Clostridium perfringens Type C
LEVELS: Highly unlikely; Severe; Already in the herd; Routine; Moderate; Negligible; Some; Available, or not needed
| Register id | clostridium_perfringens_type_c |
| Type | bacteria |
| Scientific name | Clostridium perfringens |
| NCBI taxid | 1502 |
| Evidence | 1 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Clostridium perfringens type C causes a rapidly fatal haemorrhagic enteritis of newborn piglets, usually within the first day to week of life. It is distinguished from other types by producing beta toxin, which is what destroys the small intestine. That toxin is exquisitely sensitive to trypsin, and this explains why the disease belongs to the newborn: colostrum contains trypsin inhibitors that protect the toxin from being broken down in the gut of a piglet that has just suckled. In a naive herd the effect is dramatic — every litter can be affected and case fatality in litters from non-immune gilts can approach 100%, with herd mortality reaching 60%. As sows acquire immunity the disease settles into an endemic pattern confined largely to gilt litters. Vaccinating sows with type C toxoid is highly effective and usually clears the problem within a single farrowing cycle; treating piglets once they are sick rarely works.
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. "c1l1, there are conditions in humans and neonates that seem to have pathology (and some bacteriological evidence) that CPC is involved but I am not really aware of any link that attributes pigs as the source. I am purposefully over-riding the PNG anectodotal story as unreliable and very removed from the US situation"
Basis. Section 47.2.1 runs six subsections on type C and mentions human infection in none of them. That silence is worth noting rather than reading straight: chapter 47 gives an explicit Public Health subsection to C. perfringens type A (47.2.2.2) and to C. difficile (47.2.3.2), and says outright that the histotoxic group (47.3) and the neurotoxic group (47.4) are "not zoonotic; hence, there is no public health concern". Type C alone gets neither treatment.
How this level was decided
MOVED L2 -> L1, 2026-09-04, bringing the pass into line with Eric's own ruling. His words on 2026-09-01 are the reworded level 1 almost verbatim: "there are conditions in humans and neonates that seem to have pathology (and some bacteriological evidence) that CPC is involved but I AM NOT REALLY AWARE OF ANY LINK THAT ATTRIBUTES PIGS AS THE SOURCE." Reported in people, not attributed to pigs. Nothing published changes. NOTE THAT C2 NOW CARRIES THE SEVERITY SEPARATELY, at level 4 -- enteritis necroticans requires hospitalisation and surgery and carries real mortality -- which is the whole point of the 09-04 split.
PREVIOUS ANSWER: INFERRED, AND THE FOLDER DOES NOT SETTLE IT. The chapter is structured so that a zoonosis gets a Public Health section and a non-zoonosis gets a sentence saying so, and type C gets neither -- which is a gap rather than a structured silence. Scored from outside the folder: C. perfringens type C is the cause of enteritis necroticans in people, historically "pigbel" in Papua New Guinea, associated with pork feasting. That is human infection linked to pigs, so level 1 is not available. It is rare, essentially absent from modern Western populations, and no control point in US pork production is directed at it -- both clauses of level 2. FLAGGED for Eric: this is the one cell in the batch where the level rests on knowledge the folder does not contain.
C2 Zoonotic impact
Severity of human illness caused by the agent
Severe: Infection carries a substantial risk of life-threatening illness, death, or permanent disability, even if human infections are uncommon
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. REVIEWED ON C1_C2_RECLASSIFICATION.md, 2026-09-04, after the C1/C2 rewording that separated exposure from consequence. Eric marked up every moved cell and reversed his own earlier setting on twenty of the twenty-one: "In almost every case, I agreed with new opinion and reversed my old setting." HIS MARKUP HERE WAS "L4". REVERSES HIS OWN 2026-09-01 LEVEL 1, and this is the entry whose ruling started the whole C2 question. He scored level 1 then because pigs are not the attributed source -- "I am not really aware of any link that attributes pigs as the source" -- which is now a C1 statement and is recorded there at level 1. C2 grades the agent: enteritis necroticans is a segmental necrotising jejunitis requiring hospitalisation and surgery, with real mortality.
Basis. Section 47.2.1 describes no human disease. The only human material in chapter 47 concerns C. perfringens type F (47.2.2.2) and C. difficile (47.2.3.2).
How this level was decided
RE-SCORED 2026-09-04. C2 now grades the severity of the illness the agent causes in a person, independent of how the person was exposed -- the 2026-09-01 pig-attribution reading is reversed, and C1 alone carries the source question. THIS IS THE ENTRY THAT STARTED THE WHOLE QUESTION and it now resolves the other way. The previous assessment: "Enteritis necroticans is a segmental necrotising jejunitis that requires hospitalisation and surgery and carries real mortality, which argues level 4." It was held at 1 only because Eric ruled pigs are not the attributed source -- "I am not really aware of any link that attributes pigs as the source" -- which is now a C1 statement, and C1 records it.
PREVIOUS ANSWER, written under the pig-attribution reading: INFERRED, and dependent on the C1 reading above. Enteritis necroticans is a segmental necrotising jejunitis that requires hospitalisation and surgery and carries real mortality, which argues level 4. Scored level 3 because the level 4 test is a SUBSTANTIAL risk of death or permanent disability and the disease is vanishingly rare outside specific dietary settings, so clinically important illness commonly requiring treatment is the honest reading. FLAGGED with C1 -- if Eric rules C1 to level 1 on the ground that the folder holds nothing, this goes to level 1 with it.
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
Corrected by Eric from L4 Extraordinary biosecurity required. Reason: MOVED L4 -> L1, and he is overturning HIS OWN earlier ruling of level 4 made on 2026-09-02. His words: "l1, am downgrading this on purpose. certainly does not deserve l4. My feeling is that this agent is probably present in most populations and it is other cofactors that allow the disease to be clinically expressed. We just don't see it much anymore but I don't know if it is a) because we have moved pigs indoors (i.e. l2) or b) because of vaccination (but I don't know current use of CPC vaccines though it used to be routinely combined with colibacillosis vaccines). WE DO NOTHING WITH REGARD TO L3 ROUTINE BIOSECURITY THAT I WOULD EXPECT TO EXCLUDE IT FROM A FARM so my decision is l1." NOTE THE FORM OF THE ARGUMENT, because it is a useful test for other cells: he does not know why the disease became rare, and rather than guess between housing and vaccination he asks what any farm actually DOES that would exclude the organism -- and the answer is nothing. An agent no biosecurity measure is aimed at, present in most populations, is level 1. EARLIER RULING, 2026-09-02, kept because a later decision does not erase the reasoning it replaced: CONFIRMED. "c3l4, agree with assessment. may get some pushback on this because we don't actually see the clinical disease very often and CPC vaccine use is no where as prevalent now as it used to be. However, it is hard to imagine that if you looked hard enough, you wouldn't find it. disease expression may be a function of underlying immunity, disease cofactors, colostrum intake, etc."
Basis. ch47 47.2.1.1: "Vegetative bacterial cells are shed in feces in low numbers by healthy sows and in high numbers by diseased pigs, and they may sporulate. Spores are resistant to heat, disinfectants, and ultraviolet light and may serve as a source of infection for successive litters if the farrowing environment is not sufficiently cleaned and disinfected." "Neonatal suckling pigs are infected primarily by exposure to sow feces but may also be infected by horizontal transmission from infected littermates or from spores ingested from a contaminated environment." "C. perfringens type C may be found, albeit rarely, in low numbers as a component of normal swine microbiota."
How this level was decided
Level 4. The cycle runs inside the farrowing house -- sow faeces to piglet, litter to litter -- and the spores that carry it between litters are resistant to heat, disinfectants and ultraviolet light. Housing does not break it and routine cleaning and disinfection does not reliably clear it, which is what level 4 records: exclusion needs more than the routine and may still fail. Note that what the industry actually does about type C is vaccinate rather than exclude, which is consistent with this being an agent you cannot keep out. FLAGGED: the chapter also says type C is occasionally normal swine microbiota, and if Eric reads that as decisive this is level 1. It says "albeit rarely, in low numbers", which is why it is not scored as carried by the pigs themselves.
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
Basis. ch47 47.2.1.4: "Typically, hemorrhagic diarrhea and rapid death in neonatal piglets that have gross lesions of segmental necrohemorrhagic or fibrinonecrotic enteritis are sufficient basis for a presumptive diagnosis of type C enteritis." "Under field conditions, examination of smears of intestinal mucosa in pursuit of abundant, large, gram-positive rods... adds confidence." "Detection of CPB toxin is most commonly performed by antigen immunoassays that are commercially available." "genotyping of isolates using a multiplexed PCR assay to detect genes for the major toxins is the nearly universal method to determine C. perfringens type."
How this level was decided
Both halves of level 1, stated by the chapter rather than inferred. The clinical picture is diagnostic enough on its own for a presumptive diagnosis, and confirmation is a commercially available antigen immunoassay plus culture and multiplex PCR, all of which any regional veterinary diagnostic laboratory runs. NOTE: CPB is trypsin-sensitive and degrades, so a negative does not exclude the disease -- the chapter says to freeze or add trypsin inhibitor before shipping. That is a sample-handling caution on a routine test, not a barrier to getting one.
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. ch47 47.2.1.1: "Type C enteritis may occur as epidemics in nonvaccinated populations and can reach a prevalence of 100% of litters." "The case fatality rate varies, but 100% mortality in litters of nonimmune gilts is not unusual. Total herd mortality may be as high as 60%, but is usually lower." "As dams develop immunity and provide protective lactogenic immunity to their suckling piglets, the disease becomes endemic. When endemic, peracute, and acute fatal clinical disease is observed predominantly in litters of nonimmune dams, usually gilts." 47.2.1.5: "vaccination usually eliminates the disease within one farrowing cycle."
How this level was decided
Level 3 under the standing note SCORING/production_cost_impact, which says to score modern US production rather than the chapter picture. The epidemic figures -- 100% of litters, 60% herd mortality -- describe naive unvaccinated populations, and US breeding herds vaccinate. What remains in a vaccinating herd is a standing programme cost plus recurring losses in gilt litters where seroconversion was inadequate. That is a measurable increase in cost of production that farms manage within normal operations, which is level 3. It is not level 2, because unlike the Salmonella case Eric described the losses are not short-lived -- they recur every farrowing cycle in the same part of the herd.
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 with no evidence to suggest diagnosis would impact markets"
Basis. Section 47.2.1 records no trade measure, movement control or consumer response. Infection "occurs worldwide" and the disease has been recognised in pigs since the 1950s.
How this level was decided
INFERRED. Under the standing note SCORING/market_impact this is an agent long endemic and routinely diagnosed in US herds with no historical market move on record. The losses fall in the farrowing house and are scored at C5. Level 1.
C7 Treatment potential
Potential for treatment to improve outcomes
Some: Treatment exists but is inconsistent, requires extralabel use, or works only in some circumstances
Basis. ch47 47.2.1.5: "Treatment is of little value in animals with clinical signs, and prophylaxis is the preferred approach." "Oral antimicrobials such as ampicillin or amoxicillin can also be given prophylactically, beginning immediately after birth and continuing daily for 3 days." "the organism remains uniformly susceptible to penicillins. Ceftiofur may be an alternative for the treatment of piglets, and bacitracin methylene disalicylate can be administered to sows before and after farrowing." "passive immunization with equine-origin antitoxin can protect piglets... Unfortunately, CPB antitoxin is not commercially available in most of the world."
How this level was decided
Level 2, and the label fits word for word: treatment exists but works only in some circumstances. Antimicrobials work prophylactically in the first days of life and the organism has stayed uniformly penicillin-susceptible, but the chapter says flatly that treatment is of little value once a piglet is showing signs -- the toxin is already made. The specific antitoxin that would help is not commercially available in most of the world. This is not level 3, because the outcome IS reliably improved, by prophylaxis and by vaccination rather than by treating the sick pig.
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, agree with assessment"
Basis. ch47 47.2.1.5: "Prevention is best achieved by vaccination of sows with type C toxoid at breeding or mid-gestation and at 2-3 weeks before farrowing. Commercial toxoid vaccines are quite effective, and vaccination usually eliminates the disease within one farrowing cycle. Ten-fold reductions in mortality are common." "A proportion of gilts might not sufficiently seroconvert to provide efficient passive immunity to their offspring. Administering three instead of the two initial recommended vaccine doses before the first farrowing of gilts has been suggested to improve passive protection."
How this level was decided
Level 1. Commercial toxoids are widely available in the US, the chapter calls them quite effective, and vaccination usually eliminates the disease within one farrowing cycle with ten-fold mortality reductions. That is the first clause of level 1. FLAGGED as a level 1 or 2 judgment: the gilt seroconversion gap is a real inconsistency and level 2 reads "Available but inconsistent". Scored level 1 because the chapter presents it as a dosing schedule to be improved rather than as unreliable protection, and because it names the fix.
Levels and evidence are generated from data/assignments/clostridium_perfringens_type_c.yml; the overview is authored in data/overviews/clostridium_perfringens_type_c.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.