Streptococcus (beta-hemolytic)

LEVELS: Rarely occurs; Mild; Already in the herd; Laboratory-dependent; Minor; Negligible; Some; Available but inconsistent


Register id	`streptococcus_beta_hemolytic`
Type	bacteria
Scientific name	—
Evidence	3 document(s)
Assigned	2026-09-04, against criteria version `093366e352a2`

Overview

This entry groups four beta-haemolytic streptococci of pigs that are neither S. suis nor S. zooepidemicus, both of which are scored separately: Streptococcus dysgalactiae subsp. equisimilis, S. porcinus, S. gallolyticus and S. plurextorum. Numerically the first matters most. These are opportunists carried on skin and mucous membranes, and the commonest presentation is joint infection — swelling and persistent lameness, sometimes with destruction of the joint cartilage — along with abscesses and sporadic septicaemia. Because the organisms are normal flora, disease follows a breach or a stressor rather than an introduction. Their zoonotic standing is mixed and worth stating carefully: S. dysgalactiae subsp. dysgalactiae is on the documented list of zoonotic streptococci, others such as S. porcinus have been proposed but not established, and one pig-attributed human case is on record — an abattoir worker's wound infection with S. porcinus.

C1 Zoonotic potential

Likelihood of transmission from pigs to humans

Rarely occurs: Human infection from pigs is plausible but has only rarely been reported, and specific control points are not commonly implemented to prevent 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. "c1l2, plausible and likely has happened but i don't think pigs are often the source of the infection in people"

Basis. THE ENTRY IS A GROUP OF FOUR, set by your 2026-08-18 ruling and following ch57 section 57.3, "Infections Caused by Beta-hemolytic Streptococci": S. DYSGALACTIAE SUBSP. EQUISIMILIS, S. PORCINUS, S. GALLOLYTICUS and S. PLUREXTORUM. S. suis and S. zooepidemicus are separate register entries and are not scored here. cfsph_2020_streptococcosis, listing what is established as of 2020: "zoonotic streptococci DOCUMENTED in people include S. canis, S. DYSGALACTIAE SUBSP. DYSGALACTIAE, S. equi subsp. zooepidemicus, S. halichoeri, S. iniae, S. suis and some animal-associated genotypes of S. agalactiae. OTHER ORGANISMS HAVE ALSO BEEN PROPOSED AS ZOONOTIC (E.G., S. PORCINUS, ANIMAL-ADAPTED S. GALLOLYTICUS SUBSP. GALLOLYTICUS), and it is possible that many animal streptococci might be able to infect humans under some circumstances." NOTE WHICH SUBSPECIES IS ON THE DOCUMENTED LIST -- subsp. DYSGALACTIAE, which CFSPH says is "most common in cattle"; the pig organism is subsp. EQUISIMILIS. ch57 57.3.1 records the one pig-attributed human event in the folder, and the correction that preceded it: "many strains of S. porcinus were supposedly recovered from the human female genitourinary tract and might be considered an emerging human pathogen. HOWEVER, IT WAS LATER REPORTED THAT THESE STRAINS BELONG TO A NEW SPECIES, STREPTOCOCCUS PSEUDOPORCINUS... More recently, A CONFIRMED S. PORCINUS WAS RECOVERED FROM A WOUND IN AN ABATTOIR WORKER (Shewmaker et al. 2012)." ma_2024 on the pig subspecies in people: "SDSE has been found in various animal hosts, including pets, livestock (such as cows, sheep, horses, and pigs), and wild animals... Recently, it has been acknowledged as A MORE SIGNIFICANT HUMAN PATHOGEN. Most human infections caused by SD are linked to SDSE, including skin and soft tissue infections, pharyngitis, endocarditis, bacteremia, and meningitis."

How this level was decided

RE-READ AND HELD AT L2 2026-09-04 AGAINST THE REWORDED LABELS. THE ONE PIG-ATTRIBUTED CASE IN THE FOLDER is a confirmed S. porcinus from an abattoir worker's wound -- occupational, unambiguous and singular, which is exactly what "only rarely been reported" describes.

PREVIOUS ANSWER, kept because the evidence behind it has not changed, only the level boundary: INFERRED, AND FLAGGED, because a group of four with four different zoonotic standings has to come out as one number. LEVEL 2 IS SCORED -- human infection from pigs is plausible and has been reported, rarely, and no control point is implemented against it. THE ONE PIG-ATTRIBUTED CASE IN THE FOLDER is a confirmed S. porcinus from an abattoir worker's wound, which is occupational and unambiguous but singular. WHAT KEEPS IT OFF LEVEL 3: the folder shows the record being CORRECTED DOWNWARD rather than up -- the large body of "S. porcinus" human genitourinary isolates was reassigned to a different species, S. pseudoporcinus, so the apparent human burden of this organism turned out not to be this organism. WHAT COULD PUSH IT TO LEVEL 3: S. dysgalactiae subsp. equisimilis causes real and increasing human disease and is carried by pigs, and if you read pigs as a plausible source of those cases this is an occupational risk like S. suis. The folder never makes that attribution -- SDSE is listed in cows, sheep, horses, pigs, pets and wildlife without ranking them.

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. "c2l2, mild disease in a few affected people"

How this level was decided

INFERRED, AND FLAGGED WITH C1, because the two cells answer different halves of one question and the folder splits on them. LEVEL 2 IS SCORED on what has actually been acquired from a pig: a wound infection in an abattoir worker, which is mild and treatable and is the level 2 label. THE ARGUMENT FOR LEVEL 3 OR 4 is that SDSE -- the subspecies pigs carry, not the cattle one -- causes meningitis, endocarditis and bacteraemia in people, and those are not mild. IT IS NOT TAKEN because C2 as rescoped on 2026-09-01 asks about illness ACQUIRED FROM PIGS, and no severe human SDSE case in this folder is attributed to a pig. IF YOU RULE C1 UP TO LEVEL 3, THIS CELL SHOULD MOVE WITH IT, because the reason for holding it at 2 is the same missing attribution.

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

How this level was decided

Level 1, and the chapter states it rather than implying it. These are normal swine microbiota; the piglet meets S. dysgalactiae in its dam's vaginal secretions and milk on the day it is born, and S. porcinus is among the most common organisms cultured from tonsils at slaughter. There is no introduction event to prevent, which is the level 1 label. Scored level with Streptococcus suis and Glaesserella parasuis, the two organisms this entry most resembles and both worked examples at this level. NOTE THAT PREVENTION IN THIS CHAPTER IS ABOUT SUSCEPTIBILITY, NOT EXCLUSION -- colostrum intake and less abrasive flooring -- which is what a level 1 agent gets instead of biosecurity.

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

Basis. THE ENTRY IS A GROUP OF FOUR, set by your 2026-08-18 ruling and following ch57 section 57.3, "Infections Caused by Beta-hemolytic Streptococci": S. DYSGALACTIAE SUBSP. EQUISIMILIS, S. PORCINUS, S. GALLOLYTICUS and S. PLUREXTORUM. S. suis and S. zooepidemicus are separate register entries and are not scored here. ch57 57.3.2 on the presentation: streptococci "enter the bloodstream via SKIN WOUNDS, THE NAVEL, AND TONSILS. A bacteremia or septicemia occurs, and the organisms settle in one or more tissues, giving rise most commonly to ARTHRITIS, ENDOCARDITIS, OR MENINGITIS. Infection is usually first seen in pigs between 1 and 3 weeks of age. JOINT SWELLING AND LAMENESS ARE THE MOST OBVIOUS AND PERSISTENT CLINICAL SIGNS." Hill et al. 1996 found that "in lame pigs up to 12 weeks of age, THE MOST COMMON CAUSATIVE AGENT WAS S. DYSGALACTIAE SUBSP. EQUISIMILIS." On confirmation, cfsph_2020: "Streptococci are usually identified by LANCEFIELD GROUP AND A FEW PHENOTYPIC TESTS, but some streptococcal species can be difficult to recognize or may be confused with other organisms. IDENTIFICATION OF NON-BETA-HEMOLYTIC STREPTOCOCCI TENDS TO BE MORE DIFFICULT. PCR tests have been developed for some organisms including... S. dysgalactiae." On the two newest members, ch57 57.3.4: "SO FAR, THERE ARE NO DATA ABOUT THE HABITAT OR THE VIRULENCE PROPERTIES of these two species and their role in disease pathogenesis remains to be verified."

How this level was decided

Level 2. A swollen joint in a two-week-old pig raises streptococcal arthritis in ordinary practice and Hill's survey says that suspicion is usually right, but nothing about the presentation names a species, and endocarditis and meningitis are found rather than suspected -- so this is not level 1. Confirmation is culture with Lancefield grouping at any regional laboratory, which is the level 2 label, and these organisms sit on the easier side of the line CFSPH draws: identification is harder for the NON-beta-haemolytic streptococci, and every member of this entry is beta-haemolytic by definition. NOTE THE ONE MEMBER THIS DOES NOT COVER: S. plurextorum has no habitat or virulence data at all, so a positive culture from it could not currently be interpreted. That is one of four, and it does not set the entry.

C5 Production cost

Financial impact on the infected farm's cost of production

Minor: Small and generally short-lived losses with little effect on overall cost of production

CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.

Confirmed by Eric. CONFIRMED. "c5l2, causes infrequent disease relative to other pathogens involved in similar conditions"

Basis. THE ENTRY IS A GROUP OF FOUR, set by your 2026-08-18 ruling and following ch57 section 57.3, "Infections Caused by Beta-hemolytic Streptococci": S. DYSGALACTIAE SUBSP. EQUISIMILIS, S. PORCINUS, S. GALLOLYTICUS and S. PLUREXTORUM. S. suis and S. zooepidemicus are separate register entries and are not scored here. ch57 57.3.2 on the commonest presentation: "JOINT SWELLING AND LAMENESS ARE THE MOST OBVIOUS AND PERSISTENT CLINICAL SIGNS... Necrosis of articular cartilage may be observed 15-30 days after onset and may become more severe." Hill et al. 1996: "in lame pigs up to 12 weeks of age, the most common causative agent was S. dysgalactiae subsp. equisimilis and MOST OF THE PIGS CULLED FOR ARTHRITIS WERE UNDER 6 WEEKS OF AGE." 57.3.1 gives the one member whose economics the chapter tracks over time, and the trend is downward: streptococcal lymphadenitis or jowl abscesses -- "LOSSES DUE TO THIS DISEASE IN THE UNITED STATES WERE IMPORTANT IN THE 1960S, BUT THE INCIDENCE AND IMPORTANCE HAVE SINCE DRAMATICALLY DECLINED. The disease is NOT RECOGNIZED AS AN IMPORTANT ECONOMIC ENTITY in other countries." 57.3.4 on the newest member: S. gallolyticus isolates from grower-finishers with valvular endocarditis have increased since 2015, "SUGGESTING THIS MAY BE AN EMERGING PATHOGEN." No aggregate economic figure for the group appears anywhere in the folder.

How this level was decided

INFERRED, AND FLAGGED, because the folder carries no economic figure for any member and this is a cell your field view settles better than the text does. LEVEL 2 IS SCORED: sporadic individual losses -- lame piglets culled, the occasional endocarditis condemned at slaughter -- in a herd where every pig carries the organisms and almost none get sick. That is small and generally short-lived losses with little effect on overall cost of production, and it puts the entry level with the colibacilloses and Actinobaculum suis. THE ARGUMENT FOR LEVEL 3 is that lameness is one of the commonest reasons piglets are culled and this group is its leading cause under six weeks, so the drip is continuous rather than occasional -- which is the shape the level 3 label calls endemic disease. THE ARGUMENT FOR LEVEL 1 is the chapter's own verdict on jowl abscesses, dramatically declined and not an important economic entity, though that is one member of four.

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, no reason to think diagnosis would trigger any market impact"

How this level was decided

INFERRED. Level 1 under the standing note SCORING/market_impact: organisms already resident and routinely diagnosed in US pigs, with no market move ever observed. Scored the same as Streptococcus suis, which is a far more prominent zoonosis and still sits at level 1 here.

C7 Treatment potential

Potential for treatment to improve outcomes

Some: Treatment exists but is inconsistent, requires extralabel use, or works only in some circumstances

How this level was decided

Level 2. The organisms are penicillin-sensitive, so a treatment plainly exists -- but the level 2 clause "works only in some circumstances" is satisfied twice over by the chapter itself. It works if given before the inflammatory process is well advanced, and by the time a piglet is visibly lame the cartilage damage is under way; and in the abscessed form it is not usually successful at all, nor does it clear carriers. THE LABEL QUESTION IS NOT PUT TO YOU HERE, deliberately. No US label wording is in the folder and beta-lactam swine labels use broad Streptococcus wording, which is exactly the ambiguity your 2026-09-02 note said not to guess at -- but a ruling either way could not change this cell, because the inconsistent-efficacy clause holds level 2 independently of any label. It would only matter if the pass were arguing level 1.

C8 Vaccine availability

Availability of effective vaccines or bacterins

Available but inconsistent: Commercial or autogenous vaccines exist in the US but protection may be inconsistent

How this level was decided

Level 2. Autogenous bacterins exist, are used, and have been reported to reduce arthritis when given to sows pre-farrowing, so the "available" half holds; and the evidence for them is a single 1977 report with nothing since, so protection is undemonstrated rather than established -- inconsistent in the sense the level means. NOT LEVEL 3, because level 3 is a genuine gap where no vaccine is available, and here product is made and given. NOT LEVEL 1: the chapter's line on S. porcinus, that vaccination is possible but little used because the condition is not widespread, is close to the "not needed" clause and would justify level 1 for that member alone -- but it is one of four, and the group's principal member has an autogenous product with a claimed effect.

Levels and evidence are generated from data/assignments/streptococcus_beta_hemolytic.yml; the overview is authored in data/overviews/streptococcus_beta_hemolytic.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.

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