Infectious Diseases, Microbiology & Beneficial Microbes

Viral infections are caused by viruses, tiny infectious agents that replicate inside living cells. Viruses can infect humans, animals, plants, and bacteria.

• Influenza (flu): A highly contagious respiratory infection with symptoms including fever, cough, sore throat, muscle aches, and fatigue.
• Ebola virus disease: A severe, often fatal illness with symptoms such as fever, headache, muscle pain, fatigue, diarrhea, vomiting, and bleeding.
• Zika virus infection: Spread by Aedes mosquitoes, causing mild symptoms like fever, rash, and joint pain, with potential birth defects if contracted during pregnancy.
• Herpes: Caused by HSV-1 and HSV-2, leading to painful sores, itching, and flu-like symptoms.

Fungal infections are caused by fungi, microorganisms that can lead to a variety of diseases affecting different parts of the body. Fungi are widespread in the environment and can invade the body, causing health issues.

• Athlete's foot (tinea pedis): This common fungal infection primarily affects the feet, causing itching, burning, redness, and peeling of the skin, especially between the toes.
• Ringworm (tinea corporis): Ringworm is a fungal infection that can appear anywhere on the body. It is characterized by a red, ring-shaped rash with clear skin in the center, which may be itchy or painful.
• Yeast infections: Caused by an overgrowth of Candida fungi, including Candida albicans, yeast infections can affect the mouth (oral thrush), genitals (vaginal yeast infection), and skin folds. Symptoms typically include itching, redness, swelling, and white discharge.

Parasitic infections are caused by parasites, organisms that live on or inside a host and rely on it for nourishment and survival. These parasites can include protozoa, helminths (worms), or ectoparasites like ticks and lice. Infections can occur through contaminated food or water, insect bites, or contact with contaminated soil.

• Malaria: Caused by the Plasmodium parasite and transmitted by infected female Anopheles mosquitoes. Symptoms include fever, chills, and flu-like symptoms, which can be life-threatening without prompt treatment.
• Toxoplasmosis: Caused by the Toxoplasma gondii parasite, commonly found in cat feces. It can be contracted through contaminated food or water and may cause flu-like symptoms or severe complications, especially in pregnant women and immunocompromised individuals.
• Tapeworm infections: Result from various species of tapeworms, often through undercooked or contaminated meat. Symptoms can include abdominal pain, weight loss, and nutritional deficiencies.

Prion diseases, or transmissible spongiform encephalopathies (TSEs), are rare, progressive neurodegenerative disorders caused by abnormal prion proteins. Unlike other pathogens, prions lack DNA or RNA.

• Creutzfeldt-Jakob disease (CJD): The most common prion disease in humans, presenting in sporadic, familial, or acquired forms. Symptoms include rapid dementia, muscle stiffness, involuntary movements, and eventually coma and death.
• Variant Creutzfeldt-Jakob disease (vCJD): Associated with consuming prion-contaminated beef, particularly from bovine spongiform encephalopathy (BSE), or mad cow disease. It has a younger onset age and may present with psychiatric symptoms.
• Gerstmann-Sträussler-Scheinker syndrome (GSS): A rare inherited prion disease causing ataxia, dementia, and other neurological symptoms, linked to mutations in the prion protein gene (PRNP).
• Fatal familial insomnia (FFI): An inherited prion disease marked by progressive insomnia, autonomic dysfunction, and dementia, also caused by mutations in the PRNP gene.

Currently, prion diseases have no cure and are invariably fatal. Treatment focuses on symptom management and supportive care. Prevention includes avoiding contaminated meat and implementing stringent infection control in healthcare settings.

Probiotics and prebiotics both support gut health but function differently. Probiotics are live microorganisms, typically bacteria or yeast, that confer health benefits when consumed in adequate amounts. These beneficial microbes are similar to those naturally found in the gut and are present in foods like yogurt, kefir, sauerkraut, kimchi, and in supplement form. They help maintain a healthy gut flora by encouraging the growth of beneficial bacteria and suppressing harmful ones. Probiotics have been linked to improved digestion, enhanced immune function, relief from irritable bowel syndrome (IBS), and even mental health support.

Prebiotics, on the other hand, are types of fiber that nourish beneficial gut bacteria. They are not digested by the human body but pass through to the colon, where they are fermented by gut bacteria, producing short-chain fatty acids that fuel colon cells and support gut health. Found in foods like bananas, onions, garlic, leeks, asparagus, chicory root, and whole grains, prebiotics work synergistically with probiotics to promote overall well-being.

Probiotics and prebiotics both support gut health but function differently. Probiotics are live microorganisms, typically bacteria or yeast, that confer health benefits when consumed in adequate amounts. These beneficial microbes are similar to those naturally found in the gut and are present in foods like yogurt, kefir, sauerkraut, kimchi, and in supplement form. They help maintain a healthy gut flora by encouraging the growth of beneficial bacteria and suppressing harmful ones. Probiotics have been linked to improved digestion, enhanced immune function, relief from irritable bowel syndrome (IBS), and even mental health support.

Prebiotics, on the other hand, are types of fiber that nourish beneficial gut bacteria. They are not digested by the human body but pass through to the colon, where they are fermented by gut bacteria, producing short-chain fatty acids that fuel colon cells and support gut health. Found in foods like bananas, onions, garlic, leeks, asparagus, chicory root, and whole grains, prebiotics work synergistically with probiotics to promote overall well-being.

Biofertilizers are substances containing living microorganisms that enhance plant growth by improving the availability of essential nutrients. They offer an eco-friendly alternative to chemical fertilizers by utilizing natural processes such as nitrogen fixation, phosphorus solubilization, and potassium mobilization.

• Nitrogen-fixing biofertilizers: These include bacteria like Rhizobium, Azotobacter, Azospirillum, and cyanobacteria, which convert atmospheric nitrogen into ammonia usable by plants. They are especially beneficial for leguminous crops such as soybeans, peas, and beans.
• Phosphorus-solubilizing biofertilizers: Containing microorganisms like Bacillus and Pseudomonas bacteria, and fungi such as Aspergillus and Penicillium, these biofertilizers solubilize insoluble phosphorus in the soil, making it available to plants.
• Potassium-mobilizing biofertilizers: These include microorganisms like Bacillus mucilaginosus and fungi like Aspergillus niger, which help mobilize potassium in the soil, enhancing its accessibility to plants.

Gene expression is the process by which information from a gene is used to synthesize a functional gene product, typically proteins or RNA molecules. It involves several key steps:

• Transcription: In the nucleus, DNA unwinds, and RNA polymerase binds to the promoter region of a gene to synthesize messenger RNA (mRNA). This mRNA carries genetic information from the DNA to the cytoplasm.
• RNA processing (in eukaryotes): Pre-mRNA undergoes modifications including capping (adding a 5' cap), splicing (removing introns), and polyadenylation (adding a poly-A tail).
• Translation: In the cytoplasm, ribosomes read the mRNA sequence and translate it into a polypeptide chain. Transfer RNA (tRNA) molecules bring amino acids to the ribosome.

Gene expression is tightly regulated by environmental signals, developmental cues, and cellular pathways. Dysregulation can lead to diseases such as cancer and genetic disorders.

Mutations are changes in the DNA sequence of an organism's genome and can have varying effects. Some mutations may be harmless or beneficial, while others can lead to genetic disorders or increase disease risk. Examples include mutations that cause cystic fibrosis, sickle cell disease, and Huntington's disease. Accumulation of mutations in dividing cells can also lead to cancer. Despite potential negative effects, mutations are essential for evolution. Research continues into understanding mutations and developing therapies for genetic diseases.

Track 10: Sexually Transmitted Diseases (STDs) and Infections (STIs)

Sexually transmitted diseases (STDs) and infections (STIs) are infections commonly spread through sexual activities. They can be caused by bacteria, viruses, parasites, or fungi.

• Chlamydia: Caused by Chlamydia trachomatis.
• Gonorrhea: Caused by Neisseria gonorrhoeae.
• Syphilis: Caused by Treponema pallidum.
• Human papillomavirus (HPV): Can cause genital warts and cancers.
• Herpes simplex virus (HSV): Causes genital herpes.
• HIV/AIDS: Weakens the immune system.

Prevention includes safe sex practices, regular testing, and early treatment.

Sexually transmitted diseases (STDs) and infections (STIs) are infections commonly spread through sexual activities. They can be caused by bacteria, viruses, parasites, or fungi.

• Chlamydia: Caused by Chlamydia trachomatis.
• Gonorrhea: Caused by Neisseria gonorrhoeae.
• Syphilis: Caused by Treponema pallidum.
• Human papillomavirus (HPV): Can cause genital warts and cancers.
• Herpes simplex virus (HSV): Causes genital herpes.
• HIV/AIDS: Weakens the immune system.

Prevention includes safe sex practices, regular testing, and early treatment.

COVID-19 is caused by SARS-CoV-2, first identified in Wuhan, China in 2019. It spreads through respiratory droplets and contact with contaminated surfaces. Symptoms include fever, cough, and fatigue, with severe cases leading to respiratory distress and death. Public health measures include masks, distancing, handwashing, and vaccination. The pandemic has had global health, economic, and societal impacts.

Antigen-antibody reactions are crucial to the immune response. Antigens trigger immune responses, while antibodies are proteins that recognize and bind to specific antigens. These reactions are key in immunity, diagnostics, allergy, and autoimmune responses. They are foundational in vaccine and diagnostic test development.

Recent developments include mRNA vaccines like Pfizer-BioNTech and Moderna, and vector-based vaccines like Oxford-AstraZeneca. These innovations allow rapid response to emerging pathogens. Advances also include monoclonal antibodies and antiviral drugs. These tools improve prevention and treatment of infectious diseases.

Infectious diseases result from bacteria, viruses, parasites, or fungi. Prevention includes vaccines, hygiene, and vector control. Cancer involves uncontrolled cell growth due to genetic and environmental factors. Treatment includes surgery, chemotherapy, radiation, and immunotherapy. Infections such as HPV and hepatitis B/C are linked to cancer development.

These affect animals and can be zoonotic. Examples include:

• Canine distemper: Viral disease in dogs.
• Feline panleukopenia: Viral infection in cats.
• Rabies: A fatal viral disease transmissible to humans.
• Foot-and-mouth disease (FMD): Viral disease in livestock.
• Control includes vaccination, biosecurity, and veterinary care.