What is a common symptom of tetanus?

Muscle contractions are the hallmark symptom of tetanus, a serious bacterial infection caused by the bacterium Clostridium tetani. This condition is characterized by severe muscle stiffness and spasms, particularly in the jaw, neck, and back, leading to the characteristic "lockjaw" or difficulty opening the mouth. These muscle contractions can be painful and may result in complications such as difficulty with breathing or swallowing.

The other choices do not encapsulate the main features of tetanus. While frequent headaches, nausea, and fatigue can be associated with various illnesses, they are not defining symptoms of tetanus. The specific type of muscle contractions that occur in tetanus is due to the toxin produced by the bacteria, which interferes with normal motor neuron signaling, leading to these characteristic muscular responses.