Poxvirus Infection

Avian pox is a globally distributed viral disease in a broad range of wild, captive, and domestic birds, including chickens and turkeys, caused by large DNA viruses of Poxviridae family. The slow-spreading disease is characterized by the formation of proliferative lesions of the unfeathered skin areas (cutaneous form or dry pox) or the upper respiratory and digestive tract (diphtheritic form or wet pox). In commercial poultry, avian poxvirus infection is associated with a significant economic impact, constrained by a drop in egg production, reduced growth rates in young birds, and increased mortality. Among other avian species, turkeys are also broadly affected. The disease can be controlled by vaccinating turkeys using live attenuated fowlpox vaccine by thigh application at the age of about 8 weeks. In breeder flocks, a booster may be necessary before the start of production. After a week of vaccination, birds should be checked for a “vaccinal take,” such as skin swelling or scab, at the application site to assess the success of the vaccination. In this chapter, we will discuss in more detail the etiology, clinical signs, diagnosis, and vaccination of poxvirus in turkeys.