infectious diseases in human

• Diseases can be caused by having a lifestyle that includes smoking or excessive intake of saturated fats and cholesterol in the diet.
• Disease is a condition that causes the body to function less effectively and produces specific signs or symptoms
• Sign of a disease can be observed or measured, such as rashes, fever, coughing, or vomiting
• Symptom of a disease can be described or felt by the patient, such as headaches, fatigue, and nausea
• Pathogens are disease-causing organisms like bacteria, viruses and fungi that can cause the body to function less effectively
• Infectious disease is a transmissible disease that can be spread from one person to another and it is usually caused by a pathogen that can cause the body to function less effectively.

  
  

  eg: Influenza, Pneumonia, COVID-19, HIV/AIDS, and Malaria
• Non-infectious diseases are not caused by pathogens but can be inherited genetically or due to environmental factors and lifestyle choices
• Vaccine contains a deactivated pathogen that stimulates white blood cells to produce antibodies and prevent infectious diseases
• Virulence is the ability of a pathogen to cause a disease
• Infectious diseases can be spread through droplets in the air, direct contact, and contaminated food and water
• Droplets in the air:

  • Spread by respiratory droplets or aerosols suspended in the air when an infected person coughs or sneezes. These droplets or aerosols contain pathogens
  • Close contact can lead to infection
  • Prevention: wear masks, social distance, wash hands, clean surfaces, quarantine
• Direct contact:

  • Direct person-to-person contact or through the exchange of body fluids with an infected person e.g. sexual intercourse with infected partner/breastfeeding by an infected mother
  • Can occur in STIs like HIV/AIDS
  • Encourage protected sex
• Contaminated food and water:

  • Diseases can be spread when a person consumes contaminated food and water that has not been hygienically handled or stored
  • Pathogens like bacteria can contaminate food and water
  • Proper storage and handling methods can prevent contamination
• Bacterial cells lack membrane-bound organelles like mitochondria and can carry out respiration
• Viruses lack ribosomes and require a living host cell to reproduce and synthesize proteins
• Antibiotics treat bacterial infections by inhibiting bacterial cell wall synthesis, protein synthesis, and enzyme action
• Antibiotics are ineffective against viruses because viruses lack cell walls, membranes, and ribosomes
• Antibiotic resistance can occur when bacteria mutate and become resistant to antibiotics, leading to "superbugs"
• How antibiotic resistance comes about:

  • Exposure to mutagenic agents can cause gene changes in bacteria
  • Mutated bacteria become resistant to antibiotics
• How antibiotic resistance can be reduced:

  • Avoid misusing or overusing antibiotics
  • Complete prescribed antibiotic courses
  • Use antibiotics only when necessary
• Vaccination is the process of receiving a vaccine
• Vaccines can be taken orally or administered through an injection
• The vaccine contains an agent that resembles a pathogen
• 1. Wbc binds to antigens on pathogen
  2. Wbc is stimulated to divide

  • Many antibodies produced by copies
  • Antibodies help destroy pathogen
  • Some wbc remain in the bloodstream for a long time as memory cells. In the future, when the same pathogen enters the body, the memory cell can recognise and produce the antibodies to destroy it
• antibiotics

  • Drugs used to treat BACTERIAL infections
  • Made by microorganisms
  • Used to kill or inhibit the growth of bacteria of fungi
  • Interferes w the growth & metabolic activities of the pathogens
  • Ineffective against viruses
  • Chemically modified to make them more effective in treating diseases
• antibiotics inhibit cell membrane function

  Bacterial cell is no longer protected from its environment and substances can move into the bacterial cell
• antibiotics inhibit the synthesis of bacterial cell walls

  • Some antibiotics (eg penicillin) prevent the synthesis of cell walls
  • When cell walls are weakened, water enters the cell by osmosis
  • The cell then expands, bursts and dies
• Inhibits enzyme action in cytoplasm

  • Bacteria requires folic acid (vitamin) for growth
  • Some antibiotics inhibit the enzyme needed for the synthesis of folic acid
  • Inhibits the growth of bacteria
• Inhibits protein synthesis in ribosomes

  • Some antibiotics bind to bacterial ribosomes → prevents ribsomes from taking part in protein synthesis →  inhibiting growth
• Bacteria has a cell wall and cell membrane, cytoplasm, loop of DNA (generally), flagella, ribosomes

  Bacteria can reproduce by itself
• both bacteria and viruses have genetic material, but no nuclei
• a typical virus has a protein coat enclosing its genetic material, which is either DNA or RNA, but not both in the same virus
• viruses requires a living host cell to reproduce and make more copies of itself as the host cell contains the necessary materials for reproduction, such as enzymes, and organelles like ribosomes
• ROLE OF ANTIBODIES IN DEFENCE OF THE BODY AGAINST PATHOGENS:

  a.Specific antibodies have a complementary shape

  b. to the antigens on the surface of the pathogens;

  c. These antibodies recognizes

  d. and binds to these antigens,

  e. marking them for destruction or

  f. phagocytosis by white blood cells;
• Vaccine contains an agent that resembles a pathogen. This stimulates white blood cells to produce antibodies that have a complementary shape to the pathogen.

  These antibodies recognizes and binds to these pathogens that cause infectious disease and mark them for destruction by phagocytes.