Hemorrhagic septicemia is a highly fatal bacterial disease seen mainly in cattle and water buffalo.

Etiology

Hemorrhagic septicemia results from infection by Pasteurella multocida subsp. multocida, a Gram-negative coccobacillus in the family Pasteurellaceae. P. multocida multocida can cause a variety of diseases in animals, but only two serotypes B2 AND B6 of this organism classically cause hemorrhagic septicemia.

Transmission

P. multocida is transmitted by ingestion or inhalation, either during direct contact or via fomites such as contaminated feed and water. The serotypes that cause hemorrhagic septicemia are probably shed into the oropharynx. Some animals become carriers, maintaining the organism in the lymphatic tissues associated with the upper respiratory tract, and periodically shedding it in nasal secretions. Excretion may be triggered by stress. P. multocida does not remain viable for long periods in the environment, but it can survive for hours and possibly days in damp soil or water. Rainy conditions and high humidity facilitate transmission.

Clinical Signs

Most cases in cattle and water buffalo are acute or peracute. Although the disease is very similar in both species, buffalo tend to have more severe clinical signs and a shorter course of disease. A fever, dullness and reluctance to move may be the first signs. Salivation and a profuse serous nasal discharge develop, and edematous swellings become apparent in the submandibular region. These swellings spread to the neck and brisket. In calves, hemorrhagic gastroenteritis has also been reported. Respiratory distress occurs, with frothing at the mouth, and the animal usually collapses and dies 6 to 48 hours after the initial clinical signs. Either sudden death or a protracted course up to a few days is also possible. Animals with clinical signs, particularly buffalo, rarely recover. Chronic cases have not been reported.
 

Control

Hemorrhagic septicemia can be eradicated with quarantines, movement controls, tracing of contacts, euthanasia of infected and exposed animals, and cleaning and disinfection of the premises. P. multocida is susceptible to most common disinfectants, as well as to mild heat (55°C/131°F). In endemic areas, this disease is mainly prevented by vaccination. The removal of carriers from the herd is also helpful. Management to keep the animals in good condition can reduce the risk of clinical signs and/or transmission of the organism. Animals should not be crowded or stressed, especially during wet weather. Antibiotic treatment is effective only if it is started very soon after the onset of clinical signs.