How are they done? What are the 6 Agents of Disease? What are some examples of each? How are they transmitted?Treated? Why are viruses and prions different from the other agents? What is a Chain of infection? What is a reservoir? What do you need to know about an infectious agent in order to break the chain? Differentiate between Innate (non specific) E acquired (specific) immunity. What are the parts of the immune system that are considered innate? What are the parts of the immune system that are considered acquired? Consider an "attack" on your body by a foreign invader, what are the levels or immunity or steps that your body would go through to defend you? What is aseptic technique? Why is it used when working with bacteria and other microorganisms? What is an isolation streak? Why are they done? Where in a plate would you find isolated colonies?

Let's explore the fascinating world of infectious diseases and the body's defense mechanisms.<br /><br />**What are the 6 Agents of Disease? What are some examples of each? How are they transmitted? Treated?**<br /><br />1. **Bacteria:** Single-celled organisms that can cause disease by releasing toxins or damaging tissues. Examples include *Streptococcus pyogenes* (strep throat), *Escherichia coli* (food poisoning), and *Mycobacterium tuberculosis* (tuberculosis). Transmission varies (airborne, foodborne, contact). Treatment often involves antibiotics.<br /><br />2. **Viruses:** Tiny particles that invade host cells and replicate, disrupting cell function. Examples include influenza virus (flu), HIV (AIDS), and SARS-CoV-2 (COVID-19). Transmission varies (airborne, contact, vectors). Treatment can include antiviral medications, but many viral infections are managed symptomatically.<br /><br />3. **Fungi:** Eukaryotic organisms that can cause infections like athlete's foot, ringworm (caused by various dermatophytes), and candidiasis (caused by *Candida albicans*). Transmission often involves direct contact or spores. Treatment involves antifungal medications.<br /><br />4. **Protozoa:** Single-celled eukaryotic organisms. Examples include *Plasmodium* (malaria), *Giardia lamblia* (giardiasis), and *Entamoeba histolytica* (amoebiasis). Transmission can occur through contaminated food or water, or via vectors like mosquitoes. Treatment involves antiparasitic medications.<br /><br />5. **Helminths:** Parasitic worms. Examples include roundworms (ascariasis), hookworms (hookworm infection), and tapeworms (taeniasis). Transmission often involves ingestion of eggs or larvae. Treatment involves anthelmintic medications.<br /><br />6. **Prions:** Misfolded proteins that can cause other proteins to misfold, leading to neurodegenerative diseases. Examples include Creutzfeldt-Jakob disease (CJD) and bovine spongiform encephalopathy (mad cow disease). Transmission can occur through consumption of contaminated tissue or inheritance. There is no effective treatment for prion diseases.<br /><br />**Why are viruses and prions different from the other agents?**<br /><br />Viruses are not considered living organisms because they lack cellular structure and cannot reproduce independently. They require a host cell's machinery to replicate. Prions are even simpler, being misfolded proteins and not organisms at all.<br /><br />**What is a Chain of Infection? What is a reservoir?**<br /><br />The chain of infection describes the six links necessary for an infection to spread: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host. A reservoir is the habitat where an infectious agent normally lives and multiplies. This can be a human, animal, or environment (e.g., soil, water).<br /><br />**What do you need to know about an infectious agent in order to break the chain?**<br /><br />Understanding the agent's mode of transmission, survival requirements (temperature, humidity), susceptibility to disinfectants, and weaknesses allows for targeted interventions to break the chain. For example, knowing that a virus is transmitted through respiratory droplets informs the use of masks and social distancing.<br /><br />**Differentiate between Innate (non-specific) & Acquired (specific) immunity.**<br /><br />* **Innate immunity:** Present from birth, provides immediate, non-specific defense against a wide range of pathogens. It includes physical barriers (skin, mucous membranes), cellular defenses (phagocytes), and chemical defenses (inflammation, fever).<br /><br />* **Acquired immunity:** Develops over time in response to specific pathogens. It involves specialized cells (lymphocytes) and antibodies that recognize and target specific antigens. It has memory, leading to a faster and stronger response upon re-exposure to the same pathogen.<br /><br />**What are the parts of the immune system that are considered innate? Acquired?**<br /><br />* **Innate:** Skin, mucous membranes, phagocytes (macrophages, neutrophils), natural killer cells, complement system, inflammation, fever.<br /><br />* **Acquired:** B lymphocytes (produce antibodies), T lymphocytes (helper T cells, cytotoxic T cells), antibodies.<br /><br />**Consider an "attack" on your body by a foreign invader, what are the levels or steps that your body would go through to defend you?**<br /><br />1. **First line of defense (innate):** Physical barriers (skin, mucous membranes) prevent entry.<br />2. **Second line of defense (innate):** If the pathogen breaches the first line, phagocytes engulf and destroy it. Inflammation and fever are also activated.<br />3. **Third line of defense (acquired):** If the innate response is insufficient, acquired immunity kicks in. Antigen-presenting cells activate helper T cells, which then activate B cells to produce antibodies and cytotoxic T cells to kill infected cells.<br /><br />**What is aseptic technique? Why is it used when working with bacteria and other microorganisms?**<br /><br />Aseptic technique refers to practices and procedures used to prevent contamination from pathogens. It's crucial when working with microorganisms to protect yourself, others, and the integrity of your experiment or procedure.<br /><br />**What is an isolation streak? Why are they done? Where in a plate would you find isolated colonies?**<br /><br />An isolation streak is a technique used to obtain pure cultures of bacteria. It involves streaking a sample across an agar plate in a specific pattern to dilute the bacteria and allow individual cells to grow into isolated colonies. These isolated colonies, found at the end of the streak lines, represent a single bacterial species and are essential for studying the characteristics of a specific microorganism.<br />