The bacterium Pasteurella multocida is a Gram-negative coccobacillus highly prevalent in domestic rabbits, which serve as a primary host for the organism. Understanding this common bacterial agent is important for rabbit owners, as it has the potential for zoonotic transmission, meaning it can pass from animals to humans. A significant percentage of rabbits, ranging from 30% to 90%, may carry P. multocida without showing any signs of illness, making it a constant factor in rabbit husbandry.
Transmission Risk to Humans
Transmission of Pasteurella from rabbits to humans is possible, although relatively uncommon. This bacterium is considered a zoonotic pathogen, but it requires a specific route of entry into the human body to cause infection. The most frequent method of cross-species transmission involves a direct breach of the skin barrier, such as through a bite or a scratch from an infected rabbit. Transmission can also occur if the bacteria, present in the rabbit’s nasal or oral secretions, contacts a person’s mucous membranes or an existing wound. Less often, the bacteria may be transmitted through the inhalation of aerosolized droplets, a mechanism that can occur if a severely infected rabbit forcefully sneezes. Simple casual contact with a healthy rabbit, such as petting, does not typically lead to infection in people with intact skin.
What is Pasteurella and How Does It Affect Rabbits?
Pasteurella multocida is the causative agent of a condition in rabbits known as pasteurellosis. The bacteria colonizes the upper respiratory tract of the rabbit, where it may remain dormant or cause acute and chronic disease. In its active form, the infection primarily manifests as rhinitis, characterized by sneezing and a watery or thick nasal discharge.
Infected rabbits often attempt to wipe their noses with their front paws, leading to matted fur on the inside of their forelegs, which is a telltale clinical sign. Beyond the respiratory system, the infection can spread throughout the body, causing localized abscesses under the skin, pneumonia, or ear infections. An inner ear infection can result in a severe head tilt, known as torticollis, due to the effect on the rabbit’s balance. Many rabbits that recover from an active infection become asymptomatic carriers.
Symptoms and Medical Management in Humans
If a human is infected with P. multocida, the infection usually presents as a localized soft tissue infection at the site of the bite or scratch. Symptoms develop rapidly, often within 24 hours of the injury, and include noticeable swelling, tenderness, redness, and the formation of pus drainage.
More serious, systemic infections are rare but can occur, particularly in individuals with compromised immune systems or underlying health conditions like chronic lung disease. These severe manifestations can include cellulitis, which is a deeper soft tissue infection, or infections of the joints, bones, and even the central nervous system, leading to meningitis. Immediate medical attention is necessary to prevent these complications. Treatment typically involves thorough wound disinfection followed by a course of antibiotics, with penicillin or its derivatives being highly effective against the pathogen.
Reducing Exposure Risk
Preventing the spread of Pasteurella from rabbits to humans involves practicing hygiene and handling methods. Any bite or scratch that breaks the skin should be washed immediately and thoroughly with soap and warm running water for several minutes.
Regular and careful hand washing is a preventative measure, especially after handling rabbits, their bedding, or their environment. People who are immunocompromised, such as those undergoing chemotherapy or with certain chronic illnesses, should avoid handling any rabbit showing signs of illness, such as sneezing or nasal discharge. Maintaining a clean, low-stress environment for the rabbit helps support its immune system, reducing the likelihood that a carrier state will progress to an active infection that sheds more bacteria.