Respiratory Disease complex
By §§ By Prof. Dr. Dr. Mohamed Mohamed §§ Prof. H. H. H. Awaad Awaad H. Facultyof of Veterinary Veterinary §§ Faculty Medicine, Cairo Cairo Medicine, University University
Economic losses § § § § § § §
High mortality (e.g. Avian influenza). Down grading of carcasses and condemnation at slaughter (e.g. CCRD). Lowering fertility and hatchability (e.g. Mycoplasmosis). Severe drop in egg production and egg quality (e.g. ND and IB). Loss of weight and poor feed conversion (e.g. Colibacillosis). Increased medication costs. Increased post vaccination reaction.
Predisposing factors (Stresses) I- Immunosuppressive factors
A-Feed: Mycotoxins, antibiotics, pesticides, chemicals, deficiency (vitamins, Protein & minerals).
B-Environment: Bad ventilation (ammonia and dust), temp. extremes, high relative humidity.
C-Organisms: Viral (CAV, ALV,REV, Reo, IBDV, MDV, NDV & AIV). Bacterial: MG & MS. Coccidiosis. II- Management factors: 1-System of management (Multiage). 2-Distance to the nearest farm and between houses. 3-Stocking density (over crowding - social stress). 4-Chick quality. 5-Poor biosecurity (Rodents, Insects, Animals, man). 6- Litter (dry or wet). 7-Duration between successive cycles. 8-Vaccination and medication.
Classification of Respiratory Diseases according to etiological agent(s) 1- Viral (ND, IB, ILT, Paramyxoviruses other than ND, Avian influenza, Adenoviruses, Reoviruses,and Avian poxvirus “ Avian diphtheria ” ). 2-Bacterial (Colibacillosis, ORT, Salmonellosis, Pasteurellosis, Mycoplasmosis, Infectious coryza, and Chlamydiosis). 3- Mycotic (Aspergillosis “ Brooder pneumonia). 4-Parasitic (Cryptosporidia,Syngamus trachea in chickens and turkeys, and Cyatostoma bronchialis). 5-Non-infectious (Vitamin A deficiency).
Classification according to site of affection 1- Outbreaks which affect the upper respiratory tract; nasal discharge and distended sinuses with or without lower respiratory symptoms) e.g. Infectious coryza, Mycoplasmosis, Diphtheritic form of Avian pox and Avitaminosis A.
2- Outbreaks that affect mainly lower respiratory tract without obvious nasal discharge or sinusitis are likely to be due to mild ND,IB,ILT or Aspergillosis.
N.B.: This classification depends on the early detection of the first clinical signs. (Complications).
Epizootiology I-Susceptibility: a-Species: *Limited to species (e.g. IB, ILT, IC) *Wide host range (e.g. ND, AI, FC) b-Age: *First few weeks (E.coli, Asp., Salm., Mycoplasm). *Semimature and Adults (ILT, IC, FC). *All ages (ND, IB).
II-Mode of infection and transmission: *Inhalation (Most of Respiratory Diseases). *Ingestion (AI, ND, IC, FC). *Conjunctival infection (ILT, FC). *Insect biting (Fowl Pox). *Vertical transmission (MG, MS, Salmonellosis, E.coli).
Epizootiology( continue) III-Incubation period: *Very short (1-3 days e.g. IB, IC, AI). *Moderate (4-6 days e.g. ND). *Long (Over 6 days e.g. Mycoplasmas, ILT, Avian Pox).
Clinicopathological picture Symptoms: ยง Respiratory signs include nasal discharge, sneezing, coughing, rales, gasping, and dyspnoea. ยง + General clinical signs of ruffling of feathers, loss of appetite, huddling together, constant peeping young birds, and depression. +Specific signs of each disease.
Post mortem lesions: Rhinitis, pharyngitis, laryngitis, tracheitis, bronchitis, lung congestion or pneumonia. + Specific lesions of each disease.
Specific clinicopathological picture of certain Respiratory diseases
Newcastle disease Septicaemic contagious- respiratory and/or nervous, facial edema, greenish diarrhea, Lowering egg production (quantity and quality).
Variation of clinicopathology depends upon 1- Virus agent (Virulence, degree of exposure). 2-Host (Age, general health condition, immune status).
forms: I- Acute lethal VVND (Doyle’s form). II- Acute often lethal respiratory + nervous NVND (Beach’s form). III- Less pathogenic NVND-mesogenic (Beaudett’s form). IV- Mild respiratory-lentogenic (Hitchener’s form). V- Non obvious disease (Asymptomatic-enteric form).
Infectious bronchitis (IB) Contagious disease of chickens only Mainly respiratory, may cause problems in intestine, kidneys (INNS) or reproductive system. Caseous plugs (pathognomonic lesion). Drop in egg production, misshapen eggs with watery albumin, false layers with abdominal ovulation. Severe nephrosis and nephritis (INNS) with lesions of gout (nephrotoxic strains).
Infectious laryngeotracheitis (ILT) Contagious disease of chickens and pheasants-dyspnoea and expectoration of bloody exudate.
Hemorrhagic tracheitis - free blood or blood tinged cheesy plugs is pathognomonic
Avian pox (Avian Diphtheria) ยง Contagious disease - Skin eruptions of unfeathered parts and / or diphtheritic lesions on mucus membranes of upper respiratory and digestive tracts (Pseudombrane).
Avian influenza Variety of disease syndromes ranging from subclinical to acute generalized fatal disease (Fowl plague).
Fowl plague Rapidly fulminating - increasing mortality - periorbital edema - edema of the head - swollen sinuses - cyanotic hemorrhagic wattles, comb and legs. Post mortem lesions consist of a variety of congestive-hemorrhagic-transductivenecrotic changes.
Infectious coryza *Acute respiratory disease of only chickens. *Acute spread with nasal discharge swelling of eye-lids and sinusitis - edema of the wattles - 10-40% drop in egg production
Avian Mycoplasmosis “ CRD” § Uncomplicated Inapparaent or very mild with poor egg production and reduced hatcability. § In turkeys severe
sinusitis “ IS” .
§ Airsacculitis is so far a pathognomonic lesion.
Avian Colibacillosis ยง Air sac disease either separately or complicating mycoplasmosis (CCRD). ยง Poor feed conversion and lesions of pericarditis, perihepatitis and airsacculitis (serous to caseous).
Salmonellosis ยง Subacute form of S.gallinarum in baby chicks may show respiratory signs. ยง Lesions are whitish nodules in lungs, cardiac muscle or pancreas - Ceca may contain caseous cores Swollen joints - Retardation of yolk sac absorption).
Avian Pasteurellosis ยง Catarrhal or Roup form of Chronic fowl cholera. ยง Rattling respiration or rales - Catarrhal discharge from nostrils - Conjunctivitis.
Chlamydiosis ยง Latent infection ยง Stress conditions ยง Acute disease ยง (Respiratory signs, diarrhea, trembling, locomotor disturbances, leg paralysis, spleenomegaly and hepatomegaly, serofibrinous exudates in abdominal cavity).
Ornithobacterium rhinotracheale (ORT) Discovered since December 1991 Respiratory manifestation with different clinical courses. Mild respiratory symptoms and sinusitis)
Mortality Egg production Performance Foamiest â€œyogurt-likeâ€?exudate Fibrinous Pneumonia and Pericarditis.
Aspergillosis ยง Respiratory lesions: Milliary nodules up to larger nodules with localized hepatization in lungs. Visible mycelial masses in air passages and bronchi. Disc-shaped necrotic mass or nodules with concave surface. Thickened air sacs that covered with fur-like growth of mold.
ยง Eye lesions: Yellow cheesy pellet beneath the nictitating membrane causing plugging of the eye-lids. Central ulceration of the cornea.
ยง Nervous manifestations: Torticollis and lack of equilibrium.
Tracheal worms ยง Parasitising the trachea and bronchi giving signs similar to ILT (Dyspnoea). Syngamus trachea (chickens , turkeys, peacocks and pheasants).
Cytostoma bronchialis (ducks, geese and turkeys).
Avitaminosis A (Nutritional Roup) ยง Poor growth - Inflamed eyes - Nasal catarrh - Swelling of sinuses Keratoconjunctivitis - Excessive lacrimation - Drop in egg production.
Diagnosis ยง * Clinicopathological picture (Tentative). ยง * Lab. Diag.(Definite diagnosis): l
Early stages (Isolation and identification of pathogenic agent-Direct methods). Convalescent stages (Detection of rising Ab titers in sera). N.B.:
Lab. Diag. Is necessary to rule out the possibilities of a mixed infection.
Prevention and Control Lines of Defense In Avian Respiratory Tract *Cilia: (lining mm of trachea and bronchi) act as moving brush. *Mucus producing cells: secrete protective layer of mucus. *Local antibodies: Harderian gland, floods mm of upper respiratory tract with antibodies(IgA). Lymphoid tissues in submucosa of conjunctiva, nasal cavity, larynx and trachea.
Prevention and Control 1- Strengthen resistance of the host i Breeding for resistance. i Improved nutrition. i Vaccination. i Chemotherapy (Prophylactic and therapeutic). i Competitive exclusion (CE) and Probiotics.
2- Destruction of large numbers of invaders: i Disinfection. i Feed decontamination ď ż Physical destruction of microorganisms ( irradiation, pelting) ď ż Chemical mechanisms (Dietary acid additives).
3-Veterinary biosecurity + hatchery hygiene.