Pasteurellosis (Fowl cholera) Dr. Latif Ahmad (DVM-PhD), Assistant Professor, HOD

Some Diseases by family Pasteurellaceae Four distinct dis. are usually grouped together: Caused by org. that are genotypically & phenotypically related & Induce dis. in com. poultry that may present in a cl. similar way. Fowl cholera caused by Pasteurella multocida, Riemerella anatipestifer inf., Ornithobacterium rhinotracheale inf., and Another avian dis. by family Pasteurellaceae is fowl coryza caused by Avibacterium paragallinarum is distinctly dif. from dis. mentioned above. Bordetellosis. These dis. have some similarities as under:

Riemerella anatipestifer (RA) inf. is a contagious dis Riemerella anatipestifer (RA) inf. is a contagious dis. in domestic ducks, turkeys & other fowl. Most characteristic gross lesion: deposit of fibrinous exudate on pericardium, liver capsule or air sacs. 

Air sac with deposition of yoghurt like exudates in O rhinotracheale inf. bird. Tracheitis, exudative pneumonia, pleuritis, air sacculitis, pericarditis, sinusitis, characterize inf.

Avian Bordetellosis/Turkey Coryza (Bordetella avium) Morbidity may reach 100% within 24 hrs. Mortality varies, but is usually understood to be dis of high morbidity & low mortality. Signs that will occur suddenly in flock following a Bordetella avium outbreak include sneezing, coughing, presence of a foamy conjunctivitis around medial canthus of eye & open- mouth breathing. The bacteria are highly contagious, meaning dis is easily transmitted by direct contact & also from bedding, litter & housing.  Head of bird including feathers appear wet then proceed to have a brown crusted exudate over parts.

Turkeys with characteristic bordetellosis have watery eyes & extensive mucus in the sinuses & trachea, rarely extending below tracheal bifurcation. Lining of trachea may have extremely mild hem. & softening of tracheal rings is usually felt. A dorsal/ventral flattening of the trachea can sometimes be observed.

Pasteurellosis/Fowl cholera Fowl cholera - septicaemic dis. (blood inf.) - chickens In its severest form. fowl cholera is one of most harmful & highly contagious dis. inflicting heavy mortality, but less severe (chronic) & harmless conditions also occur. Losses from fowl cholera usually occur in laying flocks. Chickens < 16 wks of age are usually quite resistant. Mortality range = 0 to 2%. Greater losses also reported. Reduced egg prod. & persistent localized inf. usually occur

Cause/Etiology A bacterium called Pasteurella multocida (several serotypes). Strains of P. multocida vary in their disease- producing power (virulence). Some are: Most harmful, Others moderately so, and A certain number harmless

Species affected/Host range Susceptible bird species include: Chickens, Turkeys, Game birds and other

Spread/Transmission Mainly bird to bird by contaminated water/ feed: Spread of P. multocida within a flock is mainly by excretions from mouth, nose, and conjunctiva (eye), & via injury. of dis. birds. These excretions & rodents (rats and mice) also contaminate their environ., esp feed & water. Spread be by people (clothing/footwear). Spread through air does occur b/w pens; but, spread via water & feed more common. Dis. is not egg-transmitted.

Signs Dis. occurs in several forms. Severest form has no preceding symptoms & numerous birds in flock are found dead, in good bodily condition. 50% or more may die. Most susceptible age: 2 & 18 wks. Foul-smelling greenish coloured diarrhoea. Chronic form is seen in birds which survive severe dis. Chronically inf. birds may die, remain inf. for long periods, or recover. Symptoms include: In less severe form, Depression, Marked depression, Difficult breathing, & later Loss of appetite, Lameness, twisting of neck to one side, & Mucus discharges from openings, Swelling of wattles. One or both wattles may be swollen containing cheesy, hard deposit. Ruffled feathers, Bluish discoloration of comb & wattles, &

In the chronic form of fowl cholera, birds that survive the acute infection or birds exposed to a low virulence strain of Pasteurella multocida, often develop swelling of the wattles, sinuses, foot pads, sternal bursa, and joints. This chicken has a large abscess on the right wattle as a result of localized infection.

Pathology Haem. & congestion of liver, spleen & kidneys. ACUTE cases show enlargement of spleen & liver. Haem. & congestion of liver, spleen & kidneys. Punctate hemorrhages of viscera including heart. SUBACUTE cases: gray granulomatous foci in liver. Caseous cellulitis of wattles & seropurulent arthritis may be present in CHRONIC cases. Cheesy exudates found in infra-orbital bsinuses, b/w intestines & on liver & heart.

Small areas of necrosis in the liver (corn meal liver)

Cheesy exudate in the Infraorbital Sinus

Diagnosis & Treatment Laboratory examination is required to isolate and identify P. multocida from specimens of heart blood, liver, and spleen. In acute cases, characteristic bipolar organisms may be observed in Giemsa-stained smears of heart blood. Tetracycline incorporated: Into feed at a level of 200 - 400 g/ton or In water at 250 - 500 mg/L will suppress clinical signs and reduce mortality Chronic carrier birds have been found in flocks of chickens after Rx. If cl. fowl cholera with mortality reappears in such flocks, one must treat again.

Prevention Stringent biosecurity Eradication of rodents Breeder males or flocks subjected to environ. stress may be vaccinated with relatively milder PM- 1 & PM-9 strains in place of CU strain to avoid reaction. Eradication of rodents Antibiotics avoided 1 wk before & 1 wk after administration of a live attenuated vaccine. Immunization of flocks in endemic areas. Routine vaccination is essential on farms where previous cases have occurred. Inactivated vaccines to protect flocks if reaction to live vaccine. For effective control, inactivated bacterins must be homologous with endemic strains of P. multocida. In some areas or integrations, autogenous, inactivated vaccines are required. Live-attenuated vaccines (CU; PM-1; PM-9 strains) are administered by wing-web stab twice during the rearing, at approx. 10 and 14 wks of age.