Reticuloendotheliosis virus

Reticuloendotheliosis virus (REV) is one of three tumor-causing viruses that commonly affect chickens worldwide. It is a gammaretrovirus which causes tumors to develop in affected chickens, and involves either B or T lymphocytes.

Transmission: Poultry can become infected vertically (through the egg from parents to chick), or horizontally (through contamination of the environment with feces or skin dander, direct contact with respiratory secretions or skin), or through mosquitoes.

Chickens can also become infected by receiving the Marek's disease virus vaccine or fowl pox vaccine, which are frequently contaminated.