Colibacillosis is a very important widespread bacterial disease responsible for significant loss to poultry industry.
Synonyms: coli septicaemia, E.coli infections, hjarres disease, coli granuloma, peritonitis, salpingitis, synovitis, omphalitis, Air sacculitis, Mushy chick disease.
It is caused by various strains of Avian pathogenic Escherichia coli (APEC). More than 150 serotypes are found. Most of these are aerobic or facultatively anaerobic, gram negative, non sporulating bacilli. All of them produces acid and gas from the fermentation of lactose.
These are the most common pathogens in all Avian species. All domestic and wild birds suffer from E. coli. Report of this pathogen (APEC) attacking humans and other mammals have not been found.
Mortality among the hosts differ depending upon the virulence and causal strains of E. coli. The mortality rate varies from 5%-10% and upto 50%-100%. Airsacculitis affects only 0.5-2.5% of flocks.
The disease is widely prevalent in avian species throughout the country. In year 2015/2016, in veterinary teaching hospital of AFU, chitwan, nepal; out of 593 cases of poultry, the most frequently diagnosed disease was colibacillosis followed by coccidiosis, mycotoxicosis and others. In case flow analysis of National Avian Disease Investigation laboratory (NADIL), chitwan, nepal; during august 2016 to january 2017; Colibacillosis(14.16% incidence) was dominant followed by CRD (10.60) and other diseases
MODE OF TRANSMISSION
1. Faecal contaminated feed and water.
2. Eggshell contamination at cloaca by excreta is also common with the bacteria present in the nest.
3. Respiratory route may be involved due to contaminated dust in poultry house.
4. Ovarian route, with birds shading E.coli through uterine infection. Infected breeder hens transmit it to newly hatched chicks.
5. Contaminated feed is a frequent cause of transmision.
E. coli are considered as a normal bacterial flora of intestine. Stress favours the normal E. coli of the gut to assume pathogenic role. The E. coli may pave the way for other organisms. Common
associated organisms include Mycoplasma sp., infectious bronchitis and ranikhet disease virus. Ammonia, stress, unhygienic condition and immuno suppression especially from IBD virus lead to multiplication of E. coli leading to colisepticaemia. Emergence of antibiotic resistant strain causing high mortality in young chicks, mortality in adults and appreciable drop in egg production.
The most common manifestations are as follows:
1. Coli septicemia:
Young chickens are mostly affected. Susceptible age group is 8-11 days. Morbidity rate is high. There is reduced appetite, listlessness, ruffled feathers, and signs of respiratory distress due to bronchopneumonia. PM findings: Milky fluid in pericardium, percarditis and perihepatitis. Air sac becomes thick and cloudy.
2. Coligranuloma (hjarre’s disease):
Weakness, lethargy, non-inclination to move on stimuli and considerable emaciation. PM findings: Millet sized nodules present in entire intestine, liver, lungs and kidney. Microscopic: The section of nodules show caseous necrosis in the centre covered by macrophages, lymphocytes and giant cells, as in tuberculosis.
3. Coliform omphalitis/ Yolk sac infection:
Also known as mushy chick disease. This is a hatchery induced problem. The E. coli may invade the egg shell and finally the yolk sac. The affected birds may die without showing apparent signs. Unabsorbed egg yolk get infected and thus produce toxaemic condition in birds. There will be presence of unabsorbed egg on post mortem of the bird.
4. Infective arthritis:
Joints are swelled and painful. Lameness is the predominant signs, mainly hock joints affected. Pus accumulates within the joint cavity.
5. Air sacculitis:
It generally spread from colliform dust inhalation. Oedema and catarrhal or fibrinous exudate deposition in the air sac and pericardium.
6. Pan opthalmitis:
Birds become blind due to clouding of cornea(hypopyon). Usually one eye is affected. The infection is hatchery borne. Birds used to die following infection.
Young chicks may suffer from fatal diarrhoea. Birds are dehydrated and weak. Haemorrhagic enteritis may ensue.
It is due to septicaemic changes. The affected birds sit on haunches and show gasping followed by death.
9. Egg pertionitis:
This is also referred as salpingitis.This condition may result due to combined E. coli infection and hormonal influence. Egg escape into the abdominal cavity(internal laying).
Diagnosis can be made by Isolation and identification of organism from heart blood and other organs, reproduction of the disease by inoculation of material in air sac of young chicks, charateristic lesions, indirect haemagglutination test(IHT) and ELISA are sensitive methods for detecting antibodies to pathogenic E. coli.
1. Mycoplasmosis revealing facial swelling, swollen eyes, nasal discharge and 50% drop in egg production.
2. Salmonellosis shows necrotic foci in liver, paleness of the comb and wattle, unabsorbed and coagulated egg yolk.
3. Fowl cholera can be diagnosed with bipolar staining organism swelling of the face and wattle, distressed breathing, high morbidity and mortality.
4. In staphylococcal arthritis, the long bones as fibro-tarsus is involved, 4-8 week old birds are most susceptible.
1. Selection of drug of choice by drug sensitivity test.
2. Gentamycin @2-5 mg per bird(adult),In a day old chick dilute 5ml gentamycin , 0.5 to 1 mg per chick.
3. Cephalexin @35-40 mg per kg BW, PO.
4. Ampicillin @250 mg per kg via feed for for 5-10 days.
5. Colistin sulphate@100,000 IU/ kg BW, PO per day.
6. Drugs like nitrofurans, trimethoprim-sulphonamide, tetracycline, nalidixic acid , sulphadimidine can be used in usual dose for treatment.
7. Affected birds should be provided with adequate warmth.
PREVENTION AND CONTROL
1. Avoid stress and over crowding.
2. Maintain adequate sanitation and ventillation measures.
3. Try to purchase birds from tested farm.
4. Immunize the birds against Ranikhet and infectious bronchitis since these disease pave the ways for E. coli.
5. Fumigate the incubators and hatching materials.
6. Disinfect the eggs prior to set for hatching.
7. Dispose the droppings and excretion with proper care. 8. Provide high protein and vitamin E to make birds less susceptible.