Avian Mycoplasmosis Study Guide

Overview and Clinical Importance

Avian mycoplasmosis is a collective term for clinical diseases caused by pathogenic Mycoplasma species in poultry. The two most economically significant pathogens are Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS). These organisms are WOAH-listed respiratory pathogens that cause substantial economic losses worldwide through decreased weight gain, reduced feed conversion efficiency, decreased egg production, increased embryo mortality, carcass condemnation, and treatment costs.

Mycoplasmas are unique bacteria belonging to the class Mollicutes. They lack a cell wall, which has important implications for antibiotic selection. They are the smallest self-replicating prokaryotes known and possess highly variable surface proteins that enable immune evasion.

Etiology and Classification

Four major pathogenic mycoplasmas affect poultry: M. gallisepticum (MG), M. synoviae (MS), M. meleagridis (MM), and M. iowae (MI). MG and MS are the most clinically significant and are WOAH-listed pathogens.