infectious diseases

• Bacteria and viruses are the main disease-causing pathogens in humans
• Bacteria are prokaryotic cells with genetic information stored in a circular strand of DNA, while viruses consist of nucleic acid enclosed in a protein coat with genetic material in the form of DNA or RNA
• Bacteria do not require a host to survive, whereas viruses are entirely dependent on their hosts and cannot survive without them
• Viruses are significantly smaller than bacteria
• Bacteria have a cell membrane, cell wall, cytoplasm, ribosomes, plasmids, flagellum, and pili, while viruses possess no such structures
• Infectious diseases can spread between organisms by physical contact, through the air, or through vectors such as mosquitos
• Non-infectious diseases, like sickle cell anaemia and lung cancer, are not caused by pathogens and do not spread between organisms
• Tuberculosis (TB) is caused by the bacteria Mycobacterium tuberculosis, infecting phagocytes in the lungs, leading to breathing problems, coughing, weight loss, and fever
• HIV (Human Immunodeficiency Virus) causes AIDS, with symptoms including fevers, tiredness, and headaches, and can lead to AIDS when the immune system becomes weakened
• Malaria is found in hot, humid countries near the equator due to high mosquito numbers, while HIV/AIDS infections are mostly in less economically developed countries, especially in sub-Saharan Africa
• Antibiotics can kill bacteria by destroying their cell wall (bactericidal antibiotics) or inhibit their growth by stopping protein synthesis and nucleic acid production (bacteriostatic antibiotics)
• Some bacteria become resistant to antibiotics through natural selection, passing on the allele for antibiotic resistance to their offspring, creating resistant strains
• There is an ongoing evolutionary race between organisms and pathogens, with pathogens evolving adaptations to survive and reproduce, like the changing protein coat of HIV to evade the immune system
• Antibiotics do not work on viruses as they are designed to target bacteria specifically, and viruses replicate rapidly within cells
• Hospitals control the spread of antibiotic-resistant infections by screening new patients, isolating and treating infected individuals, using antibiotics only when necessary, and ensuring staff follow strict hygiene regimes