Five hundred and seventy-three clinical submissions with fowl adenovirus (FAdV) involvement were examined to investigate the association of different types of FAdV with clinical problems related to FAdV infection. Samples were received from 2000 to 2006 and originated from seven Canadian provinces. Four hundred and eighty-seven submissions were inclusion body hepatitis (IBH) related, while 86 were not IBH related. Viruses isolated from 287 samples were further analysed by hexon gene loop 1 sequencing. Twenty-seven genotyped FAdVs were from Alberta, 20 from British Columbia, 16 from Manitoba, one from Nova Scotia, 82 from Ontario, 64 from Quebec and 77 from Saskatchewan. Two hundred and forty-six analysed FAdVs were from IBH cases, confirmed by liver histopathology, by FAdV isolation from the liver, or both. Based on hexon gene loop 1 sequencing analysis, FAdVs associated with IBH outbreaks were genetically related to FAdV02 (nine isolates, 99.4%), FAdV08a (100 isolates, 99.4% to 100%) and FAdV11 (98 isolates, 99.4% to 100%). Thirty-nine viruses were 93.7% to 94.3% identical to FAdV07 strain x11a, but the genetic and immunogenic properties of this strain require further investigation. In IBH cases, the co-infection rates for infectious bursal disease virus, infectious bronchitis virus, reoviruses and Newcastle disease virus were 3.47%, 1.04%, 6.25% and 0.69%, respectively. Forty-one genotyped FAdVs were from "non-IBH" cases. Viruses isolated from non-IBH cases consisted of 22 FAdV01, 15 FAdV11, two FAdV08a and one each of FAdV02 and FAdV04 viruses. Co-infection rates in non-IBH submissions were 50.00% for infectious bursal disease virus, 40.70% for infectious bronchitis virus, 27.91% for reoviruses and 1.16% for Newcastle disease virus.

No abstract

For this retrospective study, infectious bursal disease virus (IBDV) was detected in 134 bursal samples that originated from flocks with conditions such as airsacculitis, tracheitis, pneumonia, septicaemia, inclusion body hepatitis, coccidiosis, and/or a history of production problems without overt clinical symptoms. Samples were from seven Canadian provinces: Ontario, Quebec, Manitoba, British Columbia, Nova Scotia, Alberta, and Newfoundland and Labrador. Viral RNA was identified in bursae with moderate to severe and acute to chronic bursal damage. The ages of the flocks from which samples were collected ranged from 3 to 63 days. Following reverse transcriptase-polymerase chain reaction the nucleotide sequence of the VP2 hypervariable region was determined and compared with sequences available in GenBank. The most common Canadian IBDV field strains were North-American variant viruses. Forty-four viruses were highly related (97.5% to 100.0%) to the US IBDV strain NC171. Moreover, 16 field viruses whose VP2 sequences were 99.2% to 100% identical to the South African 05SA8 IBDV strain appeared closely related to the NC171 group. Delaware E-related field viruses, 98.3% to 100.0% identical to the prototype virus, were identified in 33 samples. Thirty-four Canadian IBDVs showed the highest identity, 94.2% to 98.3%, to US IBDV strain 586. Five samples contained vaccine-related viruses, while two field strains showed the best match to Del A (United States) and IBDV strains SP_04_02 (Spain). Very virulent IBDVs were not detected in Canada.

Genomes of two low pathogenic H5N1 avian influenza (LPAI) viruses, A/Turkey/ON/84/1983 and A/Mallard/ON/499/2005 from Ontario, Canada were cloned and genetically characterized. Phylogenetic analysis showed that the Canadian isolates cluster with other North American AIVs and are distinct from the Euro-Asian H5N1 isolates. Individual gene comparisons demonstrated that the Ontario isolates were most similar to the viruses isolated from around the same time period and geographical area. A long deletion of 22 amino acids was identified in the stalk region of NA of A/Turkey/ON/84/1983 isolate, a characteristic mutation related to its adaptation to domestic birds. To our knowledge A/Turkey/ON/84/1983 genomic sequence is the first and only available entire genomic sequence of a H5N1 AIV from domestic birds in Canada and USA.

Increased mortality was reported in two flocks of Muscovy ducklings from two consecutive hatches originating from the same breeder flock. Coughing, dyspnea, and gasping were observed in some ducklings between 6 and 11 days of age. Opaque white plugs of exudate were seen in the tracheas with some ducklings having multiple tracheal plugs. Tracheal and bronchial epithelium was hyperplastic and superficial epithelial cells contained eosinophilic intranuclear viral inclusions. Virus particles compatible with adenovirus morphology were observed in tracheal epithelial cells by electron microscopy and in the supernatant from cell cultures inoculated with filtered tracheal homogenates. The isolated virus was genetically indistinguishable from duck adenovirus 1 (DAdV-1). Our report confirms for the first time the presence of DAdV-1 in Canada and also reports for the first time adenovirus-associated respiratory disease in ducklings and supports previous findings that some DAdV-1 can be pathogenic even in waterfowl.