Teschovirus Encephalomyelitis

Teschovirus encephalomyelitis

Services
Changed on: 22.01.2019
Icon

The Teschen disease (Syn.: Teschen/Talfan Disease, Contagious swine paralysis, Polioencephalomyelitis enzootica suum, Porcine enterovirus encephalomyelitis, Benign enzootic paresis) is a virus-related infectious disease of pigs. It is caused by the Porcine teschovirus (PTV) (in current nomenclature cited as teschovirus A) of the genus Teschovirus of the family Picornaviridae.
 
The suspicion of teschovirus encephalitis must be reported to the official veterinarian. With appropriate clinical symptoms and the diagnostic detection of PTV-1, the official veterinarian decides whether locking and/or culling measures are necessary - depending on virulence and/or progressive form of the disease.

More information

The Teschen disease (Syn.: Teschen/Talfan Disease, Contagious swine paralysis, Polioencephalomyelitis enzootica suum, Porcine enterovirus encephalomyelitis, Benign enzootic paresis) is a virus-related infectious disease of pigs. It is caused by the Porcine teschovirus (PTV) (in current nomenclature cited as teschovirus A) of the genus Teschovirus of the family Picornaviridae.
 
The suspicion of teschovirus encephalitis must be reported to the official veterinarian. With appropriate clinical symptoms and the diagnostic detection of PTV-1, the official veterinarian decides whether locking and/or culling measures are necessary - depending on virulence and/or progressive form of the disease.

More information

Occurrence

Infections with the virulent strain of Porcine teschovirus (PTV-1) are very rare. In Western Europe mainly mild strains and progressive forms of Porcine teschovirus dominate.

Transmission

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

The first replication occurs in the tonsils and in the intestinal epithelium (particularly ileum, colon). Enteral phase is not clinically significant and is characterized by the absence of morphological symptoms.

Viremia and invasion of the CNS follow the enteral phase showing the typical image of a non-suppurative (encephalo)myelitis (brain and/or spinal cord inflammation). During the viremic phase some serotypes show affinity for the uterus. An infection of the uterus can lead to fetal death.

Symptoms

The infection occurs most often in weaners due to the decrease of maternal immunity and due to the co-location of animals from different sources, which is typical for this age. The virus can be detected after 24 hours in large amounts in the tonsils and cervical lymph nodes; after 48 hours in the mesenteric lymph nodes and in the feces. Most infections are asymptomatic, but they can also lead to nervous system symptoms about 6 days p.i.. Co-infection of Teschovirus with other Picornaviridae, e.g. Porcine enteroviruses, can occur.

There are historically two different clinically relevant forms:

Teschen disease (severe, fatal / lethal form)

  • Pathogen: virulent strain of Porcine teschovirus 1 (PTV 1)
  • Occurrence: Europe (detected in 1929 in Cieszyn, Czech Republic), sporadically Africa
  • high morbidity (individuals in a population), high mortality (up to 90 %) in all age groups
  • Clinic: convulsions, opisthotonos, nystagmus, coma, death after 3-4 days, surviving animals have often residual paralysis

Talfan disease (mild form)

  • Pathogen: less virulent teschovirus strains, including PTV-1
  • Occurrence: worldwide and more frequently than Teschen disease
  • lower morbidity and mortality, clinically apparent in young animals; these mild progressive forms are prevalent nowadays
  • Clinic: paresis, ataxia, paralysis rare, often asymptomatic, 95% of animals abandoned to this form of disease develop a latent or inapparent infection

Measures/prevention

In Austria, Teschovirus Encephalomyelitis (infection with porcine teschovirus 1 (PTV 1) is a notifiable disease (§16 of the Animal Diseases Act - TSG).

Diagnosis

The clinical signs allow merely a presumptive diagnosis. The suspicion of Teschovirus encephalitis must be reported to the official veterinarian.

Samples from freshly euthanized animals are perfect for diagnostics: whole animals or brain and spinal cord.

National Reference laboratory:
Inst. for Veterinary Disease Control Mödling, AGES
Robert Koch-Gasse 17
2340 Mödling, Austria

A definitive diagnosis is based on the clinical signs and epidemiology, the pathomorphological changes (non-suppurative (encephalo) myelitis, Fig. 1) and on successful detection of pathogens.

Methods for laboratory diagnosis:

  • RT-PCR (possibly assisted by sequencing)
  • Virus isolation in cell culture
  • Serological tests
  • Histopathological examination
  • Immunohistochemical detection of antigen on tissue section

Interpretation of the results - recommendations for practice:

Appropriate clinical symptoms, corresponding histological CNS alterations ((encephalo)myelitis) and molecular biological pathogen detection (detection of PTV-1) are the basis of the decision of the official veterinarian whether locking  and/or culling of infected animals is necessary – this depends on the virulence  and/or progressive development of the disease).

In case of detection of other Teschovirus- or enterovirus serotypes (other than PTV-1) the disease often has a mild form, without therapeutic consequences, becausethe disease is not treatable. Animals with severe symptoms must often be euthanized, but also self-healing can occur.

Differential diagnoses:
Colienterotoxemia, selenium poisoning or other intoxication, vertebral canal abscessWirbelkanalabszesse, trauma, bacterial meningoencephalitis (encephalitis), Aujeszky's disease, European swine fever, African swine fever.


x