Fatiguing illness among employees in three large state office buildings, California, 1993: was there an outbreak?
Shefer, A, Dobbins, J G, Fukuda, K et al. · Journal of psychiatric research · 1997 · DOI
Quick Summary
Researchers surveyed over 3,300 state office workers in California to see if there was an unusual outbreak of long-lasting fatigue or ME/CFS-like illness. They found that about 18% of workers reported fatigue lasting at least a month, but this rate was similar in buildings thought to have clusters and in a comparison building, suggesting there was no outbreak. The study identified that certain groups—including women, Hispanic workers, Native American workers, and those with lower income or education—were more likely to report fatigue.
Why It Matters
This study is important because it uses a systematic, population-based approach to investigate alleged ME/CFS outbreaks in occupational settings—a common concern that is rarely rigorously evaluated. By identifying social determinants and demographic risk factors for fatiguing illness, it highlights that ME/CFS and fatigue-related conditions affect vulnerable populations disproportionately and that outbreak investigations must account for underlying population disparities.
Observed Findings
18.7% of surveyed employees reported fatigue lasting at least one month; 11.5% reported fatigue lasting at least six months; 2.3% had symptoms compatible with CFS-like illness.
Female employees were 1.5 times more likely to report one-month fatigue and 3.2 times more likely to have CFS-like illness than males.
Hispanic and Native American employees had elevated odds of reporting one-month fatigue (OR 1.7 and 2.4, respectively).
Employees with household income below $50,000 and those without college education were 1.3 times more likely to report one-month fatigue.
Prevalence rates of all fatigue categories were not significantly different among the three office buildings studied.
Inferred Conclusions
No outbreak of CFS-like illness occurred in the two state office buildings; prevalence of fatiguing illness was comparable to the control building.
Female sex is a strong risk factor for ME/CFS-like illness in occupational populations.
Socioeconomic status and ethnicity are important demographic risk factors for fatigue lasting one month or longer, suggesting health disparities in fatiguing illness.
Remaining Questions
What are the biological mechanisms linking female sex, ethnicity, and socioeconomic status to increased risk of ME/CFS and prolonged fatigue?
What This Study Does Not Prove
This study does not prove that environmental or occupational exposures play no role in ME/CFS etiology—the case definition used was compatible with, but not equivalent to, strict CFS criteria, and the study design cannot determine causation. The finding of similar prevalence across buildings does not exclude the possibility of risk factors specific to office environments more broadly. Additionally, cross-sectional questionnaire data may not capture acute incident cases or severe cases unable to work.
Tags
Symptom:Fatigue
Method Flag:PEM Not DefinedWeak Case DefinitionExploratory Only
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
Could the lack of building-specific differences reflect widespread occupational or environmental exposures common to all three buildings rather than truly ruling out workplace risk factors?
What is the longitudinal trajectory of these fatiguing illnesses, and what proportion of those with one-month or six-month fatigue go on to develop chronic ME/CFS?
Why are certain demographic groups at higher risk, and are there unidentified social stressors, healthcare access barriers, or biological factors contributing to these disparities?