Fowlpox are one of the most serious infectious diseases in poultry farming in terms of commercial losses. Systematic, preventative use of live vaccines and improved hygiene conditions are the reasons why Avian pox infections have not been observed in poultry that has been kept intensively for a long time. However, there have been repeated Fowlpox infections in Austrian poultry livestock since 2006, possibly as a result of the forgoing of the protective vaccinations that had previously been carried out. In Austria, Fowlpox is not a disease that must be reported to the authorities.
The infection of poultry and other birds with Avian pox is caused by a virus of the genus Avipox (subfamily Chordapoxvirinae, family Poxviridae). There are thirteen species of this virus that are known members of the genus Avipox to date, the names of which are based primarily on the species of bird the virus has been isolated from. Phylogenetic studies based on the virus sequence distinguish five clusters, of which Cluster 1 includes the pox virus species for poultry and fowl (Fowlpox virus, Turkeypox virus, Sparrowpox virus).
The Avipox virus has a rectangular shape, measuring 330x280x200 nm and is characterised by a surface with a filament protein structure (Image 2). Like all other pox viruses, the Avipox virus is made of an envelope in the form of a double membrane made of lipoproteins (le), two lateral bodies (lb) and a central, bi-concave core (co) or nucleotide. The core contains the viral genome, closely associated with proteins arranged in an s-shape (Image 3). The Canarypox virus genome is larger than the Fowlpox virus (FWPV) at 365 kbp. The genome of the Fowlpox virus (field isolate) is 288 kbp in size in its entire sequence and is barely distinguishable from the genome of the Fowlpox vaccine. Various tests in Australia and the USA found evidence of an integration of a reticuloendotheliosis virus (REV)-specific sequence into the FWPV genome. The pathogenicity of FWPV increased by REV integration has been discussed as a potential factor in the incidence of Fowlpox in vaccinated livestock in the USA.
Hosts, Epidemiology, Risk to Humans
Fowlpox infections are widely spread and occur in poultry, exotic birds, raptors and wild birds. To date, Avian pox has been diagnosed in over 230 bird species, across 23 orders. Animals of all ages can be affected by this disease. The infection usually occurs during the cooler seasons (autumn, winter); additionally, sporadic infections may take place between frequently occurring cases after longer intervals. The acquisition of poultry without maintaining quarantine standards presents a substantial risk in terms of importing the pathogen into the livestock kept.
Avipox viruses are harmless to humans. However, adhering to general hygiene regulations (washing hands after handling infected animals) is recommended, given the potential danger of spreading the disease.