What is Pasteurellosis?
Pasterellosis (hemorrhagic septicemia) is an acute infectious disease characterized by fever, general intoxication, inflammation of the skin, subcutaneous tissue, arthritis, osteomyelitis. Refers to zoonosis.
Causes of Pasteurellosis
The causative agent – Pasleurella multocida – a short ovoid bacillus (0.3–1.5 µm long and 0.15–0.25 µm wide) is Gram-negative, immobile, grows well on ordinary nutrient media. Bipolarity is noted when coloring according to Romanovsky-Giemsa. The microbe is not very stable in the environment, dies when heated, under the influence of ultraviolet rays, under the influence of disinfectants. In the land and manure, the germ lasts 3-4 days. There are 4 serotypes of Pasteurella (A, B, D, and E); some of them have subtypes. The pathogen is able to produce exotoxin.
Epidemiology. Diseases are relatively rare. Until 1955, only 95 cases of human pasteurellosis were described, from 1955 to 1963. there were 21 more cases, in the following years 1-5 diseases. The source of infection are many species of animals (cattle and small cattle, cats, dogs, rabbits, pigs, hares, rats, birds, etc.). Most often, pasteurellosis occurs after the bites of cats and dogs, as well as after scratches caused by cats (bacterial carriage in cats reaches 80%). Some authors admit the possibility of alimentary infection and transmissible transmission of infection, but there is no concrete evidence to confirm this mechanism of transmission. There were no cases of human infection from a person. However, a case of transmission from the mother to the fetus was described, which led to premature labor, the development of sepsis in the child and his death. Pasteurella culture was isolated from the endometrium of the mother.
Pathogenesis during Pasteurellosis
Gates of infection are more often the skin at the site of the bite or scratches caused to animals (the animals themselves remain healthy). Allowed the possibility of penetration of the pathogen through the mucous membranes. On the site of damaged skin inflammatory changes develop. In some cases, hematogenous spread of pathogens is observed with the formation of secondary foci in various organs (lungs, brain, joints, etc.). Septic forms may be accompanied by the development of infectious-toxic shock and thrombohemorrhagic syndrome.
Symptoms of Pasteurellosis
The incubation period lasts from 1 to 5 days. The literature describes three groups of pasteurellosis. In the first group, the main manifestations were local inflammatory changes in the area of the gates of infection (bite or scratch of cats, dogs), sometimes arthritis and osteomyelitis are additionally detected, in patients of the second group the main manifestations are chronic inflammatory lung changes. The third group is characterized by hematogenous dissemination of the pathogen, damage to many organs (meningitis, brain abscesses, purulent arthritis, sinusitis, endocarditis, pyelonephritis, mastoiditis, etc.) and a very severe course.
In the case of skin form of pasteurellosis, swelling and reddening of the skin and pain on palpation appear first at the site of introduction of the pathogen. Soon pustules are formed at this place, filled with muddy contents, after the destruction of the bladder, a scab forms. The inflammatory process can take even deeper sections, phlegmon or more limited abscesses can develop. Sometimes the process goes to the bone, causing the development of arthritis or osteomyelitis. During the development of inflammatory changes, limited only by the skin and subcutaneous tissue, the general condition of the patients remains satisfactory, the body temperature remains subfebrile, there are no pronounced signs of general intoxication.
The chronic course of pulmonary manifestations can be caused either by pasteurella alone, or by its combination with a secondary infection by other bacterial agents. The disease proceeds according to the type of chronic bronchitis, sometimes with the development of bronchiectasis or in the form of sluggish current interstitial pneumonia. Affection of the lungs can also develop with a septic form, in these cases lung abscesses, empyema are possible.
The septic form is the most difficult, accompanied by high fever, the temperature curve of the wrong type with a large daily span. Secondary foci appear in various organs (endocarditis, brain abscesses, purulent meningitis, purulent arthritis, etc.). Infectious toxic shock may develop.
Diagnosis of Pasteurellosis
In recognizing pasteurellosis, epidemiological factors are primarily taken into account. Most of the cases described are associated with dog bites and especially cats (bites and scratches), less often the bites of other animals (a case of pasteurellosis is described even after a lion bite), contacts with other animals are less important. Of the clinical manifestations, the most informative is the appearance of pronounced inflammatory changes in the area of the gates of infection (more severe forms also often begin with skin inflammatory changes). To confirm the diagnosis, it is necessary to isolate the pathogen (from discharge of skin ulcers, blood, abscess pus, cerebrospinal fluid). Serological reactions are of secondary importance.
Penicillin, tetracyclines, the dose and duration is determined by the clinical form of the disease.
Precautions in the care of animals.