Detection of Teschovirus type 13 from two swine herds exhibiting nervous clinical signs in growing pigs

Abstract

Recently, the number of clinical reports of growing pigs showing neurological signs possibly related to viral infections has increased. The objective of this report was to describe two outbreaks of an atypical condition observed in 6- to 7-week-old pigs with a morbidity of 20% and a fatality rate of 60% in two unrelated farms of the same company. During the acute phase of the disease, fever, sudden death, neurological signs, ear necrosis and occasional corneal opacity were observed. Histopathological examination revealed interstitial pneumonia, lymphoid depletion and lymphocytic vasculitis in different organs and mild polioencephalomyelitis suggesting a potential viral infection. Possible aetiologies such as exogenous intoxications, salt intoxication, mineral deficiencies/intoxications (Se, Cu, Cd and Zn), oedema disease and mycotoxicosis were ruled out through the diagnostic process. No clinically relevant bacteria could be consistently isolated from affected animals, and the presence of the common swine viruses was ruled out by PCR or RT-PCR. Porcine Teschovirus serotype 13 was the only virus detected by RT-PCR within central nervous system (CNS) of acutely affected pigs. This is the first description of PTV serotype 13 within the CNS of clinically affected pigs.

Postweaning mortality in commercial swine production II: review of infectious contributing factors

“…In recent years, an increase in the incidence of neurological syndromes has been observed and, in many cases, associated with diagnosis of viral infectious agents. This is still an area of ongoing research efforts, but multiple viruses recently have been associated with neurological syndromes, including porcine sapelovirus ( Schock et al, 2014 ; Arruda et al, 2017b ), porcine astrovirus type 3 ( Boros et al, 2017 ; Rawal et al, 2019 ; Matias Ferreyra et al, 2020 ), and porcine teschovirus ( Bangari et al, 2010 ; Deng et al, 2012 ; Carnero et al, 2018 ). The recently described atypical porcine pestivirus has been associated with congenital tremors ( de Groof et al, 2016 ; Postel et al, 2016 ; Schwarz et al, 2017 ) but is not believed to be a major contributor to postweaning mortality ( Gatto et al, 2019 ).…”

Two novel porcine teschovirus strains as the causative agents of encephalomyelitis in the Netherlands

“…In several countries worldwide, such as Spain and Brazil, an increased prevalence of PTV-associated neurological disease is noted [2,8]. Recent reports have identified other viral causes of encephalomyelitis in pigs of similar age.…”

“…The genus Teschovirus has been frequently associated with neurologic disease in pigs [2][3][4][5]. Porcine teschovirus (PTV) currently comprises 13 known serotypes [6][7][8], which is likely to expand with the continuous discovery of novel genotypes [9,10].…”

“…The most recent severe outbreak of PTV-1 with high mortality occurred in the Republic of Haiti in 2009 [17]. However, this virulent manifestation is now considered rare and only milder forms of neurologic disease associated with PTV-1 or other PTV serotypes have been reported in growing pigs in Canada, Spain and Brazil during the last years [2,5,8]. Although co-infections were not detected in these cases, immunosuppressive pathogens, such as porcine circovirus type 2 (PCV-2) and/or porcine reproductive and respiratory syndrome virus (PRRSV) could predispose animals to develop neurologic PTV disease [3,18].…”

Novel species of Teschovirus B comprises at least three distinct evolutionary genotypes

“…These values were significantly (p < .01) higher than those in pigs at other growing stages including gilts, sows, suckling pigs, nursery pigs (4-6 weeks) and fattening pigs (>12 weeks, Table S1). Although sporadic PTV infections have been associated with a variety of clinical symptoms (Carnero, Prieto, Polledo, & Martinez-Lobo, 2018;Lin, Cui, & Zell, 2012), PTV infections are commonly asymptomatic (Knowles, 2006). These results agree with a previous study that described an 85.7% PTV infection rate in asymptomatic pigs aged 8-12 weeks in Shanghai, China (Sun et al, 2015).…”