Enteric viruses in Brazilian turkey flocks: Single and multiple virus infection frequency according to age and clinical signs of intestinal disease

Abstract

Poult enteritis complex has been associated with enteritis and reduction in growth rates in commercial turkeys worldwide. Intestinal samples from 76 turkey flocks from different Brazilian states affected or not with intestinal disorders were evaluated for the presence of adenovirus groups 1 and 2 (TAV), astrovirus types 1 and 2 (TAstV-1 and TAstV-2), turkey coronavirus (TCoV), reovirus, rotavirus, and avian nephritis virus (ANV) using PCR. The percentage of positive samples was categorized according to the geographic origin, age of the flocks, and presence of clinical signs of intestinal disease. The percentage of samples that were positive for at least one virus was 93.4%, whereas the percentage of samples that were positive for more than one virus was 69.7%. An average of 3.20 viruses per sample was detected in turkeys in the growing phase of the production cycle (1 to 4 wk of age). The TAstV-1 and TCoV were the most frequently observed viruses in growing phase turkeys and occurred simultaneously in 85% of these samples. In turkeys in the finishing phase of development (5 to 18 wk), a lower average number of viruses was observed (2.41), and the most frequent viruses isolated in these turkeys were TAstV-1 (57.1%) and rotavirus (51.8%). Overall, every virus was detected more frequently in growing phase turkeys than in finishing phase turkeys with the exception of TAV. Samples from flocks exhibiting clinical signs of intestinal disease showed a higher rate of positivity, and TAstV-1, TAstV-2, and TCoV were the most frequently occurring viruses in this cohort. Birds without clinical signs most frequently harbored TAstV-1 and rotavirus. Future studies should focus on the description and elucidation of the role of each virus, as well as the pathogenic and immunological implications of the different combinations of viruses in turkeys.

Prevalence and molecular characteristics of rotaviruses from Polish turkey flocks between 2008 and 2011

“…In the studies, rotaviruses were detected in flocks with enteric disease, but also in turkeys without any symptoms of the disease. This is in accordance with the results of previous studies, which demonstrated rotaviruses in both enteric and healthy birds (7,18).…”

“…In subsequent studies of these authors, the monitoring of five flocks of apparently healthy breeder turkeys over the period of nine weeks revealed that 30.6% of samples were rotavirus-positive and the virus was detected in 1-to 9-week-old, in both healthy and enteric turkeys (7). In Brazilian study, rotavirus infections were identified in 51.8% of surveyed turkey farms, and birds in most tested flocks were described as healthy (18). Among 51 diseased turkeys examined in Germany and the Netherlands between 2005 and 2008, 60.7% were identified as RV-positive (20).…”

Molecular characterization of turkey enteric reovirus S3 gene

“…Avian reovirus is an important cause of diseases in chickens and turkeys and is involved in myocarditis, viral arthritis, infectious tenosynovitis, malabsorption, runting and stunting syndrome, and respiratory and enteric diseases (Glass et al, 1973;Hieronymus et al, 1983, Rosenberger, 2003Pantin-Jackwood et al., 2008;Jindal et al, 2010a;Mor et al, 2013a, b;Moura-Alvarez et al, 2013). The reoviruses detected in turkeys are commonly called turkey reoviruses (TRVs) as opposed to ARV in chickens.…”

Enteric viruses in turkey flocks: a historic review

“…PCR and RT-PCR started to be considered as diagnostic methods when specific techniques for each agent involved in turkey enteric syndromes were standardized Breslin et al, 1999;Hess et al, 1999;Xie et al, 1999;Koci et al, 2000b;Da Silva et al, 2008;Zsak et al, 2008;Bunger et al, 2009;Moura-Alvarez et al, 2013;Nuñez & Piantino Ferreira, 2013;Moura-Alvarez et al, 2014).…”