Colibacillosis (Scour in Ruminants)

Colibacillosis (Scour in Ruminants) is caused by Escherichia coli. It is a normal inhabitant of the digestive tract of mammals and birds. The disease is usually sporadic and is more common in dairy than beef calves.

Many strains of the E.coli are non pathogenic but some strains causes different disease conditions.

In poultry, it causes Yolk sac infection, coligranuloma (Hjarre’s disease), egg peritonitis and coli septicemia.

Colisepticemia is a common disease of calves and lambs below one week old and chronic bacteremia with localization of organism occurs.

Etiology

• E. coli is a gram negative, flagellated and rod shaped organism.
• It measures 2-3 um in length 0.6 um in width.
• Serotypes are mainly identified by their somatic antigen (O), capsular antigen (K) and flagellar antigen (H).
• The capsular antigen can be identified by Rapid Slide Agglutination test.

Epidemiology

Predisposing factors

• Poultry Colispeticemia:
  • The disease occurs due to poor ventilation in houses.
  • Inter current infections such as Mycoplasmosis, Colispeticemia, coccidosis, New Castle disease, infectious bronchitis, infectious bursal disease, viral tracheitis, Haemorrhagic enteritis, Aspergillosis and nutritional deficiency.
• Egg peritonitis:
  • Flock peritonitis outbreak associated with cannibalism or vent pecking.
  • Overcrowding and huddling leads to vent pecking.
  • Yolk Sac infection Intercurrent infection caused by Bacillus cereus, staphylococcus, pseudomonas proteus, clostridia and yolk sac infection.
  • Humid environment in poultry houses favors the incidence of yolk sac infection.

Source of infection

• E.coli involves either as a primary source of infection or as a secondary opportunistic pathogen.

Transmission

Poultry

• Yolk sac infection occurs through unhealed navel.
• Sometimes, following fecal contamination of egg shell occurs.
• Ingestion of contaminated materials, feeds and water.

Animals

• In groups of calves, transmission is by direct nose-to-nose contact, urinary and aerosols. Through navel, and feco-oral route.

Host affected

• All poultry and avian species are susceptible for infection.
• E.coli affecting, chicken, turkeys, ducks, pheasants but most commonly chicken are affected.
• Yolk sac infection mainly in chicks in the first week of age.
• All animals are susceptible and young age group are highly susceptible.

Pathogenesis

Calves

• Invasion occurs mainly via nasal and oral route.
• The organism crosses the intestine or via the umbilicus and umilical veins.
• Septicemic phase is followed by death due to endotoxemic shock.
• In a prolonged course of the disease localization of infection occurs resulting in polyarthritis, meningitis, less commonly uveitis and nephritis.
• In chronic phase in calves marginal levels of circulating immunoglobulin present.
• The organism is excreted in nasal and oral secretions such as urine and feces.
• Excretion starts during the preclinical bacteremic phase.

Poultry

• Collisepticemia E.coli found in large numbers in digestive tract especially in lower part of small intestine and caeca.
• Yolk sac infection:
  • The organism multiply in the intestines of newly hatched chicks, and spread rapidly to other chicks in hatchery and brooders.
  • It causes 100% mortality in a batch of chicks in first week of life.
  • After first week the mortality may be 5% to 10%.
  • The infection is associated with thick inflammed navel.

Pigs

• Neonatal diarrhoea or scour in piglets.
• E. coli normally present in the gut of pigs and in other mammals.
• Haemolytic E.coli are highly pathogenic.
• This is a harmful bacteria attached to the wall of the intestine and produce toxins.
• It affects the function of the intestine and causes loss of fluid in to gut and produces scour and dehydration.

Clinical Signs

Calves

• In acute disease, the clinical course is short (3-8 hr), and signs are related to the development of septicemic shock.
• Rectal temperature is subnormal.
• Calves show listlessness, loss of interest in sucking, depression, poor response to external stimuli , recumbency and collapse.
• Tachycardia, a poor pulse rate and a prolonged capillary refill time observed.
• The feces is loose and mucoid.
• Mortality approaches 100%.
• In prolonged clinical course, the infection localize and develops polyarthritis and meningitis.
• In such calves, tremor, hyperesthesia, ophisthotonus, and convulsions are seen occasionally, but stupor and coma are more common.

Poultry (Colisepticemia)

• Very young birds are affected.
• Inappetence leads to listlessness, dejection, dry and ruffled feathers.
• Rapid laboured breathing, occasionally gasping with snicking.
  Mortality <5% and morbidity >50%.
• Following recovery unsatisfactory performances of the birds are noticed.
• Yolk sac infection: Affected birds appears distressed with distended abdomen. Tendency to huddle, visibly thick navel which is prominent and necrotic.

Poultry (Coligranuloma)

• This disease causes a sporadic death in adult.
• There is no specific signs but the affected birds die of infection after depression and loss of bodily condition.

Necropsy Findings

Colisepticemia lesions

• Colisepticemia lesions are very featuristic.
• Air sacculitis, peritonitis, perihepatitis, pericarditis and fibrinous pericarditis seen.
• Pericardial sac appears to be thick with white membrane adhering to the surface of heart is a characteristic findings.
• In septicaemic carcasses, liver, spleen, lungs and kidneys appears dark.
• Liver surface is covered by a thin fibrinous material.
• Air sacs are thickened, opaque and with white deposits adhere to this.

Collibacillosis

• Swollen bile stained liver in birds.

Colisepticemia – Perihepatitis

• Neonatal colibacillosis in pig has full stomach with clotted milk and watery intestinal content
• Typical dehydrated and died piglet in colibacillosis.

Egg peritonitis

• Egg peritonitis is indicated with salphingitis, peritonitis, impaction of the oviduct.
• Inspissated yolk mass, yolk debris and caseous materials are the important signs under post mortem examination.
• Milky fluid present in the abdominal cavity.
• Inflammation and distortion of ovaries, salphingitis, seen.
• Obstruction of oviduct by a core of inspissated and inflammtory debris due to rupture of oviduct wall may be observed.
• A whole or partly developed egg found in the oviduct.
• Immediately after death organism should be isolated.
• The percentage of death in layers is less that 1%.

Yolk sac infection

• In septicemic carcasses, the blood vessels supplying to the yolk sac and sub cutaneous route is engorged and dilated.
• Congested liver and dark swollen kidneys.
• Inflammed unabsorbed yolk sac with abnormal colour and consistency of the yolk is a striking feature.
• Yolk is yellow/brown in color, watery and often fetid.
• Peritonitis and haemorrhagic lesion in serosal surfaces of intestines is a regular picture.
• Coligranuloma: Hard yellow, nodular granulomas in mesenteric wall of intestine and particularly in caeca.
• Affected liver exhibits hard, blotchy, swollen and discoloured liver.
• In addition, synovitis, arthritis, tracheitis, air sacculitis, panophthalmia and localized abscesses are caused by E.coli in poultry.
• Presence of severe purulent peritonitis is characteristic feature of this disease.

Diagnosis

• Based on clinical signs and necropsy findings.
• Isolation and identification of organism.
• Immediately after death organism should be isolated in case of egg peritonitis.
• Calves:
  • A moderate level of leukocytosis and neutrophilia in early stages followed by leukopenia in terminal stage.
  • The joint fluid contains increased inflammatory cells and protein.
  • CSF shows pleocytosis and an increased protein concentration Organism is visible by microscopic examination.
  • Culturing and characterization of organism is necessary for confirmation.
  • Demonstration of deficiency of circulating IgG in the affected calves can be done using Zinc sulfate turbidity test or total protein estimation.

Differential diagnosis

• Pullorum disease
• Fowl typhoid
• Fowl cholera
• Salmonellosis

Treatment

• Antimicorbials such as Furazolidone 0.04% in feed for 10 days, Chlortetracyclin 600 mg/5 liters of water for 5 days usually is effective.
• Other antibiotics, vitamins and minerals should be added in water or feed materials.
• Calves:
  • Initially bactericidal antibiotics having efficacy against gram-negative organisms.
  • Antibacterial therapy combined with aggressive fluid, drug, and other supportive therapy.

Prevention

• The disease can be prevented by high managemental condition.
• Vaccination of farm piglets is under practice in some countries.
• Calves:
  • Prevention depends mainly on management practices to ensure an adequate and early intake of colostrum.
  • Calves should be fed 2-4 L of first-milking colostrum, within 2 hr of birth, followed by a second feeding at 12 hr.

Control

• Reducing spread of infection.
• Reducing reservoir of infection.
• Increasing immunity in sows and piglets.
• Restrict the movement of animals.
• De promote the access of farm by rodents.
• Disinfection of farm premises.
• Vaccination of piglets and dam. Maintain high hygienic standards of poultry houses.
• Procure chicks from disease free well managed hatcheries.
• Pathogenic serotypes transmitted into hatcheries via fecal contamination of eggs and so p urchase can be made from flocks free of infection and should have been vaccinated against IBD, IB and ND.
• Application of coccidiostats is warranted.
• Litter material should be dried but not dusty and avoid accumulation of ammonia gas.