The other day a relative was accidentally injured by a rusty nail while working, and came to the hospital after pulling it out and treating it hastily. The surgeon told my relative after asking for medical history and looking at the wound. He said that the nail tract should be cut open to remove the foreign body and open the wound. My relative did not understand, but after the doctor told him about tetanus, he finally got it. Tetanus is an idiosyncratic infection often associated with trauma. In addition to the possibility of occurring after various traumas, it can also occur in mothers and newborns who give birth in unclean conditions. The organism is Clostridium tetani, which is exclusively anaerobic and Gram-stain positive. Normally present in the intestinal tract of humans and animals, with the feces out of the body, in the state of budding cells distributed in nature, especially in the soil is common. This bacterium has strong resistance to the environment and can resist boiling. The contamination rate of traumatic wounds is high, and the contamination rate in the battlefield can reach 25% to 80%. However, the incidence of tetanus only accounts for 1% to 2% of those contaminated, suggesting that the onset must have other factors, the main factor is the hypoxic environment. In the case above, after the nail was pulled out, a hypoxic environment was formed in the nail path. In trauma, Clostridium tetani can contaminate deep tissues (e.g., blind canal trauma, deep stab wounds, etc.). If the external wound opening is small, and the wound is filled with necrotic tissue or blood clots, or filled too tightly, local ischemia, etc., a hypoxic environment suitable for the growth and reproduction of the bacterium is formed. If there is also an aerobic bacterial infection, the latter will consume the oxygen remaining in the wound, making the disease more likely to occur. The incubation period for tetanus is usually 7 to 8 days and can be as short as 24 hours or as long as several months or years. The shorter the incubation period, the worse the prognosis. About 90% of patients develop tetanus within 2 weeks after the injury, and occasionally patients develop tetanus symptoms after the removal of foreign bodies that have remained in the body for many years. The anterior symptoms are generalized weakness, dizziness, headache, chewing weakness, local muscle tightness, tearing pain, and hyperreflexia. Typical symptoms are paroxysmal intense spasms based on tense muscle contractions (muscle tonicity, stiffness), usually the first muscle group affected is the masticatory muscles, followed by the facial expression muscles, neck, back, abdominal, limb muscles, and finally the diaphragm. The corresponding signs are: difficulty in opening the mouth (teeth closed), frowning, mouth corner down, grinning “bitter smile”, neck straightening, head tilting back; when the back and abdominal muscles contract at the same time, because the back muscle group is more powerful, the trunk is twisted into an arch, combined with the neck, limbs of the knees, bent elbows, half clenched fist and other spastic posture, forming “When the diaphragm is affected, the face and lips are blue and the ventilation is difficult, and apnea may occur. These seizures can be triggered by minor stimuli such as light, sound, contact, and water. The length of the interval varies, and frequent seizures often indicate a serious condition. The seizures are characterized by clear consciousness and painful expressions, and each seizure lasts from a few seconds to several minutes. Intense muscle spasms can cause muscle rupture or even fracture. Spasm of the bladder sphincter can cause urinary retention. Sustained respiratory muscle and diaphragm spasms can cause respiratory arrest. Patients die mostly from asphyxia, heart failure, or pulmonary complications. The duration of the disease is usually 3 to 4 weeks. If treated aggressively and without specific complications, the seizures can gradually decrease in severity, with an average remission period of about 1 week. However, muscle tension and hyperreflexia can continue for a period of time; some psychiatric symptoms, such as hallucinations, speech and confusion of action, can also appear during the recovery period, but they can mostly recover on their own.