I would first like to say that I am sorry your bird is not feeling well, and I hope it gets better soon.
Now, with Mareks, most birds (if they are to get it ) will catch it between 5-25 weeks of age. The most common type are eye, visceral (tumor producing), and nerve.
The nerve version is known by some Fanciers as 'down in the leg', and symptoms range from slight to severe paralysis in the wings, legs, or neck, and usually results in death from trampling by other chickens, and/or the inability to get to food and water. There can be 'transient' paralysis that disappears after a few days, such as a dropped wing that suddenly corrects itself. In the eye version, you'll detect an irregularly shaped pupil, cloudy eye ('gray eye'), or sensitivity to light. It can result in blindness. The visceral version should be considered when a bird is just generally 'wasting'.
Mareks is extremely contagious but does not spread vertically (to the egg). Youngsters should develop a natural immunity (called 'age resistance'), by the time they're five months old. This is one of the reasons it is important to raise your youngsters separately from your oldsters. The older birds that have encountered Mareks and have managed to survive are carriers. New birds coming in from other flocks are always potential carriers.
Cutaneous form: Enlarged reddened feather follicles and white bumps on the skin that form
brown crusty scabs.
Neural form: Characterized by one, all, or none of the following symptoms -
Progressive paralysis, usually of the leg or wing, a typical leg-paralysis victim will
have one leg extended forward and one leg extended back. A swelling of the sciatic
nerve is the cause.
Weight loss
Labored breathing
Diarrhea
Starvation and death due to an inability to reach feed and water and to trampling by pen mates.
Cutaneous (skin form)
Neural (nerve form)
Ocular (eye form)
Visceral (internal-organ form)
Ocular form:
Gray eye color
Misshapen iris
Weight loss
Blindness
Death
Visceral Form: Tumors on internal organs including heart, ovary, liver and lung.
Hope this helps and good luck
