Objective: 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.
Methods: 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.
Results: 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).
Conclusion: 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.