Marek Disease is a bacterial infection that mostly affects chickens in poultry farms as a result of herpes virus

 

Marek Disease is a highly contagious bacterial infection of chicken characteristic by T-cellullar lymphomas, parainfluenza, and peripheral nerve paralysis. Clinical features include fever, persistent lymphadenopathy, generalized aetiomania, and lymphocytic anemia. Common diagnostic criteria for this condition include clinical presentation, history, and physical examination. Biopsy and serological testing is the key to confirm diagnosis. T-lymphocytes in the bone marrow support the growth of various immune cells. Hence, the diagnosis of Marek Disease can be achieved by immunohistochemistry, blood culture, or biopsy.

Marek Disease is caused by an acanthamoeba known as M. acanthamoeba, which is part of the herpes family. Humans are the hosts of this spore, which invades the chickens' bodies through the wounds. M. acanthamoeba prefers dark, warm, moist areas, such as those that are unclothed or those that have not been properly cleaned. M. acanthamoeba is not active during daylight hours. Thus, common clinical manifestations include lymphocytic anemia, generalized aetiomania, and neurological symptoms, including ataxia, dysphagia, myelination, seizures, and permanent eye palsy or loss.

This disease is highly transmissible among chickens and can easily be transmitted from one bird to another. The infectious agent is extremely virulent and is able to survive for more than five days without feeding. Marek Disease attacks young birds who are still immature, and it is often fatal. The name "Marek Disease" is derived from the name of the veterinary doctor who first recognized and described this condition.

A variant on Marek Disease is Chickenpox, which may also be transmitted among chickens. The symptoms of this disease in chickens are similar to that of Marek Disease; however, these include a rash, fever, and chicken pox signs. The difference lies in the fact that there is no characteristic rash or pox signs seen in the case of Chickenpox, whereas Marek Disease produces lesions in the body, which look like chicken pox. It is infectious through direct contact with an infected bird or the spores of this disease. For instance, in April 2021, the German pharmaceutical company, Boehringer Ingelheim, launched a new range of vaccines for Marek’s disease in the U.K. to enhance protection for breeders and broilers.