Outbreak study of workers with irritative symptoms woking in the microbiology and clinical analysis laboratories of a tertiary public hospital

Abstract

Background: In April 2018, an unusually high number of irritative symptoms, nonspecific digestive symptoms and dizziness were identified in workers of the laboratories of microbiology (LAM) and clinical analysis (LCA) of a third level hospital in Mallorca, associated with an unusual smell as well. Objective: To confirm the outbreak, to identify its causes, and to contribute to its prevention and control. Methods: Epidemiological study of the outbreak involving qualitative and quantitative components. The first one was based on the focus group technique. The quantitative study allowed the development of epidemic curves, based on workers visits to the Occupational Health Service (OHS) due to discomfort and episodes of sickness absence (SA). Finally, the available hygiene reports were reviewed, assessing possible relationships with the distribution of cases. Results: Two operational case definitions were established through the focus groups, along with the identification of possible explanations of the outbreak according to the workers' perceptions. The quantitative study confirmed the outbreak in the LAM, but not in the LCA. The SA episodes in the LAM between weeks 16 and 39 exceeded the number of expected cases by four times. The number of visits to the OHS also showed an excess of cases in the same weeks. Conclusions: The quantitative study confirms an epidemic outbreak that has ended, although the qualitative study shows the persistence of bad smell and discomfort. The improvement of epidemiological surveillance systems as a result of the study will facilitate the monitoring and control of other possible outbreaks in the future.