Fungal Pathogens and Immune Evasion

Fungal Pathogens and Survival Strategies

• Yeasts can survive in phagosomes, evading immune attacks, allowing dissemination via a Trojan horse mechanism.
• Shape shifting in fungi enhances their growth within hosts, promoting infection.

Macroparasites

• Macroparasites are visible to the naked eye and include organisms like head lice, fleas, ticks, and worms.
• While not microorganisms, they still function as pathogens and can cause diseases.

Prions

• Prions are infectious particles made of misfolded proteins, leading to neurodegenerative diseases such as mad cow disease.
• Infected prions induce misfolding of normal proteins in the brain, resulting in neuron damage and tissue degeneration.

Viruses

• Viruses replicate inside host cells, creating thousands of copies, causing cell damage that leads to illness.
• Common viral infections include measles, mumps, chickenpox, and the common cold.

Protists

• Protists (protozoa) are single-celled eukaryotes, can be parasitic, and may resemble animals, plants, or fungi.
• Malaria, caused by protists, is transmitted through mosquito bites, initiating a life cycle within the human body.

Life Cycle of Malarial Protists

• Infection begins when an infected mosquito bites a healthy person, injecting the parasite into the bloodstream.
• The parasite invades the liver and red blood cells, leading to malaria; it can spread through further mosquito bites.

Features of Fungi

• Multi-cellular fungi include toadstools, mushrooms, and mold, characterized by cells with chitin-based walls.
• Fungi use saprotrophic nutrition, secreting enzymes to digest nutrients and absorbing them.
• Hyphae, thread-like structures in fungi, produce spores facilitating dispersion.

Fungal Pathogen Shape Shifting

• Fungal pathogens exhibit different shapes, aiding in infection spread: small spores for deep lung penetration, and budding cells for entry into the bloodstream.
• Some fungi can form large clusters, avoiding phagocytosis by immune cells.

Human Pathogens

• Micro-organisms, or microbes, are too small to be seen without a microscope, classified into five groups: viruses, bacteria, fungi, algae, and protozoa.
• While many microbes are harmless or beneficial, a small fraction can cause diseases.

Microbial Role and Definitions

• Microbes are crucial for life, aiding in gas fixation and decomposition of organic matter, essential for the food chain.
• They are also utilized in medicine, food production, and waste management.
• Pathogens are defined as microbes with the potential to cause disease, while infections describe their invasion and multiplication in organisms.