Pasteurellosis
Bacteria of the genus Pasteurella were recognized as disease causing organisms in 1880 when Louis Pasteur established Pasteurella multocida (PM) as the etiological agent of fowl cholera and the genus was subsequently named in his honor. The importance of PM has been known for more than 125 years, yet this bacterium continues to significantly impact swine health worldwide as a cause of atrophic rhinitis (AR) and pneumonia. You can read more about atrophic rhinitis by clicking here and more about pneumonia by clicking here.
Why is this so important and included in the zoonotic section of the website? Pasteurella Multocida is an important zoonotic agent and is responsible for most human infections related to animal bites or scratches. Dogs and cats are the predominant source, but infection following bites from pigs, rabbits, rats and various wild animals have also been reported. This can be an accidental head swipe resulting in a puncture wound or scratch from a pigs tusk.
Human pasteurellosis most often presents as skin or soft tissue infection, typically with rapid onset, characterized by inflammation, swelling and purulent exudate. Most serious manifestations generally limited to immunocompromised patients include septicemia, osteomyelitis, endocarditis, pneumonia, meningitis and peritonitis. PM is not a usual constituent of the human upper respiratory tract, but strains genetically identical to those found in the swine reservoir are frequently isolated from pig farmers and inhabitants of regions with intensive pig breeding. Most human carriers remain healthy, but PM may also be associated with acute or chronic respiratory disease. It has been proposed that pneumonic pasteurellosis be considered an occupational disease. Appropriate precautions should be observed by persons who have contact with swine infected with PM, particularly those who are immunocompromised.
The epidemiology of PM in swine is not well understood. The organism is present in practically ALL herds and can be detected in the nose and tonsils of healthy animals. Aerial transmission has been postulated (suggested) but only low numbers of airborne PM could be recovered in large pig operations. Although the bacterium may occasionally be spread via aerosols, nose to nose contact is probably the most common route of infection. PM can persist in herds for months or even years, sometimes with vert little evidence of the disease. Some evidence suggests occasional interspecies spread of avian, bovine, ovine and porcine strains. Rodents, cats, dogs and other hosts that commonly carry PM should be considered possible sources of exposure to pigs. Whether or not healthy human carriers can transmit PM to swine is unknown.
Molecular typing techniques have been used to better understand the epidemiology of PM in pigs but comparisons among studies are problematic because there is no widely adopted and standardized method, many of the studies fail to provide a quantitative measure of diversity. Nonetheless, it appears that there is limited genetic diversity. PM poorly colonizes (finds a place and stays there) the respiratory tract in the absence of preexisting damage to the mucosa. In vitro studies using swine cells from the nasal cavity or teaches consistently demonstrate little to no attachment. (Chung et al. 1990; Frymus et al. 1986; Jacques et al. 1988; Nakai et al. 1988) The tonsil, particularly the tonsils crypt, appears to be the preferred habitat of PM in swine and may protect bacteria from inflammatory cells or act as a physical barrier to removal by swallowing.
What does this mean for you? If your pig purposefully or accidentally pierces your skin, YOU are at risk for developing this PM infection since it can be passed from pig to person, typically in the form of a bite. A pig bite should NOT be closed with "glue" like closure agents, often times, bites or larger gashes are sutured, but that may still trap the bacteria inside and allow it to travel throughout the body resulting in sepsis which can be life threatening if not treated. Typically doctors who are aware the injury was sustained by an animal bite know to leave the wound open unless there are extenuating circumstances that require sutures/wound closure. (If the benefit outweighs the risk) If you are bit by a pig and exhibit any signs of infection, YOU NEED TO SEE YOUR DOCTOR and let them know whats going on and how it happened so you can be treated appropriately with the right medications. Most of the time, doctors aren't prepared for a pig bite and do not know the diseases that can be passed along to humans. Just something to keep in mind since it is KNOWN to happen.
Written by Brittany Sawyer 2016
Source: Diseases of Swine, 10th edition
Veterinarians Guide for animal owners
Why is this so important and included in the zoonotic section of the website? Pasteurella Multocida is an important zoonotic agent and is responsible for most human infections related to animal bites or scratches. Dogs and cats are the predominant source, but infection following bites from pigs, rabbits, rats and various wild animals have also been reported. This can be an accidental head swipe resulting in a puncture wound or scratch from a pigs tusk.
Human pasteurellosis most often presents as skin or soft tissue infection, typically with rapid onset, characterized by inflammation, swelling and purulent exudate. Most serious manifestations generally limited to immunocompromised patients include septicemia, osteomyelitis, endocarditis, pneumonia, meningitis and peritonitis. PM is not a usual constituent of the human upper respiratory tract, but strains genetically identical to those found in the swine reservoir are frequently isolated from pig farmers and inhabitants of regions with intensive pig breeding. Most human carriers remain healthy, but PM may also be associated with acute or chronic respiratory disease. It has been proposed that pneumonic pasteurellosis be considered an occupational disease. Appropriate precautions should be observed by persons who have contact with swine infected with PM, particularly those who are immunocompromised.
The epidemiology of PM in swine is not well understood. The organism is present in practically ALL herds and can be detected in the nose and tonsils of healthy animals. Aerial transmission has been postulated (suggested) but only low numbers of airborne PM could be recovered in large pig operations. Although the bacterium may occasionally be spread via aerosols, nose to nose contact is probably the most common route of infection. PM can persist in herds for months or even years, sometimes with vert little evidence of the disease. Some evidence suggests occasional interspecies spread of avian, bovine, ovine and porcine strains. Rodents, cats, dogs and other hosts that commonly carry PM should be considered possible sources of exposure to pigs. Whether or not healthy human carriers can transmit PM to swine is unknown.
Molecular typing techniques have been used to better understand the epidemiology of PM in pigs but comparisons among studies are problematic because there is no widely adopted and standardized method, many of the studies fail to provide a quantitative measure of diversity. Nonetheless, it appears that there is limited genetic diversity. PM poorly colonizes (finds a place and stays there) the respiratory tract in the absence of preexisting damage to the mucosa. In vitro studies using swine cells from the nasal cavity or teaches consistently demonstrate little to no attachment. (Chung et al. 1990; Frymus et al. 1986; Jacques et al. 1988; Nakai et al. 1988) The tonsil, particularly the tonsils crypt, appears to be the preferred habitat of PM in swine and may protect bacteria from inflammatory cells or act as a physical barrier to removal by swallowing.
What does this mean for you? If your pig purposefully or accidentally pierces your skin, YOU are at risk for developing this PM infection since it can be passed from pig to person, typically in the form of a bite. A pig bite should NOT be closed with "glue" like closure agents, often times, bites or larger gashes are sutured, but that may still trap the bacteria inside and allow it to travel throughout the body resulting in sepsis which can be life threatening if not treated. Typically doctors who are aware the injury was sustained by an animal bite know to leave the wound open unless there are extenuating circumstances that require sutures/wound closure. (If the benefit outweighs the risk) If you are bit by a pig and exhibit any signs of infection, YOU NEED TO SEE YOUR DOCTOR and let them know whats going on and how it happened so you can be treated appropriately with the right medications. Most of the time, doctors aren't prepared for a pig bite and do not know the diseases that can be passed along to humans. Just something to keep in mind since it is KNOWN to happen.
Written by Brittany Sawyer 2016
Source: Diseases of Swine, 10th edition
Veterinarians Guide for animal owners