THE DISEASE PROCESS

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CHAPTER 3

• THE DISEASE PROCESS

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Introduction

• By understanding how the disease process works,
  health care providers can better protect
  themselves from infectious disease.

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Differentiation of Infectious Communicable
Diseases

• An infectious disease is one that results from an
  invasion of a host from a disease-producing
  organisms.
• This organism may be in the form of a virus,
  bacteria, fungus, or parasite.

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Differentiation of Infectious Communicable
Diseases

• A communicable disease is an infectious disease
  that may be transmitted from one person to
  another.
• Employees at risk of occupational exposure to
  blood and body fluids should be especially
  concerned with HIV, Hepatitis B virus (HBV),
  hepatitis C virus (HCV), and tuberculosis (TB)

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Direct Exposure

• Direct may occur by direct person-to-person
  contact through events such as sexual contact or
  a contaminated needlestick.

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Indirect Exposure

• Indirect may be through handling soiled linens or
  touching a contaminated object

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Causes of Disease

• Viral, bacterial, fungi, protozoa, and rickettsia
  are all known to cause infectious disease.

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Bacteria

• Are living microorganisms that can produce
  disease in a host. Bacteria are also capable of
  living outside the host.
• Bacteria can self-reproduce and some may produce
  toxins that are harmful to their host.

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Bacteria

• Diseases like bacterial meningitis, tetanus, food
  poisoning, tuberculosis (TB), and syphilis are
  caused by bacteria.

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Viruses

• Are microorganisms that reside within other
  living cells and cannot reproduce outside a
  living cell.
• Viruses like HIV, HBV, HCV and influenza may pose
  risks to those with occupational exposure.

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Fungus

• A plantlike organism that grows as single cells
  (e.g., yeast) or as multicellular colonies (e.g.,
  mold).
• Since fungi do not contain chlorophyll, they
  depend on a parasitic or saprophytic existence.

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Fungus

• Example of fungal infectious disease include
  tinea (ringworm) and dhobie itch.

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Protozoans

• Are the simplest organisms in the animal kingdom.
• Many are single-celled, although some colonize.
• Examples include malaria, dysentery, and sleeping
  sickness.

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Rickettisas

• Parasitical creatures who depend on living cells
  for growth.
• Usually transmitted by fleas, ticks, lice, and
  mites.
• Examples include Rocky Mountain Spotted Fever and
  several forms of Typhus.

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Helminths (worms)

• May also cause infectious disease.
• While many worms are not parasitic, parasitic
  worms like pinworms and tapeworms may be acquired
  by eating under-cooked meat

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TRANSMISSION

• Communicable disease is passed from one person to
  another, in a series of events, creating a chain
  of infection. Fig.3-3
• First of these events is transmission, either
  airborne, bloodborne, or vector borne.

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Airborne Transmission

• Typically accomplished through droplets in a
  sneeze or cough.
• These aerosolized droplets travel through the air
  and are inhaled through the respiratory system or
  absorbed through mucous membranes.
• TB is a common airborne transmissible disease

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ALERT!!

• It may be difficult to determine exposure to
  airborne transmissible disease
• Health care providers should observe standard
  precautions when caring for any patient with a
  cough or sneeze.

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Bloodborne Transmission

• Takes place when infected blood or
  blood-containing body fluid is introduced into
  the body of another person.
• Common ways this is accomplished are through
  needlesticks, splashing into the mucous
  membranes, or blood contacting non-intact skin.

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Vector Borne Transmission

• Transmission of a disease-causing organism
  through an outside source, or a vector.
• This includes a mosquito that carries malaria or
  a tick that carries Rocky Mountain Spotted Fever.

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Sexual Transmission

• Transmission of a disease through sexual contact
  with an infected person.
• Transmission is usually accomplished through the
  contact of infected body fluids with mucous
  membranes.

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Sexual Transmission

• Sexually transmitted diseases (STDs) include
• Gonorrhea
• Syphilis
• Genital herpes

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Transmission by Casual Contact

• Some disease are transmitted person-to-person by
  casual contact or household contact.
• This includes close body-to-body contact,
  sleeping in the same bed, and sharing hairbrushes
  or combs.

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Transmission by Casual Contact

• Children who become infested with lice or scabies
  frequently catch them through casual contact at
  school.

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Seroconversion

• Once a disease is introduced into the body, a
  period of time elapses before a blood test will
  read positive.
• This process of converting from a negative to a
  positive blood test is called seroconverison.

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Seroconversion

• The period of time that elapses between an
  exposure and a positive blood test is referred to
  as the Window Phase.

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Seroconversion

• The duration of the window phase may vary
  considerably from one individual to another,
  depending on the overall health, response of the
  immune system in the infected person, and the
  strength of the pathogen.

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Seroconversion

• Symptoms do not normally appear immediately with
  seroconversion.
• The time that passes between seroconversion and
  the appearance of symptoms is called the
  Incubation Period.

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Seroconversion

• For hepatitis B (HBV) this period may be up to
  200 days.
• For HIV may be as long as 10 years.

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Seroconversion

• IMPORTANT that both the patient and the caregiver
  realize that a single negative blood test and
  lack of immediate symptoms do not necessarily
  mean that a person is free from a disease.
• Follow-up testing at prescribed intervals is
  highly recommended.

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Seroconversion

• The importance of protecting oneself from
  exposure to blood and other potentially
  infectious material (OPIM) is apparent when we
  realize that the carrier of HIV may display no
  signs or symptoms for up to 10 years.

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Stop And Consider!!

• Consider the example of why knowledge of
  seroconversion is important to health care
  providers
• Nancy, a RN is attending her sons Little League
  baseball game when another child is struck in the
  face by a batted ball, resulting in profuse
  bleeding from the nose and mouth. The patient
  appears in good health, but Nancy has no gloves
  readily available. She helps control the
  bleeding without the benefit of personal
  protective equipment (PPE)..

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Stop and Consider!!

• Though the childs young age and apparent state
  of health may make Nancy feel comfortable
  treating him without personal protective
  equipment, she may be placing herself in danger
  by assuming that he is free from infectious
  disease

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Stop and Consider!!

• Suppose the seven-year-old has been exposed to
  hepatitis C (HCV) but does not yet know he is
  infected?
• Though he feels fine and looks healthy, he could
  still pass the virus on to anyone who comes in
  contact with his blood, including Nancy.

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Stop and Consider!!

• Many nurses do not use PPE with the elderly
  patients because they do not believe that they
  are high risk for communicable disease.

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Stop and Consider!!

• What about all the 90 year-old patients that have
  received numerous blood transfusions?
• What about the 90 year-old patients that are
  still sexually active without using protection?

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Stop and Consider!!

• What about the newborn that looks so sweet and
  cuddly, but yet mom was HIV positive?

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Rule of Thumb!!

• Regardless of how safe the patient looks, he may
  still be infected with a communicable disease.

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ALERT!!

• Regardless of the situation, use standard
  precautions with EVERY patient.

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Latent Period

• Period after infection when an infectious agent
  can not be transmitted to another host.

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Communicable Period

• Period after infection when an infectious agent
  can be transmitted to another host.

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Incubation Period

• Time between exposure and onset of symptoms

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Window Phase

• Period where antigen is present but
  seroconversion has not yet taken place.

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Disease Period

• Time between onset of symptoms and resolution of
  symptoms

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Conclusion

• By knowing how the disease process works, the
  employee at risk of occupational exposure can be
  better protected against exposure to disease.