Newcastle disease primarily affects the respiratory system and can lead to lesions that are particularly evident in various tissues. The damage caused by the virus is due to its targeting of multiple systems within the body, particularly the respiratory epithelium, neurons, and lymphoid tissues.
Lymphoid tissues are critical to the immune response, and damage here can impair the overall ability of the host to respond to infections. Additionally, the virus's neurotropic nature means it has a propensity to affect neurons, which can result in neurological signs.
Therefore, lesions resulting from Newcastle disease can be attributed to the combined effect of viral replication in lymphoid tissues and neurons. This multifocal infection is significant for understanding the clinical manifestations of the disease, which can range from respiratory distress to neurological symptoms. This multifaceted approach highlights the importance of recognizing that Newcastle disease does not constrain its damage to a single body system but rather impacts several key areas crucial for both immune response and neurological function.