Natural tetanus immunity in lepromatous leprosy patients.

35 lepromatous leprosy patients with recurrent trophic ulcers were analysed for tetanus antitoxin levels by passive haemagglutination test (PHA). 42.85% patients and 32% controls had protective levels of antitoxin in their serum (greater than or equal to 0.1). All the patients (100%) demonstrated measurable antitoxin levels. The findings indicate immunological protection from tetanus and support the clinical impression of it's rarity in leprosy patients.