Eosinophilia-myalgia syndrome among the non-L-tryptophan users and pre-epidemic cases

Eosinophilia-myalgia syndrome (EMS) has been associated with L-tryptophan (LT) use since 1989, but as yet no etiologic agent has been identified. We describe the non-L-tryptophan associated cases of EMS, and those patients with illness onset preceding the 1989 epidemic.

Review of all patients in the EMS national state based surveillance system administered by the Centers for Disease Control and Prevention (CDC) who satisfied the EMS surveillance case definition.

Of 1345 persons with EMS that satisfied the CDC surveillance case definition for EMS, 26 (2%) persons reported not having used LT (non-LT). Persons who did not use LT were significantly younger (mean age 39 years; p = 0.02) and were more likely than LT users to have onset of their illness before the EMS epidemic (before July 1, 1989) (p < 0.001). Non-LT users reported fewer pulmonary symptoms but had rates of neuropathy and scleroderma-like skin changes similar to LT users. Non-LT users had lower mean eosinophil counts (5.6 x 10(9) cells/I LT users 6.2 x 10(9) cells/I), reported no EMS attributable deaths, but were hospitalized (48%) more often than LT users (34%). Of the 1345 EMS cases, 191 (14%) reported a pre-epidemic illness onset. Symptoms of peripheral edema, rash, scleroderma-like skin change, alopecia, and neuropathy were more prevalent in pre-epidemic patients. Mean eosinophil count was significantly higher for epidemic patients than for pre-epidemic patients (p = 0.004).

Non-LT EMS cases were more likely to be younger and to have a pre-epidemic illness onset of EMS, but otherwise were similar to LT associated EMS cases. Pre-epidemic EMS cases were more likely to report the presence of neuropathy and scleroderma-like skin change, but not pulmonary symptoms, hospitalization, or death.