Linda Virus
LEVELS: Highly unlikely; No human illness; Routine biosecurity keeps it out; Reference or research laboratory required; Minor; Negligible; Little; Available, or not needed
| Register id | linda_virus |
| Type | virus |
| Scientific name | Linda virus |
| NCBI taxid | 2014960 |
| Evidence | 3 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Linda virus — the name is an acronym for lateral-shaking inducing neurodegenerative agent — is a pestivirus identified in Austria in 2015 from piglets with congenital tremor, and it has never been reported anywhere else. The first outbreak, in Styria, involved piglets shaking so severely they could not suckle, with raised preweaning mortality; a second, in Carinthia in 2022, began with abortions, stillbirths, mummified piglets and neonatal deaths, followed by congenital tremor in twenty litters. As with the other pestiviruses associated with congenital tremor, the damage is prenatal: infecting immunocompetent piglets after birth produces a brief viraemia and rapid seroconversion with no clinical signs and no lesions. It circulates at low prevalence — around 0.7% of Austrian farms — and interestingly one farm carrying a related strain never showed congenital tremor at all. It has not spread: a survey of 200 wild boar in the German region bordering Austria found no antibody at all, showing it has not established in the central European wild boar population the way atypical porcine pestivirus has. Studying it is awkward — no serological test existed until researchers built a chimeric virus to make one. There is no treatment, no vaccine and no control programme. 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." THE WHOLE OF THE EVIDENCE FOR THIS ENTRY IS THREE SENTENCES IN THE CHAPTER OVERVIEW. ch35 35.1: "Another pestivirus, provisionally called Linda (lateral-shaking inducing neurodegenerative agent) virus, was identified in Austria in 2015 from piglets with congenital tremor. Linda virus has not been reported outside Austria but appears to circulate at a low prevalence in the Austrian pig population. The natural hosts of Bungowannah virus and Linda virus remain to be determined." And: "Linda virus, a cause of piglet congenital tremor and pre-weaning mortality, likewise has a limited known geographical distribution (Austria)." Linda has no section of its own in chapter 35.
How this level was decided
Level 1. Unusually for an entry this thin, this cell is properly supported: the chapter's public health statement is made for the whole genus Pestivirus, not for individual species, so it covers Linda virus directly.
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." THE WHOLE OF THE EVIDENCE FOR THIS ENTRY IS THREE SENTENCES IN THE CHAPTER OVERVIEW. ch35 35.1: "Another pestivirus, provisionally called Linda (lateral-shaking inducing neurodegenerative agent) virus, was identified in Austria in 2015 from piglets with congenital tremor. Linda virus has not been reported outside Austria but appears to circulate at a low prevalence in the Austrian pig population. The natural hosts of Bungowannah virus and Linda virus remain to be determined." And: "Linda virus, a cause of piglet congenital tremor and pre-weaning mortality, likewise has a limited known geographical distribution (Austria)." Linda has no section of its own in chapter 35.
How this level was decided
Level 1, on the same genus-wide statement. No human infection with any pestivirus is on record.
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. Schulz 2024: 200 wild boar collected in southern Germany, the region bordering Austria, ALL tested seronegative for LindaV by neutralisation. "The absence of neutralizing antibodies in the analyzed sample pool indicates that LindaV is not present at higher prevalence (> 1.5%) in the monitored population." "our results demonstrate that LindaV did not become highly prevalent in the central European wild boar population, as it has been the case for APPeV." Hawko 2022: "epidemiological studies performed in Germany and Switzerland regarding the prevalence of LindaV RNA in porcine serum samples tested negative", and "Linda V seems to be confined in Austria". Critically for the carrier question: "infections of immunocompetent piglets with LindaV result in temporary viremia with a QUICK SEROCONVERSION, although the virus persisted in the tonsil and lymphoid organs and was still detectable after 21 days."
How this level was decided
Level 3, and the two new papers convert this from the weakest cell in the batch to a supported one. The assessment had scored L3 while flagging that it could be L4 if Linda produced the immunotolerant antibody-negative carriers its relatives do -- that is exactly what makes bungowannah_virus L4. Both halves of the flag are now answered. There is no wildlife reservoir: 200 wild boar next door to the only affected country were all seronegative, and serum surveys in Germany and Switzerland found nothing. And postnatally infected piglets seroconvert QUICKLY, so serological screening of incoming stock works on them, unlike Bungowannah where a fifth of boars carried viral RNA in semen despite high neutralising titres. Source is other pig herds, and quarantine plus screening closes it. NOTE THE ONE THING STILL UNTESTED, because it is the same gap in a narrower place: the challenge study was postnatal, and whether a CONGENITALLY infected piglet becomes an immunotolerant lifelong shedder -- the pattern for CSFV, BVDV, BDV and Bungowannah -- is not addressed by either paper.
C4 Detection difficulty
Difficulty of recognizing and confirming infection
Reference or research laboratory required: A validated assay exists, but only at a national reference or research laboratory rather than at local or regional level
Basis. Hawko 2022: "Based on the reported literature and the detection method mostly based on LindaV-Specific RT-qPCR Assay, Linda V seems to be confined in Austria." Its Table 3 records the diagnostic methods used in both published outbreak investigations as RT-PCR and IHC, the latter "using pestivirus E2-specific monoclonal antibody". Schulz 2024, on serology: no assay existed, so "To establish a serological test system, we made use of the interchangeability of the surface glycoproteins and created a chimeric pestivirus using Bungowannah virus as synthetic backbone. The E1 and E2 glycoproteins were replaced by the heterologous E1 and E2 of LindaV resulting in the chimera BV_E1E2_LV."
How this level was decided
MOVED L4 -> L3 on 2026-09-02, on the two new papers. The assessment had scored level 4 by analogy with Bungowannah -- no validated assay, identification depending on sequencing -- and that is now wrong. A LindaV-specific RT-qPCR exists, it is described as THE detection method for the virus, and it has carried at least four published studies including two national serum surveys and both Austrian outbreak investigations, with IHC on a pestivirus E2 monoclonal alongside it. That is a validated assay, which rules out level 4. It sits at level 3 rather than 2 because everything about it is reference and research work: the assays live in Austrian and German institutes, no US laboratory holds them, and serology did not exist at all until Schulz built a chimeric virus by reverse genetics to make one. Nothing clinical would prompt the request either -- congenital tremor has five recognised type A causes and APPV is the one that is worldwide.
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. Hawko 2022 on the 2015 Styria index outbreak: piglets "exhibited severe lateral shaking and were unable to suck milk, with elevated preweaning death rates". On the 2022 Carinthia outbreak: "reproductive disorders in sows and gilts (i.e., abortions, neonatal deaths, stillborn, and mummified piglets) followed by signs of congenital tremors in 20 litters". Against that: "Up to now, LindaV has been detected with a 0.7% seroprevalence at the farm level in Austria. Interestingly, clinical signs of congenital tremors had never been observed on that farm, even if a novel, genetically related LindaV strain was isolated." And on postnatal challenge: "no clinical signs nor macroscopic nor histological lesions were observed in challenged animals".
How this level was decided
Level 2 unchanged and now supported rather than inferred, with both sides of it measured. When it hits a breeding herd the loss is real and named twice -- piglets that cannot suck, elevated pre-weaning death, abortions, stillbirths, mummies and twenty affected litters in one Carinthian farrow-to-finish unit. But 0.7% farm-level seroprevalence in the only country where it occurs is a very small denominator, the farm carrying strain Austria2 never saw a tremor at all, and postnatal infection produces no lesions of any kind. Small and generally short-lived losses falling on the herds that meet it. Level 2, scored the same as atypical_porcine_pestivirus, which causes the same syndrome on the same evidence pattern.
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
Basis. Two documented outbreaks in Austria, an EU member state, in 2015 and 2022 (Hawko 2022), followed by prevalence surveys in Austria, Germany and Switzerland (Hawko 2022, Schulz 2024). No trade measure, movement control or consumer response is recorded in either paper or in ch35. Linda virus is not WOAH-listed.
How this level was decided
Level 1, and it now passes the precedent test in SCORING/market_impact on observation rather than on inference. Something has happened, twice: outbreaks in 2015 and 2022 inside the European Union, investigated, published, followed by cross-border surveillance in two neighbouring countries. A decade of that produced no market consequence anyone recorded. That is an observed precedent of no reaction, which is what makes the cell scoreable at all -- contrast dengue_virus, where Eric ruled C6 unassessable because nothing has ever happened anywhere.
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. Neither paper describes any treatment for Linda virus. Hawko 2022 on postnatal challenge: "infections of immunocompetent piglets with LindaV result in temporary viremia with a quick seroconversion... However, no clinical signs nor macroscopic nor histological lesions were observed in challenged animals." The clinical entity in both outbreaks is congenital tremor with hypomyelination of the spinal cord white matter, present from birth.
How this level was decided
Level 1 on the second clause, and now demonstrated rather than assumed. The pig that could be treated is not the pig that is harmed: immunocompetent piglets challenged postnatally cleared the virus with no clinical signs and no lesions at all, while the damage that matters is hypomyelination laid down in utero and complete before birth. A pathogen-directed treatment has nothing to act on. 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. No vaccine for Linda virus is described in either paper or in ch35, and no control programme of any kind is described. Hawko 2022: "0.7% seroprevalence at the farm level in Austria", and Linda "seems to be confined in Austria, while no other outbreaks have been reported in other locations". Schulz 2024 found no evidence of spread to wild boar in the bordering German region.
How this level was decided
Level 1 on the second clause of the reworded criterion. No vaccine exists, and the question is whether one is warranted: a virus on 0.7% of farms in one country, absent from its neighbours by two independent surveys, causing a syndrome that the worldwide atypical porcine pestivirus also causes, does not clinically or economically justify vaccinating. Contrast classical_swine_fever_virus in this batch at level 1 for the opposite reason -- there the vaccines exist and work.
Levels and evidence are generated from data/assignments/linda_virus.yml; the overview is authored in data/overviews/linda_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.