Stages of infection

• Disease


  An abnormal condition affecting the body of an organism
• Disease


  • Often construed to be a medical condition associated with specific signs and symptoms
  • May be caused by factors originally from an external source such as infectious diseases or internal dysfunctions such as autoimmune diseases
  • Any condition that causes pain, dysfunction, distress, social problems, or death to the person affected
• Physical injuries or disabilities are not classified as disease
• Causes of disease


  • Infection by a pathogen
  • Genetics (as in many cancers or deficiencies)
  • Noninfectious environmental causes
  • Inappropriate immune responses
• Infection


  The successful colonization of a host by a microorganism
• Infection


  Can lead to disease, which causes signs and symptoms resulting in a deviation from the normal structure or functioning of the host
• Pathogens


  Microorganisms that can cause disease
• Signs


  Objective and measurable, and can be directly observed by a clinician
• Vital signs


  • Body temperature (normally 37 °C [98.6 °F])
  • Heart rate (normally 60-100 beats per minute)
  • Breathing rate (normally 12-18 breaths per minute)
  • Blood pressure (normally between 90/60 and 120/80 mm Hg)
• Syndrome


  A specific group of signs and symptoms characteristic of a particular disease
• Nomenclature of Symptoms


  • cyto- (cell)
  • hepat- (of the liver)
  • -pathy (disease)
  • -emla (of the blood)
  • -itis (inflammation)
  • -lysis (destruction)
  • -oma (tumor)
  • -derma (of the skin)
• Morbidity


  The number of cases of a disease
• Mortality


  The number of deaths due to a disease
• Communicable


  Capable of being spread from person to person through either direct or indirect mechanisms
• Non-communicable infectious disease


  Not spread from one person to another (e.g. tetanus)
• Non-infectious diseases


  Not caused by pathogens (e.g. Down syndrome)
• Iatrogenic disease


  The result of diagnostic and therapeutic procedures undertaken on a patient
• Zoonotic diseases


  Not transmitted between humans directly but can be transmitted from animals to humans
• Incubation Stage


  1. The onset of contagious disease wherein the virus multiplies until it affects the body's defenses

  2. The period when infection and the first signs and symptoms associated with a disease appear
• Incubation Stage


  • During this stage, a sick person may actually spread the disease-causing microorganisms without knowing because this is symptom-less stage where microbes can multiply inside the body and also spread to other people
  • The length of this period is dependent on the kind of microorganism that invades the person and his/her immune system
• Prodomal Stage


  1. Although the person does not feel weak, sick, or may not appear sick, the virus has become stronger than the body's defenses

  2. The illness may be spread to other people

  3. This is a short stage of disease development where a person begins to feel that they are getting sick
• Prodomal Stage


  • The signs and symptoms during this stage typically result from activation of the immune system, such as fever, pain, soreness, swelling, or inflammation
• Illness Stage


  1. The illness has developed

  2. This is the stage where a person feels the typical signs and symptoms associated with the disease
• Illness Stage


  • This is also the stage where the person can most easily transmit a communicable disease to another person
  • The peak of illness intensity is known as acme point
• Decline Stage


  1. The immune system begins to bring microbial replication under control which leads to the lessening of the signs and symptoms associated with the disease

  2. Damaged tissues begin to repair, and pathogen numbers decrease
• Convalescence Stage


  1. The microbial replication is fully stopped and the person returns to the pre-illness stage

  2. Depending on the disease, the person may not proceed to this stage and may die from their disease or be disabled
• Infection


  • An invasion of pathogens or microorganisms into the body that are capable of producing disease
  • The invasion and reproduction of microorganisms in a body tissue that can result in a local or systemic clinical response such as cellulitis, fever etc.
• Infection Control


  • Includes all of the practices used to prevent the spread of microorganisms that could cause disease in a person
  • Infection control practices help to protect clients and healthcare providers from disease by reducing and/or eliminating sources of infection
• Cycle of infection


  1. Agent

  2. Susceptible Host

  3. Reservoir

  4. Portal of Inlet

  5. Portal of Exit
• The Six Links


  • Pathogen
  • Reservoir
  • Place of Exit
  • Method of Transmission
  • Port of Entry
  • Susceptible Host
• Reservoir


  • The place for a pathogen to live and grow
  • Direct transmission: Human or animal body (host)
  • Indirect transmission: Contaminated food or water, Animal/insect, Infected soil
• Place of Exit


  Ways pathogens escape the reservoir: Mouth, Nose, Broken skin
• Method of Transmission


  • Directly: Body fluids (i.e. blood, secretions)
  • Indirectly: Intermediate hosts (i.e. toothbrushes, animals, drinking fountains, food)
• Port of Entry


  Ways to enter a new host: Broken skin, Mouth, Nose, Eyes, Genitals, Insect bites
• Susceptible Host


  • Those that have little (if any) resistance to the pathogen and thus, lack the ability to fight them off
  • Carriers: Those who carry germ, but show no signs or symptoms; can spread disease, but often do so unknowingly
• If even ONE link is broken, an infection will not occur!
• Break the Chain


  1. Kill the pathogen

  2. Prevent contact

  3. Prevent its escape

  4. Prevent Transmission

  5. Block the Ports

  6. Resistant Host
• Kill Pathogen


  If you kill the pathogen, you stop it from spreading
• Kill Pathogen


  1. Use antibiotics or other medications

  2. Wash hands
• Prevent Contact


  By preventing things from coming in contact with an infected source, the pathogen has no place to escape to