________________________________________________________ Infection Control for Dental Professionals
COMMON MODES OF INFECTION TRANSMISSION
Category
Definition
Direct contact Person-to-person transmission of pathogens (e.g., through skin, blood, or body fluid contact) Indirect contact An intermediate person or item acts as a transport between the portal of exit in one person and the portal of entry to the next person (e.g., via unwashed hands, shared equipment, needlesticks) Droplets a Large respiratory droplets propelled by an infected person coughing, sneezing, talking, or breathing heavily. Droplets settle rapidly within 6 feet of the individual on surfaces and in the upper airway of individuals exposed via the eyes, nose, or mouth.
Airborne (aerosols) a
Small particles or micro-droplets are released into the air by an infected person coughing, sneezing, talking, or breathing heavily. Airborne pathogens can linger for long periods of time and travel longer distances, landing on surfaces and being breathed in by other individuals into the lower airway. Contact with a contaminated inanimate object (e.g., used gloves, pens, used tissues, soiled laundry, keyboards, furniture).
Fomites
Water Water may be contaminated by micro-organisms in dental water unit lines, causing patient contamination as well as dispersing infected airborne particles and droplets. a In 2024, a global consensus was reached to replace the terms droplet, airborne, and aerosol with a general umbrella term of “through the air transmission,” regardless of infected respiratory particle size and/or distance traveled. Source: [5; 6; 8] Table 1
DIRECT AND INDIRECT CONTACT The most common modes of transmission in the healthcare setting are through contact, both direct and indirect. Because it addresses the weakest link in the chain of transmission, hand hygiene is the single most important procedure for preventing the spread of infection. Items moving between patients should be cleaned and sterilized after each use to avoid indirect trans- mission of pathogens. Standard Precautions in conjunction with identified Contact Precautions are often used in the dental setting. Bloodborne Pathogens Healthcare employees can be exposed to blood through needle- stick and other sharps injuries, damaged mucous membranes, and broken skin exposures. The pathogens of primary concern to dental professions are HIV, hepatitis B virus, and hepatitis C virus. Hepatitis B Virus Healthcare personnel who have received the hepatitis B vaccine and developed immunity to the virus are at virtually no risk for infection. For a susceptible person, the risk from a single needlestick or cut exposure to hepatitis B-infected blood ranges from 6% to 30%, depending on the hepatitis B antigen status of the source individual. While there is a risk for hepatitis B infection from exposures of mucous membranes or nonintact skin, there is no known risk for infection from exposure to
is approximately 1.8%. The risk following a blood exposure to the eye, nose, or mouth is unknown but is believed to be very small; however, hepatitis C virus infection from blood splashes to the eye has been reported. There also has been a report of hepatitis C virus transmission that may have resulted from exposure to nonintact skin, but there is no known risk from exposure to intact skin. Documented transmission of hepatitis C or hepatitis B virus has resulted from using the same syringe or vial to administer medication to more than one patient, even if the needle was changed [5; 10]. The prevalence of hepatitis C virus infection among dentists and surgeons is similar to that among the general population, approximately 1% to 2% [5]. No studies of transmission from hepatitis C virus-infected dental healthcare personnel to patients have been reported, and the risk for such transmission appears limited [10]. HIV/AIDS The average risk of HIV infection after a needlestick or cut exposure to HIV-infected blood is 0.3%; 99.7% of needle- stick or cut exposures do not lead to infection. The risk after exposure of the eye, nose, or mouth to HIV-infected blood is estimated to be 0.1%. There have been no documented cases of HIV transmission due to an exposure involving a small amount of blood on intact skin (i.e., a few drops of blood on skin for a short period of time) [5; 10]. In the United States, the risk of HIV transmission in dental settings is extremely low. According to surveillance data from 1981 to 2013, a total of 58 cases of HIV seroconversion had been documented among healthcare personnel after occupa- tional exposure to a known HIV-infected source, but none were among dental care personnel [12].
intact skin [5; 10]. Hepatitis C Virus
Hepatitis C is transmitted primarily through percutaneous exposure to infected blood. The average risk for infection after a needlestick or cut exposure to hepatitis C virus-infected blood
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