Mycoplasma gallisepticum

Mycoplasma gallisepticum (MG) is a bacterium belonging to the class Mollicutes and the family Mycoplasmataceae. It is the causative agent of chronic respiratory disease (CRD) in chickens and infectious sinusitis in turkeys, chickens, game birds, pigeons, and passerine birds of all ages. Mycoplasmosis is the infection of Mycoplasma bacteria. Mycoplasmas have many defining characteristics. Mycoplasma lack cell walls, have highly variable surface proteins and a distinctive plasma membrane, and are the smallest self-replicating prokaryotes. Mycoplasma can cause disease in humans, animals, insects, and plants. Mycoplasma attach to host epithelial cells, such as in the respiratory tract, which causes cell damage and inflammatory response. There are currently over 100 species of Mycoplasma known. The following have been isolated from wild birds: Mycoplasma buteonis, Mycoplasma corogypsi, Mycoplasma falconis, Mycoplasma gypis, Mycoplasma sturni, and Mycoplasma gallisepticum. M. gallisepticum has the most significant effect on wild birds. The disease was first described in 1905. It was described as a respiratory disease that was found in domestic poultry. However, it wasn’t for another 50 years that the causative agent, Mycoplasma gallisepticum, was cultivated. In 1980, M. gallisepticum was isolated from wild turkeys in Colorado, Georgia and California. This was because of the mixture and close contact between the wild turkeys and domestic poultry during feeding time. This led to an increased awareness of the disease and health monitoring protocols in wild turkey restoration programs. These protocols are still being followed today by state wildlife agencies. House finches were introduced into the eastern U.S. from California in the 1940s after being released from the pet trade that became illegal. House finches at the time were called Hollywood finches. In January 1994, the first house finches with symptoms of M. gallisepticum were observed in the Washington DC area, including part of Maryland and Virginia.In the winter of 1994, an epidemic of mycoplasmal conjunctivitis caused by M. gallisepticum began in house finches. In 1994, efforts were made across North America to collect data on the spread and prevalence of M. gallisepticum using the House Finch Disease Survey. A few years later the epidemic that started in the mid-Atlantic states spread to the entire eastern population of house finches. The only house finches to have this disease are those introduced to the eastern United States. It is believed that these house finches are less resistant to the disease because they were introduced and were highly inbred. The disease was stopped by the Rocky Mountains. M. gallisepticum infection in house finches (Haemorhous mexicanus) causes conjunctivitis with the symptoms of periocular swelling, swollen eyelids, ocular and nasal discharge, impaired vision, depression, and weight loss. These symptoms cause house finch populations to decline due to increased predation and susceptibility to trauma from impaired vision. House finch conjunctivitis is most frequent during colder months when birds are using bird feeders and can cause birds to be reluctant to leave the feeders. Birds have been seen rubbing their eyes on branches or on bird feeders, which can help spread the disease. Some major clinical signs of M. gallisepticum in chickens include those of respiratory distress such as coughing, sneezing, slight to marked rales, and difficulty breathing.Swollen eyelids, ocular discharge, and loss of sight are signs and symptoms that are very important for this disease as well. Poor productivity, leg problems, nasal discharge, stunting, inappetence, slow growth, reduced hatchability, reduced chick viability, and abnormal feathers are also some relevant clinical signs of the disease. M. gallisepticum infections in chickens result in relatively mild catarrhal sinusitis, tracheitis, and airsacculitis.' M. gallisepticum causes respiratory infection in turkeys which can induce sinusitis, pneumonia, and airsacculitis. With infectious sinusitis, the birds have symptoms of coughing, swollen sinuses, nasal and ocular discharge, tracheal rales, labored breathing, impaired vision, depression and weight loss. The disease can even cause death and found to especially occur if combined with E. coli. Outbreaks in turkeys occur at an early age usually between 8 and 15 weeks and about 90% of birds show signs. With breeding females, there could be a decline in egg production. 'Occasionally an encephalitic form is seen in growing birds. A tenovaginitis may also develop and the organism can be found in the oviduct and semen of infected male birds, leading to infection in the egg and eventually of the young poulty.'