The infectious disease process involves three essential components:
Disease can be caused by microorganism, chemical substance or form of radiation and excessive presence or relative absence (in deficiency diseases).
Pathogenic agents include a variety of microorganisms such as fungi, bacteria, viruses and protozoa. Pathogens may be present in human blood (blood borne pathogens) and other infectious agents such as saliva and dental procedures. The bloodborne pathogens that the dental professionals have to guard against are Hepatitis B, Hepatitis C and HIV.
Although transmission of blood borne pathogens (e.g. HBV, HCV and HIV) in dental health-care settings can have serious consequences, but such transmission is rare. Exposure to infected blood can result in transmission from patient to dental practitioners, from dental practitioners to patient and from one patient to another. The possibility for transmission is greatest from patient to dental practitioners, who frequently encounter patient blood and blood- contaminated saliva during dental procedures.
The risk of occupational exposure to bloodborne viruses largely depends on their prevalence in the patient population and the nature and frequency of contact with blood and body fluids through percutaneous or permucosal routes. The risk of infection after exposure to a bloodborne virus depends on inoculum size, route of exposure and susceptibility of the exposed dental practitioner. The focus has been on bloodborne pathogens HBV, HCV and HIV and these pathogens present different levels of risk to the dental practitioners.
The risk of transmission of HBV, HCV and HIV, as well as other pathogens, is influenced by factors such as:
3 A susceptible host is a person who lacks effective resistance to a particular pathogenic agent. The severity of the disease resulting from an infection are influenced by many factors including heredity, nutritional status, use of medications, therapeutic agents, underlying diseases and immunization status.
The mechanism by which an infectious agent is mode of transferred to a susceptible host is known as mode of transmission. Most infectious agents are transferred by direct contact and through inhalation of organisms in the air.
Transmission may occur through direct contact with infectious body fluids, such as blood into an open wound. It may occur through indirect contact, e.g. through a contaminated object such as a used instrument or a patient contact surface. It may also occur through contact with airborne contaminants present in either droplet splatters or aerosols.Tuberculosis and measles are classic examples of diseases that can be transmitted via aerosols. Blood borne viruses, such as HBV, HCV and HIV are not transmitted this way.
By eliminating any one of these components, an infection cannot occur. This principle forms the foundation of an acceptable infection control strategy.