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By

Prof. Dr. Mohamed H. H. AwaadFaculty of Veterinary Medicine, Cairo University

Mycoplasma gallisepticum infection: Mycoplasma gallisepticum infection: Contagious disease of chickens and turkeys of all ages, characterized by air sacculitis with caseous exudates.

Mycoplasma synoviae infection: Mycoplasma synoviae infection: Infectious disease of chickens and turkeys characterized originally as joint infection and more recently as a respiratory disease.

Mycoplasma meleagridis infection :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 poults.

• 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.

Mycoplasma species:

✺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 pathogenic capabilities).

✺Very small colonies (0.1-1 mm). Fried egg appearance.

✺MG (Most pathogenic and economically significant mycoplasma pathogen of poultry).

Etiology…cont.

• 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 live vaccines.

Class MollicutesClass Mollicutes Order MycoplasmatalesOrder Mycoplasmatales

Family MycoplasmetaceaeFamily Mycoplasmetaceae

●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 lower levels.● Contact with infected or carrier birds may occur upper respiratory tract and/or conjunctiva are portals of entry for the organism in aerosols or droplets.

Vertical transmission

Horizontal

transmission

carriercarrier

Contact infectio

n

Healthy

HealthyHealthy

Infected

egg

Infected

● 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.

Localization sites: Localization sites: 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 MSMS.

MGMG vary widely in pathogenicity; S6 strain S6 strain of Zander (brain of a turkey). Live FF strainstrain MG vaccine (more pathogenic for turkeys than chickens). The 6/856/85 and ts-ll ts-ll vaccine strains vaccine strains ((less pathogenic for both chickens and turkeys than F strain)F strain).

Pathogenesis Pathogenesis (spread of infection)(spread of infection)

Chronic Respiratory Disease (CRD) In Chickens Chronic Respiratory Disease (CRD) In Chickens Infectious Synositis (IS) In Turkeys Infectious Synositis (IS) In Turkeys

Chronic Respiratory Disease (CRD) In Chickens Chronic Respiratory Disease (CRD) In Chickens Infectious Synositis (IS) In Turkeys Infectious Synositis (IS) In Turkeys

It is a serious disease problem of It is a serious disease problem of chickens and turkeys chickens and turkeys

characterized by respiratory characterized by respiratory signs and inflect heavy economic signs and inflect heavy economic

losses. losses.

Primary etiology is Mycoplasma species Mycoplasma species (PPLO) (PPLO) causing CRD.

Complications:Complications:E.coliE.coli (most commonly) and respiratory viral infection (ND, IB, or (ND, IB, or even vaccination witheven vaccination with

CC

RD

CC

RD

CRDCRD

Weeks

their living vaccines) their living vaccines) complicate CRD and produce what is called complicated chronic respiratory disease (CCRD).

MycoplasmaMycoplasma alone alone Relatively mild infection.

ComplicationComplication Extensive outbreaks of severe respiratory disease. Signs:Signs: Develop slowly in the flock (coughing, sneezing, snicks, and rales, ocular and nasal discharge). In adults; feed consumption and egg production drop.

The course: The course: 1-2 months.Incubation period: Incubation period: 6-21 days (average 11-18 days)

Foamy lesions develop on air sacs

Within one weak later become 8-10 folds thicker than normal

Lesions consolidate producing opaque air sacs

Formation of yellowish purelent exudate

Hyperplasia and mononuclear cells infiltration with large

number of polymorphonuclear leukocytes in CRD infected air

sac.

Histological appearance of normal air sac

Secondary E.coli infection leads to severe fibrinopurelent

or Caseous exudates on pericardium and liver capsule

(fibrinous pericarditis and fibrinous perihepatitis)

Section through nasal passages and sinuses of infected chicken. Notice the unilateral mucosal thickening of sinus and

nasal passage.

Section of sinus in chicken. Notice the

subepitheilial infiltration of mononuclear cells and

the lymphofollicular reaction.

Catarrhal inflammation of the nasal passages, sinuses, trachea, and bronchi.

Turkeys: Severe clinical signs (sinusitis, respiratory distress, depression, decreased feed intake, and weight loss). More severe outbreaks with high morbidity and mortality result with complication.

Encephalitic form: of MG (in 12—16-week-old) (torticollis and opisthotonos). Drop in egg production.

Partial to complete closure of eyes results from severe sinus swelling .

Synovitis -Synovitis -increased joint increased joint

fluidfluid

Synovitis Form (lamness, lethargy, reluctance to move, swollen joints, breast blister).

Swollen joints

Tenosynovitis (foot pad)Tenosynovitis (foot pad)

Mild Mild airsacculitisairsacculitis

Incised swollen foot pad Incised swollen foot pad with granulation tissue with granulation tissue and purulent exudate and purulent exudate surrounding digital surrounding digital

flexors. flexors.

Ulceration Ulceration of articular of articular surface of surface of

distal distal tibiotarsus tibiotarsus Hyperplastic synovial membrane Hyperplastic synovial membrane

with multiple subsynovial with multiple subsynovial lymphoid aggregateslymphoid aggregates

✺High mortality in very young poults. ✺Drop-off in production and hatchability in breeder flocks.✺Resp. distress, stunting, crooked neck with deformity of cervical vertebrae, leg deformy & thoracic airsacculitis.

Bowing of tarsometatarsal

bones.

Airsacculitis.

•CPPCPP (Tentative diagnosis).

•Laboratory Diagnosis Laboratory Diagnosis (Final diagnosis):

a-Isolation & Idntification: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 b- Seroconversion (For detection of carriers)

1-SPA: Quick, relatively inexpensive, and sensitive. (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. (Time consuming; reagents are not commercially available; and test may lack sensitivity).

3-ELISA tests: Less sensitive but 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 screening”).

MPM 19 20 R 6/85 ts-11

Strain identification by RAPD-PCR

Rapid slide agglutination test - MS

Breeders:Breeders:Eradication/monitoring and egg treatment. Chemotherapy.Vaccination (killed/live).

Replacement pullets and Layers:Replacement pullets and Layers:Vaccination (killed/live).Chemotherapy.

Broilers:Broilers:Chemotherapy.

I- Serological testing: I- Serological testing: Uninfected breeding flocks to be used as a nucleus for breeding replacing infected stock and separation of uninfected chickens from infected flocks.

II-Destruction of Mycoplasma II-Destruction of Mycoplasma Inside Eggs:Inside Eggs:✺Force antibiotics through shell of incubating eggs prewarmed 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 incubation temp.

Automated INOVOJECT® system, allows automated mass application (up to 50 000

eggs per hour).

Complete elimination:Complete elimination: Unrealistic expectation in mass production.

Treatment:Treatment: For short-term amelioration of disease rather

than as a long-term solution to the problem).

Antimicrobials:Antimicrobials: Macrolides: (e.g. Josamycin,Tylosin,Spiramycin,

Tiamulin, Kitassamycin).

Lincomycin, Clindamycin, Spectinomycin, Tetracyclines, 3rd generation Quinolons.

Precautions For MG VaccinationPrecautions For MG Vaccination1-Used only where eradication is not

feasible.2-Vaccination should be prior to

field exposure.3-Keep vaccinated stock isolated

from MG free stock.

6/85 strain

ts-11 strain

Connecticut

F strainVirulenceNoNoLow

Administ.Fine Spray

6 Ws.

Eye

9 Ws.

Eye-drop, intranasal, coarse spray or drinking water. 8-14 Ws (2 Ws or less if chicks are at risk).

Uselayerslayers

Broiler breeders replacement flocks (reduce possible egg transmission).

Layers (more eggs) unvaccinated hens in flocks with endemic MG

✺ Single dose - vaccinated birds remain permanent carriers.

✺ Concentrated suspension of MG in an oil emulsion. ✺ Administered S/C to layer pullets at 12–16 weeks of age.✺ 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 recommended.✺ Long-term use of F strain results in displacement of field strains.✺ F strain displace challenge strains than did others.✺ Strains 6/85 and ts-11 are safer than F strain.

N.B.:N.B.:

Depends upon:Depends upon:✺Breaking cycle of venereal transmission (Serological procedures with culture tests of phallus, semen and vagina before breeding).

✺Practicing the hygienic method of artificial insemination.✺Veterinary biosecurity.

ThankThank youyou