Teschovirus bishikawa (Teschovirus B)
LEVELS: Highly unlikely; No human illness; Already in the herd; No validated assay; Negligible; Negligible; Little; Available, or not needed
| Register id | teschovirus_b |
| Type | virus |
| Scientific name | Teschovirus bishikawa |
| NCBI taxid | 3432769 |
| Evidence | 3 document(s) |
| Assigned | 2026-09-06, against criteria version 093366e352a2 |
Overview
Teschovirus B is a second teschovirus species, comprising three types, described from sequence data rather than from clinical investigation. It was separated from Teschovirus A on genetic grounds when the genus was reorganised, and the reference chapter records little more than that it has been described. Nothing distinguishes it clinically from the far better-characterised Teschovirus A: no distinct syndrome, no prevalence figure, no diagnostic assay of its own, no treatment and no vaccine. What is said about the genus applies — teschoviruses are ubiquitous in pigs, most infections are subclinical, and they are not infectious for people. It is on the register as a separate unit because the taxonomy now separates it, and because an entry that exists can be scored as unknown, while one that is absent looks like an oversight.
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. "c1l1, no evidence this is a zoonotic agent"
Basis. ch36 36.5.3, covering the genus: "PTVs are not infectious for humans." Section 36.5.2 records that Teschovirus bishikawa comprising TV-B1, TV-B2 and TV-B3 "has been described" from sequence data (Oba et al. 2018; Yang et al. 2018b, 2020b), with no separate public health statement. shic_2021_porcine_teschovirus: "PTV is not considered to be zoonotic." "Swine, including wild boar, are the only known hosts for PTV."
How this level was decided
INFERRED, by extension from the genus statement rather than from evidence about this species. The chapter public health section addresses PTVs collectively and says they are not infectious for humans; nothing suggests the B species differs. Level 1. The inference is small but it is an inference -- this species was described from sequence data and has not been studied for human infectivity. Level 1 confirmed.
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. "c2l1, no evidence this is a zoonotic agent"
Basis. No human disease is described for teschoviruses anywhere in ch36 36.5. shic_2021_porcine_teschovirus: "PTV is not considered to be zoonotic."
How this level was decided
INFERRED, on the same genus-level statement. C2 scores level 1 whenever the agent does not cause disease in people. 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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c3l1, best information at this time is that the virus is likely widespread and not causing significant disease"
Basis. ch36 36.5.1: "PTVs are ubiquitous, and no conventional pig herd has been shown to be free of infection." 36.5.4: transmission "is most frequently by the fecal-oral route", the viruses are "relatively stable", and infection is maintained in groups of weaned piglets. TV-B1 to TV-B3 were identified in pig faeces. shic_2021_porcine_teschovirus: "PTV cannot likely be excluded from farm environments."
How this level was decided
INFERRED. The chapter establishes that teschoviruses as a group are ubiquitous, faecal-orally transmitted and maintained within herds, and the B species was found by sequencing pig faeces, which is consistent with the same pattern. Already carried by the pigs, so no introduction event to prevent. Level 1. The inference is from the genus to a species the chapter does not survey. Level 1 confirmed on the same statement as Teschovirus A.
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, I'm not aware there are generally validated tests available so we will make it L4"
Basis. ch36 36.5.2 records Teschovirus bishikawa and its three types as described on "serological and/or molecular sequence data". Every assay named in 36.5.8.1 -- virus neutralisation, complement fixation, immunofluorescence, and the RT-PCR assays of Palmquist, Zell, Cano-Gomez, Chiu and Krumbholz -- was developed against Teschovirus asilesi, not this species. shic_2021_porcine_teschovirus: "Until recently, all PTVs belonged to the species Teschovirus A; however, a second species, Teschovirus B, has now been described." "There are at least 13 distinct PTV serotypes. New PTVs are being frequently detected."
How this level was decided
MOVED L3 -> L4 under the rewording, and the previous justification had already argued itself most of the way there: it noted that a species distinguished by sequence would be identified by sequencing, then stopped short of level 4 on the ground that "a species-specific RT-PCR is straightforward to design from a published genome". That is the ease-of-design assumption the rewording rejects. No assay of known reliability exists for the B species. Level 4. Level 4 held. Every assay the factsheet describes was developed for PTV as the older single species, and Teschovirus B is a recent split with nothing validated against it specifically. A moving target with new serotypes frequently detected is the situation the 2026-08-29 rework put at level 4 -- an assay of unknown accuracy does not give a trustworthy answer.
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: "c5l1, little evidence to suggest it causes any clinical disease"
Basis. ch36 36.5.2 records the existence of Teschovirus bishikawa and its three types from sequence and serological data. Nowhere does the chapter attribute any clinical syndrome, lesion, morbidity, mortality or economic loss to the B species specifically. The clinical section 36.5.6 and the lesions section 36.5.7 describe PTV, which is Teschovirus asilesi. shic_2021_porcine_teschovirus: "Most infections are subclinical, but some strains cause severe central nervous system disease (polioencephalomyelitis) with high mortality. Why some PTVs cause polioencephalomyelitis and others circulate inapparently is not known."
How this level was decided
NOT ASSESSED. No level assigned. C5 asks for the magnitude of a financial effect, and every level from 1 to 4 is a claim about how much a disease costs -- including level 1, which asserts no measurable effect. The folder does not establish that this species causes disease at all, so it cannot support any of them. Inferring level 1 from the genus would be inventing a finding: the other teschoviruses are mostly subclinical, but Teschen disease is also a teschovirus. THIS MAKES THE ENTRY UNEXPORTABLE, which is the correct signal for a virus known only from sequence. LEVEL 1 ON ERIC'S RULING of 2026-08-29, "c5l1, little evidence to suggest it causes any clinical disease". The factsheet is consistent: it cannot separate Teschovirus B from Teschovirus A on clinical impact and says outright that nobody knows why some teschoviruses are virulent and others are not. CORRECTION TO THIS PASS, 2026-09-06: first described as null, which was reading the stored level instead of the resolved one.
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, little evidence to suggest the market would react to a diagnosis"
Basis. Nothing in ch36 records a trade measure, movement control or consumer response associated with the B species, which is known from faecal sequencing in Japan and China. shic_2021_porcine_teschovirus: "PTV is not currently an OIE-listed disease. There are no restrictions for importation of animals from countries or zones affected by PTV."
How this level was decided
INFERRED. A virus described from sequence data, with no attributed disease and no regulatory status, has no mechanism to move pork supply or demand. Level 1 rests on the absence of any pathway rather than on evidence about the agent, which is a weaker footing than usual but is a claim the folder can carry. Level 1 held.
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, no clinical imperative to develop a treatment"
Basis. ch36 36.5.10: "control measures for PTV depend on prevention rather than treatment. Potential antiviral chemotherapeutics for porcine enteric picornaviruses have received little attention." No disease is attributed to the B species. shic_2021_porcine_teschovirus: "There is no treatment for pigs infected with PTV."
How this level was decided
INFERRED, and weakly. C7 asks how much better outcomes would be with a treatment, and no adverse outcome has been attributed to this species, so there is nothing to improve -- the second clause of level 1. NOTE: this rests on the same silence that made C5 unassessable. It is scored where C5 was not because level 1 here follows from there being no known disease, whereas every C5 level would have required asserting a cost. Level 1 held.
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, no clinical imperative to develop a vaccine"
Basis. No vaccine is described for the B species. ch36 36.5.10 records Teschen disease vaccines and explains why no SMEDI vaccine exists, both in relation to Teschovirus asilesi. shic_2021_porcine_teschovirus: "no PTV vaccines are currently available."
How this level was decided
INFERRED. No vaccine exists and none is warranted for a virus with no attributed disease. Level 1 on the second clause of the reworded criterion. Level 1 held. The contrast with teschovirus_a at level 3 is deliberate and is the standing note applied: the demonstrated gap is against Teschen disease, which is a Teschovirus A syndrome. For Teschovirus B, whose clinical significance is undescribed, there is no established disease to warrant a vaccine.
Levels and evidence are generated from data/assignments/teschovirus_b.yml; the overview is authored in data/overviews/teschovirus_b.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.