Poxvirus in a Swine Farm in Italy: a Sporadic Outbreak? O

Mariano_imp:ok 20-06-2016 11:23 Pagina 219

V. Mariano et al. Large Animal Review 2015; 21: 219-220 219

Poxvirus in a swine farm in Italy: a sporadic outbreak? O

V. MARIANOa, A. NARDIa, E. VERGARIa, F. CARLETTIb, L. BARBIERIc, G. CARDETId a Laboratory of Veterinary Diagnostic Disease of Grosseto, Istituto Zooprofilattico Sperimentale del Lazio e della Toscana “M. Aleandri”, Via Europa 30, Grosseto, Italy b Virology Laboratory, National Institute for Infectious Diseases, IRCCS “L. Spallanzani”, Via Portuense 292, 00149 Rome, Italy c Veterinarian freelancer, Grosseto, Italy d Laboratory of Electron Microscopy and Specialistic Virology, Biotechnology Dept., Istituto Zooprofilattico Sperimentale del Lazio e della Toscana “M. Aleandri”, Via Appia Nuova 1411, Rome, Italy

SUMMARY The aim of this report is to describe the occurrence of a Swinepox virus (SWPV) outbreak in Central Italy in 2013 and the pos- sibility of its reappearance. SWPV is the only member belonging to the Suipoxvirus genus in the Poxviridae family and it represents the etiologic agent of a worldwide disease specific for swine with an affinity for epidermis. In Italy it has been rarely observed. In November 2013 an outbreak was registered in a biological farm of about 110 animals located in Tuscany. Skin lesions were observed in a group of 3 months old piglets born in the farms from crossbreed animals. The disease affected 50 of the youngest animals. Diagnosis was based on clinical and pathological signs which were pustular lesions at first located mainly around the neck and the ears and in a later stage disseminated all around the body, especially concentrated in the groin and the abdomen. Skin samples were processed for negative staining electron microscopy technique and ruled positive for brick viral particle consistent with Suipoxvirus. To rule out Orthopoxvirus infection, possibly causative of similar pustular lesions, molecular analysis was performed but no evidence of specific target amplification for Orthopoxvirus was observed, thus it was ex- cluded as differential diagnosis. The course of the disease was of about 20 days. As a concomitant infection with Salmonella tiphymurium was found in the outbreak, it is not possible to define which of the two diseases could have been causative of the registered mortality. Unfortunately the source of the poxvirus infection has not been demonstrated, however a great role in the transmission of the disease within the farm could be attributed to the lice Haematopinus suis which was parasiting the animals. As Suipoxvirus is mechanically transmitted by lice and extensive farming systems are common in the area, as well as wild boars, future outbreaks could be expected.

KEY WORDS Swine pox, Suipoxvirus, swine, wild boar, Italy.

This short communication reports on an outbreak of swi- disease was first reported in slaughtered pigs in 2006 (data ne pox in a biological pig farm in Tuscany, Italy. Swinepox not published). In November 2013 a new outbreak was re- virus (SWPV) is the only member belonging to the Suipox- gistered in a biological farm of about 110 animals located virus genus in the Poxviridae family and it represents the in a different area in Tuscany. Skin lesions (Figure 1) were etiologic agent of a worldwide disease specific for swine observed in a group of 3 months old piglets born in the with an affinity for epidermis1,2. Suipoxvirus is morphologi- farms from crossbreed animals of the indigenous breeds cally, genetically and antigenically related to the others 8 “Macchiaiola maremmana”, “Nero dei nebrodi” and the En- genera of the subfamily Chordopoxvirinae3. This virus pre- glish breed “Large Black”. The disease affected 50 of the sents a brick-shaped complex envelope and a large linear youngest animals. “Large White” pigs kept in the same farm double-stranded DNA genome with a cytoplasmic site of didn’t show any signs of illness. At a first site an ectoparasi- replication4,5. SWPV produces generalized pustular lesions ticide was dispensed to all the animals while an antibiotic which in severe infections can be associated with a high ra- and cortisone treatment was administered to the ill ani- te (80% or more) of neonatal illness6,7. It is mechanically mals. As the condition didn’t show any improvement and transmitted by lice or through direct animal contact and a instead kept deteriorating, a first suspect of poxvirus was congenitally-acquired infection is described in literature6. formulated. Diagnosis was based on clinical and pathologi- The presence of Poxvirus in swine has been demonstrated cal signs which were pustular lesions at first located mainly in Northern Italy since 20028. However in central Italy, the around the neck and the ears and in a later stage disseminated all around the body, especially concentrated in the groin and the abdomen. One dead animal was submitted to the Diagnostic Laboratory of the IZSLT for post-mortem Autore per la corrispondenza: examination. Skin samples were sent to the Biotechnology Valeria Mariano ([email protected]). Laboratory of the IZS LT to investigate for viral agents. Mariano_imp:ok 20-06-2016 11:23 Pagina 220

220 Poxvirus in a swine farm in Italy: a sporadic outbreak?

been executed in the area since many years. The course of the disease was of about 20 days. As a concomitant infection with Salmonella tiphymurium was found in the outbreak, it is not possible to define which of the two diseases could have been causative of the registered mortality. As well the source of the poxvirus infection has not been demonstrated. Although only fences divide the farms from the surrounding area inhabited by wild boars, since now no cases have been reported in this species. On the other hand, a great role in the transmission of the disease within the farm could be attributed to the lice Haematopinus suis which was parasiting the animals. It is known that this parasite per- Figure 1 - Pustular lesions observed on piglets. mits the survival of the virus for one year2 and this could be the reason of the following less severe outbreak in piglets registered in the same farm in June 2014. Although ectoparasite treatments are dispensed as well as bio-control security measures to avoid contact with wild boars, lice eradication in semi-extensive farming systems is difficult and thus other cases are likely to be expected within the territory in the future.

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