Fowl cholera:

Synonym: Avian cholera, Avian pasteurellosis, Avian Hemorrhagic septicemia

• Fowl cholera is an acute or chronic contagious disease of poultry and wild birds having high morbidity and mortality rates.
• It causes septicemia in birds.

Etiology:

• Pasteurella multicoda
• Gram -ve, non-motile, non-spore forming rod shaped bacteria
• Organism appear bipolar in shape when stained with methylene blue or giemsa stain.
• Organisms are usually killed by household disinfectants or sunlight.

Epidemiology:

• Disease affects domestic and wild birds worldwide.
• Chickens, turkeys, ducks or geese are worst victim of disease.
• Outbreaks are often acute and fatal in adult birds, but chronic and subclinical infection also occur.
• Outbreaks occur in cold and wet weather.
• The outbreaks are often traced back to the presence of rodents in the breeding houses.
• In acute cases, morbidity and mortality rates can reach upto 100%. However, in normal condition, mortality can range from 5-20% or higher in early stages and can reaches upto 45%.
• Birds less than 16 weeks of age are usually resistant to disease.
• Birds between 12 and 18 weeks of age seems very susceptible.
• High-density farming, concurrent infections, and other stressors can predispose birds to severe outbreaks

Transmission:

• Oral, nasal and fecal secretions sheds organism. These organisms are transmitted through close contact with infected birds.
• Ingestion of contaminated food and water
• Through inhalation of aerosol
• Flies and other insects also transmit disease.
• Small canines may transmit the infection through biting of infected birds.
• Infection also spreads through contaminated equipment, cages, hands of visitors, shoes, clothing, etc.
• Recovered birds usually acts as carrier and continue to spread organism.

Pathogenesis:

Clinical Findings:

• Disease appears in several forms. It includes peracute, acute, chronic and localized.

Per-acute form:

• Death of large number of birds
• 50% or more birds may die
• Birds between 12 and 18 weeks of age are susceptible.

Acute form:

• This form is usually manifested in two forms; pulmonary form and septicemic form
• Pulmonary form is characterized by respiratory distress, coughing, sneezing, gasping, cyanosis prior to death.
• Septicemic form is characterized by general dejection and diarrhea. Other signs include:
  • Fever, depression
  • Anorexia
  • Discharge from mouth and ruffled feathers along with diarrhea
  • Feces is watery in nature having whitish appearance initially followed by greenish coloration.
  • Birds may die due to dehydration and emaciation.

Chronic form:

• Edema of comb and wattles
• Swelling of joint
• Swellings pit on pressure
• Lameness due to joint affection
• Mucoid discharge is noted in beak and nostrils.
• Exudation may appear from eye or pharynx.
• Infection spread to brain leading to incoordination, walking in circle, torticollis
• Chronically infected birds remain infected for longer time, may die or recover.

PM Findings:

• In peracute and acute forms, there is marked congestion of carcass, pinpoint hemorrhages throughout organs, and multiple pinpoint necrotic foci in liver.

• Liver is enlarged, friable and contains focal areas of coagulative necrosis.
• Petechial hemorrhages markedly in duodenum, viscid mucus in intestine.
• Pharyngitis with viscid mucus.
• Crop is filled with viscid mucus.
• Ovary is congested, yolk materials may rupture in abdominal cavity
• Pneumonic changes in lungs
• In chronic form, pericardium is thickened containing fibropurulent exudates.
• Joints are swollen containing exudates
• Ear canal are filled with caseous material.
• Swollen of one or both the wattles, rupture of wattles.

Diagnosis:

• Based on history of disease outbreaks
• Based on clincal findings and PM findings
• Isolation and identification of organism by culture. Staining of bacterial colonies shows bipolar rods.
• Serological test: rapid whole blood agglutination test, serum plate agglutination test, agar gel immunodiffusion test.

Differential Diagnosis:

1. Ranikhet disease:

• Sudden death
• Hemorrhages are found in proventriculus/cecal tonsils.

2. HPAI:

• Sudden death
• Cyanosis of comb/wattle
• Respiratory signs; sneezing, nasal discharge

3. Colibacillosis:

• There is usually fibrinous covering on surface of heart, liver
• Septicemic signs are similar to fowl cholera

4. Mycoplasmosis:

• Sinuses are usually swollen
• Thickening of air sac

5. Infectious coryza:

• Swelling of face
• Nasal discharge usually of foul odor
• Usually there is no any septicemic signs

Treatment:

• Peracute cases is so rapid, no treatment is of value.
• In less severe form, numerous antibiotics such as sulphonamides, penicillin, oxytetracycline, erythromycin have been used successfully.
• Care should be taken while treating birds with sulphonamides as it may causes kidney damage in birds.
• Oxytetracycline are usually given in feed or DW for 7-10 days.
• Penicillin can be used parenterally against sulpha resistant flock.

Control Measures:

• Good hygienic and sanitation measures in farm should be maintained.
• Recovered birds acting as carrier from farm should be removed to prevent further transmission of disease.
• Birds of different age groups should be reared in separate pen or cages.
• New birds shouldnot be introduced in flock without removing old flock.
• Infected birds should be isolated immediately and treated.
• Contaminated equipment, food and water should be removed from poultry houses.
• Dead birds should be disposed of properly. They are either burnt or buried deep in ground along with lime.
• Animals like dog, cat, pig shouldnot be allowed to come close to farm and shouldnot be allowed to eat meat of infected bird.
• Tick population should be controlled with acaricides available in market.
• Infected house should be given rest following treatment with disinfectants. Entry of new batch of birds should be made after 15-30 days.