Avian (fowl cholera)
Fowl cholera is a contagious septicaemic disease of almost all classes of fowl. The causal agent is Pasteurella multocida.Serotypes A:1 and A:3 are usually involved.
Transmission: The disease usually starts with the introduction of an infected or carrier bird from outside. Wild birds are also responsible for the spread of the disease. After introduction, disease spreads by contaminated feed and water. Carcasses of infected birds are also a source of infection.
Symptoms: Symptoms may be pneumonic, septicaemic or localized. The incubation period is 4-9 days, but in peracute outbreaks the incubation period is less than 48 hours. The birds are found dead without showing any symptoms in peracute cases. In peracute as well as in acute outbreak, the virulence drops in a few days. The ailing birds may linger on for a few days or the disease may become chronic. In less acute cases, the birds show depression, anorexia and emaciation. In pneumonic type there is gasping, coughing, sneezing and difficulty in breathing. In septicaemic type, there may be yellow or green diarrhoea. In the chronic form there may be lameness and swelling of joints of leg or wing; comb and wattles become oedematous and turn from dark red or purple to pale in colour.
Lesions: In peracute cases, there are petechial haemorrhages in the pericardium, epicardium, lungs and intestine. The liver has a cooked appearance and has necrotic foci. In chronic form, caseous material may be found in the swollen joints and in the eye cavity. There may be exudate around the nostril and beak.
Diagnosis: A tentative diagnosis can be arrived at by demonstrating bipolar organisms in blood smear. In the laboratory, liver or bone marrow material is injected in rabbit or mice. In the event of fowl cholera these animals die within 24-48 hr.
Treatment and control: Treatment is not economical. Prophylactically, the administration of sulphonamides or antibiotics is useful. Good management, sanitation and hygiene combined with vaccine are used to control the disease. Where the disease has established, the entire flock should be disposed off and the premises disinfected before introducing new birds. Vaccination with killed culture of organisms, emulsified with an adjuvant, should be given in birds between 8 and 12 weeks of age.
Sheep and goats
Septicaemia pasteurellosis is caused, usually due to P. trehalosi in feeder lambs and Mannheimia haemolytica (Previously called P. haemolytica) in nursing lambs. Enzootic pneumonia of sheep is caused by Mannheimia haemolytica.
Swine
Atrophic rhinitis of young pigs (3 weeks to 7 months) leading to turbinate destruction is caused by P. multocida (capsular type D). Signs include sneezing, epsitaxis and staining of the face due to tear-duct obstruction. Skeletal abnormalities produce lateral deviation of the snout.