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.

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In this study, we aimed to molecularly characterize 14 whole genome sequences of chicken astrovirus (CAstV) isolated from samples obtained from white chick syndrome (WCS) outbreaks in Western Canada during the period of 2014–2019. Genome sequence comparisons showed all these sequences correspond to the novel Biv group from which no confirmed representatives were published in GenBank. Molecular recombination analyses using recombination detection software (i.e., RDP5 and SimPlot) and phylogenetic analyses suggest multiple past recombination events in open reading frame (ORF)1a, ORF1b, and ORF2. Our findings suggest that recombination events and the accumulation of point mutations may have contributed to the substantial genetic variation observed in CAstV and evidenced by the current seven antigenic sub-clusters hitherto described. This is the first paper that describes recombination events in CAstV following analysis of complete CAstV sequences originated in Canada.

Arthropod-borne viruses (arboviruses) threaten the health of humans, livestock, and wildlife. West Nile virus (WNV), the world’s most widespread arbovirus, invaded the United States in 1999 and rapidly spread across the county. Although the ecology of vectors and hosts are key determinants of WNV prevalence across landscapes, the factors shaping local vector and host populations remain unclear. Here, we used spatially-explicit models to evaluate how three land-use types (orchards, vegetable/forage crops, natural) and two climatic variables (temperature, precipitation) influence the prevalence of WNV infections and vector/host distributions at landscape and local spatial scales. Across landscapes, we show that orchard habitats were associated with greater prevalence of WNV infections in reservoirs (birds) and incidental hosts (horses), while increased precipitation was associated with fewer infections. At local scales, orchard habitats increased the prevalence of WNV infections in vectors (mosquitoes) and the abundance of mosquitoes and two key reservoir species, the American robin and the house sparrow. Thus, orchard habitats benefitted WNV vectors and reservoir hosts locally, creating focal points for the transmission of WNV at landscape scales in the presence of suitable climatic conditions.

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.