Test description :
NDV is spread primarily through direct contact between healthy birds and the bodily discharges of infected birds. The disease is transmitted through infected birds' droppings and secretions from the nose, mouth, and eyes. NDV spreads rapidly among birds kept in confinement, such as commercially raised chickens. The disease can be spread easily by mechanical means. Virusbearing material can be picked up on shoes and clothing and carried from an infected flock to a healthy one. The incubation period for the disease ranges from 2 to 15 days. An infected bird may exhibit several signs, including respiratory signs (gasping, coughing), nervous signs (depression, inappetence, muscular tremors, drooping wings, twisting of head and neck, circling, complete paralysis), swelling of the tissues around the eyes and neck, greenish, watery diarrhea, misshapen, rough or thin-shelled eggs and reduced egg production.