Communicable diseases

• What is a communicable disease

  A disease caused by a pathogen which can be passed between animals or plants
• What is a pathogen

  A disease causing microorganisms
• How do bacteria cause disease

  Once inside the body they divide rapidly by binary fission. They kill cells and produce harmful toxins
• How do viruses cause disease

  They invade and reproduce inside living body cells leading to cell damage
• Give three ways in which pathogens can be spread

  • air
  • water
  • direct contact
• 4 ways in which the spread of pathogens can be reduced

  • Hygiene- hand washing,disinfectants,tissues
  • reducing contact with infected individuals-quarantine
  • removing vectors-use of pesticides and insecticides,removal of habitats
  • vaccination
• Why is it especially important to prevent the spread of viral diseases

  Scientists have not yet developed cures for many viral diseases
• What is measles

  It’s a serious viral disease that can cause blindness and brain damage.the main symptoms are a fever and a red skin rash
• How is measles spread

  By air - through the inhalation of droplets from coughs and sneezes
• What is HIV/AIDS

  HIV is a virus which attacks and damages the immune system until it can no longer function properly

  AIDS is the condtion resulting from a long term HIV infection. There’s no cure or vaccine for HIV/AIDS
• How is HIV spread

  Direct sexual contact and the exchange of bodily fluids
• How can the spread of HIV/AIDS be prevented

  • Use of condoms
  • screening of blood for transfusions
  • not sharing needles
  • bottle feeding by HIV positive mothers
  • use of antiretroviral drugs to prevent the development of AIDS
• What is tobacco mosaic virus

  A plant pathogen which causes leaf discolouration when cells are damaged. Affected areas cannot photosynthesise reducing the crop yield. As ther is no treatment farmers grow TMV-resistant crop strains to avoid infection
• How is tobacco mosaic virus spread

  Contact between infected and healthy plants.insects may act as vectors which transfer the virus between different plants
• What is salmonella

  A type of bacteria found in raw meat, poultry and eggs. If they enter the body via food poisoning, they can affect natural gut bacteria
• What are the symptoms of salmonella food poisoning

  • Fever
  • abdominal cramping
  • vomiting
  • diarrhoea

  may be fatal in very young or elderly populations due to the risk of dehydration
• How can the spread of salmonella be limited

  • Vaccinating animals intended for consumption
  • keep raw meat away from cooked meat
  • disinfect hands and surfaces after contact with raw meat
  • thoroughly cook meat
• What is gonorrhoea

  A sexually transmitted bacterial infection caused by unprotected sex with an infected individual. Early symptoms include yellow/green discharge from genitals and painful urination although it may seem symptomless.

  its spread can be controlled through the use of antibiotics and using condoms
• What is rose black spot

  A fungal disease which causes purple or black spots to develop on rose leaves. It reduces the area of the leaf which is available for photosynthesis and causes leaves to turn yellow and drop prematurely
• how is the rose black spot fungus spread

  Fungal spores are spread by the wind and in water
• How can rose black spot fungus be treated

  • Using fungicides
  • destroying infected leaves
• What is malaria

  It’s a disease caused by protist pathogens.

  the disease is carried from host to host by mosquitoes and the protists enter the human bloodstream when they feed.symptoms include fever and shaking, and it may also be fatal in some cases.
• How can the spread of malaria be reduced

  • Using insecticides
  • using insect nets to avoid bites
  • prevent mosquito breeding by removing stagnant water
  • antimalarial drugs
• How does the skin prevent pathogens from entering the body

  • Acts as a physical barrier
  • scab formation after akin is cut/wounded
  • antimicrobial secretions which can kill pathogens
  • healthy skin flora compete with pathogens and act as an additional barrier
• How does the respiratory system prevent pathogens from entering the body

  • Nose-has hairs and mucus which trap pathogens
  • trachea and bronchi - have mucus that traps pathogens. Ciliates cells move mucus to the mouth so it can be swallowed
• How does the stomach prevent pathogens infecting the body

  • Secretes hydrochloride acid-kills any pathogens present
• How does phagocytosis protect us against disease

  White blood cells (phagocytes) ingest and destroy pathogens so they cannot infect more cells
• how does antibody production protect us against disease

  White blood cells produce antibodies which are complementary to a specific antigen on a pathogen.the binding of antibodies to antigens causes pathogens to clump together ,making them easier to destroy.in the case of a second infection the correct antibodies can be produced rapidly preventing the person getting the same disease again
• How does antitoxin production protect us against disease

  Antitoxins bind to toxins released by pathogens and neutralise them
• What is a vaccination

  Contains a dead or inactived form of the pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen.in the cases of a second infection memory cells can rapidly produce the correct antibodies and prevent illness
• What is herd immunity

  If a sufficiently high proportion of a population are immune to a disease (especially through vaccination) the spread of this disease will be limited
• What are the advantages of vaccinations

  • They have eradicated many deadly diseases
  • many epidemics can be prevented by vaccinations
  • herd immunity protects those who cannot have vaccinations
• What are the disadvantages of vaccinations

  • Not guaranteed to work -might not protect against multiple strains of a pathogen
  • may be side effects or adverse reactions
• What drugs are used to cure some bacterial diseases

  Antibiotics-they can kill bacterial pathogens inside the body
• How do antibiotics work

  Antibiotics e.g. penicillin kill bacterial pathogens inside the body but do not kill human cells. Whilst some antibiotics kill a wide range of bacteria it is important that the right antibiotic is used for specific bacteria
• Why can antibiotics not be used to treat viral disease

  Antibiotics have no effect on viral pathogens as they live inside the hosts (human) cells. Therefore it is difficult to design drugs that would kill the virus and not destroy human cells at the same time
• What is antibiotic resistance

  Antibiotic resistance occurs when mutations lead to individual bacteria being resistant to an antibiotic.these bacteria are able to survive reproduce and pass on their alleles leading to a greater proportion of antibiotic resistant bacteria.this is concerning as some types of bacteria are becoming resistant to all known antibodies so the diseases that they cause cannot be cured
• How can we prevent antibiotic resistance

  • Avoid overuse and unnecessary use of antibiotics
  • finish antibiotic course this ensures all bacteria is killed
• What effect do painkillers have on infectious disease s

  Painkillers can only treat the symptoms but do not kill pathogens
• What plant is the heart drug digitalis extracted fTom

  Fox glove