Chapter 8: Infectious diseases

• Infectious diseases can be spread from person to person whereas non-infectious diseases cannot
• Infectious diseases


  Caused by pathogens such as bacteria and viruses, can be spread from person to person through bodily fluids, food and water
• Sign of a disease


  Can be observed or measured, e.g. rashes, fever, coughing or vomiting
• Symptom of a disease


  Can be described or felt by the patient, e.g. headaches, fatigue and nausea
• Disease


  A condition that causes the body to function less effectively, produces specific signs or symptoms
• Examples of diseases


  • Influenza
  • Pneumonia
  • Dust allergy
  • Malaria
  • Diabetes
  • HIV/AIDS
  • Osteoporosis
  • Covid-19
  • Asthma
• Infectious diseases can be spread from person to person, non-infectious diseases cannot
• Pathogen


  An agent that causes infectious diseases
• Examples of pathogens


  • Bacteria
  • Viruses
• How one gets a non-infectious disease


  • By inheriting it
  • By being exposed to environmental factors like pollution
  • By having a lifestyle that includes smoking or excessive intake of saturated fats and cholesterol in the diet
• When a person coughs or sneezes


  Respiratory droplets containing pathogens are expelled and can infect others nearby
• Diseases spread through direct person-to-person contact


  Such as by exchanging body fluids during sexual intercourse
• Food and water can be contaminated with pathogens


  This can occur when food and water are not properly stored or handled
• Wearing masks and social distancing can limit infection from respiratory droplets
• Washing hands, avoiding touching eyes/nose/mouth, and taking prescribed antiviral drugs can limit transmission of influenza
• Taking prescribed antibiotics can treat pneumococcal disease
• Vaccine


  Contains an agent that resembles a pathogen and prevents infectious diseases by stimulating white blood cells to quickly produce antibodies when the pathogen invades
• Antibiotics kill bacteria but are ineffective against viruses
• Misuse and overuse of antibiotics can accelerate the emergence of antibiotic-resistant bacteria
• Vaccine


  An agent that resembles a pathogen and prevents infectious diseases by stimulating white blood cells to quickly produce antibodies when the pathogen invades
• Vaccination


  The process of receiving a vaccine
• Vaccines


  • Can be taken orally or administered through an injection
• Immune response to vaccine


  1. White blood cells bind to antigens on pathogen

  2. White blood cells are stimulated to divide

  3. Many antibodies produced by copies

  4. Some white blood cells remain as memory cells to recognise and produce antibodies in the future
• Antibodies help destroy pathogen
• Antibiotics


  Drugs used to treat bacterial infections, made by microorganisms, used to kill or inhibit the growth of bacteria or fungi, interferes with the growth and metabolic activities of the pathogens, ineffective against viruses, chemically modified to make them more effective in treating diseases
• How antibiotics work


  1. Inhibit the synthesis of bacterial cell walls

  2. Inhibit cell membrane function

  3. Inhibit protein synthesis in ribosome

  4. Inhibit enzyme action in cytoplasm
• Antibiotics are ineffective against viruses because they act on bacterial cell walls, break up cell membranes, and act on ribosomes - viruses do not have these
• Antibiotic resistance


  Bacteria become resistant to antibiotics, resulting in "superbugs" that are difficult to treat
• How antibiotic resistance develops


  1. Bacteria that are less sensitive to an antibiotic survive and multiply, passing on their resistance genes

  2. Further use of the same antibiotic will not kill these resistant bacteria

  3. Resistant bacteria can spread to others, making the disease incurable
• Reducing antibiotic resistance


  • Not misusing or overusing antibiotics
  • Completing the full course of antibiotics prescribed
  • Using antibiotics only when necessary, not for minor infections
• A new strain of influenza virus has been identified that spreads three times more quickly and has a higher number of flu-related deaths
• Steps to design a way to slow down the spread of the virus


  1. Understand the science and mathematics of the problem

  2. Understand the possible engineering aspects of a solution

  3. Know the technological aspects of a possible solution