A 24-year-old male presents with numbness, weakness, and soreness in all four limbs, accompanied by difficulty swallowing and speaking for 15 hours. No urinary dysfunction is noted. Examination reveals flaccid paralysis and absent tendon reflexes in all limbs. Lumbar puncture on the second day shows normal cerebrospinal fluid (CSF) pressure and laboratory tests. Muscle enzymes are normal. Which of the following conditions should be considered?