Communicable Diseases

• What are pathogens?


  • Microorganisms that cause infectious disease
  • Bacteria, viruses, fungi, and protists
• How may pathogens be spread?


  • Direct contact
  • Water
  • Soil
  • Air
• What are bacteria?


  • Quite small
  • Multiply quickly through binary fission
  • Produce toxins that damage cells
• What are protists?


  • Some are parasites (they live on or inside organisms)
  • Can be transported by vectors (carry the disease without actually contracting it)
• What are fungi?


  • Can be unicellular or multicellular
  • Made up of hyphae (thread-like structure)
  • They can produce spores to spread to organisms
• How can we reduce the damage that disease causes?


  • Improve hygiene: hand washing, using disinfectants, tissues
  • Reducing contact (isolation)
  • Removing vectors: Pesticides/insecticides
  • Vaccination
• What are the symptoms of measles?


  • Fever
  • Red skin rash
  • Can lead to pneumonia
  • Encephalitis (brain infection)
  • Blindness
• How are measles spread?


  Air (respiratory droplets)
• How can measles be prevented?


  Vaccinations
• What are some examples of viral diseases?


  • Measles
  • HIV
  • HPV
  • TMV (Tobacco Mosaic Virus)
• What are symptoms of HIV?


  • Flu-like symptoms
  • Can lead to AIDS
• How is HIV spread?


  • Sexual contact
  • Exchange of bodily fluids
• How can you prevent and treat HIV?


  • Using condoms
  • Not sharing needles
  • Use antiretroviral drugs
• What are symptoms of TMV?


  • Discolouration of the leaves
  • Stunted growth
• How is TMV spread?


  Contact between infected plants
• How can we prevent the spread of TMV?


  • Good field hygiene
  • Growing TMV resistant strains
• What are examples of bacterial diseases?


  • Salmonella
  • Gonorrhea
• What are symptoms of salmonella?


  • Fever
  • Stomach cramps
  • Vomiting
  • Diarrhoea
• How is salmonella spread?


  Cooking preparation in unhygienic conditions
• How do we prevent the spread of salmonella?


  • Have poultry vaccinated against salmonella
  • Keep raw meat away from cooked food
  • Wash hands and surfaces
  • Cook food throughly
• What are the symptoms of gonorrhea?


  • Thick yellow/green discharge
  • Pain when urinating
• How is gonorrhea spread?


  Unprotected sex
• How is gonorrhea prevented?


  • Use condoms
  • Antibiotics (resistant strains are developing)
• What are examples of fungal diseases?


  • Athlete's foot
  • Rose black spot
• What are symptoms of rose black spot?


  • Purple/black spots
  • Smaller leaves
  • Discolouration
  • Leaves dropping
  • Stunted growth
• How is rose black spot spread?


  Spores of fungi spread by water and wind
• How is rose black spot prevented?


  • Fungicides
  • Removing affected leaves
• What's an example of a protist disease?


  Malaria
• What are symptoms of malaria?


  • Fevers
  • Shaking
• How is malaria spread?


  Vectors (female mosquitoes) puncture human skin to enter bloodstream
• How is malaria prevented?


  • Insecticides
  • Mosquito nets
  • Removing stagnant water to stop breeding
  • Antimalarial drugs
• What are the non-specific defences?


  • Skin
  • Acts as a physical barrier
  • Produced antimicrobial secretions
  • Skin flora get rid of bad microorganisms
  • Nose
  • Mucus prevents particles from entering your lungs
  • Trachea
  • Goblet cells produce mucus for pathogens to stick to
  • Cilia waft pathogens out of the trachea
  • Stomach
  • Hydrochloric acid kills pathogens
  • Lysozymes
  • Produces in eyes, mouth, and nose
• What are the three types of white blood cells?


  • Phagocytes: engulfs and digests pathogens by phagocytosis
  • Antitoxins: neutralise toxins
  • Antibodies: bind to complementary antigens resulting in white blood cells finding pathogens easily
• How do vaccinations work?


  • Insert a dead/inactive form of a pathogen
  • This incites an immune response and brings antibodies and antitoxins
  • They stay behind as memory cells
  • Next time infection happens, they are made quicker before the person becomes ill
• What are the advantages of vaccination?


  • Eradicated many diseases like smallpox
  • Epidemics can be prevented by herd immunity
• What are the disadvantages of vaccinations?


  • Not always effective in providing immunity
  • Side effects
• What's herd immunity?


  When a large majority of a population is vaccinated so it cannot be spread as easily through the population
• What are antibiotics used for?


  • Bacteria
  • Cannot kill viruses as they are inside cells
• What are painkillers?


  Treat symptoms of disease, not the disease itself
• How does antibiotic resistance work?


  • Mutations cause some bacteria to become resistant
  • The non-resistant bacteria die and the resistant ones survive
  • This means they can reproduce quickly to make identical ones with resistance
  • This repeats overtime to create antibiotic resistance