Infection + Response

• Antibiotics


  Medicines that help to cure bacterial disease by killing infective bacteria inside the body
• Clinical drug testing


  Drug testing done on healthy human volunteers and patients
• Communicable disease


  A disease that can be spread between individuals either directly or indirectly
• Double blind trial


  A study performed where neither the researcher or patient know whether the patient is taking the drug or a placebo
• Gonorrhoea


  A sexually transmitted disease (STD) caused by a bacterium with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating
• Human Immunodeficiency Virus (HIV)


  An infectious virus that weakens the immune system and can lead to AIDS (acquired immunodeficiency syndrome)
• Malaria


  A disease caused by a protist that causes recurrent episodes of fever and can be fatal
• Measles


  A serious disease caused by a virus that shows symptoms of fever and a red skin rash
• Monoclonal antibodies


  Antibodies produced from a single clone of cells that are specific to one binding site on one protein antigen
• Non-communicable disease


  A disease which cannot be spread between individuals
• Non-specific defence


  General physical and chemical barriers that defend the body against lots of different types of pathogen
• Pathogens


  Microorganisms that cause infectious disease
• Placebo


  A substance designed to be indistinguishable from a drug being tested but has no actual effect on the patient
• Preclinical drug testing


  Drug testing done in a laboratory using cells, tissues and live animals
• Rose black spot


  A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early
• Salmonella


  A bacterial disease that is spread by bacteria ingested in food and can cause a fever, abdominal cramps, vomiting and diarrhoea
• Side effects


  Other additional effects that the drug has that are different from the expected effect of the drug
• Tobacco Mosaic Virus (TMV)


  A widespread plant pathogen affecting many species of plants which produces a mosaic pattern on the leaves and limits the plant growth
• Vaccination


  The process of introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies
• White blood cell


  An important type of cell that makes up the immune system and produces antibodies and antitoxins
• Pathogens


  Microorganisms that cause infectious disease
• Types of pathogens


  • Viruses
  • Bacteria
  • Protists
  • Fungi
• Viruses


  • Very small
  • Move into cells and use the biochemistry to make many copies of itself
  • This leads to the cell bursting and releasing all of the copies into the bloodstream
  • The damage and the destruction of the cells makes the individual feel ill
• Bacteria


  • Small
  • Multiply very quickly through dividing by a process called binary fission
  • They produce toxins that can damage cells
• Protists


  • Some are parasitic, meaning they use humans and animals as their hosts (live on and inside, causing damage)
• Fungi


  • Can either be single celled or have a body made of hyphae (thread-like structures)
  • They can produce spores which can be spread to other organisms
• Ways pathogens are spread

  • Direct contact
  • By water
  • By air
• Direct contact


  Touching contaminated surfaces, kissing, contact with bodily fluids, direct skin to skin, microorganisms from faeces, infected plant material left in field
• By air


  Pathogens can be carried in the air and then breathed in (a common example is the droplet infection, which is when sneezing, coughing or talking expels pathogens in droplets which can be breathed in)
• Ways to reduce the damage of disease

  • Improving hygiene
  • Reducing contact with infected individuals
  • Removing vectors
  • Vaccination
• Improving hygiene


  Hand washing, using disinfectants, isolating raw meat, using tissues and handkerchiefs when sneezing
• Removing vectors


  Using pesticides or insecticides and removing their habitat
• Vaccination


  Injecting a small amount of a harmless pathogen into an individual's body, they can become immune to it so it will not infect them. This means they cannot pass it on.
• Viruses


  • Particularly dangerous as they can enter all types of cells, and scientists are yet to develop medicines to cure them
• Measles symptoms include fever and red skin rash, can lead to other problems such as pneumonia (lung infection), encephalitis (brain infection) and blindness
• How measles is spread

  Droplet infection
• How measles is being prevented

  Vaccinations for young children to reduce transmission
• HIV


  • Initially flu-like symptoms, then the virus attacks the immune system and leads to AIDS (a state in which the body is susceptible to many different diseases)
• How HIV is spread

  By sexual contact or exchange of bodily fluids such as blood
• How HIV is being prevented

  • Using condoms
  • Not sharing needles
  • Screening blood when it is used in transfusions
  • Mothers with HIV bottle-feeding their children instead of breastfeeding