عملي

Infectious Laryngotracheitis (ILT)

Cause
ILT is caused by a Herpesvirus, only one serotype is known.

Transmission

The natural entry of ILT is via the upper respiratory tract and ocular route. Field spread occurs via direct contact from bird to bird and/or transmission by contaminated people or equipment (visitors, shoes, clothing, egg boxes, transport crates).
Incubation period varies from 4 -12 days.

Species affected

Chickens are the primary natural host but other species (pheasants) can also be affected.

Clinical signs

An acute respiratory disease with nasal discharge and moist rales followed by gasping, marked respiratory distress and expectoration of blood-stained mucus in laying birds. Egg production can drop 10 -50% but will return to normal after 3-4 weeks. Mortality can vary from 5 -70%.
Spread through a chicken house is slower compared to IB and ND.

Post mortem lesions

Lesion are found throughout the respiratory tract but most pronounced in the larynx and trachea.
Depending on the severity of the infection you can find tracheitis with hemorrhagic and/or diphteric changes.


Diagnosis
Clinical picture with birds showing respiratory distress and expectoration of bloody mucus are indicative for ILT. Laboratory confirmation with: histopathology showing intranuclear inclusion bodies in tracheal epithelial cells, virus isolation from tracheal swabs on embryonated chicken eggs, virus detection with PCR.
Detecting antibodies from blood samples after infection.

Treatment

There is no treatment for ILT; emergency vaccination in the early stage of an infected flock may reduce the spread and limit the outbreak.

Prevention and control

In many countries vaccination is the preferred control method.

Prevention and control

Vaccines are effective in controlling clinical problems but have the risk of spreading and reversion to virulence after multiple passage through chickens.
Recent outbreaks show often the relation to the live vaccine strains used in an area. Therefore, the new generation of recombinant vector vaccines are more suitable in the control and prevention of ILT.
Recombinant vaccines based on HVT-vector carrying inserts of important immunogenic ILT proteins show good efficacy and do not spread and cannot revert to virulence because there is not a full ILT virus involved.

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Botulism


Synonyms
limberneck, bulbar paralysis, western duck sickness, alkali disease

Causes

• Clostridium botulinum is an anaerobic, Gram-positive rod-shaped cells and spore-forming bacterium.
• Most avian cases are caused by C. botulinum type C or mosaic type C/D, although outbreaks due to other toxin types have been described.
• Chickens, turkeys, pheasants, and peafowl are susceptible to toxin types A, B, C, and E, but not to D or F toxin, Furthermore, type C/D toxin has been demonstrated to be more toxic to avian species than pure type C toxin

Species affected

All fowl of any age, humans, and other animals are highly susceptible. The turkey vulture is the only animal host known to be resistant to the disease.

Incubation Period

The time to onset of paralytic symptoms varies and depends on the amount of ingested type C spores and intestinal toxin production, or preformed toxin. With high levels of neurotoxin, disease appears within hours. With low toxin doses, onset of paralysis occurs within 1–2 days

Clinical signs

Botulism is a poisoning causing by eating spoiled food containing a neurotoxin produced by the bacterium Clostridium botulinum. Paralysis, the most common clinical sign, occurs within a few hours after poisoned food is eaten.
In chickens, flaccid paralysis of legs, wings, neck, and eyelids are predominant features of the disease. Paralytic signs progress cranially from the legs to include wings, neck, and eyelids. Initially, affected birds are found sitting and are reluctant to move. Wings droop when paralyzed. Limberneck, the original and common name for botulism. Because of eyelid paralysis, birds appear comatose and may seem dead. Gasping has been reported when birds are handled. Death results from cardiac and respiratory failure. Affected chickens have ruffled feathers. Broiler chickens showing signs of botulism may have diarrhea with excess urates in the loose droppings.

Clinical signs

If the amount eaten is lethal, prostration and death follow in 12 to 24 hours. Death is a result of paralysis of respiratory muscles. Fowl affected by sublethal doses become dull and sleepy.
Birds with type C botulism lack characteristic gross or microscopic lesions.


Transmission
Botulism is common in wild ducks and is a frequent killer of waterfowl because the organisms multiply in dead fish and decaying vegetation along shorelines.
Decaying bird carcasses on poultry ranges, wet litter or other organic matter, and fly maggots from decaying substances may harbor botulism. There is no spread from bird to bird.

Treatment

Remove spoiled feed or decaying matter.
It has been reported that potassium permanganate (1:3000) in the drinking water is helpful.
Affected birds can be treated with botulism antitoxin injections.
Commercial broiler chickens in outbreaks of botulism have been successfully treated with several antibiotics including bacitracin, streptomycin, tylosin, amoxicillin, penicillin, and chlorotetracycline

Prevention

Do not feed spoiled canned vegetables. Control flies. Replace suspected feed.

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