Communicable Diseases

• Measles:

  • virus

  spreads by airborne droplets:

  • coughing
  • sneezing

  Symptoms:

  • Red skin rash
  • fever

  Treatment and prevention is MMR vaccination:

  • measles
  • mumps
  • rubella

  
• Tobacco Mosaic Virus (TMV):

  • Virus

  Spreads by plant contact.

  Symptoms:

  • discoloured leaves, forming a mosaic pattern
  • stunted growth

  no cure.

  Prevention:

  • hygiene
  • proper plant handling
  • sanitation

  
• Rose black spot:


  • fungus

  Spread by being transported:

  • In the water
  • by the wind

  Symptoms:

  • purple / black spots on leaves
  • leaf drop

  Treatment:

  • fungicides
  • removing affected leaves and destroying it, so the fungi can't spread to any other plants

  Prevention:

  • proper sanitation
  • fungicide sprays

  
• Malaria:

  • protist

  Spreads by mosquito bites (vector)

  Symptoms:

  • fever
  • headaches
  • recurrent episodes
  • fatigue
  • chills

  Treatment is antimalarial drugs.

  Prevention:

  • mosquito control
  • Drain water from swamps
  • nets
  • insecticides
• Salmonella:


  • bacteria

  Spreads by contaminated food (poultry) and water.

  Symptoms are caused by toxins from bacteria.

  • fever
  • high temperatures
  • sweating
  • chills
  • stomach cramps
  • vomiting
  • diarrhoea

  treatment are antibiotics and vaccines for animals.

  Prevention:

  • food hygiene
  • proper cooking
  • disinfect clothes / surfaces
  • wash hands before handling food & after being sick
• Gonorrhoea - a sexually transmitted disease (STD):

  • bacteria
  • spreads by sexual contact (unprotected sex)

  Symptoms:

  • painful urination
  • Thick yellow / green genital discharge
  • fever
  • nausea
  • vomiting

  treatment are antibiotics

  • preventions are barrier methods of contraception (condoms)
• How Pathogens Spread:

  • WATER
  • AIR
  • DIRECT CONTACT
  • vectors
  • exchanging of bodily fluids
• Reducing or Preventing the Spread of Disease:

  • HYGIENE:
  • WASHING hands and maintaining cleanliness
  • cleaning cookery items
  • DESTROYING VECTORS:
  • Eliminating disease - carrying organisms (like insects) by using INSECTICIDES or destroying their HABITAT.
  • ISOLATING INFECTED INDIVIDUALS:
  • Keep people with the disease AWAY from the general public to prevent them from spreading to others.
  • VACCINATION:
  • Reduces the developing and passing on the infection.
• WATER:

  Drinking or bathing in CONTAMINATED water can lead to diseases like cholera.
• AIR:


  Airborne pathogens are spread through droplets when someone with an infection COUGHS or SNEEZES.

  examples:

  • influenza
  • measels
• DIRECT CONTACT:


  TOUCHING contaminated surfaces or skin-to-skin contact can transmit diseases such as athlete's foot.
• Plants with rose black spot disease often have yellow leaves instead of green as the chlorophyll has been broken down and there's less of it.
• Plants with yellow leaves grow slowly as there's less light absorbed and less photosynthesis, so less glucose / sugar formed.
• The spread of rose black spots can be controlled using different methods:

  • Remove and burn infected leaves, so pathogens are killed.
  • Water the roots of the plant only, not the leaves:
  • reduces the chances of pathogens being spread by water droplets.
• Male mosquitos can be sterilised, so they are infertile.


  The spread of malaria is reduced by releasing sterile mosquitos into the environment as it:

  • reduces breeding in mosquitos.
  • fewer mosquitos bite people to pass on pathogens.
• Methods used to prevent people catching malaria:


  Insecticides:

  • to kill mosquitos / vector

  Mosquito nets / long clothing:

  • To avoid being bitten

  Insect repellents:

  • less likely to be bitten

  Vaccination:

  • so people are immune to malaria
• Methods used to prevent people catching malaria:

  Antibiotics / anti-malaria tables:

  • kills the pathogen / protist

  Drain swampy ground / remove pots of water / put oil on water / pond:

  • fewer breeding grounds for mosquitos

  Release sterile mosquitos:

  • prevent / reduce reproduction
• Evidence that supports the statement:

  • there's lower percentage of people with malaria, when using mosquito nets

  The statement may not be valid:

  • some people who use nets have malaria
  • data from only one area
  • sample size too small
  • uneven group sizes (nets vs. no nets), as only 50 people did not use nets.
  • no other info about people considered
  • people may have lied about using nets.

  
• Reasons for the reduced number of deaths from malaria each year:

  • use of mosquito nets
  • improved health care
  • use of mosquito control methods
  • changing behaviour to avoid being bitten by mosquitoes
• Athlete's foot:


  • Fungal infection

  Spread by direct contact:

  • Walking barefoot on contaminated surfaces

  Symptoms:

  • The skin on your feet flake off
• HIV (human immunodeficiency viruses):



  virus

  spreads by:

  • blood
  • sexual contact
  • exchanging bodily fluids
  • semen
  • vaginal fluids

  Symptoms:

  • Flu-like symptoms
  • progresses to AIDS

  Treatment is antiretroviral drugs.

  Prevention:

  • Safe sex practices
  • no needle sharing
• HIV


  When first catching HIV, there's flu-like symptoms for a few weeks like:

  • fever
  • tiredness
  • aches

  But then starts to feel better & that everything's fine:

  • But inside their bodies, parties are doing more damage to the immune system
  • it becomes so weak that it starts to catch unusual infections & even get cancers.
  • The person has developed AIDS

  This used to be the end as people would die of random infections / cancer.

  • Now, as long as people have access to antiretroviral drugs early on in their disease, they can go on to live normal lives.
• Antiretroviral drugs


  Prevents the virus from replication within out bodies
• AIDS 


  A disease / syndrome where the person's immune system can't cope anymore.
• HIV stands for Human Immunodeficiency Virus.

  This is because it affects humans, it weakens the immune system (immunodeficiency), and it is a virus.

  • The term HIV refers to the virus, not disease
• • Lots of gonorrhoea strains (different types) have become resistant to penicillin.
  • So we're having to use rarer and more expensive antibiotics.
• Plants with rose black spot disease causes purple / black spots on the leaves of plants and as the fungus does more damage, the leaves will turn yellow and drop off.