PASTEURELLA MULTOCIDA - SEPTICEMIC PASTEURELLOSIS
LEVELS: Highly unlikely: No controls necessary; Occupational exposure risk: Non-foodborne transmission pathway(s) that are strongly associated with occupational exposure and can lead to human infection; Highly effective: Routine on-farm biosecurity measures are effective in preventing farm-to-farm transmission; Moderate: Clinical signs not unique but existing tests available at local/regional laboratory(s); Minor: Low prevalence, typically non-lethal infection with recovery very likely; Negligible: Little or no market disruption when disease occurs on one or more farms; Minimal risk: Agent inherently unlikely to develop clinically important resistance to antibacterial or antiviral treatments; Minimal risk: Antibacterial or antiviral treatments rarely occur, or are typically limited to short-course individual animal therapy; Available but with uncertain efficacy: Limited treatments available in US or are only effective in some situations; No availability: Effective vaccines not currently available in the US (or have not been developed); Not feasible: Eradication extremely unlikely
OVERVIEW
Septicemic pasteurellosis is a sporadic, acute, often fatal disease of farmed and wild pigs caused primarily by capsular type B Pasteurella multocida, though types A and D have also been reported. The disease has been documented in Europe, Asia, South America, and Australia. Type B strains appear more closely related to isolates causing hemorrhagic septicemia in other hosts (cattle, water buffalo) than to swine PAR or pneumonia isolates. Clinical presentation includes sudden onset with high fever, severe dyspnea, cyanosis of the ventrum and ears, anorexia, weakness, and prostration; pigs may be found dead without prior clinical signs. A striking feature is edema and hemorrhage of the ventral neck that may become necrotic. Lesions include subcutaneous hemorrhagic edema, pharyngeal and tracheal edema, pulmonary edema and hemorrhage, hemorrhagic lymph nodes, and multifocal thrombosis with widespread vascular damage. Mortality is high. The pfhA gene has emerged as a possible genetic marker for septicemic type A strains. This is a rare presentation compared to PAR and pneumonic pasteurellosis.
FOODBORNE ZOONOTIC TRANSMISSION POTENTIAL
Level: Highly unlikely: No controls necessary
P. multocida is not transmitted through food consumption. Human infections are associated with animal bites or direct contact, not foodborne transmission.
NON-FOODBORNE ZOONOTIC TRANSMISSION POTENTIAL
Level: Occupational exposure risk: Non-foodborne transmission pathway(s) that are strongly associated with occupational exposure and can lead to human infection
P. multocida is zoonotic, though septicemic strains specifically affecting humans are not documented. General P. multocida zoonotic potential applies: occupational exposure risk for farmers, veterinarians, and abattoir workers.
EFFECTIVENESS OF ON-FARM BIOSECURITY IN PREVENTING FARM-TO-FARM TRANSMISSION
Level: Highly effective: Routine on-farm biosecurity measures are effective in preventing farm-to-farm transmission
Type B strains follow similar transmission patterns: (1) Direct contact: Nose-to-nose contact is primary route; (2) Fomites possible: "Spread related to contaminated fomites or intermediate hosts has been suggested"; (3) Wildlife source possible: "Sporadic outbreaks of fatal, acute septicemia in farmed and wild pigs" suggests potential wildlife involvement; (4) Susceptible to disinfection: Standard disinfectants effective.
DIFFICULTY OF DETECTING AND CONFIRMING INFECTION
Level: Moderate: Clinical signs not unique but existing tests available at local/regional laboratory(s)
Diagnosis requires laboratory confirmation: (1) Sudden death presentation: "pigs may be found dead without prior observed clinical signs"; (2) Laboratory confirmation required: "Diagnosis depends on detection of P. multocida in blood and affected tissues, the presence of multifocal thrombosis and necrosis, and the absence of other agents causing sudden death"; (3) Capsular typing important: Type B identification helps distinguish from other P. multocida syndromes; (4) Differential diagnosis: Must rule out other causes of sudden death.
FINANCIAL IMPACT ON FARM'S COST OF PRODUCTION
Level: Minor: Low prevalence, typically non-lethal infection with recovery very likely
Sporadic but severe when occurs: (1) High mortality: "Septicemic pasteurellosis typically has a sudden onset and acute progression of disease with high morbidity and mortality"; (2) Sporadic occurrence: Outbreaks are uncommon but severe; (3) Wild pig involvement: Reported in both farmed and wild pigs.
EFFECT ON DOMESTIC OR EXPORT MARKETS
Level: Negligible: Little or no market disruption when disease occurs on one or more farms
No significant trade implications: (1) Sporadic disease: Not endemic in a way that affects trade; (2) Not regulated: Not a reportable disease in most jurisdictions.
PATHOGEN'S ABILITY TO DEVELOP AND SPREAD RESISTANCE
Level: Minimal risk: Agent inherently unlikely to develop clinically important resistance to antibacterial or antiviral treatments
Type B septicemic strains not associated with resistance concerns. The sporadic nature of disease means limited antimicrobial pressure on these specific strains.
AMR DEVELOPMENT DRIVEN BY DISEASE MANAGEMENT
Level: Minimal risk: Antibacterial or antiviral treatments rarely occur, or are typically limited to short-course individual animal therapy
Limited antimicrobial use: (1) Acute fatal course: Disease progression is often too rapid for treatment; (2) Sporadic occurrence: Rare disease limits overall antimicrobial use for this syndrome.
AVAILABILITY OF EFFECTIVE TREATMENT OPTIONS
Level: Available but with uncertain efficacy: Limited treatments available in US or are only effective in some situations
P. multocida generally susceptible, but practical limitations: (1) Rapid progression: "sudden onset and acute progression of disease"; (2) Often found dead: "pigs may be found dead without prior observed clinical signs"; (3) Susceptible organism: Type B strains remain susceptible to common antimicrobials when treatment is possible.
AVAILABILITY OF EFFECTIVE VACCINES OR BACTERINS
Level: No availability: Effective vaccines not currently available in the US (or have not been developed)
No specific vaccines for septicemic pasteurellosis: (1) Different strains: Type B strains are genetically distinct from PAR (type D) and pneumonia (type A) strains; (2) PAR vaccines not cross-protective: Vaccines for PAR target PMT, which is not relevant to septicemic disease; (3) Hemorrhagic septicemia vaccines: Related vaccines exist for cattle/buffalo but not specifically for swine.
FEASIBILITY OF ERADICATING THE DISEASE FROM THE US
Level: Not feasible: Eradication extremely unlikely
Eradication not feasible: (1) Wild pig reservoir: "Sporadic outbreaks of fatal, acute septicemia in farmed and wild pigs"; (2) Related to hemorrhagic septicemia strains: Type B strains appear related to isolates from other species; (3) Sporadic unpredictable occurrence: Cannot target for elimination; (4) Commensal organism: P. multocida is normal flora in many species.