Module 4.1 - Communicable Diseases Flashcards
What is a pathogen and how do they live?
- an organism that causes disease
- live on or in a host organism
- take nutrients from the host ( causes damage )
Explain bacteria
- prokaryote kingdom
- reproduce rapidly
- damage cells/ release waste or toxins ( e.g in plants, live in vascular tissue and cause it to die )
Explain fungi
- can live in skin of animals and where its hyphae which form a myecilium, grow under skin. Sends out special reproductive hyphae which release spores- causes irritation and redness
- can live in vascular tissue in plants to gain nutrients, hyphae release extra cellular enzymes (e.g cellulases) to digest surrounding tissue causing decay and death. Fruit and storage organs turn black and decay, leaves become mottled in colour, shriven and curl up.
Explain viruses
- Invade cells, take over genetic machinery and organelles
- cause cell to make copies of virus
- host cell bursts releasing more viruses which infect healthy cells
Explain proctoctista
Usually enter host cells and feed in contents and grow
-e.g plasmodium ( causes malaria) has forms that feed on haemoglobin in red blood cells
What causes tuberculosis and what are its characteristics?
- bacteria: mycobacterium tuberculosis and M. Bovis
- kills cells and tissues in the body, affects the lungs the most
What causes bacterial meningitis and what are its characteristics?
- bacteria: neisseria menigitidis or streptococcus pneumonia
- infection of meninges - membranes that surround brain and spinal cord, become swollen and damage brain and nerves
What causes ring rot and what are its characteristics?
-Bacterium: clavibacter michiganesis subsp. sepedonicus
What causes HIV/ AIDS and what are its characteristics?
Virus: human immunodeficiency virus
-attacks cells in immune system and compromises immune response
What causes influenza and what are its characteristics?
- Virus: from family orthomyxoviridae
- attacks respiratory system, causes muscle pain and headaches
What causes tobacco mosaic virus and what are its characteristics?
- Virus: tobacco mosaic virus
- causes mottling and discolouration of leaves
What causes black Sigatoka and what are its characteristics?
- fungus : mycospharella fijiensis
- causes leaf spots on banana plants, reducing yield
What causes blight (tomatoes and potatoes) and whT are its characteristics?
- proctoctistan: phytophthora infestans
- affects leaves and potato tubers
What causes ringworm ( cattle ) and what are its characteristics?
- fungus: trichophyton verrucosum
- fungus growth in skin with spores causes erupting through skin, causes a rash
What causes athletes foot and what are its characteristics?
Fungus: trichophyton rubrum
-growth under skin of feet, between toes
What causes malaria and what are its characteristics?
Proctoctistan: plasmodium vivax
- carried by a vector: female Anopheles mosquito
- causes headache and fever which can cause a coma and death
What is the life cycle of a pathogen?
- travel from one host to another (transmission)
- enter a hosts tissue
- reproduce
- leave the hosts tissue
Describe the 4 main means of transmission
-direct physical contact
touching infected person or contaminated surface ( e.g HIV, bacterial meningitis, ringworm, athletes foot ). Affected by hygiene- wash hands, clean surfaces, clean cuts, sterilise surgical instruments, use condoms.
-faecal-oral transmission
eating or drinking contaminated things ( e.g cholera, food poisoning ). Treat waste and drinking water to reduce risk, wash dress food with clean water, carefully prepare food.
-droplet infection
pathogen carried by water droplets in air ( e.g tuberculosis, influenza )
Catch it, bin it, kill it. Cover mouth when coughing or sneezing, use tissue and dispose
-spores,
resistant stage of pathogen, carried in air or on soil surfaces ( anthrax, tetanus) use masks and wash skin after soil contact
What social factors affect transmission?
- overcrowding
- poor ventilation
- poor health e.g HIV/aids
- poor diet
- homelessness
- living or working with people who have migrated from areas where the disease is more common
What is direct transmission?
Pathogen passes from host to host
What is indirect transmission?
Pathogen passed from host to host via a vector
What is transmission
Passions a pathogen from an infected host to an uninflected individual
Explain the transmission of plant pathogens
- direct and indirect
- some in soil, taken up by roots ( esp if damages by replanting, burrowing animals or storm)
- fungi produce spores ( sexual or asexual ) carried by wind = airborne transmission
- infects vascular tissue, when leaves shed, pathogen in leaves carried to soil and can infect another plant
- enter fruit and seeds, distributed with seeds, infecting offspring
- indirect - insect attack, spores or bacteria attach to burrowing insect, when it attacks another plant, it transmits the pathogen. E.g beetle, the insect acts as a vector
How does climate affect disease?
- pathogens grow and reproduce more rapid when warm and moist so more common in these climates
- cold climates damage or kill pathogens or reduce ability to grow and reproduce.
- greater variety of diseases in warmer climates