Transmissible Gastroenteritis Virus
LEVELS: Highly unlikely; No human illness; Extraordinary biosecurity required; Laboratory-dependent; Moderate; Negligible; Substantial; Available but inconsistent
| Register id | transmissible_gastroenteritis_virus |
| Type | virus |
| Scientific name | Transmissible gastroenteritis virus |
| NCBI taxid | 11149 |
| Evidence | 3 document(s) |
| Assigned | 2026-09-06, against criteria version 093366e352a2 |
Overview
Transmissible gastroenteritis virus is a coronavirus first described in the United States in 1946 and, for forty years, the great killer of suckling pigs: vomiting, profuse watery diarrhoea, and mortality approaching 100% in piglets under two weeks old. It is much less of a problem now, and the reason is an accident of virus evolution. In the 1980s a naturally occurring deletion mutant of TGEV appeared that infects the respiratory tract instead of the gut — porcine respiratory coronavirus, scored separately on this register — and as it spread through pig populations it left them partly immune to TGEV. Sporadic outbreaks still occur in North America, Europe and Asia, in herds with and without that background immunity. The disease is clinically identical to porcine epidemic diarrhoea, so the two can only be separated in the laboratory. The picture has become more complicated as TGEV and PEDV co-circulate: recombinant viruses combining the two, known as swine enteric coronavirus, have been identified in Europe. Protection of piglets comes through the sow, so control is built on her immunity as much as on hygiene.
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, agree with assessment - disease has been around for at least a century with no evidence of human infection"
Basis. ch28 28.2.3, the public health section covering both TGEV and PRCV: "Pigs are the main species naturally susceptible to TGEV and PRCV. No infection of humans has been reported; however, novel canine-feline-swine spike recombinant alpha-CoVs (CCoV-HuPn-2018 and HuCCoV-Z19) with a CCoV-IIb backbone and closely related to TGEV have been identified recently in human pneumonia or febrile illness cases." SECOND SOURCE, puente_2026, which states it flatly: "TGEV and PRCV possess a well-established capacity to infect and seroconvert companion animals (dogs and cats) under experimental and field settings, YET THEY POSE NO ZOONOTIC RISK." shic_prcv: "PRCV is not zoonotic and infects only swine." PRCV "is a deletion mutant of the enteric coronavirus transmissible gastroenteritis virus (TGEV)".
How this level was decided
Level 1. No human infection with the agent itself has ever been reported. FLAGGED, because the chapter puts a genuine caveat in the same sentence and it should not be lost: recombinant alpha-coronaviruses closely related to TGEV, on a canine coronavirus backbone, have recently been recovered from people with pneumonia or febrile illness. Those are different viruses on a different backbone, and this cell scores this agent -- but the family demonstrably crosses into people, which is why the level is recorded as an examined negative on TGEV rather than as a statement about alpha-coronaviruses. Corroborated 2026-09-04, and more directly than ch28 managed: puente_2026 rates the zoonotic risk of every agent it covers and puts TGEV at none, in a review whose whole section 9.2 is about which porcine coronaviruses cross into people. The ch28 caveat about CCoV-HuPn-2018 and HuCCoV-Z19 still stands and is still about different viruses on a canine backbone. Level 1 confirmed.
C2 Zoonotic impact
Severity of human illness caused by the agent
No human illness: Agent does not cause illness in people
Basis. ch28 28.2.3, the public health section covering both TGEV and PRCV: "Pigs are the main species naturally susceptible to TGEV and PRCV. No infection of humans has been reported; however, novel canine-feline-swine spike recombinant alpha-CoVs (CCoV-HuPn-2018 and HuCCoV-Z19) with a CCoV-IIb backbone and closely related to TGEV have been identified recently in human pneumonia or febrile illness cases." shic_prcv: "PRCV is not zoonotic and infects only swine."
How this level was decided
Level 1. C2 grades illness acquired from pigs and no human infection with TGEV has been reported. NOTE FOR THE REPORT: this records that pigs are not a source of human TGEV, not that alpha-coronaviruses are harmless to people -- the chapter names TGEV-related recombinants recovered from human pneumonia cases in the same paragraph. Level 1 confirmed.
C3 Herd introduction risk
Effort required to keep the agent out of the herd
Extraordinary biosecurity required: Exclusion needs measures beyond the routine, such as air filtration, thermally treated feed and bedding, or repeated costly testing to find carriers, and may still fail
Corrected by Eric from L3 Routine biosecurity keeps it out. Reason: MOVED L3 -> L4. "c3l4, should be upgraded to be consistent with PED, SaD, etc" -- ruling on the flag the pass raised after puente_2026 was placed, which noted that the review treats globalised feed supply chains as a universal vulnerability for ESTABLISHED as well as novel enteric coronaviruses, and adds faecal persistence of over 100 days, possibly 18 months, plus a host range including dogs, cats, foxes, birds and insects. The pass had kept L3 on the observed history -- PEDV and PDCoV each went nationwide within a year and TGEV never has -- and he has overruled that on consistency: the four enteric coronaviruses face the same routes, so they take the same C3. ALL FOUR ARE NOW C3 LEVEL 4: TGEV, PEDV, PDCoV, SADS-CoV.
Basis. ch28 28.2.11.2: "swine to be introduced into a herd should originate from herds free of TGEV, should be serologically negative, and/or should be placed in isolation for 2-4 weeks before being added to the herd. After a TGEV outbreak, at least 4 weeks should elapse from the last sign of disease before introducing such animals into a clean herd. Feces from TGEV-infected swine carried on fomites can be a source of infection to other herds, requiring strict disinfection regimes, especially in cold months." 28.2.4.3: cats, dogs and foxes shed virus and starlings and houseflies have been proposed as mechanical vectors, and about 30% of Central European feral pigs are seropositive -- but "Overall, the role of non-porcine hosts and wildlife in spreading TGEV to contemporary swine production systems may be minimal." SECOND SOURCE, puente_2026: "Unlike PEDV, TGEV may persist in the intestinal tract or faeces for exceptionally long periods, over 100 days or even 18 months, although without conclusive evidence of persistent shedding of viable virus." On routes: "Indirect transmission is epidemiologically important and occurs via feed, water, trucks, clothing, footwear, and other contaminated fomites, particularly at low temperatures." "TGEV has a broader host range than PEDV; dogs, cats, and foxes can be infected and shed the virus for 1-2 weeks without clinical signs, potentially acting as sources of infection. Birds and insects may also serve as mechanical vectors." And in its comparative section: "live breeding stock movements and globalised feed supply chains represent major universal vulnerabilities facilitating the transboundary emergence of BOTH ESTABLISHED AND NOVEL enteric CoVs." shic_prcv: "PRCV may be highly stable when frozen, as is TGEV." "In PRCV endemic herds, virus can be isolated from pigs throughout the year. In other herds, PRCV temporarily disappears during summer months." "In highly swine-dense areas PRCV can spread several kilometers by aerosol."
How this level was decided
Level 3, the framework's worked example at that level, and the chapter writes the programme out: source from free herds, test serologically, isolate incoming stock for two to four weeks, wait four weeks after an outbreak, and disinfect against fomites. That is a routine biosecurity programme run continuously and capable of failing. What keeps it off level 5 is the chapter's own judgment on the wildlife question -- dogs, foxes, starlings, houseflies and feral pigs all appear, and it concludes their role in contemporary production is minimal. Contrast porcine_epidemic_diarrhea_virus and porcine_deltacoronavirus, both level 4, where feed and fomite routes have repeatedly defeated the routine programme at national scale. FLAGGED 2026-09-04 ON THE L3/L4 BOUNDARY, which is the one place the new review pushes back on a coronavirus cell. The level 3 answer above rests on ch28's judgment that the non-porcine hosts matter little in contemporary production, and that a routine programme -- source from free herds, serology, two to four weeks isolation, disinfection -- holds the virus. Puente does not contradict that directly, but it adds three things that all lean the other way: faecal persistence of over 100 days and possibly 18 months, a host range including dogs, cats, foxes, birds and insects as mechanical vectors, and an explicit statement that globalised feed supply chains are a universal vulnerability for ESTABLISHED as well as novel enteric coronaviruses. That last clause is the argument that put porcine_epidemic_diarrhea_virus and porcine_deltacoronavirus at level 4, and Puente applies it to the group rather than to those two. THE PASS KEEPS LEVEL 3 because the observed history still separates them: PEDV and PDCoV each went nationwide within a year despite routine biosecurity, and TGEV has not done that in the eighty years it has been here -- it declined instead, once PRCV spread. But the distinction now rests on outcome rather than on a difference in the routes, and you may read that as the same level 4 situation with a partially immune population masking it. YOUR CALL: leave at L3, or move to L4 alongside the other two enteric coronaviruses. Level 4 held, on Eric's ruling. The new source corroborates the mechanism behind it for the closely related deletion mutant: aerosol spread over kilometres in dense areas, and high stability when frozen, which is what puts feed and fomite routes in play. Nothing here that routine biosecurity closes.
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. ch28 28.2.9: "Because clinical signs and atrophic enteritis caused by TGEV are frequently observed in other enteric infections (rotavirus, PEDV, PDCoV, and coccidia), laboratory diagnosis of TGEV must be accomplished by one or more of the following procedures." 28.2.9.1: "Currently, real-time RT-PCR is commonly used for the detection of TGEV and differentiation of TGEV, PRCV, PDCoV, PEDV, and SADS-CoV; many singleplex and multiplex real-time RT-PCR assays have been developed for this purpose." 28.2.9.4: "TGEV serology is complicated by the fact that both TGEV and PRCV induce VN antibodies that are qualitatively and quantitatively similar", and "the accuracy of commercial ELISAs for differentiating US strains of PRCV and TGEV is low". shic_prcv: "Serological diagnosis of PRCV infection is frequently done using a blocking enzyme-linked immunosorbent assay (ELISA), which allows for the differentiation between PRCV and TGEV infection." "If enteric and respiratory disease are present concurrently, antigen detection techniques cannot differentiate PRCV and TGEV." "PRCV is generally considered to cause mild disease and is most important for its potential to confound diagnosis of TGEV."
How this level was decided
Level 2. Nothing points here clinically: watery diarrhoea with villous atrophy in a piglet is the shared presentation of five agents the chapter names, and endemic TGE in weaned pigs "may be confused with PEDV, E. coli, coccidia, or rotavirus infections". But the molecular route is solved -- validated multiplex real-time RT-PCR distinguishes all five swine coronaviruses and is run routinely by regional laboratories, with PRCV separated by primers targeting the S gene deletion. NOTE the serological trap, which is a limit on one method rather than on diagnosis: TGEV and PRCV induce indistinguishable neutralising antibodies and US commercial differentiating ELISAs perform poorly. Level 2 confirmed, and the new source names the specific difficulty this criterion should care about: PRCV confounds TGEV diagnosis, and where both enteric and respiratory disease are present antigen methods cannot tell them apart. A differentiating blocking ELISA and nucleic acid methods resolve it, so the assay exists and is validated -- but the confusion is real and is why a laboratory is needed rather than a clinical call.
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c5l3, agree with assessment. Old but significant and persistent disease in the US"
Basis. ch28 28.2.1: TGE is "characterized by vomiting, severe diarrhea, and high mortality (often 100%) in piglets less than 2 weeks of age". "The appearance and widespread prevalence of PRCV, a naturally occurring deletion mutant of TGEV, has lessened the clinical impact of TGE. However, sporadic outbreaks of severe diarrhea in piglets caused by TGEV in TGEV/PRCV seronegative and seropositive herds are still reported in North America, Europe, and Asia." 28.2.4.2: "Coincident with the widespread dissemination of PRCV, TGEV in Europe and the United States has declined to a low prevalence." 28.2.4.1: in endemically infected herds "mortality is usually under 10-20%".
How this level was decided
Level 3 under the standing note SCORING/production_cost_impact, which asks what this costs modern US production rather than what the disease can do. An epidemic in a naive breeding herd takes essentially the whole piglet crop, which reads as level 4 -- but the US herd is not naive. PRCV is widespread here and confers partial immunity, TGEV has fallen to low prevalence as a direct result, and what remains is sporadic outbreaks plus endemic TGE running at 10-20% mortality in the affected age window. Losses that measurably increase cost of production and are managed within normal operations. FLAGGED as a level 3 or 4 judgment: a genuinely seronegative unit meeting epidemic TGE loses everything born that month. Unchanged. The factsheet is about PRCV and reports no TGEV loss figures.
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, US sees local outbreaks every year but not large enough to have an effect on supply so correct answer is no effect on market"
Basis. Section 28.2 records no trade measure, movement control or consumer response. TGE has been recognised in US swine since 1946 and is endemic worldwide. NEW FACT, puente_2026, which does not change the level but should be on the record: "Unlike PED, TGE is a notifiable disease to the World Organisation for Animal Health, reflecting its potential health and economic impact."
How this level was decided
INFERRED. Under the standing note SCORING/market_impact this is an agent diagnosed in US herds for nearly eighty years with no historical market move on record -- the longest observed precedent of any entry in this batch. Level 1. Eric confirmed level 1 on 2026-09-02: "c6l1, US sees local outbreaks every year but not large enough to have an effect on supply so correct answer is no effect on market." RECORDED 2026-09-04, not raised as a gap because the ruling already covers it: puente_2026 notes TGE is WOAH-notifiable while PED is not. Notifiability is an international reporting obligation, and C6 asks what the market does; eighty years of US outbreaks with no market move is the observation, and the two are compatible. Unchanged.
C7 Treatment potential
Potential for treatment to improve outcomes
Substantial: No effective treatment (antimicrobial, antiviral, antiparasitic, herbal or other) is available, but outcomes would meaningfully improve if one existed
Basis. ch28 28.2.11.1: "No antiviral drugs have been developed for the treatment of TGEV." "The aim of treatments for TGEV is alleviation of the effects of starvation, dehydration, and acidosis. Parenteral treatment with fluids, electrolytes, and nutrients are effective in treating young pigs, but not practical under farm conditions. Oral therapy with balanced electrolyte or glucose solutions is contraindicated in young pigs." The one pathogen-directed result reported is a field trial in which piglets treated orally with human IFN-alpha "had significantly higher survival rates than placebo-treated piglets". SECOND SOURCE, puente_2026, which describes no antiviral for TGEV either and frames control entirely as biosecurity, feed mitigation and maternal immunity.
How this level was decided
Level 3. No pathogen-directed treatment exists, the chapter says so in its first sentence on the subject, and what is offered instead is warmth, water and supportive care that it then says is impractical on farm. The outcome a treatment would act on is unambiguous -- often 100% mortality in piglets under two weeks -- and the interferon trial shows the outcome IS movable. Both halves of level 3, and the same reading as porcine_epidemic_diarrhea_virus, the worked example at this level. Corroborated 2026-09-04. Level 3 unchanged. Unchanged. Level 3 stands on the standing note's neonate rule, which names TGEV explicitly.
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
Basis. ch28 28.2.11.3: "There are several licensed TGEV vaccines. All contain inactivated or live attenuated TGEV and are approved for use in pregnant or neonatal swine." Against that: "Only oral administration of live virulent virus to pregnant sows consistently stimulated high levels of protective immunity for the sow and persisting TGEV IgA antibodies in milk that passively protected piglets. The generally poor results for oral or intranasal vaccination of sows using attenuated TGEV strains may be attributed to the limited replication of most attenuated strains in the sows." "Parenteral TGEV vaccines induced even lower or inconsistent protection rates in TGEV/PRCV seronegative swine." And on active immunisation of piglets, "the presence of maternal antibodies in vaccinated pigs decreased or completely suppressed active antibody responses". shic_prcv: "PRCV has been investigated as a tool for vaccination against TGEV."
How this level was decided
Level 2, and the label is the chapter summarised: available but inconsistent. Several licensed products exist in the US for pregnant and neonatal pigs, so this is not level 3. But the chapter is unusually blunt about how well they work -- only live virulent virus fed to pregnant sows reliably protects, attenuated strains replicate too little to raise milk IgA, parenteral products leave the sow herself unprotected so she goes off milk, and maternal antibody suppresses the piglet vaccines. It states the dilemma directly: how to make a vaccine that stimulates gut IgA in the sow without causing disease in her piglets. Re-read 2026-09-04 against puente_2026, which adds nothing on TGEV vaccine products specifically -- its vaccine discussion is about the agents that have none -- so this cell continues to rest on ch28's unusually blunt account of how the licensed products perform. Level 2 unchanged. Level 2 held. Worth recording that natural PRCV infection has been examined as a TGEV-vaccinating tool, which is an unusual route to partial protection and is part of why TGEV immunity in the field is inconsistent.
Levels and evidence are generated from data/assignments/transmissible_gastroenteritis_virus.yml; the overview is authored in data/overviews/transmissible_gastroenteritis_virus.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.