Border Disease Virus in Swine
LEVELS: Highly unlikely; No human illness; Housing alone keeps it out; Laboratory-dependent; Minor; Negligible; Little; Available, or not needed
| Register id | border_disease_virus |
| Type | virus |
| Scientific name | Border disease virus |
| NCBI taxid | 358764 |
| Evidence | 1 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Border disease virus is a pestivirus of sheep that crosses into pigs regularly enough to matter. Like its bovine relative it does almost nothing to the pig after birth, but it is more consistently damaging to the fetus than BVDV is. Natural infection of sows has produced repeat breeding, mummified and stillborn piglets, and litters in which a high proportion of piglets are born with swollen eyelids, difficulty walking, and sometimes diarrhoea and joint inflammation; mortality in affected litters at two days of age ran from 30 to 70% in one report, with survivors slow-growing and prone to respiratory disease and diarrhoea. A persistently infected litter is the most likely source of infection for other pregnant sows in the herd. Historically some batches of classical swine fever and Aujeszky's disease vaccines were contaminated with a pestivirus, probably this one, because lamb kidney cells were used to make them, and the resulting disease looked like congenital classical swine fever. That resemblance is why border disease virus must be excluded whenever CSF is suspected in a free country. There is no treatment and essentially no interest in vaccinating pigs. Pestiviruses do not infect people.
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. ch35 35.1.1, which is the whole of the chapter's public health section and covers every entry in this batch: "There is no evidence of human infection with pestivirus, and they are not of any significance for public health or food safety."
How this level was decided
Level 1, stated outright for the whole genus.
C2 Zoonotic impact
Severity of human illness caused by the agent
No human illness: Agent does not cause illness in people
Basis. ch35 35.1.1, which is the whole of the chapter's public health section and covers every entry in this batch: "There is no evidence of human infection with pestivirus, and they are not of any significance for public health or food safety."
How this level was decided
Level 1. No human infection with pestiviruses is on record.
C3 Herd introduction risk
Effort required to keep the agent out of the herd
Housing alone keeps it out: Raising pigs indoors and off soil breaks the cycle, so no ongoing biosecurity program is needed and only outdoor herds stay exposed
Corrected by Eric from L3 Routine biosecurity keeps it out. Reason: MOVED L3 -> L2. His words: "L2, you would never cohouse sheep and pigs indoors, the control point is moving pigs indoors." THIS IS THE MALIGNANT CATARRHAL FEVER RULING APPLIED TO A SECOND SHEEP-SOURCE AGENT, and it sets the pattern for the ruminant pestiviruses: species separation is achieved by housing, not by a biosecurity programme, so it is level 2 rather than level 3.
Basis. ch35 35.4.3: "BDV is an important pathogen of sheep and occasionally goats, but interspecies transmission of BDV between sheep, cattle, and pigs occurs regularly." "The prolonged presence of a persistently infected litter of pigs is the most likely source of BVDV or BDV to susceptible, pregnant sows." "Pigs may also become infected through the use of modified live virus vaccines (CSF or Aujeszky's disease) or other biologicals contaminated with virus... some batches of CSF and Aujeszky's disease vaccines were contaminated by a pestivirus (probably BDV) because secondary lamb kidney cells were used to propagate the vaccine strain virus." 35.4.9: "To prevent BVDV or BDV infection in pigs, it is necessary to avoid direct or indirect contact with cattle or sheep."
How this level was decided
Level 3, on the same reasoning as BVDV and with one route sharper. The primary source is sheep and the answer is species separation, which is a management programme rather than a housing decision. The iatrogenic route is the one this entry owns: the historical outbreaks in the Netherlands and France came from CSF and Aujeszky's vaccines propagated on secondary lamb kidney cells, and the chapter's remedy is "systematic testing and treatment of bovine serum and of biological products used for the preparation of vaccines" -- supplier qualification, which is routine biosecurity. NOTE the second-generation route: once a persistently infected litter exists, it becomes the source for the rest of the herd, so an incursion propagates inside the unit. NOTE ON WHAT THIS ENTRY IS: the register unit is this ruminant pestivirus IN SWINE, so every cell is scored on what it does to pigs and how it gets into a pig herd, not on what it costs the cattle or sheep industry.
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. ch35 35.4.7: "rRT-PCR is the preferred method to detect either BVDV or BDV RNA... higher diagnostic sensitivity can be achieved using virus-species specific (i.e. BVDV and BDV) rRT-PCR assays." "In CSFV-free countries, BVDV and BDV must be considered in the differential diagnosis of CSFV and all CSFV suspect cases should be tested for BVDV and BDV." 35.4.5: BDV signs in piglets include "eyelid edema, locomotor disorders, and occasionally, diarrhea and arthritis", and in the historical contaminated-vaccine outbreaks the picture was "compatible with congenital CSFV infection".
How this level was decided
Level 2. Level 1 is out because the presentation actively misleads -- congenital tremor, eyelid oedema and reproductive loss in piglets reads as congenital classical swine fever, which is the chapter's whole reason for insisting the two be distinguished. But species-specific validated rRT-PCR exists and US laboratories are required to run it on every CSFV suspect, so confirmation is regional laboratory work once it is asked for.
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
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c5l2, agree with assessment"
Basis. ch35 35.4.5: "Natural infection of sows with BDV has been reported to result in reproductive signs, e.g. repeat breeding and mummified and stillborn pigs at farrowing. A high proportion of piglets from infected sows showed eyelid edema, locomotor disorders, and occasionally, diarrhea and arthritis. The mortality rate in affected litters at 2 days of age ranged from 30 to 70%." Leforban reported "an increase in perinatal mortality and eyelid edema, hyperthermia, and anemia in survivors during the second week of life. Slow growth rates, respiratory signs, and diarrhea developed in pigs; some of which died by 2 months of age." Against that, 35.4.1: "natural infection of pigs with BVDV or BDV is relatively uncommon", and 35.4.4: "BVDV and BDV are pathogenic for fetal pigs, but relatively nonpathogenic for pigs after birth."
How this level was decided
Level 2, and deliberately one level above bovine_viral_diarrhea_virus on the chapter's own distinction: "BDV seems to be more consistently pathogenic for fetuses, whereas variable results are obtained with BVDV viral strains." Where it does get into a breeding herd the litter losses are real -- 30 to 70% mortality by two days of age, with survivors growing slowly and some dying by two months. What holds it to level 2 rather than 3 is frequency: natural infection is uncommon, it needs sheep contact or a contaminated biological to start, and the losses fall on the litters exposed rather than persisting in the herd. Small and generally short-lived. FLAGGED: the chapter also notes that if a contaminated vaccine is the source "the initial impact is likely to be much greater", because every vaccinated sow is exposed at once.
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, seems to be little evidence that the market has or will respond to a diagnosis in pigs in the us"
Basis. Section 35.4 records no trade measure, movement control or consumer response for BDV in pigs. The historical contaminated-vaccine incidents in the Netherlands and France are described in clinical and regulatory terms only. BDV has been detected in pigs in many countries and genotypes BDV-1, BDV-4 and BDV-8 are reported in pigs.
How this level was decided
INFERRED. There is observed precedent, which is what SCORING/market_impact requires -- BDV has been diagnosed in pigs across many countries, including two documented vaccine-associated outbreaks in western Europe, and no market consequence is recorded from any of them. The response was to test biologicals, not to close a market. Level 1.
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. Chapter 35 describes no treatment for BDV in pigs. 35.4.4: "relatively nonpathogenic for pigs after birth". The damage described throughout section 35.4 is transplacental.
How this level was decided
Level 1 on the second clause. The harm is done in utero and the pig that could be treated is not the pig that is damaged -- postnatally infected pigs are essentially unaffected. Under the standing note SCORING/treatment_potential there is no imperative to treat.
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. ch35 35.4.8: "There is little interest in establishing protection by vaccination in pigs against BVDV or BDV. Consequently, there has been little done to study the immune response of pigs to these viruses."
How this level was decided
Level 1 on the second clause, stated by the chapter. NOTE the irony worth recording, because it is the mechanism rather than colour: the two best-documented BDV outbreaks in pigs were CAUSED by vaccines -- CSF and Aujeszky's products propagated on contaminated lamb kidney cells. What this entry needs is clean biologicals, not a vaccine of its own.
Levels and evidence are generated from data/assignments/border_disease_virus.yml; the overview is authored in data/overviews/border_disease_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.