Swine papillomavirus

LEVELS: Highly unlikely; No human illness; Already in the herd; No validated assay; Negligible; Negligible; Little; Available, or not needed


Register id	`swine_papillomavirus`
Type	virus
Scientific name	Sus scrofa papillomavirus
NCBI taxid	3052847
Evidence	3 document(s)
Assigned	2026-09-06, against criteria version `093366e352a2`

Overview

Swine papillomavirus causes genital warts in pigs, and the striking thing about it is how little disease it does for something so specific. It is spread venereally — by natural service or by artificial insemination from an infected boar — and it produces firm, small lesions of one to three centimetres on the vulva of the gilt or sow and in the preputial diverticulum of the boar, where they tend to be larger and more stalked. The disease is mild and self-limiting: the warts resolve over a matter of weeks once the pig's own immune response develops, and recovered animals are immune. Papillomaviruses are highly species-specific, and this one has only ever been documented in pigs; people are not at risk from it. What is not known outnumbers what is. The published reports place it in England and Belgium, and there is no information at all on how much disease it causes or how often — no morbidity figure, no mortality figure, no effect on growth or on carcass value, and no data on whether it affects the reproductive health of a herd, which is the one question that would matter commercially. It can be found by PCR using primers described for it and grown in pig kidney cell lines, but no antibody test has ever been described, so herd-level surveys are not really possible. There is no vaccine and none is warranted; the practical control, where anyone bothers, is screening semen before a boar is used for breeding. It stays on the register because it appears on the published SHIC viral matrix and SHIC maintains a factsheet on it, so a reader looking for it should find it and find out how thin the evidence is.

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. NO DISEASES OF SWINE CHAPTER. The folder is two papers. li_2023 characterised Sus scrofa papillomavirus type 1 in Chinese domestic pigs: "354 domestic pig skin samples collected from Guangxi Province were examined for SsPV DNA by PCR. THREE SsPV1s were identified WITH A PREVALENCE OF 0.847% (3/354)", and it reports "THE FIRST DETECTION OF SsPV DNA IN CHINA based on whole genome information". dibonito_2019 looked in Italian pig slurry: "three samples (13.6%) were positive for SsPV1... while SsPV2 was not found in any sample." Neither paper describes clinical disease, transmission between herds, treatment, or vaccination. THE ONLY HUMAN VIRUS FINDING IN THE FOLDER RUNS THE OPPOSITE WAY. dibonito_2019: "Using generic primers, EIGHT SAMPLES (36.4%) WERE TESTED POSITIVE FOR HUMAN PAPILLOMAVIRUS (HPV)... THE UNEXPECTED PRESENCE OF HPV IN PIG WASTE COULD BE EXPLAINED AS THE RESULT OF AN IMPROPER USE OF THE SEWAGE COLLECTION PITS AND/OR WITH IMPROPER PROCEDURES OF THE OPERATORS." li_2023 places the family: papillomaviruses "widely exist in various vertebrates, such as cattle, dogs, elk, roe deer, birds, and humans", each with its own types. No human infection with a swine papillomavirus is reported in either paper. shic_spv: "Humans are not at risk for infection with SPV." "the virus seems to be highly species-specific. SPV has only been documented in pigs."

How this level was decided

Level 1 -- no evidence that pigs transmit this agent to humans. Papillomaviruses are among the most host-restricted virus families known and the folder treats swine and human types as separate throughout. THE ONE HUMAN FINDING IS A REVERSE-ZOONOSIS ARTEFACT AND MUST NOT BE READ AS SUPPORT FOR TRANSMISSION: human papillomavirus was found in pig slurry because human sewage got into the pit, which is people contaminating pigs, and the authors say so. That is the same distinction you drew on chikungunya, where C1 was rescoped to ask about transmission FROM PIGS. Level 1 confirmed by direct statement.

C2 Zoonotic impact

Severity of human illness caused by the agent

No human illness: Agent does not cause illness in people

How this level was decided

Level 1, following C1. Pigs are not a source of human illness with this agent. Level 1 confirmed.

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 no level assigned. Reason: CLOSED 2026-09-04 AT LEVEL 1, and this was the last open null anyone could close. His ruling: "papillomavirus is c3L1". THE PASS HAD LEFT IT NULL because C3 asks what effort would keep the agent out of a herd and the folder does not describe how it gets into one -- neither paper reports a transmission route between pigs, any environmental persistence, or any measure that would exclude the virus. It also warned against the obvious inference: papillomaviruses are host-restricted skin viruses that most animals carry, so "already in the herd" is the expected answer, but the only prevalence figure in the folder is 0.847% of 354 Chinese skin samples, which is the opposite of ubiquitous. HE SUPPLIES THE FACT THE FOLDER LACKED, which is exactly the route his own 2026-09-03 note named -- "YOU CAN CLOSE THIS CELL YOURSELF if you know how common porcine papillomas are in US herds" -- and it is the same way the Saint Valerien and coxiella C3 cells were legitimately filled. WITH THIS THE ENTRY BECOMES EXPORTABLE: all eight cells now carry a level, and 142 of 155 entries have a complete score vector.

Basis. NO DISEASES OF SWINE CHAPTER. The folder is two papers. li_2023 characterised Sus scrofa papillomavirus type 1 in Chinese domestic pigs: "354 domestic pig skin samples collected from Guangxi Province were examined for SsPV DNA by PCR. THREE SsPV1s were identified WITH A PREVALENCE OF 0.847% (3/354)", and it reports "THE FIRST DETECTION OF SsPV DNA IN CHINA based on whole genome information". dibonito_2019 looked in Italian pig slurry: "three samples (13.6%) were positive for SsPV1... while SsPV2 was not found in any sample." Neither paper describes clinical disease, transmission between herds, treatment, or vaccination. On prevalence, the only two figures in the folder: 0.847% of 354 Chinese pig skin samples, and 3 of 22 Italian slurry samples. NEITHER PAPER DESCRIBES A TRANSMISSION ROUTE between pigs or between herds, any environmental persistence, or any measure that would exclude the virus. shic_spv: "Transmission of SPV is sexual and occurs through natural servicing or artificial insemination of a gilt/sow by an infected boar." "To prevent transmission of SPV, semen can be screened before a boar is used for breeding." "The geographic distribution of SPV is unclear. The few published reports that exist document SPV in England and Belgium."

How this level was decided

NOT ASSESSED. C3 asks what effort would keep this agent out of a herd, and the folder does not describe how it gets into one. THE PASS WOULD OTHERWISE HAVE WRITTEN LEVEL 1 -- papillomaviruses are host-restricted skin viruses that most animals carry, so "already in the herd" is the expected answer -- AND THAT IS THE INFERENCE TO RESIST, because the only prevalence figure in the folder is 0.847%, which is the opposite of ubiquitous. Under the rule you set on PCV4 and applied again to coxiella tonight, where the folder cannot support the claim the cell stays empty, because a filled-in level is indistinguishable from a real one. YOU CAN CLOSE THIS CELL YOURSELF if you know how common porcine papillomas are in US herds; that is how the Saint Valerien and coxiella C3 cells were legitimately filled. LEVEL 1 HELD, AND FLAGGED, because the new source cuts against it twice. The published reports place SPV in England and Belgium and not in the United States, so "already in the herd" is not established here; and the route is venereal, through natural service or AI from an infected boar, which semen screening closes -- that is a routine biosecurity measure and reads as level 3. I have not moved it because the factsheet also says the geographic distribution is unclear and the literature is thin rather than negative, so absence of US reports is not evidence of absence for a mild, self-limiting genital lesion nobody submits. This cell was filled by Eric's correction from a null, so it is his to revisit.

C4 Detection difficulty

Difficulty of recognizing and confirming infection

No validated assay: No pathogen-specific test of known reliability exists anywhere, and identification depends on sequencing or on primers that have not been critically evaluated

Basis. NO DISEASES OF SWINE CHAPTER. The folder is two papers. li_2023 characterised Sus scrofa papillomavirus type 1 in Chinese domestic pigs: "354 domestic pig skin samples collected from Guangxi Province were examined for SsPV DNA by PCR. THREE SsPV1s were identified WITH A PREVALENCE OF 0.847% (3/354)", and it reports "THE FIRST DETECTION OF SsPV DNA IN CHINA based on whole genome information". dibonito_2019 looked in Italian pig slurry: "three samples (13.6%) were positive for SsPV1... while SsPV2 was not found in any sample." Neither paper describes clinical disease, transmission between herds, treatment, or vaccination. On how the virus is found, both papers use the same approach and nothing else exists in the folder. li_2023: "examined for SsPV DNA BY PCR", followed by sequence and phylogenetic analysis of L1 and L2. dibonito_2019: "analysis by NESTED PCR AND DNA SEQUENCING using PUBLISHED AND NEWLY DESIGNED SPECIFIC PRIMER PAIRS for Sus scrofa papillomavirus type 1 and 2, along with DEGENERATE PV-SPECIFIC PRIMERS targeting the major coat protein L1 and the helicase protein E1." No serological assay, no commercial test, and no cell culture system is mentioned. li_2023 frames its own contribution as providing "a scientific basis for the DEVELOPMENT of SsPV pathogenic biology, epidemiology, and prevention, as well as control technology research." shic_spv: "Polymerase chain reaction (PCR) can be used to amplify the virus; SPV-specific primers have been described." "No assays to detect anti-SPV-antibody have been described." "The virus can be isolated in porcine kidney cell lines."

How this level was decided

Level 4 -- no pathogen-specific test of known reliability exists, and identification depends on sequencing or on primers that have not been critically evaluated. The label describes this folder exactly: nested PCR with newly designed primers, degenerate family-level primers, and sequencing to say which type was found. There is no serology and no validated assay of any kind. Scored level with porcine norovirus, sapovirus, astrovirus and Bungowannah virus. NOTE THAT THE CLINICAL HALF FAILS TOO: a wart on a pig is visible, but nothing about it names the virus, and both papers detected the agent by screening rather than by investigating a case. Level 4 confirmed, and this is a textbook application of the 2026-08-29 rework: SPV-specific primers have been DESCRIBED, and a described primer set is not a validated assay. No antibody assay exists at all.

C5 Production cost

Financial impact on the infected farm's cost of production

Negligible: No measurable effect on cost of production

Corrected by Eric from no level assigned. Reason: RULED NOT ASSESSABLE AND ROUTED TO KISS ANALYSIS, 2026-09-03, WITH A REVIEW ATTACHED. Against the five open cells on this entry he wrote "KISS", and against the first of them he added "TWO PAPERS IN INBOX TO REVIEW AGAINST ALL CRITERIA". THE TWO PAPERS TURNED OUT TO BE THE TWO ALREADY IN THE FOLDER. Both were run through import_sources.py on 2026-09-03 and both came back ALREADY IN LIBRARY; SHA-256 of each inbox PDF is byte-identical to the library master and to the pdf_sha256 in the provenance header of the copy placed in this entry on 2026-08-19 -- 39394bfe... for li_2023_sscpv1_guangxi and c1d1d9c9... for dibonito_2019_papillomavirus_pig_slurry. SO THERE IS NO NEW EVIDENCE, and the KISS ruling was made against the complete folder rather than against a partial one. The entry is signed off on that basis. It reopens if a paper describing a clinically affected pig is found -- which is the one thing missing, and one line of his own judgment on whether porcine papillomas are trivial would close C5, C7 and C8 together. THE FOLDER AT THE TIME OF THE RULING held two papers, neither of which reported a single clinically affected pig: li_2023 found SsPV1 DNA in 0.847% of 354 Chinese pig skin samples, and dibonito_2019 found it in 3 of 22 Italian slurry samples. The word "tumour" appears once, in a definition, and is never cashed out in a live animal. NOTE THAT C6 MOVES FROM A LEVEL TO A NULL: the pass had scored it level 1 on the anthrax reasoning, and he has nulled it with the rest, which is consistent -- if the production impact is unknown, so is whether anything would reach a market. CLOSED 2026-09-04 AT LEVEL 1. Asked the one question the folder could not answer, Eric ruled: "papillomavirus is clinically trivial". That is the judgment the 09-03 null was waiting for -- the folder's single clause, "Sus scrofa papillomatosis is a tumour", was never cashed out in a live animal, and neither screening survey looked at whether its positive pigs were affected. His ruling supplies the missing fact directly rather than by inference, so level 1 is now a statement of his rather than a guess from silence: no measurable effect on cost of production.

Basis. NO DISEASES OF SWINE CHAPTER. The folder is two papers. li_2023 characterised Sus scrofa papillomavirus type 1 in Chinese domestic pigs: "354 domestic pig skin samples collected from Guangxi Province were examined for SsPV DNA by PCR. THREE SsPV1s were identified WITH A PREVALENCE OF 0.847% (3/354)", and it reports "THE FIRST DETECTION OF SsPV DNA IN CHINA based on whole genome information". dibonito_2019 looked in Italian pig slurry: "three samples (13.6%) were positive for SsPV1... while SsPV2 was not found in any sample." Neither paper describes clinical disease, transmission between herds, treatment, or vaccination. li_2023 states what the agent does in one clause -- "SUS SCROFA PAPILLOMATOSIS (SsP) IS A TUMOUR CAUSED BY SUS SCROFA PAPILLOMAVIRUSES" -- and nowhere describes a clinical case, a lesion in a live pig, an effect on growth, a carcass consequence, or an economic figure. dibonito_2019 examined slurry and never saw a pig. shic_spv: "There is no information available on SPV-induced morbidity or mortality." "The disease is typically mild and self-limiting." "Disease caused by SPV is limited and resolves after a matter of weeks."

How this level was decided

NOT ASSESSED. Neither paper reports a single clinically affected animal. The word tumour is doing a lot of work in that sentence and the folder never cashes it: papillomas in other species are benign warts that usually regress, but nothing here says that about pigs, and importing it would be reasoning from cattle and dogs rather than from the evidence. SCORING LEVEL 1 WOULD ASSERT NO MEASURABLE EFFECT ON COST OF PRODUCTION, which nobody has established -- and level 1 is as much a magnitude claim as level 4. AN EXAMINED NEGATIVE IS EVIDENCE, A SILENCE IS NOT, and both of these studies were screening surveys that never looked at whether the positive pigs were affected. Level 1 confirmed. Note the tension the factsheet leaves: there is no morbidity or mortality information at all, which in other entries has argued for a null. Here the affirmative statement that the disease is mild and self-limiting and resolves in weeks supports the level rather than leaving it unsupported.

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. RULED NOT ASSESSABLE AND ROUTED TO KISS ANALYSIS, 2026-09-03, WITH A REVIEW ATTACHED. Against the five open cells on this entry he wrote "KISS", and against the first of them he added "TWO PAPERS IN INBOX TO REVIEW AGAINST ALL CRITERIA". THE TWO PAPERS TURNED OUT TO BE THE TWO ALREADY IN THE FOLDER. Both were run through import_sources.py on 2026-09-03 and both came back ALREADY IN LIBRARY; SHA-256 of each inbox PDF is byte-identical to the library master and to the pdf_sha256 in the provenance header of the copy placed in this entry on 2026-08-19 -- 39394bfe... for li_2023_sscpv1_guangxi and c1d1d9c9... for dibonito_2019_papillomavirus_pig_slurry. SO THERE IS NO NEW EVIDENCE, and the KISS ruling was made against the complete folder rather than against a partial one. The entry is signed off on that basis. It reopens if a paper describing a clinically affected pig is found -- which is the one thing missing, and one line of his own judgment on whether porcine papillomas are trivial would close C5, C7 and C8 together. THE FOLDER AT THE TIME OF THE RULING held two papers, neither of which reported a single clinically affected pig: li_2023 found SsPV1 DNA in 0.847% of 354 Chinese pig skin samples, and dibonito_2019 found it in 3 of 22 Italian slurry samples. The word "tumour" appears once, in a definition, and is never cashed out in a live animal. NOTE THAT C6 MOVES FROM A LEVEL TO A NULL: the pass had scored it level 1 on the anthrax reasoning, and he has nulled it with the rest, which is consistent -- if the production impact is unknown, so is whether anything would reach a market. CLOSED 2026-09-04 AT LEVEL 1, and it follows from his ruling by his own stated reasoning. He nulled this cell on 09-03 with the note "if the production impact is unknown, so is whether anything would reach a market". The production impact is no longer unknown -- "papillomavirus is clinically trivial" -- so the ground of the null is removed and the pass's original level 1 stands, on the anthrax reasoning recorded there: a benign cutaneous virus family found across most vertebrate species has no pathway to a market, and a wart on a pig is not conspicuous.

How this level was decided

INFERRED. Level 1, and it is scored rather than nulled on your anthrax reasoning: a benign cutaneous virus family found across most vertebrate species, well known in cattle and dogs, has no pathway to a market, and a detection in pigs would be a variation on something long familiar rather than a novel event. THE STANDING NOTE'S NULL CASE IS WHERE NOTHING HAS EVER BEEN OBSERVED AND THE EVENT WOULD BE CONSPICUOUS; a wart on a pig is not conspicuous. This is the one cell on this entry where the surrounding knowledge is strong enough to carry the claim without the folder spelling it out. Unchanged.

C7 Treatment potential

Potential for treatment to improve outcomes

Little: Effective pathogen-directed treatment is available and works, or animals recover acceptably without it

Corrected by Eric from no level assigned. Reason: RULED NOT ASSESSABLE AND ROUTED TO KISS ANALYSIS, 2026-09-03, WITH A REVIEW ATTACHED. Against the five open cells on this entry he wrote "KISS", and against the first of them he added "TWO PAPERS IN INBOX TO REVIEW AGAINST ALL CRITERIA". THE TWO PAPERS TURNED OUT TO BE THE TWO ALREADY IN THE FOLDER. Both were run through import_sources.py on 2026-09-03 and both came back ALREADY IN LIBRARY; SHA-256 of each inbox PDF is byte-identical to the library master and to the pdf_sha256 in the provenance header of the copy placed in this entry on 2026-08-19 -- 39394bfe... for li_2023_sscpv1_guangxi and c1d1d9c9... for dibonito_2019_papillomavirus_pig_slurry. SO THERE IS NO NEW EVIDENCE, and the KISS ruling was made against the complete folder rather than against a partial one. The entry is signed off on that basis. It reopens if a paper describing a clinically affected pig is found -- which is the one thing missing, and one line of his own judgment on whether porcine papillomas are trivial would close C5, C7 and C8 together. THE FOLDER AT THE TIME OF THE RULING held two papers, neither of which reported a single clinically affected pig: li_2023 found SsPV1 DNA in 0.847% of 354 Chinese pig skin samples, and dibonito_2019 found it in 3 of 22 Italian slurry samples. The word "tumour" appears once, in a definition, and is never cashed out in a live animal. NOTE THAT C6 MOVES FROM A LEVEL TO A NULL: the pass had scored it level 1 on the anthrax reasoning, and he has nulled it with the rest, which is consistent -- if the production impact is unknown, so is whether anything would reach a market. CLOSED 2026-09-04 AT LEVEL 1, moving with C5 exactly as the 09-03 ruling said it would. Under SCORING/treatment_potential, level 1 holds where animals recover acceptably without treatment or there is no imperative to treat at all. "Clinically trivial" is that finding stated by him, which is what the null was for: the pass was forbidden from asserting it, because his 2026-09-02 rule bars the easy answer that nobody treats what nobody diagnoses.

How this level was decided

NOT ASSESSED, AND IT MOVES WITH C5. C7 asks whether outcomes would meaningfully improve if a treatment existed, and no outcome has been described in a pig -- so there is nothing to improve and nothing to rule out. SCORING LEVEL 1 WOULD ASSERT THAT PIGS RECOVER ACCEPTABLY WITHOUT TREATMENT, which is probably true of a wart and is nowhere established here, and your 2026-09-02 rule forbids the other easy answer, that nobody treats what nobody diagnoses. Level 1 confirmed -- animals recover acceptably without treatment, which is the clause level 1 was widened to carry.

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

Corrected by Eric from no level assigned. Reason: RULED NOT ASSESSABLE AND ROUTED TO KISS ANALYSIS, 2026-09-03, WITH A REVIEW ATTACHED. Against the five open cells on this entry he wrote "KISS", and against the first of them he added "TWO PAPERS IN INBOX TO REVIEW AGAINST ALL CRITERIA". THE TWO PAPERS TURNED OUT TO BE THE TWO ALREADY IN THE FOLDER. Both were run through import_sources.py on 2026-09-03 and both came back ALREADY IN LIBRARY; SHA-256 of each inbox PDF is byte-identical to the library master and to the pdf_sha256 in the provenance header of the copy placed in this entry on 2026-08-19 -- 39394bfe... for li_2023_sscpv1_guangxi and c1d1d9c9... for dibonito_2019_papillomavirus_pig_slurry. SO THERE IS NO NEW EVIDENCE, and the KISS ruling was made against the complete folder rather than against a partial one. The entry is signed off on that basis. It reopens if a paper describing a clinically affected pig is found -- which is the one thing missing, and one line of his own judgment on whether porcine papillomas are trivial would close C5, C7 and C8 together. THE FOLDER AT THE TIME OF THE RULING held two papers, neither of which reported a single clinically affected pig: li_2023 found SsPV1 DNA in 0.847% of 354 Chinese pig skin samples, and dibonito_2019 found it in 3 of 22 Italian slurry samples. The word "tumour" appears once, in a definition, and is never cashed out in a live animal. NOTE THAT C6 MOVES FROM A LEVEL TO A NULL: the pass had scored it level 1 on the anthrax reasoning, and he has nulled it with the rest, which is consistent -- if the production impact is unknown, so is whether anything would reach a market. CLOSED 2026-09-04 AT LEVEL 1, moving with C5. THE LIMIT THAT KEPT THIS CELL NULL IS NOW SATISFIED: under SCORING/vaccine_availability, asserting a vaccine is not needed is itself a claim about the disease, so it could not be made for an agent whose clinical significance in pigs was undescribed -- the rule he imposed on pasivirus_a and pcv4. He has now made that claim himself. "Clinically trivial" is exactly the no clinical or market imperative test, so level 1 on its second clause: the disease does not justify vaccinating.

How this level was decided

NOT ASSESSED, AND IT MOVES WITH C5, under the rule you imposed on pasivirus_a and pcv4 and applied again to coxiella tonight: ASSERTING THAT A VACCINE IS NOT NEEDED IS STILL A CLAIM ABOUT THE DISEASE, and it cannot be made for an agent whose clinical significance in pigs is undescribed. THE THREE NULLS ON THIS ENTRY MAKE IT UNEXPORTABLE, which is the intended outcome; it joins the others on the KISS list. IF YOU FILL C5 -- and a one-line judgment that porcine papillomas are trivial would do it -- then C7 and C8 follow immediately and the entry becomes exportable. Level 1 held. Mild and self-limiting, so no clinical or market imperative -- and here the claim is affirmatively supported rather than inferred from silence, which is what the standing note requires before level 1 can be used.

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