BPH 118: Principles of Disease Control

Introduction to Disease Control and Prevention

• This course provides an introduction to core concepts and principles in disease control and prevention.
• Students will be introduced to infectious disease surveillance data, disease transmission, and outbreak investigation.

Course Objectives

• Understand biological concepts of diseases
• Recognize the properties of different types of pathogens and the mechanisms of pathogenesis
• Understand the principles of control and prevention of diseases
• Identify and describe current public health issues related to the most important diseases in Ghana
• Appreciate strategies and interventions put in place to control and prevent diseases in Ghana

Course Content

• Disease principles, diagnosis, and detection
• Disease control and prevention principles
• Antibiotic resistance
• Prevention of disease spread/vaccinology
• Therapeutics, emergency responses to emerging diseases
• Strategies and interventions for control and management

Overview of Diseases

• A disease is a harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and differing in nature from physical injury.
• The study of disease is called pathology.

Types of Diseases

• Communicable diseases (infectious, transmissible disease)
• Non-communicable diseases (long-lasting, progress slowly, also referred to as chronic diseases)

Communicable Diseases

• Examples of communicable diseases include:
  • Airborne diseases (TB, measles, meningitis)
  • Water and foodborne diseases (cholera, typhoid)
  • Helmintic diseases (guinea worm, roundworm)
  • Vector-borne diseases (yellow fever, malaria)
  • Sexually transmitted diseases (HIV/AIDS)
  • Contact diseases (ringworm, Yaws)
  • Diseases transmitted by animals (rabies)
  • Other diseases (tetanus)

Non-Communicable Diseases

• Noncommunicable diseases can arise from environmental exposures or from genetically determined abnormalities.
• The World Health Organization (WHO) has identified four major types of noncommunicable diseases:
  • Cancer
  • Cardiovascular disease (e.g., heart attack, stroke)
  • Chronic respiratory diseases (e.g., asthma)
  • Diabetes mellitus
• WHO estimates that, combined, these four groups of conditions account for 82% of all deaths from noncommunicable disease.

Epidemiologic Terminologies

• Host: a person or other living animal that harbors or nourishes an infectious agent under natural conditions.
• Communicable disease: an illness due to a specific infectious agent or its toxic products that arises through transmission of that agent or its products from an infected person, animal, or inanimate source to a susceptible host.
• Definitive host: the primary host in which a parasite attains maturity or passes its sexual stage.
• Secondary host: the intermediate host in which a parasite is in a larval or asexual state.
• Transport/paratenic host: a carrier in which the organism remains alive but does not undergo development.
• Reservoir host: any animal (species) that is infected by a parasite and which serves as a source of infection for man or other species.

Infection and Contamination

• Infection: the entry and development or multiplication of an infectious agent in the body of man or animals.
• Infective dose: the quantity of the organism needed to cause clinical disease.
• Infectiousness: indicates the relative ease with which an infectious agent is transmitted to other hosts.
• Contamination: the presence of an infectious agent on a body surface, on or in clothes, beddings, toys, surgical instruments, or dressings, or other articles or substances including water and food.

Infestation and Contagious Disease

• Infestation: the lodgment, development, and reproduction of arthropods on the surface of the body or in the clothing.
• Contagious disease: a disease that is transmitted through contact.

Vector of Infection

• An insect or any living carrier that transports an infectious agent from an infected individual or its wastes to a susceptible individual or its food or immediate surroundings.

Sporadic, Nosocomial, and Opportunistic Infections

• Sporadic disease: a disease that occurs occasionally, and the cases are few and separated widely in time and place.
• Nosocomial infection: an infection occurring in a patient in a hospital or other healthcare facility in whom the infection was not present or incubating at the time of admission.
• Opportunistic infection: an infection by organisms that take the opportunity provided by a defect in host defense to infect the host and thus cause disease.