Page 203 - Avian Virology: Current Research and Future Trends

196 | Kibenge et al.

enteritis with occasional high mortality in turkey poults (Ger- from young geese with lesions of splenitis, hepatitis with miliary
showitz and Wooley, 1973; McFerran et al., 1976; Saif et al., 1985), necrotic foci, epicarditis, arthritis, and tenosynovitis at necropsy
decreased weight gain (Spackman et al., 2005a), age dependent (Palya et al., 2003).
moderate to severe atrophy of the bursa of Fabricius causing
transient or possibly permanent immunosuppression (Spackman Avian orthoreovirus disease in Bobwhite quail
et al., 2005a; Day et al., 2008), and myocarditis (Shivaprasad et (Colinus virginianus) and other captive exotic avian
al., 2009; França et al., 2010). Nersessian et al. (1985b) noted species
that turkeys inoculated with a turkey enteric orthoreovirus had Avian orthoreovirus as a pathogen in young Bobwhite quail
a viraemia 7 days PI with virus distributed in most organs by (Colinus virginianus) was first reported in a commercial operation
3–7 days PI and virus recovered from tendons at 3–7 days and (Magee et al., 1993). Affected quail were lethargic, had respira-
28 days PI. Turkey reovirus isolated by Sharafeldin et al. (2014) tory distress, and had hepatic necrosis, air sac lesions and sinusitis
fulfilled Koch’s postulates which established the causal rela- at necropsy with 95% flock mortality. Guy et al. (1987) and Ritter
tionship between reoviruses and tenosynovitis in turkeys, and et al. (1986) reported concomitant orthoreovirus and Crypto-
recently, seven more orthoreoviruses were isolated and geneti- sporidium in bobwhite quail with enteritis; however, neither
cally characterized from clinical cases of arthritis in turkeys from claimed that orthoreovirus was the primary causative agent. Guy
Pennsylvania, USA (Tang et al., 2015). et al. (1987) suggested that Cryptosporidium promoted systemic
Avian orthoreoviruses were implicated in a number of multi- spread of orthoreovirus and orthoreovirus intensified Crypto-
factorial enteric syndromes in young turkeys, and the milder form sporidium infection in Bobwhite quail.
was characterized by diarrhoea and poor weight gain. However, in Avian orthoreoviruses were isolated from other commercial
some cases, high mortality was observed in the affected flocks and poultry species. Tanyi et al. (1994) reported pancreatitis caused
in these instances the disease was called poult enteritis complex by an orthoreovirus in commercially reared, 1- to 3-week-old
(PEC) (Spackman et al., 2005a), and an even more severe form guinea-fowl. An orthoreovirus was isolated from fresh intestinal
of the disease has been documented as poult enteritis mortality content of a healthy, 1-year-old ostrich (Struthio camelus) from a
syndrome (PEMS) (Day et al., 2008). PEMS is highly infectious breeder farm in Japan (Sakai et al., 2009).
in young turkeys and is characterized by diarrhoea, increased
feed consumption, increased time-to market runting, stunting, Orthoreoviruses in wild avian species
decreased weight gain, immune dysfunction, and mortality (Day Avian orthoreoviruses have been associated with a variety of
et al., 2008). In addition to orthoreoviruses, numerous viruses, disease syndromes in captive and free living (wild) birds. The
including turkey coronavirus and turkey astrovirus type 2, have first recoded isolation of orthoreovirus from pigeons (Columba
been associated with PEC and PEMS and have been the cause of spp.) was by McFerran et al. (1976). The virus was from a pigeon
substantial economic losses to the turkey industry (Spackman et with diarrhoea and was isolated on chicken kidney and chicken
al., 2005b). However, (Heggen-Peay et al., 2002) demonstrated embryo liver cell cultures. This pigeon reovirus isolate shared a
that orthoreovirus alone was capable of inducing some of the common antigen with known chicken orthoreoviruses which
clinical signs associated with PEMS, including the intestinal provided the evidence for the ability of avian orthoreoviruses to
lesions and suppression of bursal and hepatic growth and devel- cross species boundaries. Although diarrhoea and hepatitis were
opment. commonly associated with orthoreovirus infections in pigeons
(McFerran et al., 1976; Vindevogel et al., 1982), the attempts at
Avian orthoreovirus disease in Muscovy ducks experimental reproduction of the lesions failed, suggesting that
(Cairina moschata), ducks and geese other factors might have been involved with the naturally occur-
Orthoreoviruses were isolated from Muscovy Ducks (Cairina ring disease (Vindevogel et al., 1982).
moschata) in South Africa, France, Israel, and Hungary (Malkin- Avian orthoreoviruses were regularly isolated from imported
son et al., 1981; Heffels-Redmann et al., 1992; Palya et al., 2003), psittacine birds (Meulemans et al., 1983), and as the commercial
and the disease caused by orthoreoviruses usually affects young market for imported psittacine birds has grown, outbreaks in these
Muscovy ducklings between 2 and 4 weeks of age. The clinical bird species have increased in frequency over the years (van den
signs included general malaise, diarrhoea, respiratory signs, Brand et al., 2007). Rigby et al. (1981) tested 269 consignments
stunted growth, (Malkinson et al., 1981; Heffels-Redmann et of imported birds (mainly psittacine and passerine avian species)
al., 1992), and microscopic, multifocal hepatic, splenic and renal to Canada, between January 1977 to August 1980 and isolated
necrosis (Malkinson et al., 1981). Liu et al. (2011) and Chen orthoreovirus from 22 consignments, and 17 of the isolates were
et al. (2012) reported the isolation of a highly virulent duck associated with enteritis in the shipped birds. Meulemans et al.
orthoreovirus from Pekin ducklings (Anas platyrhynchos) suffer- (1983) tested 28 batches of dead imported psittacine birds and
ing from severe mortality due to hepatic and splenic necrosis, and isolated orthoreoviruses from 15 batches. The main lesions pre-
further studies revealed that the isolates were closely related to sent were enteritis and hepatic congestion with focal necrosis, and
Muscovy duck orthoreoviruses. McFerran et al. (1976) isolated splenomegaly was present in some cases. An outbreak of reovirus
an orthoreovirus from faeces of normal farmed mallard ducks disease with high mortality was reported in Italy among imported
in chick kidney and chicken embryo liver cell cultures. A goose African grey parrots (Psittacus erithacus erithacus) and Australian
reovirus related to Muscovy duck orthoreovirus was isolated king parrots (Alisterus scapularis) (Conzo et al., 2001). Senne et