Health and Disease

• Health


  A state of physical and mental wellbeing
• Factors affecting health


  • Disease
  • Communicable
  • Non-communicable
  • Diet
  • Stress
  • Life situations
• Communicable disease


  A disease that can be passed from one organism to another, caused by pathogens
• Types of pathogen


  • Bacteria
  • Fungi
  • Protist
  • Virus
• How diseases are spread

  1. Through contaminated food

  2. Passed by another animal

  3. Through dirty water

  4. Through the air

  5. By direct physical contact
• Pathogen


  A microorganism that can cause disease
• Bacteria


  • Reproduce rapidly inside the body, release toxins that make us ill
• Virus


  • Live and reproduce quickly inside our cells, causing cell damage
• Fungi


  • Multicellular organisms that prefer damp/moist environments
• Protist


  • Microorganisms that have features belonging to plants, animals and fungi
• All communicable diseases are caused by pathogens
• Bacteria reproduce by binary fission, producing cells identical to the parent cell
• Bacteria produce toxins, and when there are many bacteria in our bodies releasing toxins this makes us feel ill
• More pathogens


  More toxins, more unwell
• Viral diseases


  • HIV (human immunodeficiency virus)
  • Ebola virus
• Bacterial diseases


  • Cholera
  • Tuberculosis
  • Helicobacter
• Fungal disease


  • Chalara ash dieback
• Pathogens can spread through direct contact, air, and water. A vector like mosquitoes can spread disease from one organism to another
• Poor diet, stress, and life situations can also affect health
• Ebola virus


  Causes haemorrhagic fever with internal and external bleeding leading to multiple organ failure
• Bacterial Diseases


  • Cholera
  • Tuberculosis
  • Helicobacter
• Cholera


  Spread via contaminated drinking water, causes diarrhoea and can kill if left untreated, often a consequence of a humanitarian crisis, reduced by clean drinking water and good sanitation
• Tuberculosis (TB)


  Bacteria spread through the air in tiny droplets when an infected person sneezes or coughs, can cause lung damage, vaccination programme in place to reduce spread
• Helicobacter


  Contributory factor in development of stomach ulcers, transmitted orally through saliva, reduced by not sharing food/cutlery/cups and avoiding saliva exchange with infected person
• Fungal Disease


  • Chalara ash dieback
• Chalara ash dieback


  Causes leaf loss and lesions in the bark, trees usually die or become weakened, no known cure, spread through airborne transmission of fungal spores, reduced by cleaning machinery/tools/vehicles/footwear, burning or composting infected leaves, warning all land users
• Protist Disease


  • Malaria
• Malaria


  Caused by a protist spread by mosquitoes feeding on infected blood and then biting a human, mosquitoes are animal vectors, can be fatal, spread controlled by preventing mosquito breeding and using mosquito nets
• Diseases


  • Malaria
  • Chalara ash dieback
  • Cholera
  • HIV
  • Ebola
• Symptoms


  • Recurrent fever
  • Leaf loss and bark lesions
  • Diarrhoea
  • Flu-like illness
  • Haemorrhagic fever
• Transmission methods


  • Animal vector
  • Airborne
  • Waterborne
  • Sexual contact or bodily fluids
  • Bodily fluid - direct contact
• Disease control measures


  • Preventing mosquito breeding or using nets
  • Removing infected leaf litter, cleaning tools/vehicles/footwear
  • Clean drinking water and good hygiene/sanitation
  • Use of condoms, clean needles, antiretroviral drugs
  • Avoid contact with infected people
• Causative agents

  • Protist
  • Fungus
  • Bacteria
  • Virus
  • Virus
• Visible symptoms


  One way to identify plant diseases
• Diagnostic testing


  Another way to identify plant diseases
• Nitrate


  Ion needed for healthy growth in plants
• Magnesium


  Mineral ion likely to be absent if a plant has yellow leaves
• Cuticle


  • It is a physical barrier to infection
• How some fungi overcome plant defences to infect the plant


  Explain how
• Plants with physical damage, such as a wound or cut in the surface are more easily infected by pathogens than undamaged plants