Swinepox Virus
LEVELS: Highly unlikely; No human illness; Routine biosecurity keeps it out; Routine; Minor; Negligible; Little; Available, or not needed
| Register id | swinepox_virus |
| Type | virus |
| Scientific name | Swinepox virus |
| NCBI taxid | 10276 |
| Evidence | 2 document(s) |
| Assigned | 2026-09-06, against criteria version 093366e352a2 |
Overview
Swinepox virus is the only poxvirus that infects pigs, and pigs are the only species it infects — attempts to infect rabbits, guinea pigs and non-swine cell cultures have all failed. It occurs sporadically in domestic pigs worldwide, including North America, where it was first reported in 1929. The main route between pigs is the bite of the pig louse, which is why swinepox tracks sanitation and ectoparasite control; stable flies can carry it mechanically, and it also passes by direct contact with nasal and oral secretions, through shed scabs meeting skin abrasions, and occasionally across the placenta. Disease is most severe in piglets and pigs under three or four months, where morbidity may be high but mortality is very low; in adults it is mild and self- limiting. The lesions run a characteristic course over about a week — macule, papule, umbilicated pustule, crust — on the flanks, belly and ears, and recovered pigs are immune. Congenitally infected piglets may be stillborn or die within days, but such cases are sporadic. The reason the diagnosis matters more than the disease is the differential: pox lesions have to be told apart from foot-and-mouth disease and vesicular exanthema, among others, which is done by histopathology or a specific qPCR. There is no treatment beyond antibiotics for secondary skin infection, and no vaccine has been developed because the economic impact is low and sporadic. It is not zoonotic.
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. ch40 40.3, the whole Public Health section in one sentence: "SWINEPOX VIRUS IS NOT A ZOONOTIC VIRUS AND THERE IS NO EVIDENCE THAT SWPV IS A THREAT TO PUBLIC HEALTH." 40.1: "swine (SUS SCROFA) IS THE ONLY SUSCEPTIBLE SPECIES." 40.4 records the experimental confirmation: "Under experimental conditions, SWPV FAILED TO CAUSE LESIONS IN THE SCARIFIED SKIN OF RABBITS AND GUINEA PIGS AND WAS UNABLE TO INFECT KIDNEY CELLS FROM CATTLE AND RABBITS", and 40.2 that attempts to grow it in non-swine cell cultures have been unsuccessful. shic_swpv: "Swine are the only natural hosts for SwPV. Humans are not affected; however, SwPV in pigs cannot be easily distinguished from vaccinia virus (VV), which is zoonotic."
How this level was decided
Level 1, and it is an EXAMINED negative rather than a silence, which is worth stating because most level 1 cells here are not. Somebody scarified rabbit and guinea pig skin with this virus and nothing grew; it will not replicate in non-swine cells at all. The host restriction is a laboratory finding, not an absence of reports. NOTE THE ONE HISTORICAL CURIOSITY IN THE CHAPTER, which runs the OTHER WAY and should not be misread: during the smallpox campaign, vaccinia from HUMAN vaccination spread TO pigs and caused pox lesions. That is people infecting pigs with a different virus. Level 1 confirmed. The vaccinia caveat is a DIAGNOSTIC confusion, not a transmission route -- it belongs to C4, and the factsheet answers it there with a differentiating PCR.
C2 Zoonotic impact
Severity of human illness caused by the agent
No human illness: Agent does not cause illness in people
Basis. ch40 40.3: "Swinepox virus is not a zoonotic virus and there is NO EVIDENCE that SWPV is a threat to public health." shic_swpv: "Humans are not affected."
How this level was decided
Level 1, following C1. Pigs are not a source of human illness with this agent because it does not infect people, which is one of the two reasons the level 1 label actually names. Level 1 confirmed.
C3 Herd introduction risk
Effort required to keep the agent out of the herd
Routine biosecurity keeps it out: Quarantine of incoming stock, transport and fomite control, cleaning and disinfection, and the usual monitoring reliably exclude it
Basis. ch40 40.4: "SWPV IS ASSUMED TO BE MOST COMMONLY TRANSMITTED BETWEEN SWINE BY THE BITE OF THE PIG LOUSE, HAEMATOPINUS SUIS, whose prevalence in pig populations is variable and geographically dependent, e.g., 96.1-100% in Kenya AND 2.5% IN GERMANY. POOR SANITATION CAN INCREASE SUSCEPTIBILITY TO LICE INFESTATION. Biting insects such as the stable fly have also been implicated as MECHANICAL VECTORS... SWPV may also be horizontally transmitted between pigs by DIRECT CONTACT of nasal and oral secretions and by DESQUAMATED SCABS encountering skin abrasions. VERTICAL (TRANSPLACENTAL) SWPV TRANSMISSION IS POSSIBLE." 40.10: "THE BEST STRATEGIES FOR PREVENTION OF SWINEPOX ARE GOOD ANIMAL HUSBANDRY, INCLUDING ECTOPARASITE CONTROL AND ISOLATION OF INFECTED ANIMALS in the event of an outbreak with concomitant improvements in sanitation." 40.1: swinepox "OCCURS SPORADICALLY in domestic pigs worldwide and is GENERALLY ASSOCIATED WITH POOR SANITATION." shic_swpv: "SwPV is mechanically transmitted by the hog louse, Hematopinus suis, and possibly by biting flies (Stomoxys calcitrans) and black flies (Simuliidae). Pig-to-pig transmission can also occur." "SwPV is associated with poor sanitation, making cleaning and disinfection an important preventive measure. Swine can be treated with anti-parasitic drugs or insecticides to reduce lice infestation." "SwPV can persist in the environment, even in dry conditions."
How this level was decided
Level 3, and it is scored to sit consistently with its own vector. The dominant route is the bite of the pig louse, and you confirmed haematopinus_suis at C3 level 3 earlier this evening -- an agent whose main vehicle is excluded by a routine programme is excluded by the same programme. The chapter names that programme: ectoparasite control, isolation of affected animals, sanitation. NOT LEVEL 1: swinepox is sporadic rather than universal, and louse prevalence varies from 2.5% of German herds to nearly all Kenyan ones, so this is plainly something a herd can be without. NOT LEVEL 4: nothing here needs filtration, treated feed or carrier testing -- it needs a pour-on and a clean pen. Level 3 confirmed, and the control list is the routine one almost verbatim: louse control with anti-parasitic drugs, insecticides, cleaning and disinfection, sanitation. Note the louse vector is itself a register entry that Eric ruled completely eradicable and excludable without a vaccine, which is consistent with routine rather than extraordinary effort here.
C4 Detection difficulty
Difficulty of recognizing and confirming infection
Routine: The disease would be suspected from clinical signs, history and epidemiology in normal practice, and confirmed by tests that local or regional laboratories run routinely
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c4l1, somewhere between l1 and l2. For someone that has seen the disease before, there are few other clinical differentials and the lab test (simple histopathology) is widely available so is an l1. Only excuse for others is that the disease seems to be so infrequent anymore that many vets have never seen it before."
Basis. ch40 40.8: "A PRESUMPTIVE DIAGNOSIS OF SWINEPOX IS BASED ON THE OBSERVATION OF TYPICAL POX LESIONS ON THE SKIN OF AFFECTED ANIMALS, ESPECIALLY UNDER POOR SANITARY CONDITIONS AND THE PRESENCE OF LICE and/or fly infestations... EXAMINATION OF SKIN LESIONS BY HISTOPATHOLOGY MAY CONFIRM THE INVOLVEMENT OF SWPV DUE TO PATHOGNOMONIC CHANGES IN EPIDERMIS such as ballooning degeneration of keratinocytes containing cytoplasmic eosinophilic inclusion bodies and a vacuolated nucleus... SWPV-SPECIFIC QUANTITATIVE POLYMERASE CHAIN REACTION (qPCR) ASSAYS PROVIDE A RAPID AND SENSITIVE METHOD TO RELIABLY DETECT SWPV DNA IN SAMPLES." 40.6 describes a lesion sequence that is its own signature: macule to papule to umbilicated pustule to crust, over about a week, on the flanks, ventral abdomen and ears. THE DIFFERENTIAL IS LONG AND SERIOUS: "foot-and-mouth disease virus, vesicular exanthema of swine virus, vesicular stomatitis virus, swine vesicular disease virus, Seneca Valley virus, and skin lesions associated with classical swine fever virus, erysipelas, pityriasis rosea..." shic_swpv: "Classic pox disease is characterized by formation of macules, followed by progression to papules, vesicles, pustules, and crusts." "SwPV may be cultivated in a range of host cells in vitro. Immunofluorescence and immunohistochemistry are used to detect SwPV antigens in infected epithelium. A polymerase chain reaction (PCR) assay has been developed for rapid detection and differentiation from the clinically similar and zoonotic vaccinia virus (VV)."
How this level was decided
INFERRED. Level 1 -- the disease would be suspected from clinical signs and history in normal practice, and confirmed by tests a regional laboratory runs routinely. Umbilicated pox lesions on a young pig in a lousy, dirty pen is a picture that names itself, the epidemiological context is part of the diagnosis, and histopathology is PATHOGNOMONIC, which is a word the chapter uses and which few entries in this register earn. Scored level with swine erysipelas for the same reason -- a near-pathognomonic skin lesion. THE ARGUMENT FOR LEVEL 2 IS THE DIFFERENTIAL, and it is not trivial: five vesicular diseases sit on that list, four of them foreign animal diseases, and a vesicle on a pig is a regulatory event before it is a diagnosis. If you read the vesicular differential as meaning the presentation does not point specifically, this is level 2. Level 1 confirmed. The lesion sequence is pathognomonic enough to suspect clinically, the virus cultivates readily, and a PCR exists specifically to separate it from vaccinia -- suspected clinically, confirmed locally.
C5 Production cost
Financial impact on the infected farm's cost of production
Minor: Small and generally short-lived losses with little effect on overall cost of production
Basis. ch40 40.10 gives the chapter's own economic verdict in passing: "NO VACCINE AGAINST SWPV HAS BEEN DEVELOPED THUS FAR GIVEN THAT SWINEPOX HAS A RELATIVELY LOW AND SPORADIC ECONOMIC IMPACT." 40.6 on what it does: "The disease is MOST SEVERE IN PIGLETS AND YOUNG PIGS <3-4 MONTHS of age. In affected piglets, MORBIDITY MAY BE HIGH, BUT MORTALITY IS USUALLY VERY LOW. In contrast, SWPV INFECTION IN ADULTS IS USUALLY MILD AND SELF-LIMITING... The lesions usually become umbilicated and are replaced by crusts IN APPROXIMATELY 1 WEEK." The exception: "In CONGENITAL INFECTIONS, THE AFFECTED PIGLETS MAY BE STILLBORN OR DIE WITHIN A FEW DAYS AFTER BIRTH", though these are described as sporadic cases. shic_swpv: "Morbidity can be very high in pigs up to four months of age. Mortality is generally low (<5%), although congenital infections are frequently fatal." "Disease primarily occurs in pigs up to four months of age, while infection in adults is typically self-limiting." "Secondary bacterial infections can also occur."
How this level was decided
Level 2 -- small and generally short-lived losses with little effect on overall cost of production, and the chapter states it: relatively low and sporadic economic impact. High morbidity with very low mortality, resolving in a week, is the definition of a short-lived loss. NOT LEVEL 1, because the losses are real where they occur -- crusted growing pigs, congenital litters that die, and the delayed recovery the chapter notes when secondary bacterial and parasitic infections follow. Scored level with the colibacilloses and porcine rotaviruses. Level 2 confirmed -- high morbidity but under 5% mortality and self-limiting in adults.
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, old disease, no market impact"
Basis. Swinepox occurs sporadically in domestic pigs worldwide including North America, first reported there in 1929 (ch40 40.4), and no trade measure, movement restriction or consumer response is recorded anywhere in the chapter.
How this level was decided
INFERRED. Level 1 under the standing note SCORING/market_impact: an agent present and diagnosed in US pigs for nearly a century with no market move ever observed. The one thing that could conceivably move a market is the vesicular differential rather than the disease -- a pox lesion investigated as possible foot-and-mouth disease -- and that is an event about the suspicion, not about swinepox. 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
Basis. ch40 40.10: "ALTHOUGH THERE IS NO SPECIFIC TREATMENT FOR SWINEPOX, ANTIBIOTIC TREATMENT IS RECOMMENDED TO CONTROL SECONDARY BACTERIAL SKIN INFECTIONS." On outcome without one, 40.6: lesions "are replaced by crusts in approximately 1 week. Eventually crusts fall off, leaving spots on the skin", infection in adults is "usually MILD AND SELF-LIMITING", and 40.9: "CONVALESCENT PIGS ARE RESISTANT TO SWPV CHALLENGE, indicating that SWPV infection induces protective immunity." shic_swpv: "Swine can be treated with anti-parasitic drugs or insecticides to reduce lice infestation." "infection in adults is typically self-limiting." "Recovered animals are immune to reinfection."
How this level was decided
Level 1 on the second clause of the label -- animals recover acceptably without pathogen-directed treatment -- and the treatable part of the disease is treated. This is the same structure as porcine rotaviruses at this level: no antiviral exists and none is the point, because what harms the pig is the secondary bacterial infection in the broken skin, and that has antibiotics. NOT SCORED LEVEL 1 ON THE GROUND THAT NOBODY TREATS POXVIRUSES, which your 2026-09-02 rule forbids; the ground is that the lesions crust over in a week and the pig is then immune. Level 1 confirmed on both halves of the clause: animals recover acceptably without treatment, and the actionable intervention -- treating the louse vector -- already has labelled products.
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
Basis. ch40 40.10, which states the absence and the reason in a single sentence: "NO VACCINE AGAINST SWPV HAS BEEN DEVELOPED THUS FAR GIVEN THAT SWINEPOX HAS A RELATIVELY LOW AND SPORADIC ECONOMIC IMPACT." 40.9 adds that natural infection already does the job: "CONVALESCENT PIGS ARE RESISTANT TO SWPV CHALLENGE", and maternal antibody protects suckling piglets, though "passive protection may not be adequate" in every case. shic_swpv: "There are currently no available vaccines against SwPV." "Recovered animals are immune to reinfection." "To reduce congenital infections, which are often fatal, further research is required."
How this level was decided
Level 1 on the "not needed" clause, and THIS IS THE CLEANEST INSTANCE OF THAT CLAUSE IN THE WHOLE REGISTER. Under the standing note SCORING/vaccine_availability the operative test is your own recurring phrase, no clinical or market imperative to develop a vaccine, and here the chapter does not merely permit that inference -- it makes the argument itself, in the causal direction the criterion needs: no vaccine exists BECAUSE the economic impact is low and sporadic. That is the opposite of a gap. Level 3 would read as a funding recommendation, and nobody is recommending it. Level 1 held. No clinical or market imperative: mortality under 5%, self-limiting in adults, solid natural immunity after recovery, and the disease is controlled by attacking its louse vector -- the eradicable-and-excludable route in the standing note, the same one Eric used on Sarcoptes and Haematopinus.
Levels and evidence are generated from data/assignments/swinepox_virus.yml; the overview is authored in data/overviews/swinepox_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.