What is a significant effect of the poison produced by Clostridium tetani?

The poison produced by Clostridium tetani is called tetanospasmin, which is responsible for the clinical symptoms of tetanus. A significant effect of this toxin is the stimulation of motor neurons, leading to sustained muscle contractions. This results in the characteristic muscle spasms that are painful, as the continuous contraction can lead to discomfort, muscle fatigue, and injury. This painful muscle contraction is also known as spastic paralysis.

In contrast, other options, such as severe joint inflammation and tissue necrosis, are not directly related to the action of tetanospasmin. While tetanus can lead to complications and secondary issues such as muscle damage or joint problems due to immobility, these are not primary effects of the toxin itself. Painless muscle contraction is also not representative of the clinical effects of tetanus, as the contractions induced by this toxin are indeed painful. Understanding the action of tetanospasmin and its effect on the nervous system highlights the importance of proper vaccination against tetanus to prevent these severe manifestations.