Understanding Health, Disease, and Infectious Illnesses

1. Health and Disease

When all organs and body systems function correctly, we consider ourselves healthy. If any part of the body is impaired and cannot perform its function properly, it causes disease. When a person becomes ill, characteristic symptoms of the disease appear, often accompanied by some deterioration. Key factors in maintaining health include:

• A proactive approach to health.
• Adopting healthy habits and lifestyles.
• Personal characteristics such as age or hereditary factors.
• An effective health system.

2. Disease Categories

Diseases can be categorized in various ways:

• Infectious: Caused by microorganisms that enter the body and can be transmitted from person to person.
• Non-infectious: Not caused by microorganisms and therefore not transmitted from person to person.
• Acute: Manifest quickly and are short-lived.
• Chronic: Develop slowly and last long.
• Epidemic: When a disease affects many people in a short period.
• Pandemic: When an epidemic spreads across many countries.

3. Infectious Diseases

About half of the diseases affecting humans are caused by pathogens:

• Bacteria: Single-celled organisms that cause disease directly or through toxins they produce.
• Fungi: Unicellular or multicellular organisms causing infections like histoplasmosis.
• Protozoa: Single-celled organisms, some of which are parasitic.
• Viruses: Not cellular organisms and not considered living things. They reproduce by entering the cells of a living being.

3.1. Transmission Routes of Infectious Diseases

• Direct Contact: The pathogen passes directly from an infected individual to a healthy one.
• Inanimate Objects: Pathogens can be transmitted through objects like handkerchiefs, glasses, or saliva droplets.
• Contaminated Water: Pathogenic microorganisms can contaminate drinking water.
• Contaminated Food: Food can be contaminated by pathogenic microorganisms.
• Airborne Transmission: Pathogens can be present in dust particles or float freely in the air.
• Animal Vectors: Animals, often insects, can carry and transmit pathogens to humans.