Swine Erysipelas
LEVELS: Sometimes occurs; Mild; Already in the herd; Routine; Moderate; Negligible; Little; Available, or not needed
| Register id | erysipelothrix_rhusiopathiae |
| Type | bacteria |
| Scientific name | Erysipelothrix rhusiopathiae |
| NCBI taxid | 1648 |
| Evidence | 2 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Erysipelothrix rhusiopathiae causes swine erysipelas, a disease described by Pasteur in 1882 and still with us. The organism is everywhere and the domestic pig is its main reservoir: depending on the study, a substantial proportion of clinically healthy pigs carry it in their tonsils, and carriers shed it in urine, faeces and saliva for long periods. It survives months in buildings and on equipment. Disease takes three forms. The acute form is a septicaemia with fever up to 42 °C and the diamond-shaped raised skin lesions that give it away at a glance; in a naive herd it can kill 20–40%. The subacute form is milder. The chronic form is what usually costs money — arthritis that leaves a permanently lame, slow-growing pig, and vegetative growths on the heart valves. Of at least 28 serotypes, three cause most field cases. The organism remains highly susceptible to penicillin, which is still the treatment of choice, and sow vaccination is routine and effective, giving six to twelve months of protection. It is also a genuine occupational zoonosis: butchers, abattoir workers, veterinarians and farmers get a localised skin infection called erysipeloid, usually on the hands.
C1 Zoonotic potential
Likelihood of transmission from pigs to humans
Sometimes occurs: Known risk of transmission to humans (foodborne or occupational), but requires failure of one or more control points for transmission to humans
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c1l3, recognized zoonotic agent through occupational exposure generally"
Basis. ch48 48.3: "Though human infections by E. rhusiopathiae are rarely reported, THIS BACTERIUM HAS LONG BEEN RECOGNIZED AS ZOONOTIC. MOST HUMAN CASES ARE A CONSEQUENCE OF OCCUPATIONAL EXPOSURE (BUTCHERS, ABATTOIR WORKERS, VETERINARIANS, FARMERS, fishermen, fish handlers, and domestic food preparers) TO INFECTED ANIMALS OR THEIR TISSUES AND OCCUR VIA SCRATCHES OR TRAUMATIC PENETRATION OF THE SKIN. Not accidentally the most common clinical manifestation in humans is known by names such as... 'PORK FINGER'." 48.4 on how much is out there: "APPROXIMATELY 30-50% OF APPARENTLY HEALTHY PIGS HARBOR E. RHUSIOPATHIAE IN THEIR TONSILS and other lymphoid tissues", and the organism persists in facilities and on equipment for months. SECOND SOURCE, zoric_2026: human infections "are uncommon and mainly associated with occupational exposure, such as farming and slaughterhouse work", and the authors close on the wild boar result -- 45.5% tonsil carriage -- as "a potential source of infection for hunters and others handling carcasses".
How this level was decided
Level 3. Both halves of the label are present and the chapter names them: a known occupational risk -- the human disease is called pork finger -- and a control point that has to fail, namely skin integrity and wound hygiene, since entry is by scratch or penetrating injury while handling infected tissue. THE PIG ATTRIBUTION IS EXPLICIT rather than inferred, which is what separates this from the entries you have trimmed to level 1 today: the occupational groups named include butchers, abattoir workers and farmers, and a third to a half of healthy pigs carry the organism. CORROBORATED 2026-09-04 by zoric_2026, which describes the same occupational route independently. IT ALSO CUTS THE OTHER WAY ON EXPOSURE INTENSITY and the cell is left at level 3 anyway: the authors conclude that "the low prevalence in domestic pigs suggests limited occupational risk in the Swedish pig industry". That is an argument about how MUCH exposure a modern indoor system delivers, not about whether the route exists, and C1 asks whether pigs are a source with a control point that has to fail. They are, and skin integrity is still the control point.
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED AT LEVEL 2, after the cell was held rather than written. HIS SHEET SAID "c2l3, mild disease in most cases", and the stated level and the stated reasoning disagreed: C2 level 2 reads "Mild: Human illness is usually mild and self-limiting, and serious disease occurs only rarely", which is his sentence almost verbatim and the level the pass had already assigned, while level 3 reads "Clinically important illness is common and may require medical treatment or hospitalization". Asked which he meant, under his own instruction of 2026-09-02 to ask when a ruling is not clear, he answered: "make erysipela c2l2". THE ENTRY THEREFORE REMAINS THE C2 LEVEL 2 WORKED EXAMPLE in criteria_levels.yml, which an L3 ruling would have required moving. This is the second time the held-cell rule has paid for itself, after sads_cov/market_impact on 2026-09-02 -- and note that it resolved the OPPOSITE way to that one, where he confirmed the upgrade his prose described. The rule is not that the prose wins; it is that the disagreement gets put to him.
Basis. ch48 48.3: "The clinical form in humans is called ERYSIPELOID and manifests as ACUTE LOCALIZED CELLULITIS WITH SKIN REDDENING... cutaneous infections are usually confined to the extremities. Additional clinical presentations include a generalized cutaneous form and A SEPTICEMIC FORM, WITH ENDOCARDITIS PRESENT IN ABOUT ONE THIRD OF PATIENTS." "HUMAN-TO-HUMAN TRANSMISSION OF E. RHUSIOPATHIAE HAS NOT BEEN ESTABLISHED to date."
How this level was decided
Level 2, and it is the worked example at this level. The usual outcome is a localised cellulitis of a finger or hand -- mild and self-limiting, which is the label. NOTE THE FIGURE THAT LOOKS LIKE A LEVEL 4 ARGUMENT AND IS NOT: endocarditis is present in about a third of patients WHO DEVELOP THE SEPTICAEMIC FORM, and that form is itself rare against a background of cutaneous cases. The denominator is the rare form, not all human infections. Read the other way this cell would move two levels, so the sentence is worth keeping intact in any brief.
C3 Herd introduction risk
Effort required to keep the agent out of the herd
Already in the herd: Present in most herds, or carried by pigs themselves, so there is no introduction event to prevent
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED, and this is his ruling on the sharpest evidence conflict in the register. "c3l1, though it can be soil borne we also know it is carried in healthy pigs and would be very difficult to exclude so l1 is correct." THE FLAG HE IS ANSWERING: zoric_2026 cultured tonsils from 200 apparently healthy Swedish slaughter pigs and found ER in 3.0%, against the 30-50% ch48 states and that this cell's level 1 argument was built on, with a cited Swiss study finding none in 250 -- and the authors credit indoor rearing, age-segregated rearing, sow vaccination, biosecurity and restricted straw, which is close to the US confinement system C3 is scored against. HE RULES ON CARRIAGE, NOT ON PREVALENCE: the organism is carried by healthy pigs, so it is already inside the herd and there is no introduction event to prevent, and a lower carriage rate under good husbandry does not make it excludable. The entry stays the C3 level 1 worked example in criteria_levels.yml.
Basis. ch48 48.4: "Erysipelothrix rhusiopathiae HAS A GLOBAL DISTRIBUTION AND IS UBIQUITOUS. THE DOMESTIC PIG IS CONSIDERED THE MOST IMPORTANT RESERVOIR... APPROXIMATELY 30-50% OF APPARENTLY HEALTHY PIGS HARBOR E. RHUSIOPATHIAE IN THEIR TONSILS AND OTHER LYMPHOID TISSUES. Carriers and pigs with acute erysipelas can shed the organism in their excretions (urine, feces) and secretions (saliva, nasal secretions) FOR EXTENDED PERIODS OF TIME." On the environment: "its presence in facilities and on equipment is well documented, PERSISTING FOR UP TO SEVERAL MONTHS under certain conditions." SECOND SOURCE, AND IT CONTRADICTS THE FIGURE THIS CELL RESTS ON. zoric_2026 cultured tonsils from 200 apparently healthy Swedish fattening pigs at ten abattoirs covering 88% of national slaughter, one pig per herd, and recovered ER from SIX (3.0%) -- against the 30-50% ch48 states. It also cites a Swiss study in which "all 250 tonsils samples from healthy pigs at slaughter" tested negative. Wild boar in the same study ran 76/167 (45.5%). The authors attribute the difference to husbandry: "Swedish pig husbandry, characterized by indoor rearing of fattening pigs, age-segregated rearing, sow vaccination, enhanced biosecurity, and restricted straw access largely prevents tonsillar colonization by ER aligning with the low occurrence of clinically diagnosed erysipelas in such herds."
How this level was decided
Level 1, and it is the worked example at this level. A third to a half of clinically healthy pigs carry it in their tonsils, the pig is the principal reservoir, and carriers shed for extended periods -- so there is no introduction event to prevent. The months-long environmental persistence would matter if there were a clean herd to protect; there is not. FLAGGED 2026-09-04, and this is the one cell in the register whose stated basis a new paper has directly contradicted. The level 1 argument above is built on "a third to a half of clinically healthy pigs carry it in their tonsils", and zoric_2026 found 3.0% in a national sample of exactly that population, with a cited Swiss study finding none in 250. The husbandry the authors credit -- indoor rearing, age segregation, sow vaccination, biosecurity, little straw -- is close to the modern US confinement system the whole C3 ladder is scored against, which is what makes this awkward rather than merely foreign. THE CELL IS LEFT AT LEVEL 1 AND PUT IN FRONT OF YOU RATHER THAN MOVED, for three reasons the pass cannot settle on its own. First, 3.0% is not zero and the US herd is not the Swedish herd -- straw use, outdoor access and vaccination coverage all differ. Second, the rest of the level 1 argument is untouched: ch48 still says the domestic pig is the principal reservoir, that carriers shed for extended periods, and that the organism persists in facilities and on equipment for months, so there is a question about whether housing EXCLUDES it or merely suppresses how much of it is carried. Third, moving it lands on level 2 (housing alone keeps it out), and that is a claim about US barns that this Swedish study is being asked to carry a long way. YOUR CALL: leave at L1, or move to L2 on the ground that modern confinement demonstrably keeps carriage down to a few percent.
C4 Detection difficulty
Difficulty of recognizing and confirming infection
Routine: The disease would be suspected from clinical signs, history and epidemiology in normal practice, and confirmed by tests that local or regional laboratories run routinely
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c4l1, often very characteristic clinical signs and lesions and presentation"
Basis. ch48 48.7: "THE NEARLY PATHOGNOMONIC GROSS LESIONS OF ACUTE SWINE ERYSIPELAS CONSIST OF MULTIFOCAL PINK TO PURPLE RHOMBOID (DIAMOND-SHAPED) SLIGHTLY RAISED SKIN LESIONS predominantly around the snout, ears, jowls, throat, abdomen, and thighs." 48.8: "TIMELY AND ACCURATE DIAGNOSIS OF ERYSIPELAS IS IMPORTANT SINCE EFFECTIVE TREATMENTS ARE AVAILABLE... ISOLATION OF ERYSIPELOTHRIX SPP. FROM TISSUES WITH MORPHOLOGICAL LESIONS PROVIDES A DEFINITIVE LABORATORY DIAGNOSIS. DIRECT CULTURE FROM NONCONTAMINATED SPECIMENS IS USUALLY FAST AND EASY AND CAN BE CONDUCTED USING BASIC LABORATORY EQUIPMENT." Several PCR methods and an immunohistochemical assay are also available; the differential for the acute septicaemic form is long (Salmonella Choleraesuis, Actinobacillus, Glaesserella, Streptococcus suis, CSF, ASF). zoric_2026 used the same route in practice: selective broth with sodium azide and crystal violet, then horse blood agar with kanamycin and neomycin, with identification by MALDI-TOF MS.
How this level was decided
Level 1, the worked example at this level. Both halves hold at the easy end: diamond skin lesions are nearly pathognomonic and are recognised pen-side, and confirmation is direct culture with basic laboratory equipment. NOTE THE ONE HARD CASE the chapter names, which does not lower the level: chronic and antimicrobial-treated animals are difficult to culture and need selective enrichment or immunohistochemistry. The acute septicaemic pig, which is the one that matters, is straightforward. Corroborated 2026-09-04: zoric_2026 recovered the organism from routine abattoir tonsil samples by selective culture and MALDI-TOF, which is ordinary regional laboratory work.
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c5l3, disease occurs sporadically in individuals but also at a group level. Severe disease with uncertain recovery and high welfare cost. Vaccines generally control if they are being used." RE-CONFIRMED 2026-09-04 on the re-assessment sheet, in words that add the boundary: "c5l3, could also be c5l2 and really depends on the farm and nature of a specfic occurrence. Will leave at l3." NOTE FOR THE HARVESTER, because this nearly went back to him as a question he had already answered: naming two levels before choosing one used to trip the ambiguity guard, and the report truncated the quote at 88 characters -- which cut off "Will leave at l3". Both were fixed the same day.
Basis. ch48 48.1: "Swine erysipelas, WHEN UNCONTROLLED, IS ECONOMICALLY SIGNIFICANT AND CAPABLE OF AFFECTING ALL STAGES OF PORK PRODUCTION. THE GREATEST LOSSES CAN BE ATTRIBUTED TO CASES OF SUDDEN DEATH AND ACUTE SEPTICEMIA IN GROWER-FINISHER PIGS. A frequent sequela of surviving an acute infection is CHRONIC LAMENESS AND ARTHRITIS, WHICH RESULTS IN POOR GROWTH AND ABATTOIR CONDEMNATIONS." On frequency and scale: "ERYSIPELAS OCCURS SPORADICALLY in the pig population, but there is evidence that MORE SEVERE AND PREVALENT OUTBREAKS OCCUR IN RECURRING INTERVALS OF APPROXIMATELY 10 YEARS", and 48.6: "In outbreaks of acute swine erysipelas IN NAIVE HERDS, MORTALITY CAN QUICKLY RISE TO 20-40%." Against that, 48.9: "SOWS ARE ROUTINELY VACCINATED against E. rhusiopathiae."
How this level was decided
INFERRED. Level 3 -- losses that measurably increase cost of production but remain manageable within normal farm operations. Scored on modern US production per the standing note, which here means a routinely vaccinated breeding herd in which the disease is sporadic rather than absent: what remains is the vaccination programme itself, sporadic acute deaths in grower-finishers, and the chronic arthritis and condemnations that follow survivors. THE 20-40% MORTALITY FIGURE IS FOR NAIVE HERDS and must carry that qualifier -- under your Menangle rule a level is a claim about the general case, and the general case in the US is a vaccinated herd. IT IS NOT LEVEL 2 because the chronic arthritic sequel is not short-lived; it is a permanently lame pig that grows badly and is trimmed or condemned.
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. "c6l1, old disease, no impact on markets"
Basis. Erysipelothrix rhusiopathiae is ubiquitous and endemic in US herds, carried by 30-50% of healthy pigs (ch48 48.4), and no trade measure, movement restriction or consumer response to a swine erysipelas diagnosis is recorded anywhere in the chapter.
How this level was decided
INFERRED. Level 1 under the standing note SCORING/market_impact: an agent long endemic and routinely diagnosed in US pigs with no market move ever observed. NOTE THAT THE ZOONOTIC DIMENSION DOES NOT LIFT IT: erysipeloid is an occupational infection of the people handling the pig, not a foodborne consumer risk, and the chapter records no human-to-human transmission.
C7 Treatment potential
Potential for treatment to improve outcomes
Little: Effective pathogen-directed treatment is available and works, or animals recover acceptably without it
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c7l1, labelled and effective treatments available" -- ruling on the flag the pass raised after the ch48 re-extraction recovered 48.10, which says that "therapy during the chronic course of erysipelas is usually ineffective due to structural damage in joints and the endocardium". That is the level 2 wording on the entry that IS the level 1 worked example, so it was put in front of him rather than absorbed. He answers on the label test of 2026-09-02: a labelled product names the agent and works, which is level 1. The chronic case is damage already done rather than a drug that fails.
Basis. ch48 48.10, NOW READ IN FULL after the 2026-09-04 re-extraction recovered the two pages the original extraction had lost: "E. RHUSIOPATHIAE IS HIGHLY SUSCEPTIBLE TO PENICILLIN, WHICH REMAINS THE TREATMENT OF CHOICE... ANTIMICROBIAL THERAPY EARLY IN THE COURSE OF E. RHUSIOPATHIAE INFECTION USUALLY RESULTS IN A GOOD RESPONSE IN THE AFFECTED PIG WITHIN 24-36 HOURS; HOWEVER, THERAPY DURING THE CHRONIC COURSE OF ERYSIPELAS IS USUALLY INEFFECTIVE due to structural damage in joints and the endocardium." The same section adds a stewardship caution: tetracycline, erythromycin, lincosamides and quinolones "should be limited, given the increasing reports of bacterial resistance", with named resistance mechanisms in gyrA/parC, tet(M) and erm genes. 48.9 records the other established therapy: "THERAPY WITH ANTISERUM HAS BEEN WIDELY USED AS TREATMENT FOR ACUTE SEPTICEMIA." 48.8 frames why it matters: "timely and accurate diagnosis of erysipelas is important SINCE EFFECTIVE TREATMENTS ARE AVAILABLE." SECOND SOURCE, zoric_2026: "The bacterium is highly susceptible to penicillin, and early antibiotic treatment usually results in recovery within 24-36 h."
How this level was decided
Level 1, the worked example at this level, and the truncation that qualified this cell is gone: the folder now holds the whole of 48.10 and a second source that says the same thing. Effective pathogen-directed treatment exists, is cheap, and works -- penicillin, to which the organism is highly susceptible, remains the treatment of choice, and both sources put recovery at 24-36 hours. Penicillin G swine labels name swine erysipelas explicitly, so the label test of 2026-09-02 is satisfied on the plain wording rather than by inference. FLAGGED 2026-09-04 ON ONE CLAUSE THE OLD TRUNCATED FILE DID NOT CONTAIN, because it is new information about your own worked example: "therapy during the chronic course of erysipelas is usually ineffective due to structural damage in joints and the endocardium". That is the level 2 wording -- treatment that "works only in some circumstances". The pass keeps level 1 because the failure is not the drug failing: the arthritic and endocarditic damage is already done, no antimicrobial could reverse it, and C7 asks what a pathogen-directed treatment could achieve, which here is everything it can achieve if given early. But the entry is the L1 exemplar in criteria_levels.yml, so you should see the sentence before it goes on teaching the level.
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c8l1, effective vaccines widely avaialble"
Basis. ch48 48.10, RECOVERED BY THE 2026-09-04 RE-EXTRACTION and stated directly where before it had to be inferred from 48.9: "PREVENTION OF SWINE ERYSIPELAS IS BEST ACCOMPLISHED BY IMMUNIZATION PROGRAMS. CURRENT VACCINES ARE BASED ON E. RHUSIOPATHIAE SEROTYPES 1 OR 2 AND ARE EITHER INACTIVATED BACTERINS FOR INTRAMUSCULAR INJECTION OR ATTENUATED (AVIRULENT LIVE) VACCINES DESIGNED FOR WHOLE HERD MASS TREATMENT VIA THE DRINKING WATER... VACCINATION IS GENERALLY EFFECTIVE IN PREVENTING SWINE ERYSIPELAS, AND THE DURATION OF IMMUNITY VARIES BETWEEN 6 AND TO 12 MONTHS for both correctly administered bacterins and avirulent vaccines." The same passage records the limit: "VACCINATION MAY NOT BE AS EFFECTIVE IN PREVENTING CHRONIC ARTHRITIS since sequestration of E. rhusiopathiae in the cytoplasm of chondrocytes of articular cartilage may provide protection from host immunity." 48.9: "SOWS ARE ROUTINELY VACCINATED AGAINST E. RHUSIOPATHIAE", with a live serotype 2 vaccine protecting against challenge with serotypes 1a, 1b, 2, 5, 8, 11, 12, 18, 19 and 21 -- including all three that cause most field cases -- but not 9 and 10. SECOND SOURCE, zoric_2026: "Vaccination provides effective protection for 6-12 months when correctly administered", and sow vaccination is named as one of the practices holding Swedish carriage to 3%.
How this level was decided
LEVEL 1, AND NOW SUPPORTED RATHER THAN INFERRED. This is the cell TODO.md predicted the re-extraction would repair, and it did: the previous answer had to reach level 1 through 48.9's remark that sows are routinely vaccinated, because the section that actually describes the products had been lost. It now states outright that prevention is best accomplished by immunization, names both product classes and both routes, and gives 6-12 months of protection. Eric confirmed this cell at level 1 on 2026-09-03 -- "c8l1, effective vaccines widely avaialble" -- and the recovered text is exactly what he was describing. THE ARGUMENT FOR LEVEL 2 is now on the page rather than inferred, and it still does not carry: vaccination "may not be as effective in preventing chronic arthritis", and the serotype 9 and 10 gap remains. Neither touches availability or general efficacy, which is what level 1 asserts, and the serotypes that escape are not the ones causing disease.
Levels and evidence are generated from data/assignments/erysipelothrix_rhusiopathiae.yml; the overview is authored in data/overviews/erysipelothrix_rhusiopathiae.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.