Research Compliance and Tech Transfer

Chapter 6: Routes of Transmission

The risk of exposure to biological agents in a research environment depends on several parameters (e.g., pathogenicity, virulence, infectious dose, communicability, subject’s susceptibility, route of transmission, etc.). The biosafety procedures used are designed to prevent exposures by containing the agents. To properly design the containment, it is important to recognize the potential routes of transmission for the given agent.

Skin and Mucous Membrane Contact

Decanting of liquids, pipetting, removal of screw caps, vortex mixing, streaking agar plates, and inoculation of animals may all result in the generation of infectious aerosols or droplets. Any direct contact between the infectious material and the subject’s skin, mucous membranes, or eyes may serve as a direct route of exposure.

Ingestion

Splashing of material into the mouth or indirect oral exposure through touching the mouth with contaminated hands can result in the ingestion of infectious material. Storage and/or consumption of food, drinks, or eating utensils in the lab can also lead to ingestion of infectious material. Mouth pipetting presents an extremely high risk of ingestion and is prohibited at UM.

Percutaneous Inoculation

Use of syringes and needles are considered the greatest risk of exposure through inoculation. Accidental inoculation can also occur by way of cuts and scratches incurred from contaminated syringes used for animal inoculations, or from the animals themselves in the form of bites or scratches.

Inhalation

Many procedures have the potential for generation of aerosols, including sonication, centrifugation, “blowing out” of pipettes, heating inoculating loops, and changing litter from the cages of infected animals.

Routes of Transmission for Biological Agents

This table summarizes the primary routes through which laboratory personnel may be exposed to infectious biological agents. Each transmission route is defined with typical examples, associated biological hazards, and recommended preventive measures. This reference is intended to aid in risk assessment and reinforce safe laboratory practices across various research settings.