Which chicken disease is characterized by causing paralysis in affected birds?

Marek's Disease is indeed characterized by paralysis and is a significant concern in poultry health. This viral disease affects chickens by attacking their nervous system, which can lead to various symptoms, including lameness and paralysis of the legs, wings, or neck. Infected birds may exhibit a characteristic drooping posture as they struggle to move.

The virus responsible for Marek's Disease is highly contagious and can remain in the environment, infecting other birds through contaminated dust or feather dander. The paralysis seen in affected birds can be a clear indicator of this disease, making it distinct from other poultry health issues.

In contrast, while Avian Influenza can lead to various symptoms including respiratory distress, it primarily affects the respiratory system rather than causing paralysis. Coccidiosis is an intestinal disease caused by parasites and does not result in paralysis but rather affects the digestive system, leading to diarrhea and general poor condition. Newcastle Disease can cause respiratory symptoms and neurological signs, but paralysis is not as typical or defining as it is with Marek's Disease.

Thus, Marek's Disease is uniquely identified by its association with paralysis, making it the correct answer in this context.