Progressive atrophic rhinitis (PAR)
LEVELS: Highly unlikely; Mild; Routine biosecurity keeps it out; Laboratory-dependent; Moderate; Negligible; Little; Available, or not needed
| Register id | progressive_atrophic_rhinitis |
| Type | bacteria |
| Scientific name | — |
| Evidence | 2 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Progressive atrophic rhinitis is the severe, permanent form of atrophic rhinitis, and it takes two organisms. Bordetella bronchiseptica colonises the young pig's nose first and damages the lining; toxigenic strains of Pasteurella multocida then establish themselves and produce a dermonecrotic toxin that destroys the turbinate bones inside the snout. The result is a shortened, twisted face, and in advanced cases pigs are stunted as well. It is distinguished from the non-progressive form caused by B. bronchiseptica alone, which is milder and reversible. Diagnosis rests on clinical and post-mortem findings together with demonstrating that the P. multocida present is toxigenic — a bent snout on its own is not proof, since several things can distort a growing face. Maternal antibody protects piglets against the lesions but not against becoming infected, so the organisms persist in a herd regardless of vaccination status, and control is aimed at preventing damage rather than at exclusion.
C1 Zoonotic potential
Likelihood of transmission from pigs to humans
Highly unlikely: Human infection with the agent has never been reported, or has been reported but is not attributed to pig or pork exposure
Basis. "Human illness resulting from B. bronchiseptica infection is rare but on the rise... Most at risk are infants and immunocompromised individuals with exposure to carrier animals; however, disease in immunocompetent adults also occurs." Transmission of animal strains "to humans or vice versa is plausible but currently unknown". (ch44 sec 44.3)
How this level was decided
MOVED L2 -> L1, re-read 2026-09-04 AGAINST THE REWORDED LABELS. Follows bordetella_bronchiseptica, the same chapter and the same finding: human illness comes from carrier animals, mostly dogs and cats, and transmission of animal strains to humans is "plausible but currently unknown". Scored on toxigenic P. multocida the pig route is weaker still -- human infection is mostly from dog and cat bites.
PREVIOUS ANSWER, kept because the evidence behind it has not changed, only the level boundary: Re-read against the corrected "from pigs" label on 2026-08-27; level 2 unchanged. The chapter is already framed as animal-to-human -- "exposure to carrier animals", "transmission of animal strains to humans... plausible but currently unknown" -- which is level 2 read either way: plausible, rarely reported, no control points implemented. Worth noting the syndrome rule cuts the other way here without changing the answer: scored on toxigenic P. multocida rather than B. bronchiseptica, human infection is mostly from dog and cat bites rather than pigs, which is if anything a weaker pig route, and still level 2.
C2 Zoonotic impact
Severity of human illness caused by the agent
Mild: Human illness is usually mild and self-limiting, and serious disease occurs only rarely
Basis. "A variety of clinical presentations have been documented, including tracheobronchitis, whooping cough..." in infants and immunocompromised individuals. (ch44 sec 44.3)
How this level was decided
Respiratory illness usually mild and self-limiting in the immunocompetent, with serious disease confined to infants and the immunocompromised.
C3 Herd introduction risk
Effort required to keep the agent out of the herd
Routine biosecurity keeps it out: Quarantine of incoming stock, transport and fomite control, cleaning and disinfection, and the usual monitoring reliably exclude it
Corrected by Eric from L1 Already in the herd. Reason: "c3l2 is correct, B.bord is probably not excludable from herds both toxigenic P.mult is excludable" [MERGED 2026-09-01. This cell had been recorded twice and YAML was silently keeping only this copy. Eric stated the same ruling on an earlier sheet, 2026-08-28, in these words: "stays at c3l2 due more to the importance/requirement for P.mult toxigenic strain rather than B.bord for clinical disease to occur. The disease/P.mult agent can be tested for and excluded from a farm."]
Standing note. CONTEXT supporting the L2 correction above, which is where that ruling lives. Eric, 2026-08-26: "C3L2 is correct and we definitely need to base this on toxicgenic P. mult, not B. bronch. Some of the research actually indicates B. bord may not even be strictly necessary and my suspicion is B. bord is present on most herds anyway." That last point strengthens the rule rather than complicating it -- if B. bronchiseptica is neither necessary nor discriminating, the toxigenic agent is the only thing that decides whether the registered disease occurs.
Basis. "Bordetella bronchiseptica has a worldwide distribution... It is highly prevalent among swine and frequently isolated from pigs with pneumonia or atrophic rhinitis, as well as those that are apparently healthy." (ch44 sec 44.4)
How this level was decided
B. bronchiseptica is carried by clinically normal pigs in most herds, so there is no introduction event to prevent for the predisposing agent. What varies is whether toxigenic P. multocida is also present, which is a strain question rather than an exclusion question. JUDGMENT: a two-agent syndrome is scored on its most ubiquitous agent. Flagged in case Eric would rather score it on the toxigenic P. multocida, which would give level 2.
C4 Detection difficulty
Difficulty of recognizing and confirming infection
Laboratory-dependent: The presentation does not point to this disease specifically, but local or regional laboratories can confirm it with a validated assay once it is suspected
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "l2, most well equipped labs dealing with pig cases should be able to confirm without referral to another lab"
Basis. "A definitive diagnosis of PAR depends on clinical and pathological observations and demonstration of toxigenic P. multocida... snout deformation alone is not pathognomonic." (ch54 sec 54.8.1)
How this level was decided
Snout deviation raises suspicion but is not diagnostic. Confirmation requires demonstrating the P. multocida present is toxigenic, which regional laboratories do.
C5 Production cost
Financial impact on the infected farm's cost of production
Moderate: Losses measurably increase cost of production but remain manageable within normal farm operations, whether acute, chronic, or associated with endemic disease
Basis. "The gross lesions of PAR are restricted to the nasal cavity and adjacent structures of the skull, although in advanced cases pigs may also be stunted." "Antibody... protects against turbinate lesions and pneumonia but not against infection." (ch54 sec 54.7.1, ch44 sec 44.9)
How this level was decided
Stunting in advanced cases plus ongoing vaccination and medication cost. Measurable, and managed within normal farm operations.
C6 Market impact
Duration of material disruption to pork and pig markets
Negligible: Little or no material disruption to supply or demand when disease occurs on one or more farms
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "should be C6L1. No regulatory or other reason that would cause a market disruption. 100% certain." The pass had this at L1 but flagged INFERRED, having found nothing in the folder about markets. His certainty settles it.
Basis. Neither chapter addresses pork or pig market disruption.
How this level was decided
INFERRED. An endemic production disease present worldwide does not disrupt supply or demand when it occurs on a farm.
C7 Treatment potential
Potential for treatment to improve outcomes
Little: Effective pathogen-directed treatment is available and works, or animals recover acceptably without it
Basis. "Antibiotics have largely been used for the treatment and control of bacterial respiratory disease in swine. Antibiotics labeled for the treatment of swine respiratory disease, and specifically B. bronchiseptica, include enrofloxacin, florfenicol, and tulathromycin." (ch44 sec 44.10)
How this level was decided
Labelled, effective antimicrobials exist for both agents. The chapter notes variable florfenicol resistance, which argues toward level 2, but treatment is available and works.
C8 Vaccine availability
Availability of effective vaccines or bacterins
Available, or not needed: Effective vaccines are widely available in the US or secured for national outbreak response, or the disease does not clinically or economically justify vaccinating
Basis. "PMT is the major protective antigen in PAR, and immunization with PMT toxoid alone alleviates the associated lesions... protection of piglets via antibody passively acquired from vaccinated sows." (ch54 sec 54.9.1)
How this level was decided
Commercial PMT toxoid and B. bronchiseptica bacterin products are widely available in the US and the chapter describes them as effective against lesions, with the caveat that they protect against disease rather than colonisation.
Levels and evidence are generated from data/assignments/progressive_atrophic_rhinitis.yml; the overview is authored in data/overviews/progressive_atrophic_rhinitis.md. Do not hand-edit this page — corrections go in data/assignments/CORRECTIONS.yml.
Quoted material marked Basis is from Zimmerman JJ, Karriker LA, Ramirez A, Schwartz KJ, Stevenson GW, Zhang J, eds. Diseases of Swine, 12th edition. Hoboken: Wiley Blackwell, 2025 — except where another source is named in the quotation itself.