8.5 Infectious Disease Transmission and Exposure Response

Bloodborne Pathogens and Transmission Routes

The three bloodborne pathogens dental teams worry about most are Hepatitis B virus (HBV), Hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Of these, HBV is the most infectious after a needlestick (it survives on surfaces for days and has a high transmission rate), but it is also the one with a safe, effective vaccine. HCV has no vaccine; HIV has post-exposure prophylaxis (PEP) but no vaccine. Recognizing relative risk—HBV > HCV > HIV per single percutaneous exposure—is a common test point.

Transmission routes in dentistry map onto the chain of infection:

The RDA's controls—gloves, masks, eyewear, HVE, surface barriers, sterilization, and safe sharps handling—each break a specific route.

Sharps Safety and the Hepatitis B Vaccine

Sharps cause most occupational bloodborne exposures, so Cal/OSHA's engineering and work-practice controls are heavily tested:

• Use safer engineered sharps (self-sheathing needles, safety scalpels) where feasible.
• Never recap a needle two-handed; use a one-handed scoop technique or a mechanical recapping device.
• Never bend, break, shear, or hand-pass an uncapped needle.
• Place sharps immediately into a closable, puncture-resistant, leak-proof, biohazard-labeled sharps container; never overfill it.
• Pass instruments below the patient's chin, not over the face.

The Hepatitis B vaccine is the host-side control. Under the Cal/OSHA Bloodborne Pathogens Standard, the employer must offer the HBV vaccine series at no cost to every employee with occupational exposure, within 10 working days of initial assignment, on work time. An employee who declines must sign a written declination but may accept the vaccine later at any time. Post-vaccination titer testing confirms immunity. This is an employer obligation, not the employee's expense—a frequent exam distractor reverses that.

Responding to an Exposure Incident

An exposure incident is a specific eye, mouth, mucous-membrane, non-intact-skin, or percutaneous contact with blood or OPIM. The correct response sequence is fixed and tested verbatim:

1. First aid at the site immediately — for a needlestick or cut, wash the wound with soap and water; for an eye/mucous-membrane splash, flush with water or saline (eyewash station) for several minutes. Do not scrub aggressively or apply caustics.
2. Report to the employer/supervisor at once — exposures are time-sensitive because PEP works best early.
3. Confidential post-exposure evaluation and follow-up — provided free under the Exposure Control Plan: evaluation of the exposure, testing of the source individual (with consent) and the exposed worker, and post-exposure prophylaxis when indicated—HBIG and/or HBV vaccine for hepatitis B, and HIV PEP when appropriate.
4. Document the incident (sharps injury log, route, source, circumstances) and complete the medical follow-up.

Silence, delay, or "finishing the appointment first" are always wrong answers—they forfeit the PEP window. Separately, if a patient discloses a communicable illness during the health-history update, the RDA does not refuse care or diagnose; the team applies Standard Precautions (already universal) and informs the dentist, who decides on any added precautions. The constant theme: prompt, confidential, protocol-driven action breaks the chain and protects everyone.

The Exposure Control Plan and Engineering Controls Hierarchy

Cal/OSHA requires every dental employer to maintain a written Exposure Control Plan (ECP), reviewed and updated at least annually and accessible to staff. It lists exposure-prone tasks, the schedule for implementing controls, the HBV vaccination program, post-exposure procedures, and the Sharps Injury Log. The plan applies OSHA's hierarchy of controls in order:

1. Engineering controls (most effective—remove the hazard): safer-engineered sharps, sharps containers, biohazard labels, puncture-resistant containers, eyewash stations.
2. Work-practice controls: one-handed recapping, no hand-passing of uncapped needles, no eating/drinking in the treatment area, proper waste segregation.
3. PPE (last line, protects the host): gloves, masks, eyewear, gowns provided free by the employer.

Engineering and work-practice controls come before relying on PPE—an exam point, because the safest system removes the hazard rather than only shielding the worker.

Regulated Waste and Other Tested Pathogens

Regulated medical waste—blood-soaked gauze, extracted teeth, sharps—goes into labeled biohazard or sharps containers, not the regular trash. Beyond the big three bloodborne viruses, recognize tuberculosis (airborne—N95, refer/defer elective care), herpes simplex (avoid treating active herpetic lesions; risk of herpetic whitlow on fingers), and routine respiratory viruses spread by droplet/aerosol. The unifying RDA answer is the same: apply Standard Precautions to everyone, use the right control for the route, and act through the written plan rather than improvising.

Tie it back to the chain of infection from Section 8.1: the Hepatitis B vaccine protects the susceptible host; safe sharps handling and the sharps container block the parenteral route; PPE and hand hygiene guard the portals of entry; HVE and the rubber dam cut the portal of exit; and sterilization and surface disinfection eliminate the reservoir. Every Cal/OSHA control and CDC recommendation maps onto a link, which is why memorizing the chain lets you reason out exposure questions you have not seen before.