Which of the following statements about poliomyelitis is correct?

Poliomyelitis (polio) is a highly infectious disease caused by the poliovirus, which attacks the motor neurons of the spinal cord and brainstem. In severe cases, the destruction of these nerve cells leads to irreversible paralysis of the limbs, particularly the legs. This is why the statement that polio is capable of paralysing the limbs is correct.

Evaluating the other statements:

• Polio is a viral disease, not a bacterial one. It is caused by the poliovirus, a member of the enterovirus group.
• Effective vaccines exist against polio. The oral polio vaccine (OPV, Sabin) and the inactivated polio vaccine (IPV, Salk) have been used worldwide and have nearly eradicated the disease through mass immunisation programmes.
• While polio can technically infect people of any age, it predominantly affects children under five years old. The claim that it affects both young and old equally is misleading; it is primarily a disease of early childhood, which is why it was historically called "infantile paralysis."

Remember: polio is viral, vaccine-preventable, and primarily causes paralysis by destroying motor neurons in the spinal cord.