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Enteric disorders are one of the most important groups of diseases affecting turkeys and continue to cause high economic losses in many areas world-wide. Several pathogens (viruses, bacteria and parasites) have ben incriminated as possible causes of enteric disorders either alone, in synergy with other microorganisms or with noninfectious causes such as feed or/and management related factors. Under field conditions, however, it is difficult to determine the true cause of enteric disorders. Viruses from several virus families have been implicated as causative agents in enteric diseases in turkey such as turkey coronavirus, avian rota- and astroviruses. Currently there are no data available on the prevalence of these viruses in German meat turkey flocks.
The aim of the present investigation was therefore to establish reliable diagnostic tools and to monitor turkey flocks.
All samples were tested using transmission electron microscopy (TEM) as well as RTPCR. For RT-PCRs, we designed specific primers for astro- and rotaviruses. The coronavirus identification was performed by a PCR which was developed by Cavanagh et al. (2001). For differential diagnosis of causes of enteric diseases we tested for Salmonella spp. and parasites.
Eight different commercial turkey farms located in Southern Germany were monitored. Faecal samples from hens and toms were collected separately at 2 week intervals from the 2nd to the 16th and 20th week of age (age of slaughter of females and males respectively) and screened for virus infections. One farm reared only hens.
Using TEM dual infections with rota- and astroviruses were detected in 18% of 107 samples tested. The incidence of astrovirus detection ranged between 28 and 36% in males and females respectively. For rotaviruses, the detection rate was 35% in males and 49% in females.
Using RT-PCR, infection with rota- and astroviruses was detected in all flocks. 84% (90/107) of the faecal samples tested were positive for both viruses at the same time. The incidence of astrovirus infection ranged between 98-100% in toms and hens respectively. For rotaviruses the detection rate in males and females ranged between 83 and 87%.
No coronaviruses were detected in any of the flocks or samples using both TEM and RT-PCR.
A comparison of the results of both detection methods used exhibited higher sesitivity
of the PCR assays compare electron microscopy.
The results of this study revealed a high prevalence of astro and rotavirus in turkey flocks in Germany. In contrast, no coronaviruses were detected by either RT-PCR or TEM.