Teschen Disease (Teschovirus Encephalomyelitis) Eradication in Czechoslovakia: a Historical Report
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Historical Report Veterinarni Medicina, 54, 2009 (11): 550–560 Teschen disease (Teschovirus encephalomyelitis) eradication in Czechoslovakia: a historical report V. Kouba* Prague, Czech Republic ABSTRACT: Teschen disease (previously also known as Klobouk’s disease), actually called Teschovirus encepha- lomyelitis, is a virulent fatal viral disease of swine, characterized by severe neurological disorders of encephalomy- elitis. It was initially discovered in the Teschen district of North-Eastern Moravia. During the 1940s and 1950s it caused serious losses to the pig production industry in Europe. The most critical situation at that time, however, was in the former Czechoslovakia. A nationally organized eradication programme started in 1952. That year the reported number of new cases of Teschen disease reached 137 396, i.e., an incidence rate of 2 794 per 100 000 pigs, in 14 801 villages with 65 597 affected farms, i.e., 4.43 affected farms per village and 2.10 diseased pigs per affected farm. The average territorial density of new cases was 1.07 per km2. For etiological diagnosis histological investigation of the central nervous system, isolation of virus and seroneutralization were used. Preventive meas- ures consisted in feeding pigs with sterilized waste food and in ring vaccination. Eradication measures took the form of the timely detection and reporting of new cases, isolating outbreak areas, and the slaughter of intrafocal pigs followed by sanitation measures. Diseased pigs were usually destroyed in rendering facilities. The carcasses of other intrafocal pigs were treated as conditionally comestible, i.e., only after sterilization. During the years 1952–1965 from a reported 537 480 specifically diseased pigs 36 558 died; i.e., Teschen disease mortality rate was 6.80% while other intrafocal pigs (88.12%) were urgently slaughtered. During the whole eradication programme there were a reported 542 971 Teschen disease cases. The disease was found mainly in small private farms where domestic refuse was used for pig feeding without proper sterilization. During 1959–1972 there were a reported 16 981 529 vaccinations using a vaccine of national origin. The ratio of vaccination to national pig population was reduced from 0.4904 in 1959 to 0.0786 in 1972. During 1959–1965 the ratio of reported vaccinations to reported new diseased pigs was 521 : 1 and during 1960–1965 the ratio of reported vaccinations to reported intrafocal pigs was 85 : 1. After eradication the vaccination was stopped. The last cases were detected in 1973 and from that time Czech and Slovak territories have been free from this dangerous infection. Keywords: Klobouk’s disease; Talfan disease; porcine enterovirus encephalomyelitis; encephalomyelitis enzootica suum non purulenta; pig infection; pig vaccination; animal infection control Teschen disease, actually called Teschovirus en- strains of porcine teschovirus serotype 1 (PTV-1) cephalomyelitis (previously also known as Klobouk’s of the genus Teschovirus, family Picornaviridae. disease, virus encephalomyelitis of swine, porcine The disease was named after the Teschen district enterovirus encephalomyelitis – PTV or porcine in Czechoslovakia, where it was first reported in teschovirus infection) is a particularly virulent and 1929. During the 1940s and 1950s it caused seri- highly fatal viral disease of swine, characterized by ous losses to the pig breeding industry in Europe severe neurological disorders of encephalomyelitis and also spread to other continents. According to and causes major economic losses. It is caused by international data on Teschen disease occurrence *Formerly: Chief, Animal Health Service, Food and Agriculture Organization of the United Nations; Chief Epi- zootiologist, Czechoslovak and Czech State Veterinary Service, Prague; Professor of Epizootiology, University of Veterinary Sciences, Brno 550 Veterinarni Medicina, 54, 2009 (11): 550–560 Historical Report from that time, the most critical situation was in and RT-PCR methods for identification have been the former Czechoslovakia. The disease was identi- developed (Jimenez-Clavero et al., 2003; La Rosa fied for the first time by Professor MVDr. Antonin et al., 2006; Kaku et al., 2007). The presence of por- Klobouk as a virosis initially called “encephalomy- cine Teschovirus antigen has been demonstrated elitis enzootica suum non purulenta” (Klobouk, by immunochemical methods in the nerve cells of 1931a,b, 1933, 1935a,b, 1936). After the Second the brain stem and in the spinal cord and gangli- World War this infection, called also “Klobouk’s on cells of the spinal ganglion from infected pigs disease”, became internationally notifiable among (Yamada et al., 2007). The distribution of porcine the most dangerous diseases and was listed among Teschovirus antigens was consistent with lesions Czechoslovak national priority diseases to be eradi- characteristic of nonsuppurative encephalomyelitis cated. This was achieved with the elimination of the (Yamada et al., 2008). Sequencing of field isolates last case in 1973. The eradication of Teschen dis- collected from animals presenting with neuro- ease was a must for facilitating normal pig breed- logical disorders, prove that serotypes other than ing, production of pork and export of live pigs and porcine Teschovirus-1 may also cause polioen- their products. More information is available in cephalomyelitis of swine (Zell et al., 2001). Twenty Historical Sources, listed in References. seven strains of porcine enteroviruses, isolated over Transmission of Teschen disease takes place be- the period from 1960 to 1980 and deposited in the tween infected and susceptible pigs through both Collection of Animal Pathogenic Microorganisms direct and indirect contact. The infective dose is (CAPM, Brno, Czech Republic), were reclassified very small, which is why these viruses are so easily using an RT-PCR protocol that allows detection of transmitted. Infection occurs by the oral or intrana- the genus Teschovirus and the porcine Teschovirus sal route and the virus is present in faeces and oral serotype 1 (PTV-1). Two PCR amplifications with secretions. A frequent source of infection is insuf- cDNA were performed for detection of the genus ficiently cooked contaminated garbage (swill) fed to Teschovirus and PTV-1. Amplification of fragments pigs. Long distance spread is facilitated by national characteristic for the genus Teschovirus was suc- and international trade, mainly through swine car- cessful for all tested viral strains. The characteris- casses contaminated in abattoirs by the brain or tic PTV-1 fragment was detected in all save three spinal cord liquid of infected pigs slaughtered dur- strains (Prodelalova et al., 2009). ing incubation periods when they appeared clini- The presence of teschoviruses in water points to cally healthy. There is no specific treatment for contamination with pig faecal residues. A real-time Teschen disease. Infection with less virulent PTV reverse transcriptase PCR method is able to detect strains may result in mild disease, formerly called 92 fg of porcine Teschovirus RNA per ml of sample. Talfan disease or benign enzootic paresis of swine Faeces from other animal species (cattle, sheep, or infectious poliomyelitis suum. and goats) were shown to be negative in this highly Teschovirus encephalomyelitis still affects swine specific test for the assessment of water contami- herds in Haiti. The FAO recommends that coun- nation of porcine origin (Jimenez-Clavero et al., tries of Central America and the Caribbean region 2003). It is also significant that a high resistance of should be aware of the situation in Haiti and apply porcine Teschovirus to chemical inactivation has basic preventive measures to avoid the entry of this been demonstrated (Dvorakova et al., 2008). virus into their swine population and its poten- tial dissemination (Domenech, 2009). Enterovirus encephamomyelitis in pigs caused by porcine MATERIAL AND METHODS Teschovirus has been described in Japan (Yamada et al., 2004). Feng et al. (2007) have isolated and Available sources of data for this paper consist identified the porcine Teschovirus in China and mainly of selected national literature on Teschen Prodelalova et al. (2009) in the Czech Republic. disease, official statistical data as reported to the Antibodies against porcine Teschovirus have been State Veterinary Service in Prague, directives of the detected in Lithuania (Sereika et al., 2007). The Ministry of Agriculture and of the Chief Veterinary structure of porcine Teschovirus, namely the in- Officer, and the personal notes of the author ternal ribosome entry site element, has been the (former assistant to Prof. Klobouk) taken between subject of study of late (Hellen and de Breyne, 2007; 1958–1978 and who as the Chief Epizootiologist Bakhshesh et al., 2008; Belsham et al., 2008, 2009) of the Czechoslovak and Czech State Veterinary 551 Historical Report Veterinarni Medicina, 54, 2009 (11): 550–560 Service was professionally responsible for Teschen ing pig carcass offal). However, the best scenario disease eradication strategy, management and re- was not to use such refuse at all for pig feeding sults. Unfortunately, not all the historical data for purposes. Control zones were set up to minimize complete time series of selected epizootiological pig movement and to avoid the transfer of pigs to indicators were available to the author. other territories for further breeding. The first step in the nationally organized eradica- Surveillance was intensified