4.1 Communicable Disease Flashcards
what is a pathogen?
a microorganism that causes disease
how do pathogens survive?
- live in hosts
- take nutrition from their host and cause damage at the same time
what is bacteria?
prokaryotic organisms that are able to reproduce rapidly
how does bacteria cause disease?
animals: damage cells and release toxic waste products
plants: bacteria live in vascular tissue and cause blackening and death of these tissues
tuberculosis
- caused by mycobacterium tuberculosis
- spreads by air droplets from infected to uninfected host
- destroys lung tissue and other body tissues
meningitis
- (caused by neisseria meninitidis)
- infects the meninges, membrane that surrounds the brain and spinal cord, they become swollen and may cause damge to the brain and nerves
ring rot
- (caused by clavibacter michiganensis)
- cause ring of decay in vascular tissue
- leaves wilt
how dies viruses cause disease?
- invade cells and take over genetic machinery and other organelles in the cell
- cause cell to produce more copies of the virus
- host cell bursts releasing lots of new viruses which infect healthy cells
HIV
human immunodeficiency virus
- attacks cells of the immune system resulting in death from opportunistic disease such as tuberculosis
Influenza
- constantly change and mutate
- attack respiratory system
- muscle pains
tobacco mosaic virus
- cause mottling and discoloration of leaves
- doesn’t kill plants
how does fungi cause disease in animals?
- often live in the skin of host, its hyphae grow under the skin and form a mycelium (mass of hyphae)
- fungus sends out specialised reproductive hyphae to the surface of the skin it cause redness and irritation
athlete’s foot
- (caused by trichophyton rubrum)
- grows under skin of foot
- fungi
ringworm
growth of fungus in skin with spore cases erupting through skin to cause a rash
how does fungi cause disease in plants?
- plant fungi live in vascular tissue in order to gain nutrients
- hyphae sends out extracellular enzymes to digest the surrounding tissue which cause decay
- leaves become mottled, curl up, shrivel and die
- fruit and tubers turn black and decay
black sigatoka
- caused by mycospharella fijiens
- grow on surface of banana leaf, penetrating into leaf through stomata
- cause leaf spots and reduce yield of crop
- fungi
how do protoctists cause disease?
- one of the kingdoms of living things
- pathogenic protocitists enter host cells and feed on contentsaz\
malaria
- plasmodium malariae
- invade blood cells and feed on the haemoglobin
- protists
potato blight
- caused by phytophthora infestans
- affects both the tubes and leaves of potatoes (and tomatoes)
- protists
why do bacteria and fungi most often live in the vascular tissue?
the vascular tissue contains plenty of water, minerals and dissolved sugars because they are transported in the xylem and phloem.
- with all these nutrients bacteria will be able to reproduce quickly
- can carry out their life processes
how is HIV a retrovirus?
carries RNA instead of DNA so also carries the enzyme reverse transcriptase which generates complementary DNA from RNA template which means copies of the virus can be created
what is droplet infection?
pathogens are carried in tiny water droplets in the air
- eg. tuberculosis and influenza
how do you reduce the risk of droplet infection?
- sanitizing surfaces with antibacterial spray
- use of face mask
- cover mouth when coughing and sneezing
- wash hands after coughing
what could increase droplet inflection?
- not covering mouth when coughing
- overcrowding
- poor ventilation
what is transmission by direct contact?
touching an infected person or surface contaminated with pathogens
- eg. athlete’s foot and meningitis
how could you reduce transmission by direct contact?
- washing hands after using the toilet
- cleaning and disinfecting cuts
- sterilizing surgical instruments
how is direct contact transmission increased?
touching an infected person or surface contaminated with pathogens
what is transmission by spores?
spores carried in air or live on surfaces or in soil
- eg. anthrax and tetanus
how to reduce transmission by spores?
wash skin after contact with soil
what is transmission via a vector?
another organism is used by the pathogen to carry a pathogen from one host to another
- eg. malaria
how to reduce malaria?
- covering body with clothing or netting
- insect repellent spray
what increases malaria?
warmer wetter climate encourages breeding grounds
what is faecal -oral transmission?
eating or drinking food/water contaminated by a pathogen
- eg. cholera and food poisoning
how to reduce oral transmission?
- treatment of waste water
- thorough cooking of food
how is oral transmission increased?
using human sewage water to fertilize crops
