Unit 1: Medical Zoology

Table of Contents

1. Basic concept of pandemic, epidemic, endemic, and outbreak

These terms describe the scale and prevalence of a disease. The key difference is the geographical area and whether the number of cases is expected or not.

Term Definition Geographical Scale Example
Endemic A disease that is always present in a specific geographical area or population at a predictable, baseline level. Limited to a specific area (e.g., a country, a region). Malaria in many parts of sub-Saharan Africa.
Outbreak A sudden increase in the number of disease cases, greater than what is normally expected, within a limited area and time. Small and localized (e.g., a school, a town). A cluster of food poisoning cases linked to a single restaurant.
Epidemic An outbreak that has spread over a larger geographical area, such as an entire country, affecting many people at once. Large area (e.g., a city, a state, or a country). The Ebola virus spread in West Africa in 2014.
Pandemic An epidemic that has spread across multiple countries or continents, affecting the entire world. Global (across international borders). COVID-19 or the 1918 Influenza ("Spanish Flu").
Exam Tip: Remember the progression: An outbreak is localized. If it spreads, it becomes an epidemic. If that epidemic spreads globally, it becomes a pandemic. An endemic disease is the "normal" level of that disease in an area.

2. Basic concept of parasite, zoonotic diseases with examples

Basic Concept of a Parasite

A parasite is an organism (like a protozoan, worm, or arthropod) that lives on or in another organism, called the host. The parasite benefits by deriving sustenance and protection from the host, while simultaneously injuring the host.

Basic Concept of Zoonotic Diseases

A zoonotic disease (or zoonosis) is an infectious disease that is spread between animals and people. Animals can be a source of infection, and the disease can be caused by viruses, bacteria, fungi, or parasites.

Examples of Zoonotic Diseases (Parasitic)

3. Basic concept of communicable and non-communicable diseases with examples

Diseases are broadly classified based on whether they can be transmitted from one person to another.

Communicable Diseases

  • Definition: These are infectious diseases caused by pathogens (like bacteria, viruses, fungi, or parasites) that can be spread from one person to another.
  • Transmission: Spread can occur directly (e.g., coughing, touching) or indirectly (e.g., through contaminated water, food, or insect vectors).
  • Examples:
    • Tuberculosis (TB)
    • Measles
    • Influenza (Flu)
    • COVID-19
    • HIV/AIDS
    • Malaria

Non-Communicable Diseases (NCDs)

  • Definition: These are chronic diseases that are not passed from person to person. They are typically of long duration and result from a combination of genetic, physiological, environmental, and behavioral factors.
  • Characteristics: NCDs are the leading cause of death globally.
  • Examples:
    • Cardiovascular diseases (e.g., heart attacks, stroke)
    • Cancers
    • Diabetes
    • Chronic respiratory diseases (e.g., asthma, COPD)
    • Alzheimer's disease