L3 - non specific immunity

• Tuberculosis:

  -caused by airborne bacteria

  -Mycobacterium tuberculosis

  -widespread disease that affects the respiratory system

  -one third of the world’s population is currently infected with the bacterium

  -can be treated using a course of antibiotics, however some antibiotic resistant strands have emerged
• Tuberculosis response:

  -an immune response is produced

  -in healthy people, macrophages (white blood cells) engulf the bacteria by phagocytosis, controlling the infection

  -a tissue mass called a tubercle forms around the site

  -after 3 to 8 weeks the infected region heals

  -bacteria can survive inside macrophages for years until the immune system becomes weak
• Symptoms of tuberculosis:

  -if the immune system can’t contain the infection, active tuberculosis may occur, destroying lung tissue

  -coughing

  -shortness of breath

  -appetite loss

  -weight loss

  -fever and night sweats occur due to neutrophils and macrophages releasing fever causing substances as a part of the immune response; these chemicals affect the hypothalamus and increase the body’s core temperature

  -extreme fatigue
• HIV stands for human immunodeficiency virus
• AIDS stands acquired immunodeficiency virus
• AIDS targets T helper cells in the immune system of the body. it gradually destroys the immune system so affected people are open to other infections, such as TB and pneumonia, as well as some types of cancer
• HIV is a retrovirus with RNA as its genetic material. it contains the enzymes reverse transcriptase, which transcribes the RNA to a single strand on DNA to produce a single strand of DNA in the host cell before interacting with the genetic material
• the virus is passed from one person to another in bodily fluids, (most commonly unprotected sex), shared needles, contaminated blood products, and from mothers to babies during birth, pregnancy or breastfeeding
• in 2012, around 35 million people were living with HIV and 1.6 million had died of the disease. girls and women are at particularly high risk in many countries
• practises such as female genital mutilation increase the risk of HIV/AIDS infections; especially when the same equipment is used multiple times. these women are also more vulnerable to infection during intercourse
• sub-saharan africa is the region worst affected y HIV/AIDS; 25 million people living with HIV/AIDS (around 70% of the global total)
• malaria is caused by protoctista, Plasmodium, and spread by the bites of infected, Anopheles, mosquitoes (a vector)
• Plasmodium parasite:

  -complex life cycle with two hosts (mosquitoes and humans)

  -reproduce inside female mosquitoes

  -female needs to take two blood meals to provide her with protein before she lays her eggs (when the parasite is passed onto people)

  -invades red blood cells, liver, and even the brain
• Around 200 million people are reported to have malaria each year and over 600,000 die
• malaria:

  -disease recurs making people weak and vulnerable to to other infections

  -no vaccine against it and limited cures but preventative measures are effective

  -key to prevent it is to control the vector
• anopheles mosquitoes can be destroyed b insecticides and by removing the standing water where they breed. simple measures such as mosquito nets and long sleeves can also prevent the spread of malaria