Credit: Prof Dr. UM Singh

1. Mycoplasmosis
• Mycoplasmosis is an problematic infectious
disease of domestic poultry characterized by
sinusitis, tracheitis, airsacclitis.
• Broilers of 4-10 weeks more susceptible
• It can also occur as secondary invaders.
• Artritis and salphingitis in chicken

2. Etiology
• Small(0.2-0.3 µm) coccobacilli
• Organisms isolated as round colonies with central
nipple
• Colonies are 0.25-0.3 mm in diameter
• There are 22 Mycoplasma species from birds
• M. gallisepticum - occurs in chicken and turkey
• M. synoviae - ,,
• M.meleagridis - occurs in turkeys
• M.anatis – ducks
• Organism is fragile outside the body of hosts

3. • M.gallisepticum in infection is known as
Chronic respiratory disease(CRD), Avian
respiratory Mycoplasmosis
• It plays a significant role in the respiratory
disease complex.
• Reduce productivity and hatchability and
livability of chicks and poults.
• It infects chicken from few weeks to 18
months

4. • In broilers, outbreaks at 4-8 weeks of age
• Disease most common during winter
• Pathogenesis: The organism gains entry
through respiratory tract or via the infected
embryo.
• Aggravated by E.coli, P. multocida, IB, ND

5. Spread
• The disease spreads through direct contact
and susceptible bird by both vertical and
horizontal transmission.
• Infection can occur from air borne dust ,
droplet and feathers.
• Indirect infection can occur through
contaminated equipment, feed bags and
personnel
• Wild birds and rodents may also transmit

7. Signs
• Respiratory syptoms and prolonged course
• Decreased appetite, decreased weight gain
• Upper respiratory infection is more severe in
turkeys than in chicken.
• In turkey swelling of one or more infraorbital
sinuses( sinusitis) may occur.
• Nasal exudates accompanied by sinusitis and
respiratory rales, sneezing, coughing,
conjunctivitis, occular and nasal discharge,
gurgling sound(tracheal rales)

8. • In layer flocks decrease in egg production(20-
50%) and is more severe during winter
• Sinusitis and swelling of paranasal sinuses in
turkeys.
• In chronic cases emaciation and purulent
nasal discharge
• Swelling of infraorbital sinus also occurs

9. Gross lesions
• Excess of Catarrhal exudates in the nares, trachea and
lungs.
• Oedema of air sac walls
• Frothy and cheesy exudates, cloudy appearance in air sac.
• Dilatation of infraorbital sinus(Sinusitis) particularly in
turkeys.
• Congestion of trachea, lungs(pneumonia) and conjunctiva
• It is exacerbated by E.coli infection- colisepticaemia.
• In severe in young chicks(4-10weeks) fibrinous
perihepatitis, pericarditis with severe air sacculitis

10. • Microscopically thickening of mucous
membrane, infiltration of mononuclear cells
and hyperplasia of mucous glands and
Lymphphoid follicle.

11. Diagnosis
• Gross lesions in air sacs
• This disease is diagnosed by isolation and
characterization of organisms
• Immunofluorescence tests and
Serological tests like
• Rapid plate agglutination test
• Haemagglutination inhibition(HI) test,
• ELISA and PCR.

13. Infectious sinovitis
Etiology
• Mycoplasma synoviae
• The infection occurs in chicken and turkeys.
• Common in 4-16 weeks age
• Turkeys are susceptible than chicken.
• Spread is by direct contact. Vertical
transmission also occurs.

14. Signs
• Usually there is shrinkage of comb, lameness
and retarded growth.
• Swelling of joints, specially of feet and hocks ,
breast blisters are common.
• Respiratory form occurs with mild rales and
coryza.
• Drop in igg production 20-30%

17. Lesions:
• Oedema and thickening of synovial
membranes of foot and hock joints.
• Thick creamy or cheesy material in the
synovial sac of hock joints and foot pads
• Swelling of liver and kidney
• Emaciation and dehydration

18. Diagnosis
• Isolation and identification of then organisms
from trachea, lungs & air sacs and joints.
• Plate agglutination test for M.gallisepticum
• Antibody demonstration by serology-
• ELISA
• PCR
Signs

19. M. meleagridis in turkeys
• Young ones show poor growth, air saculitis
and osteodystrophy
M. iowae occurs in turkeys and cause leg and
joint abnormalities, mild air sacculitis

20. Yersiniosis
• Avian pseudotuberculosis
• It is widespread in all domestic poultry
• A variety of wild and caged birds, turkeys,
ducks, guinea fowls and rodents.
• It is reported in man but not important
zoonosis. Turkeys are most frequently
affected.

21. Etiology:
Yersinia pseudotuberculosis is Gm –ve,
coccobacillus.
• Turkey and young birds are most susceptible.
Overcrowding predisposes the disease.
• Infection spreads by contamination of food.
• Organisms gain entry through the intestinal
mucosa or occasional breaks in skin.

22. Sign:
• Clinical signs are similar to fowl cholera.
• Birds die without any signs.
• In chronic cases persistent diarrhoea,
weakness
• ruffled feathers
• lameness.
• emaciation

23. Gross lesions:
• Enlargement of liver and spleen in acute cases.
• In chronic cases multiple caseous tubercle like
lesions of varying sizes in liver, spleen and lungs.
Severe enteritis may be observed
Diagnosis:
• Clinical signs and lesions.
• Isolation and identification of coccoid organisms.
• Pseudotuberculosis is nonmotile at 37°C but
motile when grown at 20°C

24. Avian chlamydiosis
Syn: Psittacosis, ornithosis, parrot fever
• As it is contracted from parrot it is called "Parrot
fever".
• Psittacosis affects human, mammals and psittacine
birds ( parrots and parakeets).
• Ornithosis occurs in birds other than psittacine birds.
• Turkey, ducks and pigeons are most susceptible and
chickens are rarely affected.
• Ingestion and inhalation are major route of
transmission

25. Etiology:
• Chlamydia psittaci
• Gm –ve coccoid organisms. There are 6 serotypes
in birds.
• Infectious form is the elementary body(EB) and is
small, dense, spherical body, 0.2-0.3 µm in
diameter responsible forattaching to target host
cell and promoting entry.
• Noninfectious form is the reticulate body(RB) is
intracellular active form, 0.6-0.8 µm osmotically
fragile wall, which divides by binary fission.

26. Spread
• Spread of infection is by direct means indirectly
through fomites and biting insects.
• Elementary bodies found in faeces and
respiratory secretions are highly resistant and
survive in dried faeces faeces for many months.
• The organisms are highly resistant outside host
and can remain for many months.
• Spread by inhalation of contaminated dust. Stress
, overcrowding and concurrent infection
contribute for precipitation of disease.

27. Pathogenesis
• After inhalation of organisms multiply in the
lungs , air sac and pericardium.
• By haematogenous spread reach liver, spleen ,
kidney and growth and replication occurs in
these organs

28. Signs
Human
• febrile illness
• upper respiratory involvement
• pneumonia
• severe debility

29. Birds- depends on strain species and age of the bird.
• Clinical signs may be absent, mild or severe cases
occur. Serous or purulent exudates from eyes or nostril.
• Depression and weakness
• anorexia, diarrhoea with greenish yellow faeces often
gelatinous consistency.
• Respiratory distress is common.
• Nasal discharge and conjunctivitis
• Turkey, ducks and pigeons show depression with
ruffled feathers.

30. Lesions
• Serofibrinous exudates covers serosal
surfaces( specially pleural cavities)
• Fibrinous Pericarditis
• Fibrinous pneumonia,
• Fibrinous air sacculitis and perihepatitis
• enlargement of liver and spleen.

31. Microscopic-lesions
• Spleen with mononuclear cells containing
organism
• Liver with focal necrosis.
• Kidney shows epithelium packed with
LCL(Levinthol,Coles and Lillies) bodies which
are basophilic bodies.

32. • In lungs few alveoli shows severe exudates.
• Intestine with erosion of mucosa.
• Infiltration of lymphocytes and plasma cells in
lamina propria and submucosa.
• In macrophages and epithelial cells,
cytoplasmic bodies may be seen which can be
demonstrated by Giemsa, Machiavello,
Castaneda or Gemenez method of staining.

33. Diagnosis
• Demonstration of organisms or isolation and
identification of organisms or serological
examination
• Smears or secretions of peritoneal, pericardial,
liver and spleen lesions for intracellular
organisms.
• Complement Fixation Test,
• Fluorescent Antibody Technique,
Immunoperoxidase Test
• ELISA and PCR

34. Necrotic enteritis
Clostridial enteritis, enterotoxaemia
• It is sporadic disease of chickens and turkeys. It
ioccurs in birds of > 4 weeks age.
• The disease is caused by C. perfringens type A or
C. α toxin is produced by C. perfringen type A& C
and β toxin by type C are responsible for
intestinal mucosal necrosis.
Spread:
• Organisms can be found in faeces, soil, dust and
contaminated feed and litter or intestinal
contents.

37. Predisposing factors
• Outbreaks of coccidiosis
• Impaction of lower intestine
• Rapid changes in feed components
• Removal of the antibiotic growth
promotersfrom feed

38. Signs:
• depression, anorexia,diarrhoea.
• Birds are found just dead.
Lesions:
• Thickening of small intestine with extensive
necrosis of mucosa.
• In acute cases large amount of necrotic
epitheliumal debris in lumen of small intestine.
Diagnosis: - Gross and microscopic lesions.
- Isolation of organisms

41. Staphylococosis
• It is caused by Staphylococcus aureus
Impotant conditions are
• yolk sac infection
• Gangrenous dermatitis,
• Bumble foot(sub dermal abscess)
• Spondylitis
• Arthritis and synovitis
• Staphylococcal septicaemia
Injuries to skin or mucous membrane may predispose to
tissue invasion

42. Yolk sac infection- covered in colibacillosis
Gangrenous dermatitis
• This occurs in birds of all ages
• Most common in broilers and growers of 15-20
weeks of age
• The wing tips and the dorsal pelvic region are
affected
• The affected sites are dark, moist and
gangrenous(decaying) in appearance

44. Spondylitis
• S. aureus may cause absxess in the bodies of fifth to
seventh vertebrae with periostitis and osteomyelitis
• Pressure on spinal may result in paresis or paralysis
Arthritis and synovitis
• The affected joints hock joint are hot, painful and
causing lameness
• The synovial membranes are congested and
oedematous
• Necrosis and fibrin deposits with caseous exudate

45. Bumble foot
• It is an abscess in the foot pad
• It usually occurs in mature birds
• The abscess formation is accompanied by
swelling, heat, and pain leading to lameness
• The under surface of the foot is first affected
and the lesion may spread to whole feet

47. Staphylococcal septicaemia
• It is cause by invasion of organisms in blood
• It occurs from a local site of infection and may
result to sudden death
• Symptoms include ruffled feathers, limping on
one leg, severe depression and death

48. Diagnosis
• Symptoms and Post mortem lesions
• Isolation and identification of organisms