Infectious Diseases

CHAPTER 33: INFECTIOUS DISEASES

Page 1

• Title: Chapter 33 Infectious Diseases

• Author: Becky Mannel, OTD, MOT/OTR/L, 092 OST

Page 2: CHAIN OF TRANSMISSION (INFECTION)

• Definition: Process by which an infectious agent is conveyed from a reservoir to a susceptible host.

• Importance: Understanding each infectious disease helps in prevention by disrupting transmission links.

Page 3: COMPONENTS OF CHAIN OF TRANSMISSION

• Infectious Agent

  • Types: Bacteria, Fungus, Protozoon, Rickettsia, Virus

• Susceptible Host

  • Types: Animals, Elderly, Newborns, Humans, Acute/Chronically ill individuals, Immune-suppressed, Unvaccinated

• Reservoir

  • Sources can include: Equipment, Food, Soil, Water

• Pathways

  • Entry: Body orifices, Blood, Mucous membranes, Secretions

  • Exit: Blood, Excretions, Broken skin

• Means of Transmission

  • Types: Airborne, Contact, Droplet, Vector (e.g., insects), Vehicle

Page 4: INFECTIOUS DISEASE MECHANISMS

• Infectious Agents: Virus, Bacteria, Fungus, Parasite, Prion

• Reservoir Hosts:

  • Environmental, Food, Water, Soil, Contaminated surfaces, Human, Animal, Zoonosis

Page 5: PATHWAYS OF EXIT AND ENTRY

• Pathways of Exit: Blood, Exudates, Excretions, Secretions

• Pathways of Entry: Body orifices, Mucous membranes, Broken skin

Page 6: MEANS OF TRANSMISSION

• Direct Transmission:

  • Via contact, secretions, mucous membranes, and droplets in close proximity

• Indirect Transmission:

  • Airborne, Vector-borne, Vehicle-borne; droplet nuclei can remain airborne

Page 7: SUSCEPTIBLE HOST RISK FACTORS

• Factors include:

  • Tobacco/Alcohol use, Genetics, Age, Immunity, Poverty, Lack of clean water, Preexisting health conditions

Page 8: INFECTIOUS DISEASE CLASSIFICATION TABLE (33.1)

• Classification by Microbiology and Transmission:

  • Bacterial: TB, Clostridium difficile (C diff)

  • Viral: HIV, COVID-19

  • Fungal: Candida, Ringworm, Meningitis

  • Parasitic: Malaria, Hepatitis B

  • Prion: Creutzfeldt-Jakob disease (CJD)

Page 9: PREVENTION OF DISEASE SPREAD IN HEALTH/SOCIAL CARE

• Strategies include:

  • Blocking transmission pathways

  • Standard precautions such as hand hygiene

  • Cough etiquette and transmission-based precautions (contact, droplet, airborne)

Page 10: IMPACT OF SOCIAL AND STRUCTURAL DETERMINANTS OF HEALTH

• Social determinants contribute to disparities in infectious disease distribution:

  • Economic stability, Education access, Health care quality, Neighborhood environments, Community context

  • Factors include stigma leading to poor health outcomes

Page 11: HIV (HUMAN IMMUNODEFICIENCY VIRUS)

Page 12: HIV DESCRIPTION AND DEFINITIONS

• Zoonotic transmission with two types:

  • HIV-1: Derived from SIV strains in apes

  • HIV-2: Derived from SIV strains in sooty mangabey monkeys

• Effect: Attaches to CD4+ T cells, damaging immune responses

Page 13: HIV ETIOLOGY

• Transmissions occur through:

  • Blood, Serum, Semen, Breast milk

  • Needle/syringe sharing, unprotected sexual intercourse

• Cannot be transmitted via hugging, kissing, or sharing personal objects

Page 14: HIV INCIDENCE AND PREVALENCE

• 2019 statistics:

  • Globally, ~38 million people affected, ~1.7 million newly infected

  • 23% decline in cases since 2010

  • 690,000 died in 2019; majority of cases in Sub-Saharan Africa

  • U.S. incidence mostly men who have sex with men

Page 15: HIV SIGNS AND SYMPTOMS

• Three stages:

  • Stage 1: Highly infectious, flu-like symptoms

  • Stage 2: Few symptoms, but CD4 count decreases

  • Stage 3: AIDS with symptoms like weakness, weight loss, swollen lymph glands

  • Symptoms in infants and children include lymphadenopathy and pneumonia

Page 16: DIAGNOSTIC TESTING

• Tests include:

  • Enzyme immunoassays, Nucleic acid tests

Page 17: HIV COURSE AND PROGNOSIS

• Highly Active Antiretroviral Therapy (HAART) improves prognosis

• Risks of premature aging and cognitive impairments associated with HIV

Page 18: TREATMENT OPTIONS

• Recommended therapies:

  • Combination Antiretroviral Therapy (cART)

  • Pre-exposure prophylaxis (PrEP)

Page 19: HIV IMPACT ON OCCUPATIONAL PERFORMANCE

• Affected areas:

  • Poor sleep, Mobility, Financial management, Engagement in education, Grooming

Page 20: TUBERCULOSIS (TB)

Page 21: TB DESCRIPTION AND DEFINITIONS

• Infectious bacterial disease caused by Mycobacterium tuberculosis

• Commonly affects:

  • Lungs, bronchial areas leading to pulmonary scar tissue

  • Can also affect meninges, bones, joints, gastrointestinal system

Page 22: TB TRANSMISSION

• Transmission occurs via cough droplets inhaled into alveoli, leading to inflammatory response

Page 23: TB INHALATION MECHANISM

• Droplets containing TB bacilli are inhaled into the respiratory system and can reach lymph nodes where they multiply

Page 24: TB INCIDENCE AND PREVALENCE

• TB is a leading cause of death, particularly linked to socio-economic factors

• In 2018, 8 countries accounted for 2/3 of new cases

• Most cases are found in individuals aged 15-64, with a higher prevalence in males compared to females

Page 25: TB SIGNS AND SYMPTOMS

• Latent TB: Not transmissible, dormant but can test positive

• Active TB: Shows symptoms such as cough, chest pain, fever

• Other potential effects include alterations in cardiorespiratory function and requirement for self-isolation

Page 26: TB DIAGNOSIS

• Methods include:

  • Blood test, Mantoux Test, Sputum smear, Sputum culture, Chest radiography

Page 27: TB COURSE AND PROGNOSIS

• Active TB recoverable with first-line antibiotics over 6 months

• Risk of fatality is higher with active TB; potential for drug-resistant strains

Page 28: TB MANAGEMENT

• Treatment encompasses:

  • Duration of oral medication from a minimum of 6 months to 2 years

  • Directly Observed Therapy (DOT) programs

  • Community-based treatments and possible surgical intervention

Page 29: TB IMPACT ON OCCUPATIONAL PERFORMANCE

• Impacted areas include:

  • Daily activities such as shopping, caring for others, grooming, and sexual activity.