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Biology Module 4 - Coggle Diagram

- - - - Direct contact between infected host flora or fauna with an uninfected life, allowing the pathogen to spread. Can also occur via transmission of bodily fluids.
    - - Transmission through air, or water, fungal spores, fomites, human movements (i.e., vehicles, footwear, etc.,) and animal vectors such as mosquitoes.
  - - - Examples
        
        Tuberculosis (TB) - Bacterial disease in the lungs. Can be very serious, potentially fatal without treatment. Human TB caused by Mycobacterium tuberculosis, TB in cattle caused by Mycobacterium bovis, which can also affect humans. Treated using antibiotics and vaccinations which are available for some strains of TB but are not part of mandated vaccinations for children in the UK. Spread when infected droplets from the lungsd are coughed into the air and breathed by others. Transmission can be prevented by using tissues when coughing or sneezing and having good handwashing practice.
        
        Bacterial meningitis - Causes inflammation to membranes surrounding the brain and spinal cord. Can result in sepsis and death. Caused by different pathogenic bacteria, such as Neisseria meningitidis A, B, C, W, X, Y and Z, Streptococcus pneumoniae, haemophilus influenzae type B (Hlb.) Treated with antiobiotics. Vaccinations can help to prevent infection and spread of the disease.
        
        Ring Rot - Affects potatoes and tomatoes in cool regions of Northern and Eastern Europe. Caused by Clavibacter michiganensis, subspecies sepedonicu in potaoes and Clavicbacter michiganensis, subspecies michiganensis in tomatoes. Sometimes known as birds eye. Transmission by planting infected material and indirect contact with contaminated equipment. Control can be improved through rigoros cleaning of agricultural equipment. Can also be spread by insect vectors.
    - - HIV/AIDS - Human Immunodefficiency Disease, caused by the virus HIV. Attacks CD - 4 cells of the human immune system, so that infections become progressively more difficult to fight. Without treatment, can lead to the development of Acquired Immunuodeficiency Syndrome, AIDS, which can be life threatening. There is no cure for HIV or AIDS, but antiretroviral drugs can be used to prevent the multiplication of the virus within the body. Promoting awareness of risks of and preventative measures against HIV are essential to restricting transmission of the disease, such as promoting use of condoms, getting tested regularly and not sharing needles. Identifying infection early is also important, including screening of donated blood. Transmitted by direct contact with infected bodily fluids, such as blood, semen, vaginal secretions, and breast milk.
      - Influenza - Caused by influenza viruses A, B and C. These viruses mutate very quickly, giving rise to new strains that are difficult for the immune system to recognise and produce vaccinations against. Mutations also mean viruses that originally only infected other animals can bridge the species barrier and infect humans, becoming zoonotic. Treatment for influenza is with antiviral drugs, as well as annual vaccination programs for vulnerable to strains judged to most likely cause outbreaks that year. Influenza can be spread through both direct and indirect contact. Prevented in humans through good hygiene and handwashing, as well as using tissues for coughing and sneezing can help prevent the spread of influenza. In agriculture, restricting the movement of farm animals can prevent transmission of influenza from wild animals outside.
      - Tobacco Mosaic Disease - Affecting plants and tomatoes, first virus to be discovered and has been widely studied for years to gain insights into how viruses infect hosts. Can survive 50 years in infected material, making treatment of the disease very difficult. There is currently no fully effective chemical control. Transmission happens directly between infected plants, as well as indirectly between contaminated soil, equipment and people. The virus can contaminate seed coats, also leading to infection of the developing plant. Control of TMV is achiebed by removing and burning infected plant material and discarding infected soil, washing and bleaching of equipment and avoid touching plants when watering to help reduce cross - contimination and exposing young plants with less serious strains can help prevent infection later on.
    - - Late Blight - Caused by Phytopthora infestans, which causes spores to develop on the leaves of infected plants and germ tubes to grow through the leaf epidermis, affecting tomoatoes and potatoes. Wounds, eyes and lenticels on tubers also allow infection. Fungicides are often used, though Late Blight has begun to develop a resistance. Individual plants are unlikely to survive, sometimes dying within a week. Sporangia can be airborne or waterborne, infecting soil and plants. Spores can only develop in temperatures above 15C and may encyst if conditions are too cold. Development of blight - resistant cultivars help to reduce susceptibility of plants to the pathogen and control it's spread. Forecasting when weather may promote transmission means that fungicides can be sprayed at optimal times.
      - Malaria - Caused by species of Plasmodium genus, such as P. falciparum, which causes the most malarial deaths worldwide, and P. vivax, P. Ovale, P. malariae and P. knowlesi, which are much rarer, though P.vivax can remain in the liver for years without causing symptoms. The malarial parasite grows and multiplies in erythrocytes, causing them to burst every 2 - 3 days, releasing plasmodium into the bloodstream. Treated using antimalarial medication, such as Doxycycline and Mefloquine. Preventative medication often taken preceding a visit to a high -- risk region, reducing the risk of malaria by up to 90%. Antimalarial medication can be taken to treat the disease if preventative measures are not taken or do not work. Transmitted through female Anophele mosquitoes when it takes blood from an infected person. Removing the insect vector would guarantee the prevention of transmitting malarial, though this is often not viable on a large scale. Sleeping under mosquito nets, applying insect repellent and covering exposed skin help's to reduce the risk of being bitten by a mosquito that is potentially acting as a vector for the disease. Symptoms often include cyclical chills and fever.
    - - Black Sigatoka - Caused by Black Sigatoka fungus found in banana plants. Spread through direct and indirect contact, with transmission more likely in conditions of high humidity and rainfall. Infective spores are airborne, while infective conidia are waterborne. Control of transmission includes: Aerial application of fungicides, removal of affected leaves, maintaining space between plants, adequate drainage. Preventative measures often account for 15 - 20%
      - Ringworm - Caused by fungus Trichophyton verrucosum. Mostly affects cattle but can spread to other mammals. Treatment involves two applications of antifungal cream, 3 - 5 days apart, with crusts of the skin required to be removed to allow the cream to reach the fungus. These crusts must then be burnt to prevent transmission by indirect contact. Can spread both directly and indirectly, through contact between infected skins and fungus produced spores that can remain potent for many years in dry environments. Prevented by regularly cleaning and disinfecting animal housing, particularly when introducing new animals, avoiding high stocking densities of animals, ensuring animal housing is dry and allowing animals regular exposure to sunlight.
      - Athlete's Foot - Fungal infection affecting the feet mainly in between the toes, but can also infect any area of skin if the fungus infects that area. Caused by fungi species, of the genus Trichophyton. Treaated with antifungal creams, sprays, powders and antifungal medication. Transmission is usually through indirect contact with contaminated objects. Warm, humid environments promote growth and spread of the fungus, so transmission often occurs in showers, swimming pools and changing rooms, as well as through shared fomites such as socks and towels. Direct contact with infected skin can also transmit the fungus. Preventative methods include keeping feet clean and dry, wearing footwear in high risk areas, avoiding sharing potential fomites with other people.
  - - - Basal resistance - Reacts to the presence of microbe - or pathogen - associated molecular patterns (MAMPs or PAMPs,) such as flagellins and chitins, found in pathogens. MAMP receptors recognise the molecular patterns and stimulate a cascading series of response, causing the upregulate the expression of genes producing chemicals, resulting in an oxidative burst.
        
        An oxidative burst is a big release of chemicals such as oxygen species, nitric oxides, hydrogen peroxide and salicylic acid. This burst functions to strengthen cell wall linkages and signals to other cells the presence of a pathogen threat.
        
        Callose is a molecule found in plants. Callose is deposited between cell membrane and cell wall during basal resistance response, areas where pathogens usually infect. This strengthens the cell wall and restricts movement of pathogens into adjacent cells.
        
        During basal resistance response, stomata also close in order to prevent entry of pathogen .
      - Hypersensitive response
        
        Triggered by presence of bacteria, viruses, fungi or nematodes.
        
        Causes local cell suicide (apoptosis,) at site of infection, cutting off water and nutrients from pathogen.
        
        Can lead to systemic acquired resistance (SAR) to broad ranges of pathogens for a length of time. SAR can be artificially stimulated by spraying plants with "plant activators."
      - RNA silencing
        
        Used in plants to prevent viral spread. Produces enzymes that digest any foreign RNA being replicated in the cells.
        
        If the response is successful, plants will be able to recover from infection and recognise the virus RNA in a future invasion, similar to the verterbrate secondary immune response.
    - - Primary non - specific defenses - Initial methods to prevent the likelihood of disease that are not pathogen specific.
        
        Mucous membranes
        
        Inflammation
        
        Infected tissue may become inflamed, resulting in swelling. This means blood capillaries dilate, allowing more blood to enter the tissue, increasing the speed of transportation of blood plasma into the infected area, carrying white blood cells and antibodies required to fight infection.
        
        Skin
        
        Antibodies
        
        Opsonins - antibodies that flag pathogens for phagocytosis
        
        Agglutinins - Antibodies that clump pathogens together, making then inactive more likely to be phagocytosed
        
        Antitoxins - Bind to toxins potentially produced by pathogens, reducing damage to tissues.
        
        Blood clotting
      - Anitgens - Proteins and glycoproteins that are present on the cell surface membrane of all cells. Antigens signal the immune system if the cells are "foreign."
        
        Every cell has specific antigens, these antigens bind to complementary receptors on the cell surface membrane of the immune cells. If the antigens are foreign, this will induce on immune response.