Prof. Dr. Mohamed H. H. Awaad
Faculty of Veterinary Medicine, Cairo University
Mycoplasma gallisepticum infection:
Contagious disease of chickens and turkeys of all ages,
characterized by air sacculitis with caseous exudates.
Mycoplasma synoviae infection:
Infectious disease of chickens and turkeys characterized
originally as joint infection and more recently as a respiratory
Mycoplasma meleagridis infection :
Severe egg-transmitted infectious disease of turkeys of any
age, characterized by inapparant venereal infections in turkey
breeders and air sacculitis in embryonating or newly hatched
• Retardation of growth (extra-time needed to bring
broilers to market).
• Poor feed efficiency.
• Down grading of carcasses and presence of
large number of unmarketable birds.
• Reduced egg production and hatchability.
• High condemnation rate.
• Increased medication costs.
✺Very small colonies (0.1-1 mm). Fried
✺Smallest known free living forms of life (live
independently). Only 3 species are potent
pathogens: M.gallisepticum, M.synoviae & M.
meleagridis. M. iowa and M. gallinarum (minor
✺MG (Most pathogenic and economically significant
mycoplasma pathogen of poultry).
• Week Gram negative. Stain with Giemsa stain.
• Vary from Viruses and Rickettsia in that they do not require
living cells for growth.
• Vary from bacteria in that they have no rigid cell wall or cell
wall-mucopeptide or it’s precursers (highly pleomorphic and
resistant to antibiotics which act on bacterial cell walls)
They can pass through bacterial filters.
• The immunogenicity (and relative low virulence) and
protective characteristics of three MG strains (F, ts-11, and
6/85) have been applied to their commercial development as
●Very delicate - survive briefly in bird environments (few hours).
●Carriers are essential for their survival (Transmission by contact; respiratory
tract infection) .
● Transovarian (Egg) transmission rates decline as the post infection interval
lengthens. Transmission rates of approximately 3% at 8—15 weeks
production and approximately 5% at 20—25 weeks. During chronic
infections under field conditions, egg transmission is likely to occur at much
● Contact with infected or carrier birds may occur upper respiratory tract
conjunctiva are portals of entry for the organism in aerosols or droplets.
. Contaminated live virus vaccines ●
● In Mm high egg-transmission rate has
been recorded in infected turkey flocks
(average of 25% over a season’s lay) ,
venereal transmission is well known.
MG vary widely in pathogenicity; S6 strain of
Live F strain MG vaccine
(more pathogenic for turkeys than chickens). The 6/85 and ts-ll
vaccine strains (less pathogenic for both chickens and turkeys
(brain of a turkey).
than F strain).
Respiratory tract: trachea, lungs and air sacs.
Other sites: Cloaca, reproductive tract of layers (eggs) and
cocks (semen), brain (occasionally). Synovial membranes,
sheaths and joints in MS.
Chronic Respiratory Disease (CRD) In Chickens
Infectious Synositis (IS) In Turkeys
It is a serious disease problem of
chickens and turkeys
characterized by respiratory
signs and inflect heavy economic
E.coli (most commonly)
and respiratory viral
infection (ND, IB, or
even vaccination with
their living vaccines) complicate CRD and
produce what is called complicated chronic
).respiratory disease (CCRD
Primary etiology is
(PPLO) causing CRD.
Incubation period: 6-21 days (average 11-18 days)
The course: 1-2 months.
Relatively mild infection.
Extensive outbreaks of severe
Signs: Develop slowly in the flock (coughing,
sneezing, snicks, and rales, ocular and nasal
In adults; feed consumption and egg production drop.
Within one weak later become 810 folds thicker than normal
Formation of yellowish
develop on air sacs
producing opaque air sacs
of normal air sac
Hyperplasia and mononuclear
cells infiltration with large
number of polymorphonuclear
leukocytes in CRD infected air
Secondary E.coli infection
leads to severe fibrinopurelent
or Caseous exudates on
pericardium and liver capsule
(fibrinous pericarditis and
Section of sinus in
chicken. Notice the
of mononuclear cells and
Section through nasal
passages and sinuses of
infected chicken. Notice
the unilateral mucosal
thickening of sinus and
Catarrhal inflammation of the nasal passages,
sinuses, trachea, and bronchi.
Turkeys: Severe clinical signs
(sinusitis, respiratory distress,
intake, and weight loss). More
severe outbreaks with high
morbidity and mortality result
Partial to complete closure of eyes
. results from severe sinus swelling
of MG (in 12—16-week-old)
(torticollis and opisthotonos). Drop in egg production.
reluctance to move, swollen joints, breast
Tenosynovitis (foot pad)
Synovitis increased joint
Hyperplastic synovial membrane
with multiple subsynovial
Incised swollen foot pad
with granulation tissue
and purulent exudate
✺High mortality in very
✺Drop-off in production
and hatchability in breeder
✺Resp. distress, stunting,
crooked neck with
deformity of cervical
vertebrae, leg deformy &
•CPP (Tentative diagnosis).
•Laboratory Diagnosis (Final diagnosis):
a-Isolation & Idntification:
Isolation: Laborious process (slow growth –
complex nutritional requirement) tubes should be
incubated at 37 C for at least 14 days
before being discarded as negative.
Identification: Biochemical & Serological
(growth inhibition test, agar gel precipitation test,
ELISA, FAT, HI, Agglutination test).
b- Seroconversion (For detection of carriers)
1-SPA: Quick, relatively inexpensive,
(Nonspecific reactors with M. synoviae or
those recently vaccinated with oil-emulsion vaccines and/or
vaccines of tissue-culture origin against various agents).
2-HI: Confirm SPA.
reagents are not commercially available; and test may lack
3-ELISA tests: Less
more specific than SPA tests and less specific
but more sensitive than HI tests. (Used to detect MG
antibodies in resp. tract washings and egg yolk samples “Flock
Strain identification by RAPD-PCR
Eradication/monitoring and egg treatment.
Replacement pullets and Layers:
I- Serological testing:
Uninfected breeding flocks to be used
as a nucleus for breeding replacing
infected stock and separation of
uninfected chickens from infected
II-Destruction of Mycoplasma
✺Force antibiotics through shell of incubating eggs
eggs into chilled antibiotic solutions” 400-1000 ppm tylosin or
erythromycin for15-20 minutes”).
✺Incubator temperature gradually is raised over a 12-14 hour
period to the maximum embryo survival temp., approximately
46.9°C and then cooled immediately and rapidly to normal
Automated INOVOJECT® system, allows
automated mass application (up to 50 000
).eggs per hour
Unrealistic expectation in mass production.
For short-term amelioration of disease rather
than as a long-term solution to the problem).
Macrolides: (e.g. Josamycin,Tylosin,Spiramycin,
Lincomycin, Clindamycin, Spectinomycin,
Tetracyclines, 3rd generation Quinolons.
Precautions For MG Vaccination
1-Used only where eradication is not
2-Vaccination should be prior to
3-Keep vaccinated stock isolated
from MG free stock.
✺ Single dose - vaccinated birds remain permanent carriers.
Eye-drop, intranasal, coarse spray or
drinking water. 8-14 Ws (2 Ws or
less if chicks are at risk).
Broiler breeders replacement flocks
(reduce possible egg transmission).
Layers (more eggs) unvaccinated
hens in flocks with endemic MG
✺ Concentrated suspension of MG in an oil emulsion.
✺ Administered S/C to layer pullets at 12–16 weeks
✺ Two doses are desirable.
✺ Effective in preventing egg-production losses and
respiratory disease, but they do not prevent
infection with wild-type MG.
✺ Recently development (MG surface proteins).
✺Broilers (infection reduced by vaccination of
broiler parent breeders).
✺Turkey vaccination with live vaccines is not
✺ Long-term use of F strain results in
displacement of field strains.
✺ F strain displace challenge strains than did
✺ Strains 6/85 and ts-11 are safer than F strain.
✺Breaking cycle of venereal
transmission (Serological procedures with
culture tests of phallus, semen and vagina before
✺Practicing the hygienic method of