Pasivirus agallia (Pasivirus A)
LEVELS: Highly unlikely; No human illness; Already in the herd; No validated assay; Negligible; Negligible; Little; Available, or not needed
| Register id | pasivirus_a |
| Type | virus |
| Scientific name | Pasivirus agallia |
| NCBI taxid | 3431402 |
| Evidence | 5 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Swine pasiviruses are picornaviruses first described in 2012 and known from four genetic types. What is known about them comes from two independent detection studies on different continents, and both point the same way: the virus was found in 68% of healthy piglets and none of the healthy sows on a French industrial farm, and in 20% of 180 healthy piglets in China. It appears to be an enteric infection of young pigs that circulates and then clears. No clinical sign, lesion or production effect has ever been reported — although it is worth noting that neither study compared healthy pigs with scouring ones, so no case-control test of whether it is ever associated with disease has been done. Detection has relied on high-throughput sequencing and laboratory-built PCR; no standardised assay exists. The zoonotic question was raised and then answered: antibodies reactive to swine pasivirus were found in 15.6% of healthy people, but the rate had no relationship to eating pork or any other meat, and the authors concluded the reactivity is cross-reaction with some related picornavirus and that the virus is not zoonotic. No pasivirus was found in any of 396 human samples including children with diarrhoea and patients with suspected viral encephalitis.
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. CONFIRMED. "c1l2, at this time we have to assume a pig-sourced route is plausible given documented exposure in humans so need to put at L2" [ACCEPTED THE RE-READ, 2026-09-02. Eric: "i accept your pasivirus recommendations, sign them off." MOVED FROM HIS LEVEL 2 TO LEVEL 1. His words above stand exactly as recorded and the reasoning behind them was sound on the evidence he had -- he scored level 2 because human exposure appeared documented. Four papers placed on 2026-09-02 examined that exposure and it is not exposure. Arnold 2015 looked for the pig route four ways -- pork consumption, occupational pig contact, competition against swine sera, and comparison with hepatitis E serology as a known pig-to-human control -- found it in none, and concluded the human antibodies are "due to cross-reactivity with related antigen, perhaps a picornavirus, and that SpaV1 is not a zoonotic virus". Seroprevalence was associated only with hunting. Yu 2013 found no virus in any of 396 human samples, including 100 children with diarrhoea and 196 with suspected encephalitis. The same serological artefact he identified himself on chikungunya and Getah. Level was 2.]
Basis. Arnold 2015, whose title is the finding: "Antibodies to VP1 of swine pasivirus in humans WITHOUT evidence of transmission from a pig source". Its conclusion: "the seroreactivity frequently found in humans against SpaV1 is due to cross-reactivity with related antigen, perhaps a picornavirus, and that SpaV1 is not a zoonotic virus." Seroprevalence of 15.6% in healthy humans "was not significantly related to consumption of poultry, pork, pork liver, pork-liver sausage, small game meat, big game meat, and seafood", and the only independent association in multivariate analysis was HUNTING (adjusted OR 1.63). Competition experiments pre-incubating the plate with anti-pasivirus swine sera failed to inhibit the human sera. Yu 2013 supplies the other half: no virus was found in faeces from 100 healthy children or 100 children WITH DIARRHOEA, nor in cerebrospinal fluid from 196 children with suspected viral encephalitis, despite 63.5% seroprevalence.
How this level was decided
MOVED L2 -> L1 on the new evidence, AND THIS OVERTURNS THE BASIS OF ERIC'S OWN RULING rather than merely the machine answer. He confirmed level 2 on 2026-08-30: "at this time we have to assume a pig-sourced route is plausible given documented exposure in humans so need to put at L2." The documented exposure has now been examined and is not exposure. Arnold went looking for the pig route four ways -- association with pork consumption, association with pig contact, competition against swine sera, and comparison with hepatitis E serology as a known pig-to-human control -- and found it in none of them, concluding the antibodies are cross-reactivity with another picornavirus. Yu is the confirming negative: 396 human samples tested, including 100 children with diarrhoea and 196 with suspected encephalitis, and the virus was in none of them. That is the same artefact Eric identified himself on chikungunya and Getah -- serology reading positive on a relative. FLAGGED FOR HIS DECISION: this is his correction, and only he can withdraw it.
C2 Zoonotic impact
Severity of human illness caused by the agent
No human illness: Agent does not cause illness in people
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED AS NOT ASSESSABLE. "agreed, make this unexportable and candidate for KISS analysis." He has looked at the empty cell and ruled that it stays empty. NOTE: C8 was scored L1 by the pass, not left blank -- he is overriding that, not confirming it. The reworded C8 L1 asserts that no vaccine is needed, and for a virus whose role in swine disease ch36 36.10 says is "not known", even that is a claim the folder cannot carry. [ACCEPTED THE RE-READ, 2026-09-02, moving from NOT ASSESSABLE to level 1. Eric: "i accept your pasivirus recommendations." His ruling above was made on 2026-08-30 when the folder held only chapter 36 and there was nothing to reason from, and it was right then. Under C2 as rescoped on 2026-09-01, level 1 means pigs are not a source of human illness with this agent, which is what Arnold concludes outright and what Yu independently fails to contradict after testing children who were actually sick. An examined negative rather than an absence of evidence -- the distinction he drew on porcine_tottorivirus, now falling the other way because somebody looked. Level was null.]
Basis. Arnold 2015: "SpaV1 is not a zoonotic virus." Yu 2013: no virus detected in any of 396 human samples, including 100 children with diarrhoea and 196 with suspected viral encephalitis. No human illness attributable to swine pasivirus is described in any of the four papers.
How this level was decided
MOVED FROM NOT ASSESSED TO L1. Eric ruled this cell unassessable on 2026-08-30 -- "agreed, make this unexportable and candidate for KISS analysis" -- when the folder held only chapter 36 and there was nothing to reason from. There is now. Under C2 as rescoped on 2026-09-01, level 1 means pigs are not a source of human illness with this agent, and that is exactly what Arnold concludes and Yu independently fails to contradict after testing children who were actually sick. This is an examined negative rather than an absence of evidence, which is the distinction he drew on porcine_tottorivirus. FLAGGED FOR HIS DECISION.
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. "c3l1, as with many viruses in this family, we can assume the virus is reasonably widespread already"
Basis. Sauvage 2012: "SPaV1 was detected in fecal samples from 51/75 healthy piglets (68% of the animals) and in none of the 25 fecal samples from healthy sows, indicating that SPaV1 circulates through enteric infection of healthy piglets." Yu 2013, independently and on another continent: "A total of 36 (20.0%) fecal samples from 180 healthy piglets were positive for PLV-CHN by RT-PCR."
How this level was decided
Level 1 unchanged and now measured on two continents rather than inferred from the family. Eric confirmed it on the general ground that "as with many viruses in this family, we can assume the virus is reasonably widespread already", and the papers turn that assumption into a number: two thirds of piglets on a French industrial farm and a fifth of piglets in China, all of them healthy. Carried by the pigs themselves, so there is no introduction event to prevent.
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "l4, no generally validated method is available"
Basis. The four papers between them use high-throughput sequencing (Sauvage 2012, the founding description), 454 sequencing (Yu 2013), an in-house RT-PCR built from those genomes, and a research VP1 ELISA developed for the seroprevalence study (Arnold 2015). No commercial or standardised diagnostic assay for swine pasivirus is described anywhere, and Arnold's own ELISA is the paper that then shows the serology to be confounded by cross-reactivity.
How this level was decided
Level 4 unchanged, and Eric's ruling stands unaltered: "l4, no generally validated method is available." The new papers strengthen rather than move it. Identification still depends on sequencing or on primers designed by the discovering laboratory, which is the level 4 definition, and the one serological assay in the literature was shown by its own authors to be cross-reactive.
C5 Production cost
Financial impact on the infected farm's cost of production
Negligible: No measurable effect on 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 AS NOT ASSESSABLE. "agreed, make this unexportable and candidate for KISS analysis." He has looked at the empty cell and ruled that it stays empty. NOTE: C8 was scored L1 by the pass, not left blank -- he is overriding that, not confirming it. The reworded C8 L1 asserts that no vaccine is needed, and for a virus whose role in swine disease ch36 36.10 says is "not known", even that is a claim the folder cannot carry. [ACCEPTED THE RE-READ, 2026-09-02, moving from NOT ASSESSABLE to level 1. Sauvage 2012 found SPaV1 in 51 of 75 healthy piglets (68%) and none of 25 healthy sows on a French industrial farm; Yu 2013 found it in 20.0% of 180 healthy piglets in China. Two continents, no clinical sign, lesion or production effect reported by either. THE ARGUMENT AGAINST WAS PUT TO HIM AND HE OVERRODE IT: both studies SELECTED healthy animals, so nobody has yet compared a diarrhoeic pig, and finding a virus in healthy pigs shows it is common rather than that it is harmless. He accepted level 1 on the weight of two independent surveys. C7 moves with this cell. Level was null.]
Basis. Sauvage 2012: SPaV1 found in 68% of healthy piglets and 0% of healthy sows on an industrial farm, "indicating that SPaV1 circulates through enteric infection of healthy piglets". Yu 2013: 20.0% of 180 healthy piglets positive. Neither study reports any clinical sign, lesion or production effect. NOTE WHAT IS STILL MISSING: neither study compared healthy pigs against diarrhoeic pigs, so there is no case-control test of whether the virus is ever associated with disease.
How this level was decided
INFERRED, AND PROPOSED RATHER THAN ASSERTED -- Eric ruled this cell unassessable on 2026-08-30 and this is the machine offering him something to accept or reject. The case for level 1: two independent surveys on two continents found the virus in a large share of pigs that were all healthy, which is a great deal more than the register's other sequencing-only viruses have. The case for leaving it unassessable: both surveys SELECTED healthy animals, so finding the virus in them says the virus is common, not that it is harmless, and nobody has yet looked at a diarrhoeic pig. That is the distinction he drew on porcine_tottorivirus and restored on porcine_pegivirus -- absence of evidence rather than evidence of absence. FLAGGED FOR HIS DECISION.
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 at this time to think a diagnosis would have any effect on markets"
Basis. None of the four papers records a trade measure, movement control or consumer response. The virus has been known since 2012, has been found in France and China, and Arnold 2015 found human seroprevalence unrelated to pork consumption.
How this level was decided
Level 1 unchanged, and Eric's ruling stands: "c6l1, no reason at this time to think a diagnosis would have any effect on markets." It now passes the precedent test in SCORING/market_impact on observation rather than inference -- the virus has been published, surveyed and serologically investigated across two continents for over a decade with no market consequence, and the one plausible route to one, a pork-consumption link in people, was specifically tested for and not found.
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 AS NOT ASSESSABLE. "agreed, make this unexportable and candidate for KISS analysis." He has looked at the empty cell and ruled that it stays empty. NOTE: C8 was scored L1 by the pass, not left blank -- he is overriding that, not confirming it. The reworded C8 L1 asserts that no vaccine is needed, and for a virus whose role in swine disease ch36 36.10 says is "not known", even that is a claim the folder cannot carry. [ACCEPTED THE RE-READ, 2026-09-02, moving from NOT ASSESSABLE to level 1, together with C5 as flagged. Under the standing note SCORING/treatment_potential this is the no-imperative clause: no treatment is described in any of the five documents and no disease is described for one to address, with the virus found only in healthy pigs on two continents. The same caveat applies as on C5 -- the surveys selected healthy animals -- and he has ruled on it. Level was null.]
Basis. No treatment is described in any of the four papers, and no disease is described for a treatment to address. Sauvage 2012 and Yu 2013 both found the virus in healthy piglets only.
How this level was decided
INFERRED, AND PROPOSED RATHER THAN ASSERTED, on the same footing as C5 -- Eric ruled this cell unassessable and this is the machine offering him an answer. Under the standing note SCORING/treatment_potential, level 1 covers the case where there is no imperative to treat, and two surveys finding the virus only in healthy pigs is the beginning of a case that there is nothing to treat. It is not conclusive for the same reason C5 is not: nobody has looked at a sick pig. FLAGGED FOR HIS DECISION, and it should move with C5 rather than separately.
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, not currently any market or clinical imperative to develop a vaccine"
Basis. No vaccine is described in any of the four papers, and none of them describes a disease for one to prevent.
How this level was decided
Level 1 unchanged on the second clause, and Eric's ruling stands: "c8l1, not currently any market or clinical imperative to develop a vaccine." The new evidence supports it -- a virus found in two thirds of healthy piglets, shown not to be zoonotic, and never associated with disease, does not clinically or economically justify vaccinating.
Levels and evidence are generated from data/assignments/pasivirus_a.yml; the overview is authored in data/overviews/pasivirus_a.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.