A case of clinical tetanus in a patient with protective antitetanus antibody level.

To the Editor: Human tetanus is rare in the United States, with about 40 cases reported each year. (1) We report a case of generalized tetanus in a patient with a generally accepted "protective level" of tetanus antibody (0.01 antitoxin units per milliliter (U/mL), (2) and to stress the fact that tetanus remains a clinical diagnosis.

A 58-yr-old previously healthy man was found unresponsive. History was remarkable for well-controlled diabetes mellitus, hypertension and a dog bite to his left index finger eight days before admission. He was seen by a physician and given levofloxacin, but not tetanus immunization. The patient could not recall when he last received a tetanus immunization. He was in mild respiratory distress, and was afebrile with stable blood pressure. He responded only to painful stimuli. Extensive board-like rigidity involving the neck, back, and extremities was noted. A crusted, dry wound was noted at the dorsum of the left index finger 1 cm in length and 2 mm in depth. Urine toxicology was negative. Leukocyte count was 20,000 per [mm.sup.3], serum creatine kinase was 7,068 U/L, and serum creatinine was 1.6 mg/dL. Computed tomography of the brain was normal. A serum antitetanus antibody assay taken before immunoglobulin therapy was 0.22 U/mL. After treatment with tetanus toxoid, antitetanus immunoglobulin and 10 days of IV penicillin, the patient returned to baseline status.

There are approximately 15 cases of human tetanus with a "protective" antibody level of >0.01 U/mL. (3-5) The presence of a protective antitetanus antibody level should not be used as the basis to exclude a diagnosis of human tetanus. The amount of tetanus toxin to which the patient was exposed may be high enough to overwhelm the existing antibodies or the antibodies may not be uniform in function. Furthermore, the "true protective antibody level" in humans may be higher than the current accepted level. (3-5)

Alvaro Beltran, MD

Maimonides Medical Center

Brooklyn, NY

Eddie Go, MD

Mahenaaz Haq, MD

Hillary B. Clarke, MD

Muhammad Zaman, MD

Rose A. Recco, MD

Coney Island Hospital

Brooklyn, NY

References

1. Pascual FB, McGinley EL, Zanardi LR, et al. Tetanus surveillance-United States, 1998-2000. MMWR Surveill Summ 2003;52:1-8.

2. Sneath PAT, Kerslake EG, Scruby F. Tetanus immunity: the resistance of guinea pigs to lethal spore doses induced by active and passive immunization. Am J Hyg 1937;25:464-476.

3. Crone N, Reder A. Severe tetanus in immunized patients with high anti-tetanus titers. Neurology 1992;42:761-764.

4. Berger SA, Cherubin CE, Nelson S. Tetanus despite preexisting antitetanus antibody. JAMA 1978;240:769-770

5. Atkinson WL, Pickering LK, Schwartz B, et al. General recommendations on immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP) and the American Academy of Family Physicians (AAFP). MMWR 2002;51:1-35.

Letters to the Editor are welcomed. They may report new clinical or laboratory observations and new developments in medical care or may contain comments on recent contents of the Journal. They will be published, if found suitable, as space permits. Like other material submitted for publication, letters must be typewritten, double-spaced, and must not exceed two typewritten pages in length. No more than five references and one figure or table may be used. See "Information for Authors" for format of references, tables, and figures. Editing, possible abridgment, and acceptance remain the prerogative of the Editors.