New concepts on tetanus immunization: naturally acquired immunity.

Comments were made on misinterpretations concerning the natural resistance and natural immunization against tetanus. Arguments were given explaining why the disease itself did not determine adequate immunity. When, however, adequate conditions appear, tetanus toxin is known to stimulate the immune system and produce detectable humoral antibodies. Various possibilities resulting from the postulated harboring of tetanus bacilli by the human body and their eventual toxin production were analyzed and related to the human tetanus pathology. The existence of natural immunization was unquestionably demonstrated by presence of protective levels of tetanus antitoxin in the blood of the majority of 59 surveyed subjects considering that none of them had ever received any tetanus toxoid and most of them never received a single shot of any drug. The results of this survey originated a few arguments that may support the answer to some still intriguing phenomenona such as: 1. The relatively small number of cases of overt disease among people and animals born and living in large tetanus-risk regions all over the world. 2. The existence of "poor responders" and "good responders" to the primary tetanus toxoid stimulus. 3. The age distribution of tetanus showing evident prevalence among newborns and children. 4. The wide individual variations in the clinical picture of human tetanus as indicated by the localization and limitation of the symptoms and their severity.