PART 1. A

• Communicable diseases are often the leading causes of all illness in the country today. Most often they afflict the most vulnerable, the young and the elderly. They have numerous economic, psychological, disabling and distinguishing effects to the emergence of newly discovered diseases and the re-emergence of old ones.
• Leading causes of death/disability in low-income countries

  • HIV/AIDS
  • TB
  • Malaria
  • Hepa
  • STI
  • Neglected tropical diseases
• Communicable diseases


  Readily transferred from one infected person to a susceptible and uninfected person and may be caused by microorganisms

  
• Types of Microorganism causing Infections

  • Bacteria
  • Viruses
  • Fungi
  • Parasites
• Chain of Infection

  1. Etiologic agent (microorganism)

  2. Reservoir (host)

  3. Portal of exit from reservoir

  4. Mode of Transmission

  5. Portal of entry to the susceptible host

  6. Susceptible host
• Etiologic Agent (Microorganism)


  The extent to which any microorganisms is capable of producing an infectious process depends on the number of microorganism (pathogenicity), the ability of the microorganisms to enter the body, the susceptibility of the host, and the ability of microorganisms to live in the host's body
• Reservoir


  There are many reservoirs, or source of microorganisms. Common sources are the other humans, the client's own microorganism, plants, animals, or the general environment. People are the most common source of infection for others and for themselves.
• Portal of exit from the reservoir


  Before an infection can establish itself in a host, the microorganism must leave the reservoir. Human is the common source.
• Method of transmission


  • Direct Transmission
  • Indirect Transmission (Vehicle-borne Transmission, Vector-borne Transmission)
• Direct Transmission


  Involves immediate and direct transfer of microorganisms from person to person through touching, biting, kissing, or sexual intercourse.
• Indirect Transmission


  May either be vehicle borne or vector borne
• Vehicle-borne Transmission


  A vehicle is any substance that serves as an intermediate means to transport and introduce infectious agents into a susceptible host through a suitable portal of entry.
• Vector-borne Transmission


  A vector is an animal or flying or crawling insects that serves as an intermediate means of transporting the infectious agents. Transmission may occur by injecting salivary gland fluid during biting or by depositing feces or other materials on the skin through the bite wound or a traumatized skin area.
• Portal of entry to the susceptible host


  Before a person can become infected, microorganisms must enter the body. The skin is a barrier to infectious agents; however, any break in the skin can readily serve as a portal of entry. Often, microorganisms enter the body of the host by the same route they used to leave the source.
• Susceptible Host


  Any person who is at risk for infection. A compromised host is a person "at increased risk", an individual who for one or more reasons is more likely than others to acquire an infection. Impairment of the body's natural defenses and a number of other factors can affect susceptibility to infection.
• Ways to break the disease cycle

  • Increasing host resistance (e.g. vitamins)
  • Destruction of the source and the reservoir (e.g. removing stagnant water to avoid mosquitoes)
  • Destruction of the agent in the environment
  • Avoidance of exposure

  
• Immunization


  The process of introducing vaccines into the body to produce antibodies that will protect our body against a specific infectious agent.
• Types of Immunization

  • Active (long lasting)
  • Passive (immediate action but short-lived)
• Active Immunization


  Exposure to the agent that triggers the production of antibodies
• Types of Active Immunization

  • Natural (exposed to actual microorganism)
  • Artificial (received vaccine that weakens the agent)
• Passive Immunization


  When a person is given an antibody, e.g. maternal antibodies received through breastfeeding
• Situations for Immunization against Communicable Diseases

  • For infants
  • Following exposure
  • For all persons in endemic areas
  • For person subject to unusual risk
  • For known cases

  
• Vaccines available for routine immunization

  • DPT (Diphtheria, pertussis and tetanus)
  • OPV (Oral Polio Vaccine)
  • MMR (Measles, Mumps, Rubella)
  • Hib (H.influenza type B) polysaccharide
  • Hepatitis B
  • BCG (Bacillus of Calmette and Guerin)
  • CDT (Cholera, Dysentery, Typhoid)
• Chemoprophylaxis


  Administration of drugs to prevent occurrence of infection, e.g. Penicillin for gonorrhea, Chloroquine for malaria, INH for tuberculosis
• Mechanical Prophylaxis


  Placing mechanical barriers between the sources of agent and host such as use of mosquito nets, masks or gloves
• Protection Against Diseases

  • Handwashing
  • PPEs