Occupational diseases caused by biological agents

Bulgarian Medical Journal, 2025, 19(1), 19-28.

J. Doncheva- Dilova, V. Milanov

Department of Occupational Diseases, Medical University, University Hospital “Sv. Ivan Rilski” – Sofia

Abstract. Biological agents are defi ned as microorganisms, including genetically modifi ed, cell cultures and human endoparasites. Occupational exposure to them can lead to acute or chronic immuno-allergic diseases, infections, poisoning or toxicity, irritant eff ects. Some biological agents are classifi ed by the International Agency for Research on Cancer as Group I carcinogens. Risk assessment and management of biological agents in the workplace is a legal requirement in the European Union. Based on expert estimates, in 2021, there were 550,000 deaths worldwide due to occupational exposure to biological factors. Coronavirus disease 2019 (COVID-19) was responsible for 230,000 work-related deaths in 2021. In Bulgaria, for the period 2009-2022, only 13 cases of occupational diseases caused by biological agents were recognized. The clinical picture, diagnosis and treatment of occupational diseases caused by biological agents do not diff er from non-occupational infections. The main diffi culties in occupational risk assessment are related with the lack of systematic information about biological agents involved in many work activities, insuffi cient awareness of workers and their inadequate training on health and safety at work, lack of standardized criteria for occupational exposure to biological agents in the air. Knowledge of biological agents is very important for the prevention of disease development and mortality.

Key words: occupational disease, biological agent, risk groups, risk assessment, prevention

Address for correspondence: Assoc. Prof. Vladimir Milanov, MD, PhD, Head of Department of Occupational Diseases, Medical Faculty, Medical University – Sofia, University Hospital “Sv. Iv. Rilski”, 15, “Acad. Ivan Geshov” Blvd., Bg – 1431Sofia, Bulgaria, e-mail: