This case brings together three interrelated conditions in a single healthcare worker: an occupationally acquired chronic hepatitis C infection, a subsequently acquired latent tuberculosis infection, and hepatotoxicity arising during preventive treatment of the latter. Each raises distinct questions for occupational medico-legal assessment.

First, the attribution of hepatitis C as an occupational disease was hindered by the absence of formal notification of the 2003 percutaneous exposure. Although the worker's occupational history, with prolonged direct contact with people who use drugs and a documented reported exposure, was highly consistent with occupational acquisition, the lack of a contemporaneous record weakened the formal chain of evidence [1]. This illustrates how the recognition of occupational disease may depend as much on documentation as on clinical plausibility.

Second, latent tuberculosis infection is not, in itself, contemplated within the legal framework of occupational diseases, even when acquired through a documented workplace exposure. This creates a gap between the occupational origin of the infection and its formal recognition [2,3].

Third, the hepatotoxicity that developed during isoniazid treatment raised the question of whether it should be considered a treatment complication or an aggravation of a pre-existing, occupationally related liver condition. Isoniazid hepatotoxicity is well described, is more frequent with advancing age, and may be influenced by underlying liver disease; the patient's age and history of chronic hepatitis C are relevant to this assessment, even though the infection had been cured years earlier [4,5,6]. Determining the predominant condition to be considered for the purposes of occupational disease recognition is not straightforward when these factors overlap.

Taken together, the case underscores the multifactorial nature of medico-legal assessment in occupational health, which must weigh the interaction between occupational infection, pharmacological treatment, and the worker's prior clinical history. It also highlights the central role of a detailed clinical history and rigorous recording of occupational exposures: early and accurate documentation is essential for later medico-legal evaluation, and its absence can be decisive. Healthcare workers remain continuously exposed to complex, multifactorial biological risks, reinforcing the need for robust occupational health surveillance and reporting systems [1,2].

This case illustrates how occupational infection, its treatment, and prior clinical history may intersect in a single healthcare worker, creating a genuine diagnostic and medico-legal dilemma. Medico-legal assessment in occupational medicine should consider all contributing factors in the genesis of occupational disease, rather than viewing each condition in isolation. The case reinforces two practical messages: the immediate and rigorous notification of occupational exposures is essential for future medico-legal assessment, and healthcare workers require continued protection and surveillance against complex biological risks. Structured documentation and a multidisciplinary approach are key to fair and accurate recognition of occupational disease.

Author Contributions: All authors contributed to the conception of the report, acquisition and interpretation of the clinical information, drafting and critical revision of the manuscript for important intellectual content, and final approval of the version to be published. João Coutinho de Sousa acts as guarantor and takes responsibility for the integrity of the work.
Competing Interests: The authors declare that there is no conflict of interest.
Grant Information: The author(s) received no specific funding for this work.
Acknowledgments: Not applicable.
Ethical Considerations: Informed consent for the publication of this anonymized case was obtained from the patient. The report contains no identifying information. The study was conducted in accordance with the principles of the Declaration of Helsinki.