INTRODUCTION

Clostridium tetani is an obligatory anaerobic spore-forming microorganism. Spore germination and proliferation occurs in environments with low oxygen tension (e.g., necrotic tissue, frostbite, crush injuries). The two main toxins released by C. tetani are tetanospasmin and tetanolysin. Tetanospasmin, also known as tetanus toxin, is the neurotoxin that is responsible for the clinical manifestations of tetanus. It enters the nervous system through the neuromuscular junctions of alpha motor neurons. Tetanospasmin travels to the motor neuron body by retrograde axonal transport and then spreads transsynaptically to other neurons preventing the release of inhibitory neurotransmitters such as glycine and gamma-aminobutyric acid (GABA). Uninhibited motor neuron firing results in sustained muscular contractions and rigidity. Tetanolysin damages cell membranes and lowers the oxygen content of tissue, providing a favorable environment for proliferation of the organism.

EPIDEMIOLOGY

Tetanus is rare in the developed world, but remains widespread in developing countries. Large-scale immunization protocols, especially for infants and school-aged children, have significantly reduced the number of cases worldwide. Other factors such as availability of tetanus immunoglobulin, improved wound care management and childbirth practices, and advances in supportive care and airway management have also resulted in a decline in tetanus-associated morbidity and mortality.

Neonatal tetanus accounts for the majority of cases worldwide. However, in the United States, tetanus occurs primarily in adults, with the majority of cases reported in older adults and injection drug users (IDUs).