Pathogens are biological agents that cause infectious diseases.
Understanding Pathogens
Pathogens are diverse, encompassing a wide range of organisms and infectious agents. They share the characteristic of being able to enter a host and overcome its immune system to cause illness.
Types of Pathogens
The reference material highlights the following categories of pathogens:
- Bacteria: Single-celled organisms, some of which can cause diseases like pneumonia or strep throat. It's important to note that most bacteria are not pathogenic.
- Fungi: Eukaryotic organisms, including molds and yeasts, that can cause infections such as athlete's foot or ringworm.
- Protozoa: Single-celled eukaryotic organisms, often parasitic, that can cause diseases like malaria or giardiasis.
- Worms: Parasitic worms, such as tapeworms or roundworms, that can infect various parts of the body.
- Viruses: Microscopic infectious agents that require a host cell to reproduce; examples include the common cold or influenza virus.
- Prions: Infectious proteins that can cause neurodegenerative diseases, like Creutzfeldt-Jakob disease.
Key Characteristics of Pathogens
- Mechanisms for Entry: Pathogens must have specific ways of entering a host's body, such as through inhalation, ingestion, wounds, or insect bites.
- Evasion of Immune System: They must also be able to evade the host's immune response to establish an infection. This might involve hiding within cells, producing toxins that disrupt the immune system, or rapidly mutating to avoid detection.
How Pathogens Cause Disease
Pathogens cause disease by:
- Invasion: Entering and multiplying within the host's body.
- Tissue Damage: Causing direct damage to host tissues and cells.
- Toxin Production: Producing harmful toxins that disrupt normal bodily functions.
- Immune Response: Triggering an inflammatory response by the host’s immune system. Sometimes, this immune response is excessive and itself causes damage.
Pathogen Table
| Pathogen Type | Examples of Diseases | Key Characteristics |
|---|---|---|
| Bacteria | Pneumonia, strep throat | Single-celled organisms; most are not pathogenic |
| Fungi | Athlete's foot, ringworm | Eukaryotic organisms |
| Protozoa | Malaria, giardiasis | Single-celled eukaryotic, parasitic organisms |
| Worms | Tapeworm, roundworm infections | Parasitic worms |
| Viruses | Common cold, influenza | Microscopic; require host cells for replication |
| Prions | Creutzfeldt-Jakob disease | Infectious proteins |
