What causes poliomyelitis?

Poliomyelitis is caused by a viral infection, specifically from the poliovirus, which predominantly affects the central nervous system. The virus leads to inflammation of the gray matter in the spinal cord, which can result in muscle weakness, paralysis, and other neurological symptoms. The pathophysiologic mechanism involves the virus entering the body, typically through the oral route, and then spreading to the nervous system where it targets motor neurons. This inflammatory response can lead to the destruction of these neurons, contributing to the classic symptoms associated with polio.

The other options do not accurately describe the causation of poliomyelitis. For instance, a bacterial infection of the brain pertains to different conditions such as meningitis rather than polio, while an autoimmune response affects muscle coordination in diseases like multiple sclerosis but is not linked to poliovirus. Additionally, a genetic disorder causing muscle weakness, like muscular dystrophy, is unrelated to viral infections and their effect on the nervous system. Understanding how the poliovirus affects the spinal cord is crucial for recognizing the disease's impact and implications.