridia can also
cause yolk sac infection

18. Signs and lesions
• Affected chicks have distended abdomens and
tendency to huddle
• Navel visibly thickened, prominent and
necrotic
• Subcutaneous and yolk sac blood vessels
engorged and dilated
• Lungs congested
• Liver and kidneys dark and swollen

19. • Inflammed unabsorbed yolk sac
• Yolk being abnormal in colour and consistency
• Yolk may be yellow and inspissated or brown
green and watery with fetid, foul smelling
• Peritonitis with haemorrhages on the serosal
surfaces of intestines

20. Coligranuloma(Hjarre’s disease)
• Caused by 04,08 and 016
• Causes sporadic death in adult hens
• The clinical signs are nonspecific
• Affected birds are found dead or die after
depression and loss of condition

21. • Post mortem examination shows hard, yellow,
nodular granulomas in the mesentery and wall
of intestine particularly of caeca, small
intestines
• Microscopically caseous nodule in the centre
and lymphocytes and giant cells around
necrotic centre like in tubercular nodule

22. • Bumble foot
• Peritonitis
• Airsacculitis
• Synovitis and arthritis

23. Fowl cholera
• Avian pasteurellosis, avian cholera and avian
haemorrhagic septicaemia
• Contagious disease affecting domestic and
wild birds
• It is caused by Pasteurella multocida, 16
serotypes
• Gram negative, capsulated, bipolar, nonmotile
bacteria

24. • World wide in distribution
• All species of birds are susceptible
• Ducks and geese are highly susceptible
• Adult birds and late growing stage are more
susceptible than youger stock
• Poultry, geese, ducks, turkeys, guinea fowl,
pigeons
• In peracute form it is most virulent and highly
infectious disease

25. Spread
• Carrier birds, diseased birds
• Excretions and carcasses of birds died of infection
• Rats are reservoir for P. multocida
• Airborne infection do occur between pens
• Spread through water and feed troughs
• Oral, nasal, conjunctival routes and through
wounds

26. Pathogenesis
• Depend on strain, host species and
environment condition
• Virulence is due to fimbriae, a polysacharide
capsule, , endotoxin(lipopolysacharide), and
leukotoxin
• P. multocida enters tissues through mucous
membranes of the pharynx, conjunctiva or
cutaneous wounds

27. Signs
• Occurs in peracute, acute, chronic, and localized
form
• In peracute form there is no warning signs and
large no. birds are found dead but in good bodily
condition
• In acute form marked depression, anorexia,
mucus discharges from the orifices, cyanosis of
comb and wattle and fetid(foul smelling) green
mucoid diarrhoea
• Fever prostration and drooling of saliva
• In chronic form oedema of wattles and combs

28. • The chronic form occurs in birds which survive
from acute disease
• The clinical signs include depression,
conjuntivitis, dyspnoea and in few cases
swelling of the joints, lameness, torticollis and
swelling of wattles

29. Fowl cholera

32. Lesions
• Gross lesions in peracute and acute forms include
marked congestion of the carcass, multiple
petechiation throughout viscera(gizzard muscle,
proventriculus and serosa of intestines and
abdominal fat)
• Enlargement and dark colouration and multiple
pin point necrotic foci in liver and spleen
• In laying hens, free yolk may be present in the
body cavity

33. • Enteritis is constant feature
• Lungs congested and pneumonia
• In subacute disease oedema of lungs, pneumonia
and perihepatitis are seen
• Chronic lesions include caseous arthritis of hock
and foot joints and wattles and comb with cheesy
or thick pus
• Swelling and induration of one or both wattles
• In histopathology congestion , bipolar organisms
in tissue sections and infiltration of heterophils

34. Diagnosis
• Clinical observations
• PM examinatiuon
• Isolation and identification of P. multocida
• Impression smears of the liver heart show
bipolar organisms with methylene blue
• Animal inoculation in mice or rabbits death in
24-48 hrs

35. Infectious coryza(Fowl coryza)
• Infectious coryza is an acute, highly contagious
disease of the upper respiratory tract of chickens
• Avibacterium paragallinarum
Haemophilus paragallinarum
3 common serotypes A,B and C
• The disease is limited to chickens
• Chickens of all ages are susceptible but older
birds react more severely
• Presence of capsule and haemagglutnitation
antigen are responsible for pathogenicity

36. Spread
• Carrier birds are main source
• Spread by drinking water contaminated by
nasal discharge
• Direct contact and air borne droplets

37. Pathogenesis
• After entry of organisms first adhere to the
ciliated mucosa of upper respiratory tract
• The capsule and the haemaglutination antigen
play important role in the colonization
• Toxic substances released from the organism
during proliferation are associated with
production of lesions in the mucosa and
appearance of clinical signs
• The capsule acts as a natural defence substance
against the bactericidal power of complement

38. • H. paragallinarum is a non invasive organism
with a strong tropism for ciliated cells
• It migrates into lower respiratory tract(lungs,
air sacs) only after synergistic interaction with
other infectious agents

39. Signs
• The disease is characterized by rapid spread, high
morbidity and low mortality
• Incubation period is 1-3 days after contact
infection and signs appear in 7-10 days
• If not complicated by other infections course is
not more than 10 days in mild form, 3 weeks in
more severe form
• Acute inflammation around the eyes and upper
respiratory tract
• Seromucucoid nasal and occular discharge and
facial oedemA

40. • In severe cases marked conjunctivitis with
closed eyes, swollen wattles and difficulty in
breathing
• Decrease in feed and water consumption
• Drop in egg production
• Increase in rate of culling
• Mortality low and secondary infections eg IB,
ND, Mg, FC

42. Lesions
• Chickens have catarrhal to fibrinopurulent
inflammation of the nasal passages and infra
orbital sinus and conjunctiva
• Subcutaneous oedema of face and wattle
prominent
• Upper trachea may be involved
• Lungs and airsacs are affected only in chronic
complicated cases

43. • Microscopically loss of cilia and microvilli, cell
oedema, degeneration and desquamation of
mucosal and glandular epithelium, infiltration
of leukocytes and deposition of mucopurulent
substances

44. Diagnosis
• The history of rapidly spreading disease
• Clinical signs and lesions
• Isolation and identification of organisms from
swabs of ifraorbital sinus, swabs from the
trachea and airsacs
• Serological tests- HA, HI and FAT