Guidance for laboratory workers who handle Histoplasma

In clinical and research laboratories, workers who handle Histoplasma in both its yeast and its filamentous form are at risk for histoplasmosis.^1–2 Disturbance to soil, environmental, and clinical samples as well as laboratory cultures may result in several potential routes of exposure for the laboratorian, which include:^1–4

• Inhalation: Respirable infectious aerosols can occur during viable culture procedures, preparing soil suspensions, handling clinical specimens, preparing wet mount slides, and methods used to prepare samples for analytical procedures (pipetting, centrifugation, sonication, disturbing culture plates, decanting, and lyophilization).
• Inoculation: Contaminated needles, scalpels, or broken glass.
• Skin and mucous membrane contamination: Contaminated laboratory surfaces, spills, or splashes.

Laboratories should have comprehensive prevention plans in place to protect laboratory workers.¹ Facility laboratory safety programs are subject to local, state, and federal standards and guidelines that aim to protect workers against the transmission of infectious agents such as Histoplasma.¹ Hierarchical controls including engineering controls, administrative controls, and personal protective equipment (PPE), further reduce exposure to Histoplasma in laboratory settings. Clinical and environmental samples received in the laboratory should be handled in a biosafety level (BSL)-3 room when available. Samples suspected of containing Histoplasma should be opened and handled within a laminar flow Biological Safety Cabinet while wearing appropriate PPE.^1,5 Cultures should also be contained in sealed nutrient culture plates to minimize exposures during the handling and culture of Histoplasma. The risk of worker exposure to Histoplasma in clinical and research laboratories is further reduced through:

• Laboratorian knowledge of the facility laboratory safety manual
• Staff training
• Medical surveillance
• Containment of microbial exposures through aseptic microbiological practices that address the cultivation, storage, and disposal of biohazardous materials.¹

If you are exposed to Histoplasma in a laboratory or develop symptoms of histoplasmosis after working with Histoplasma in a laboratory, contact your supervisor following the policies and procedures of the facility and your occupational health or risk management department.