Colibacillosis:

Synonym: Colisepticemia, Hjarre’s disease, Coli granuloma, Peritonitis, Mushy chick disease, Air sacculitis, Omphalitis, Synovitis

• Colibacillosis is an important and infectious disease in poultry that are difficult to treat.
• It affects birds of various age group with higher mortality and severe economic losses to farmers.
• It is one of the most common and most troublesome bacterial disease of poultry.
• Colibacillosis can manifest in diverse ways, including acute fatal septicemia, subacute pericarditis, airsacculitis, salpingitis, peritonitis, and cellulitis. In laying hens, peritonitis and salpingitis are common, whereas disease in young chicks may include omphalitis (yolk sac infection) or swollen head syndrome.

Etiology:

• It is caused by various strains of Escherichia coli.
• More than 150 serotypes are present in environment, i.e. soil, water and air.
• Bacteria is gram -ve, rod shaped and non-sporulating bacilli.

Epidemiology:

• Disease is widely prevalent worldwide.
• According to study conducted in 2015, colibacillosis has greatest incidence in Nepal. Out of 2271 cases observed in CVL, 26% cases were of colibacillosis.
• Bacteria of these species lives normally in digestive tract of birds and most strains donot produce disease.
• It is one of the leading causes of illness and mortality in Nepal’s poultry industry with reported prevalence rates ranging from 10-60% in poultry flocks.
• The disease exhibits seasonal fluctuations, with higher prevalence during the summer and winter seasons, which may be linked to environmental conditions.
• Chicks are particularly vulnerable, with the highest disease prevalence observed in the first and second weeks of life.
• Serogroups like O78, O1, and O2 are frequently isolated from affected birds.

Transmission:

• Through ingestion of contaminated food and water
• Through ingestion of food contaminated by droppings of infected bird.
• Infected cages and incubator act as constant source of infection.
• Unhygienic environment plays important role in transmission of disease.

Pathogenesis:

Clinical Findings:

• coli infection occurs in poultry in 2 forms; systemic infection k/a Colisepticemia and localized infection restricted to limited or specific area.

1. Colisepticemia:

• It is most common in young chickens and most serious form of colibacillosis.
• There is 10-20% mortality
• Reduced appetite, listlessness, ruffled feathers, and signs of bronchopneumonia.
• Vent is pasty due to sticky droppings.

2. Coligranuloma:

• This condition is known as Hjarre’s disease.
• No specific symptoms
• Birds shows lethargy, weakness, disinclination to move and emaciation.
• Prominent keel bones.
• Mortality rate may be as high as 75%.

3. Omphalitis:

• It is infection of yolk sac and also known as mushy chick disease.
• Day old chicks gets infected in hatchery incubator and another appliance.
• Affected birds dies without showing any signs.
• Unabsorbed yolk sac is found on PM.

4. Egg peritonitis:

• This is also called salpingitis.
• Affected birds shows cannibalism (vent picking).
• Inflammation of oviduct.
• Egg escape into abdominal cavity.

5. Infective arthritis:

• Joints of affected birds are swollen and painful.
• Synovitis develop as consequence to septicemia.
• Birds recovered after 1 week or become chronically ill
• Lameness is predominant sign
• Hock joints are affected frequently.
• Pus accumulates within joint cavity.

6. Air sacculitis:

• It is noted in 5-12-week broiler.
• Edema and catarrhal or fibrinous exudate deposition in air sac and pericardium.

7. Pan ophthalmitis:

• It is not observed frequently.
• Birds becomes blind due to clouding of cornea
• Usually one eye is affected.
• Bird usually die following infection.

8. Enteritis:

• Young chicks suffer from fatal diarrhea.
• Birds are dehydrated and weak.
• Hemorrhagic enteritis may occur.

9. Pericarditis:

• It is constant feature in birds due to septicemic changes.
• Affected birds sit on haunches and shows gasping breathing followed by death.

10. Perihepatitis:

• Signs are usually non-specific; lethargy, depression, weakness
• On PM, fibrin layer is found around liver.

PM Findings:

• Air sac becomes inflamed, cloudy and exudates are found within air sac.
• Pericardial sac is filled with yellow fibrinous exudates.
• White deposition on pericardium.
• Caseous mass deposition within oviduct.
• Wall of oviduct remain thin and extended.
• Transparent to cloudy deposition on surface of liver.
• Synovial fluid becomes cloudy.
• Unabsorbed yolk sac is found in case of yolk sac infection.
• Cauliflower like nodules or millet sized nodules (granuloma) on viscera in entire intestine, liver, lungs and kidney

Diagnosis:

• Based on history of disease outbreaks
• Based on clinical findings and PM findings
• Isolation and identification of organism from heart, blood and other organs.
• Serotyping of isolates for epidemiological point of view.

Differential Diagnosis:

1. CRD:

• There is facial swelling, nasal discharge in CRD
• Mycoplasma are isolated from bacterial culture in PPLO media
• Congested and cheesy exudate filled air sac.

2. Salmonellosis:

• Drop in egg production
• Greenish diarrhea
• Paleness of comb and wattle
• Necrotic foci on liver.

3. Fowl cholera:

• Distressed breathing is observed
• Swelling of face and wattles
• Serofibrinous gelatinous material on the pericardium
• Bipolar Pasteurella organism are isolated in culture.

4. Psittacosis:

• Purulent discharge from eyes and nostrils
• Greenish diarrhea
• Distressed breathing
• Enlarged spleen

Treatment:

• Organism develop resistance to drugs very quickly. So, it is advised to perform AST before selecting appropriate antibiotic.
• Drugs like nitrofurans, gentamicin, ampicillin, trimethoprim-sulphonamide, cephalexin, tetracycline, nalidixic acid are used for treatment.
• Treatment with antimicrobial should be initiated early for effective treatment. Once peritonitis and perihepatitis is present, no treatment is effective.
• Furazolidone @0.04% in feed for 10 days or chlortetracycline @ 600mg/5 litres of DW for 5 days
• Affected birds should be provided with adequate warmth
• Electrolytes and glucose are added in water to prevent dehydration and stress.
• Vitamin B complex and liver tonic are administered as supportive therapy to reduce stress in liver.

Control Measures:

• Stress and overcrowding should be avoided in poultry house.
• Chicks should be obtained only from disease-free, well managed breeding flocks and hatcheries.
• Dry, dusty conditions in poultry houses should be avoided.
• Adequate ventilation should be provided in poultry house.
• Litter should be dry but not dusty.
• Chlorination of drinking water is recommended.
• Birds should be fed well-balanced pellet diet to provide sufficient minerals, vitamins.
• Probiotic should be provided in drinking water given to chicks and should continued for at least a week.
• Eggs should be collected frequently, nest material should be kept clean, and eggs that are contaminated with fecal matter should be discarded for hatching.
• Killed vaccines are available. Broiler hens are vaccinated at 6-12 weeks of age and repeated at 14-18 weeks of age.