Teschovirus Encephalomyelitis

Teschovirus encephalomyelitis

Changed on: 11.11.2020
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Teschovirus encephalomyelitis (Teschen disease) is an infectious disease of domestic and wild pigs caused by highly virulent strains of the Porcine Teschovirus serotype 1 (PTV-1, Fa. Picornaviridae).

Occurrence

Infections with virulent strains of the Porcine Teschovirus (PTV-1) have become very rare nowadays (only on the islands of Haiti, Madagascar and La Réunion). In Western Europe they do not occur any more, here mainly mild strains and progressive forms dominate.

Reservoir

Domestic and wild boars

Mode of transmission

The virus is transmitted directly from animal to animal (faecal-oral) or indirectly via contaminated infection carriers (objects, contaminated pig feed, etc.).

Incubation period

1 to 2 days

Symptoms

Severe forms of the disease in domestic pigs are initially characterised by high fever, fatigue, inappetence and ataxia (particularly weakness of the hind hands) and then usually progress to encephalomyelitis, which is often associated with paralysis (paraplegia or quadriplegia). Diarrhoea can occur before the central nervous disorders begin to show. The disease is fatal in 20-100% of cases, with death occurring 3-4 days after the first symptoms appear. The sub-acute forms ("Talfan disease") with low mortality are common and symptoms such as fever, ataxia and posthand paralysis also occur; however, the paralysis symptoms are usually reversible. In addition to these two clinical pictures, inapparent forms of the disease are also described.

Treatment

There is no treatment for Teschovirus encephalomyelitis.

Preventive measures

Teschovirus encephalomyelitis is an animal disease that must be notified under the Animal Diseases Act. In Austria vaccination is not permitted. Inactivated and attenuated vaccines exist, but are not used in the EU.

Situation in Austria

In Austria, Teschovirus encephalomyelitis (infection with Porcine Teschovirus 1 (PTV 1)) must be notified in accordance with Article 16 of the Animal Diseases Act (Tierseuchengesetz (TSG)). The suspicion of Teschovirus encephalomyelitis must be reported to the official veterinarian. In case of corresponding clinical symptoms and the diagnostic evidence of PTV-1, the official veterinarian will decide whether blocking/culling measures are necessary - depending on the virulence/progression of the disease. In the past 10 years only rare mild CNS progressions caused by other PTV strains and/or Porcine Enterovirus G have been detected.

Professional information

Veterinary Medicine

Synonyms: Teschovirus Encephalomyelitis, Teschen Disease, Teschen/Talfan Disease, Polioencephalomyelitis enzootica suum, Porcine Enterovirus Encephalomyelitis, Benign Enzootic Paresis

Teschen disease was first diagnosed in the Czech town of Teschen in 1929. In 1957 a PTV-1 virus with a milder clinical form was detected in Talfan (Wales).

Porcine Teschovirus A is an RNA virus belonging to the genus Teschovirus A of the family Picornaviridae. Previously, Teschoviruses were assigned to the group of enteroviruses with a total of 13 serotypes. Based on the cytopathic effect (CPE), replication properties in different cell lines of the host, serological test procedures and sequence data, the porcine enteroviruses (PEV) have been continuously reclassified and are currently divided into 3 groups: Teschovirus A (formerly Porcines Teschovirus), Sapelovirus A (formerly Porcines Enterovirus A, PEV-8) and Enterovirus G (formerly Porcines Enterovirus B, PEV-9 and PEV-10).

Infections with sapelovirus A (PSV-A), porcine enterovirus G (PEV-G), porcine parvovirus, PRRSV, Aujeszky's disease, European swine fever, African swine fever, colienterotoxaemia, selenium poisoning or other intoxications, spinal abscesses, trauma, bacterial meningoencephalitis can be diagnosed.

Transmission

The first replication occurs in the tonsils as well as in the intestinal epithelium (especially ileum, colon). The enteral phase is not clinically significant and is accompanied by no morphological changes. The enteral phase is followed by viremia and invasion of the CNS with the typical picture of a non-purulent (encephalo)myelitis (inflammation of the brain or spinal cord). During the viremic phase, some serotypes show affinity to the uterus. Colonisation of the uterine tissue with the virus can lead to intrauterine death.

The infection occurs most frequently in weaned piglets due to the decrease in maternal immunity and the common housing of animals of different origins at this age. After 24 hours the virus is detectable in large quantities in the tonsils and cervical lymph nodes, after 48 hours in the mesenteric lymph nodes and in the faeces. Co-infection of Teschoviruses with other picornaviridae such as PSV-1 and PEV-G occurs.

Symptoms

Teschen disease (severe, fatal/lethal form)

  • Pathogen: virulent strains of Porcines Teschovirus 1 (PTV-1)
  • Occurrence: originally in Europe, sporadically Africa, China, Haiti, Brazil, Canada
  • high morbidity (individuals in a population), high mortality (up to 90%), in all age groups
  • Clinical signs: convulsions, opisthotonus, nystagmus, coma, death after 3-4 days, surviving patients show residual paralysis

Talfan disease (mild forms are predominant nowadays)

  • Pathogen: Less virulent Teschovirus strains, including PTV-1
  • Occurrence: worldwide and more frequently than Teschen disease
  • Paresis, ataxias, rarely paralysis, often without symptoms, 95% of animals exposed to infection develop latent or inapparent infections

Diagnostics

Suitable sample materials are

  • Blood (EDTA/serum)
  • Brain, including spinal cord and trigeminal ganglion
  • Organs

Detection of PTV from the above-mentioned materials is possible with the following methods:

  • Real-Time RT-PCR, conventional RT-PCR (possibly supported by sequencing)
  • Virus isolation in cell culture
  • Histopathological examination
  • Immunohistochemical antigen detection on tissue section

The clinical symptoms only allow a suspected diagnosis. Suspected cases of Teschovirus encephalomyelitis must be reported to the official veterinarian. A definitive diagnosis can only be made taking into account the clinical symptoms and epidemiology, the pathomorphological changes (non-purulent (encephalo)myelitis) and successful detection of the pathogen (detection of PTV-1).

If other teschovirus or enterovirus serotypes are detected, these are mild forms of the disease without need for further action, as the disease cannot be treated. Severely affected animals should be euthanized in case of a progressive course, but in many cases self-healing occurs.

Contact, forms

Institute of Veterinary Medicine Mödling (National Reference Laboratory)

Robert Koch-Gasse 17
2340 Mödling

Telephone: +43 50 555-38112
Fax: +43(0)5 0555 38529

E-mail: vetmed.moedlingno@Spam@agesno.Spam.at

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