Disease, defence and treatment

• Diseases


  • AIDS
  • Chlamydia
  • Malaria
• Causative agent


  The agent that causes the disease
• Effect


  The impact the disease has on the body
• Treatment


  The method used to cure or manage the disease
• Prevent spreading


  The methods used to stop the disease from spreading to others
• AIDS


  HIV (Human Immunodeficiency Virus) infects lymphocytes leading to lack of immunity to other infections
• AIDS treatment


  Antiviral drugs taken for life
• AIDS prevention


  Spread by blood to blood contact - Use disposable gloves. Sexually transmitted, use condoms to prevent spread
• Chlamydia


  Chlamydia trachomatis (bacteria) causes infertility in adults, conjunctivitis and lung problems in babies
• Chlamydia treatment


  Antibiotics like tetracycline/erythromycin
• Chlamydia prevention


  Sexually transmitted, use condoms to prevent spread
• Malaria


  Plasmodium (Protist) destroys red blood cells causing fever
• Malaria treatment


  Antimalarial drugs paludrine or daraprim to kill the plasmodium
• Malaria prevention


  Spread by female Anopheles mosquitos. Prevent the mosquitos biting and infecting people by: killing mosquitoes with insecticide, releasing large numbers of infertile male mosquitoes, biological control of mosquitoes, use of mosquito nets and repellents
• Monoclonal antibody production


  1. Injection of specific antigen

  2. Antibody producing cell

  3. Hybridoma

  4. Cloning hybridomas

  5. Isolated monoclonal antibodies
• Monoclonal antibody


  Produced from cloned hybridomas which makes them identical
• Medical uses of monoclonal antibodies

  • Immunoassays
  • Tissue Typing
  • Treating cancers with chemotherapy
  • Monitoring the spread of malaria
• Immunoassays


  Monoclonal antibodies are made for the specific antigens on disease causing agents such as Chlamydia trachomatis bacteria, HIV and Plasmodium. These monoclonal antibodies are labelled (with radioactivity or fluorescence) and added to body fluids to be tested. The extent of labelling detected indicated the extent of the infection
• Tissue Typing


  The concentration of non-self-antigens in tissues is assessed. Monoclonal antibodies can be used against helper T-cells (T-lymphocytes) so B-lymphocytes, normally causing rejection, are prevented from functioning
• Treating cancers with chemotherapy

  Monoclonal antibodies can be made for cancer cell antigens (tumour markers) and carry anti-cancer drugs directly to the cells
• Monitoring the spread of malaria

  Monoclonal antibodies specific to Plasmodium antigens are used to test blood samples from a community. This detects Plasmodium living or dead and can show the spread of Malaria and give an indication the effectiveness of anti-malaria drugs
• Antibiotics


  Destroy bacteria or stop their growth. Antibiotics work only on bacteria and fungi, they do not kill viruses
• Penicillin, an antibiotic, was discovered by Alexander Fleming. It was made by a fungus. Now antibiotics are chemically modified and synthetic
• Some antibiotic resistant bacteria such as MRSA are causing problems in hospitals. This may have developed from over-use of antibiotics. Good hygiene like hand washing, alcohol gels, effective cleaning of hospital wards etc. need to be used to prevent the spread
• Microorganisms


  Most microorganisms are harmless, some even useful. Microorganisms that cause diseases are called pathogens. Fungi, protists, bacteria and viruses can all cause disease
• Pathogen transmission


  Pathogens are communicable, they can be spread by: contact, aerosol, body fluids, water, insects, contaminated food
• Body defences


  • Skin flora- bacteria that make it difficult for pathogens to become established
  • Intact skin is a barrier and blood clots immediately around wounds
  • Stomach acid and lysozyme in tears protect where skin is not present
• Phagocytes


  White blood cells that recognise the antigens on the microbe as an invader, engulf the microorganism and digest it using enzymes
• Lymphocytes


  White blood cells that recognise the specific antigens on invading microorganisms and produce antibodies and antitoxins
• Antibodies


  Mark the microbe for destruction by the phagocytes, clump microbes together so many can be destroyed at once, cause the destruction of the microbe
• Immunity development


  1. A lymphocyte recognises the antigen of an invading microorganism

  2. Lymphocyte produces the specific antibody to neutralise the microorganism

  3. The lymphocyte cell divides repeatedly producing many clones of the cell all producing the same specific antibody

  4. Once the microorganisms have been destroyed all the clone cells die off except a few. These cells are memory cells

  5. If the same microbe is encountered again the antibodies will be produced faster and in larger numbers, hopefully destroying the microbes before symptoms are felt
• Immunity


  Can be developed if you have the disease or if you are given a vaccination. This is a dead, attenuated or part of the microbe with the antigen on
• Primary response


  The first lymphocyte response takes longer and fewer antibodies are produced. If this is caused by catching the disease symptoms will be felt. However, this response can be initiated by a vaccination
• Secondary response


  If the same microbe is encountered again, memory cells recognise them quickly and a large number of antibodies are produced in a short time. No symptoms are felt, and the person is immune to this disease
• Herd immunity


  If most people in society are immune then this prevents the spread of the disease those who are not yet vaccinated
• Parents need to decide whether or not to vaccinate their children and the media have a role to play in this