Why the polio virus often causes paralysis of muscles?

Poliovirus, a highly infectious virus that primarily affects the central nervous system, often causes paralysis of muscles due to its ability to damage motor neurons, which are responsible for controlling muscle movement. Here's an explanation of how the poliovirus leads to muscle paralysis:

1. Initial Infection: Poliovirus enters the body through the mouth and multiplies in the throat and intestines. In most cases, the infection is asymptomatic or causes only mild symptoms. However, in some individuals, the virus can spread to the central nervous system.

2. Invasion of the Nervous System: The poliovirus can travel along nerve fibers to the spinal cord and brain. Once in the central nervous system, it primarily affects the motor neurons located in the spinal cord.

3. Damage to Motor Neurons: The virus infects and replicates within motor neurons, leading to inflammation and damage. This process is known as poliomyelitis. The damaged or destroyed motor neurons can no longer transmit signals to muscles, resulting in muscle weakness or paralysis.

4. Paralysis: As the affected motor neurons lose their function, the muscles they control become paralyzed. Paralysis can range from mild weakness to complete loss of muscle function. The extent and location of paralysis depend on the specific motor neurons affected by the virus.

It's important to note that not all poliovirus infections result in paralysis. Many people who are infected with the virus experience only mild symptoms or no symptoms at all. However, in severe cases, the paralysis caused by polio can be permanent and may lead to lifelong disabilities. Vaccination against polio is essential for preventing this devastating disease and its associated complications.