Fowlpox is the worldwide disease of poultry caused by viruses of the family Poxviridae and the genus Avipoxvirus. The viruses causing fowlpox are distinct from one another but antigenically similar, possible hosts including chickens, turkeys, quail, canaries, pigeons, and many other species of birds. There are two forms of the disease. The first is spread by biting insects (especially mosquitoes) and wound contamination and causes lesions on the comb, wattles, and beak. Birds affected by this form usually recover within a few weeks. It can also be transmitted via inhalation or ingestion of dust (or dander, representing virus-infected cells shed from cutaneous lesions), or aerosols, leading to the 'diphtheritic form' of the disease, with lesions on the mucous membranes of the mouth, pharynx, larynx, and sometimes trachea. The second form is spread by inhalation of the virus and causes a diphtheritic membrane to form in the mouth, pharynx, larynx, and sometimes the trachea. The prognosis for this form is poor.