What are the common signs and symptoms of tetanus infection?

The common signs and symptoms of tetanus infection primarily revolve around muscle stiffness and spasms due to the effects of the tetanospasmin toxin produced by the Clostridium tetani bacteria. Painful facial muscle spasms, also known as trismus or "lockjaw," are characteristic of tetanus and indicate the involuntary constriction of the jaw muscles. Alongside facial muscle spasms, an elevated fever can occur as the body mounts an immune response to the infection. This aligns with the body's reaction to the severe muscular and systemic disturbances caused by the toxin.

The other options do not reflect the symptoms of tetanus. Thickened and brittle nails do not have a connection to tetanus, which primarily affects the nervous and muscular systems. Itching and scaling of the groin relate more to fungal or dermatological conditions, while red-brown snakelike scaling plaque could suggest certain skin disorders, neither of which are associated with tetanus. Therefore, the identification of painful facial muscles and elevated fever as signs of tetanus infection is accurate and reflects the critical physiological response to this serious disease.