Porcine Deltacoronavirus
LEVELS: Rarely occurs; Mild; Extraordinary biosecurity required; Laboratory-dependent; Moderate; Negligible; Substantial; Needed but not available
| Register id | porcine_deltacoronavirus |
| Type | virus |
| Scientific name | Porcine deltacoronavirus |
| NCBI taxid | 1586324 |
| Evidence | 2 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Porcine deltacoronavirus was first detected in US pigs in February 2014, and it causes acute watery diarrhoea and death in suckling pigs — the same picture as PED and TGE, but generally milder. Its RNA had been found retrospectively in Chinese surveillance samples from 2012, but nobody knew whether it caused disease until the American outbreaks were investigated. It has since been reported from Canada, Mexico, much of Asia and South America, and 244 outbreaks were recorded in US breeding herds between 2014 and 2024, affecting 186 sites. Two things set it apart from the other swine coronaviruses. Its host range is unusually broad — it has been shown experimentally to infect calves, poultry and rodents — and it is the only swine coronavirus with any evidence of infecting people: viral RNA was found in the blood of three children with mild fever in Haiti. That finding is a reason to watch it rather than a demonstrated public health problem, but it is why the virus attracts attention out of proportion to the diarrhoea it causes.
C1 Zoonotic potential
Likelihood of transmission from pigs to humans
Rarely occurs: Human infection from pigs is plausible but has only rarely been reported, and specific control points are not commonly implemented to prevent transmission to humans
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c1l2, agree with assessment (reluctant, but there is evidence that says human infection has occurred so will leave at L2)"
Basis. ch28 28.4.3, the whole public health section: "There is some evidence that PDCoV has zoonotic potential. PDCoV nucleic acids were identified in plasma samples of three children (6-7 years old) with mild symptoms (fever, cough, and/or abdominal pain) in Haiti in 2014-2015. However, there is currently no epidemiological or serological evidence that PDCoV plays a role in public health." 28.4.4 records demonstrated interspecies capability: PDCoV replicated in gnotobiotic calves, and poultry and rodent studies suggest cross-species transmission. SECOND SOURCE, puente_2026, WHICH DESCRIBES THE SAME HAITIAN EVENT IN STRONGER TERMS: "PDCoV has successfully crossed the species barrier under natural field conditions, with documented acute infections and viral isolation from children presenting with acute undifferentiated febrile illness in Haiti, alongside proven experimental pathogenicity in avian, bovine, rodent, and ferret models." On the mechanism: "This broad tropism is linked to aminopeptidase N (APN) as the primary viral receptor, a highly conserved molecule across species. Hence, in vitro infection via APN has been demonstrated for PDCoV in porcine, human, and avian cells." The review rates PDCoV and SADS-CoV as possessing "the highest empirical and theoretical zoonotic potential" of the group.
How this level was decided
RE-READ AND HELD AT L2 2026-09-04 AGAINST THE REWORDED LABELS. FLAG. The Haitian children are the only human detection and puente_2026 describes it as "documented acute infections and viral isolation" under "natural field conditions" -- but no route from a pig was established, and Puente is citing the same study, not a second one. Eric confirmed level 2 on 2026-09-02 ("there is evidence that says human infection has occurred"); under the reworded level 1 the question is whether that evidence attributes the infection to pigs, and it does not.
PREVIOUS ANSWER, kept because the evidence behind it has not changed, only the level boundary: Level 2, and this is the only entry in the batch with real evidence of human infection. Viral nucleic acid was found in the blood of three children, which is more than plausibility -- but it is three children, on one island, with no serological or epidemiological follow-up, and no route from a pig was established. Human infection from pigs is plausible and has been reported once, and no control point in pork production is directed at it: both clauses of level 2. FLAGGED: an agent that replicates in calves, chickens and rodents and has been recovered from human plasma is one to watch, and a second published detection would move this. Corroborated 2026-09-04, WITH ONE CAUTION THAT MATTERS AND MUST NOT BE LOST: puente_2026 is not an independent second detection. It cites the same Haitian study ch28 cites, reference 29 in its list, so the n is still three children on one island. What has changed is the strength of the description -- ch28 says "PDCoV nucleic acids were identified in plasma samples", puente_2026 says "documented acute infections and viral isolation", which is a materially stronger claim about the same event -- plus a mechanism, APN being conserved across species and demonstrably serving PDCoV entry in human cells. Eric confirmed level 2 on 2026-09-02 ("reluctant, but there is evidence that says human infection has occurred") and this strengthens rather than moves it. THE STANDING FLAG HOLDS: a genuinely second published detection would move this cell, and this is not one.
C2 Zoonotic impact
Severity of human illness caused by the agent
Mild: Human illness is usually mild and self-limiting, and serious disease occurs only rarely
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c2l2 is consistent with the c1 rating and evidence"
Basis. ch28 28.4.3: the three Haitian children had "mild symptoms (fever, cough, and/or abdominal pain)". No other human illness attributable to PDCoV is described, and "there is currently no epidemiological or serological evidence that PDCoV plays a role in public health". SECOND SOURCE, puente_2026, which characterises the human presentation as "mild acute undifferentiated febrile illness".
How this level was decided
INFERRED, and on a very small number. The only human clinical description in the literature is three children with fever, cough and abdominal pain who recovered -- usually mild, with serious disease not observed, which is level 2. FLAGGED as the thinnest C2 in the batch: n equals three, there is no case series and no severity distribution, so this is the shape of the one report rather than a characterisation of a disease. If Eric prefers, level 1 is defensible on the ground that no pig-attributable human illness has been demonstrated at all. Re-read 2026-09-04 and LEFT AT INFERRED DELIBERATELY. Puente describes the human illness as mild, which is the level 2 wording, but it is describing the same three Haitian children -- so the number of characterised human cases is still three and there is still no case series or severity distribution. A second source repeating one report does not convert an inference into a supported finding, and recording it as supported would overstate what the register holds. Eric confirmed level 2 on 2026-09-02: "c2l2 is consistent with the c1 rating and evidence."
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c3l4, agree with assessment"
Basis. ch28 28.4.4: "PDCoV transmission is primarily fecal-oral. Feces and/or vomitus and other contaminated fomites are major transmission sources of the virus." "Subsequent to its introduction, PDCoV spread nationwide in the United States and caused extensive mortality in suckling pigs" -- detected February 2014 in five Ohio farms and nationwide within the year. "a total of 244 PDCoV outbreaks were recorded, affecting 186 sites across 22 production systems in 16 states" between 2014 and 2024, with annual incidence from 0.44% to 4.28%. "viral RNA detected for up to 19-28 days in feces and up to 42 days in oral fluids." 28.4.10: "the implementation of biosecurity procedures capable of reducing PDCoV transmission via contaminated fomites is essential". SECOND SOURCE, puente_2026, AND IT CUTS BOTH WAYS. Against level 4: "faecal viral load is lower than in other porcine enteric CoVs, and within farm spread is slower, suggesting suboptimal adaptation to pigs", and "while PDCoV shares similar potential transmission pathways, direct epidemiological evidence regarding its environmental persistence, infectious dose and large-scale feedborne dissemination remains less extensive when compared to the massive empirical data available for PEDV". For it: shedding "detected for 19-28 days, exceeding clinical disease", convalescent carriers spreading farm to farm, and "live breeding stock movements and globalised feed supply chains represent major universal vulnerabilities".
How this level was decided
Level 4, scored with porcine_epidemic_diarrhea_virus and for the same demonstrated reason. The chapter prescribes fomite biosecurity, which is a routine programme and would be level 3 -- but the record is that routine biosecurity did not hold this virus. It went from five Ohio farms to nationwide inside a year, exactly as PEDV had the year before, and it has produced 244 outbreaks across 16 states in the decade since. Shedding runs to four weeks in faeces and six in oral fluids, so infected pigs move before anyone knows. Exclusion needs more than the routine and may still fail. FLAGGED as a level 3 or 4 judgment: the chapter does not name a feed route for PDCoV as it does for PEDV, so level 4 here rests on the observed national spread rather than on a named unblockable route. Re-read 2026-09-04. Eric confirmed level 4 on 2026-09-02 ("c3l4, agree with assessment"), so the cell is not re-opened, but the new source is recorded honestly because it weakens rather than strengthens the case: it says PDCoV's environmental persistence and feed-borne evidence are thinner than PEDV's, its faecal load lower and its within-farm spread slower. That is the same doubt the original flag raised -- level 4 here rests on the observed national spread rather than on a named unblockable route -- now stated by a source rather than only by the pass. The observed spread is unchanged: five Ohio farms to nationwide inside a year, 244 outbreaks across 16 states since.
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 28.4.6: "Clinical signs of PDCoV infection in suckling and older pigs are similar to, but milder than, those of PEDV and TGEV infections in pigs of the corresponding age." 28.4.8: "The diagnostic approaches described for TGEV and PEDV apply to PDCoV. Laboratory techniques should be used to differentiate PDCoV infection from PEDV, TGEV, SADS-CoV, and rotavirus diarrhea in pigs." RT-PCR targeting M or N genes, next-generation sequencing, IF, IHC, in situ hybridisation, "some multiplex real-time RT-PCR assays have been described for simultaneous detection and differentiation of PDCoV from other enteric CoVs", and "A colloid gold immunochromatographic assay strip using MAbs against PDCoV N protein was recently described for the rapid diagnosis of PDCoV under field conditions."
How this level was decided
Level 2. The presentation cannot distinguish it -- watery diarrhoea and vomiting in a suckling pig is shared with PEDV, TGEV, SADS-CoV and rotavirus, and PDCoV is the milder version of the same picture. But the molecular answer is routine: validated multiplex real-time RT-PCR separates all the swine enteric coronaviruses and is standard regional laboratory work, with a field lateral-flow strip now described as well. NOTE the serological caution: N-protein immunoassays cross-react with other coronaviruses, so S1 is the specific antigen.
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. ch28 28.4.6: "On seronegative breeding farms, morbidity can reach up to 100% in piglets. Based on field observations in US swine in 2014, PDCoV infection caused up to a 40% mortality in suckling pigs. Similarly, outbreaks of PDCoV diarrhea in breeding farms in China and Thailand resulted in 64-80% mortality among suckling piglets." Against that, 28.4.1: "the clinical impact and clinical severity of PDCoV were less than that of epidemic PEDV and TGEV", and 28.4.6: "The disease on breeding farms is self-limiting and stops when pregnant sows develop sufficient lactogenic immunity to protect their offspring." US incidence ran 0.44% to 4.28% of breeding sites per year. SECOND SOURCE, puente_2026: clinical signs and lesions are "nearly indistinguishable from PEDV or TGEV but typically milder, consistent with a lower overall virulence", and "In breeding farms, PDCoV infection is often self-limiting due to lactogenic immunity, and mortality is particularly lower when it acts as a single pathogen, though coinfections with PEDV or TGEV are common."
How this level was decided
Level 3. An affected farrowing house loses up to 40% of its suckling pigs, which is a real and measurable cost, and the US has recorded 244 such events in a decade. What holds it at level 3 rather than 4 is that the chapter says twice that this is the milder member of the group, and that the outbreak is self-limiting -- it stops when the sows become immune, without depopulation or a control programme. Losses that measurably increase cost of production and are managed within normal farm operations. Corroborated 2026-09-04 on both halves of the level 3 reasoning -- milder than the others, and self-limiting through lactogenic immunity. Puente adds one thing ch28 does not: coinfection with PEDV or TGEV is common, so the single-pathogen mortality figures understate what an affected farm actually sees. Level 3 unchanged.
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, disease well recognized and not associated with market impacts in the US"
Basis. Section 28.4 records no trade measure, movement control or consumer response. PDCoV has been in US swine since 2014 with 244 recorded outbreaks across 16 states, and is present in Canada, Korea, China, Thailand, Vietnam, Laos, Taiwan, Japan, Mexico and Peru.
How this level was decided
INFERRED. Under the standing note SCORING/market_impact this is an agent endemic and routinely diagnosed in US herds for a decade, through 244 documented outbreaks, with no market move on record. Level 1.
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 28.4.10: "There are no treatments or vaccines to control PDCoV infection." What is offered is symptomatic: "Preventive or therapeutic antibiotic therapy can be implemented if there is a concurrent infection with enteric bacterial pathogens. Symptomatic treatment of suckling pigs with diarrhea includes intraperitoneal administration of bicarbonate fluids and free access to water to alleviate acidosis and dehydration." 28.4.6: up to 40% mortality in suckling pigs in US field outbreaks and 64-80% in China and Thailand.
How this level was decided
Level 3. No pathogen-directed treatment exists anywhere -- the chapter says so in one sentence -- and the outcome one would act on is large and quantified: up to 40% of suckling pigs dead in US outbreaks, 64-80% in Asian ones. Both halves of level 3, and the same reading as transmissible_gastroenteritis_virus and porcine_epidemic_diarrhea_virus in the same chapter. Re-read 2026-09-04: puente_2026 describes no treatment for PDCoV either. Level 3 unchanged.
C8 Vaccine availability
Availability of effective vaccines or bacterins
Needed but not available: No effective vaccine is available in the US or has been developed, and the disease would justify vaccinating if one existed
Basis. ch28 28.4.10: "There are no treatments or vaccines to control PDCoV infection, but one study evaluated the efficacy of prime and boost vaccination via the intramuscular route. An inactivated, adjuvanted PDCoV vaccine induced high titers of maternal VN antibodies in the colostrum and milk of sows, even those previously unexposed to PDCoV. Protective maternal immunity was evidenced by a markedly reduced rate of diarrhea (12.9%) in piglets born to immunized sows compared with 100% diarrheic piglets in unimmunized counterparts." SECOND SOURCE, puente_2026, which names PDCoV among the agents whose absence of a vaccine is the problem: "the lack of commercially available, universally effective vaccines for newly emerging agents (such as SADS-CoV, SeCoV and PDCoV) leaves global herds immunologically naive and highly vulnerable to outbreaks."
How this level was decided
Level 3, and this is as clean an example of the level as the register holds. No vaccine is available in the US. The disease plainly justifies one, at up to 40% suckling mortality across 244 outbreaks. And the target is not merely tractable but demonstrated: an experimental inactivated vaccine raised protective milk antibody in previously unexposed sows and cut piglet diarrhoea from 100% to 12.9%. Needed but not available, with the proof of concept already published. Corroborated 2026-09-04, and by a source that states the gap as a gap rather than leaving it to be inferred from silence. Level 3 unchanged -- needed but not available, with the proof of concept already published.
Levels and evidence are generated from data/assignments/porcine_deltacoronavirus.yml; the overview is authored in data/overviews/porcine_deltacoronavirus.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.