Communicable diseases, disease prevention and the immune system Flashcards
ring rot
- caused by gram positive bacteria
- affects potatoes, tomatoes
- damages leaves, tubers and fruit
- bacteria infect the vascular tissue and prevent the transport of water, causing the plant to wilt and die
- infection spreads into the potato tubers where the vascular tissue is arranged in a ring=black ring of rot
- infected tuber can lead to the growth of infected new plants
- spread by contaminated soil, water and equipment
- no cure
Tobacco mosaic virus (TMV)
- caused by a virus
- affects a llot of species of plants eg peppers
- damages leaves, flowers and fruit=less yields+cand lead to crop loss
- causes a distinct yellowing of the leaves which produces a mosaic pattern
- no cure but there are some reistant strains
- transmitted by leaf-to-leaf contact between plants+humans touching different plants
Potato/tomato late
blight
- caused by a fungus-like protist
- protist destroys potato and tomato crops leaving them completely inedible
- symptoms=small, dark brown marks on the leaves which quickly increase in size and number
- no curebut there are resistant strains
- careful management and chemical treatments can lower infection risk
- transmitted via spores carried by wind from plant to plant
Black sigatoka
- caused by fungus
- affects bananas
- transmitted leaf-to-leaf contact+ spread of spores by humans or within infected plant matter
- hyphae penetrate+digest the cells=prevent plant photosynthesising=parts of leaf die=producing black streaks
- good husbandry+fungicide treatment can control spread of disease but x cure
- whole leaf dies eventually
Tuberculosis
- bacteria infect the lungs+suppresses immune system=chronic cough+bloody mucus
- transmitted via airborne droplets
- associated with poor hygiene+sanitation
- M. Tuberculosis=TB in humans
- M. Bovine in cows can transmit to humans=cause TB
HIV/AIDS
- enveloped retrovirus
- viral enzyme (reverse transcriptase) produces single-stranded DNA from its viral RNA
- DNA polymerase synthesises double stranded DNA from the single strand=inserted into host
- DNA provirus used to synthesise new viruses
- transmitted by body fluids
- no vaccine+cure
Influenza
- caused by a virus
- infect ciliated epithelial cells in gas exchange system
- 3 types (A, B and C)
- cause high temp+body aches+fatigue
- influenza a is the most common+virulent & classified by proteins on their surface
- transmitted by airborne droplets
- mutate regularly
Athlete’s foot
- caused by fungus
- form of human ring worm that grows on+digests warm & moist skin between toes
- causes cracking+scaling=itchy+sore
- transmitted by skin-to-skin contact with an infected individual+contact with an item of clothing
- anti fungal creams=effective cure
Ringworm (cattle)
- caused by a fungus
- affects mammals eg cattle
- symptoms: grey-white, crusty, infectious, circular areas of skin which can be itchy
- anti fungal creams are an effective cure
Malaria
- caused by protoctista
- transmitted by infected anopheles mosquitoes=vector
- symptoms: fever, chills, fatigue
- complex life cycle with 2 hosts=reproduce inside female mosquito=needs 2 blood meals=protein to lay eggs
- invade rbc, liver, brain
- x vaccine+limited cures
- lots of effective preventative measures
Bacterial meningitis
- caused by a bacteria
- affects meninges (protective membranes of the brain), can be spread to the rest of the body=septicaemia=blood poisoning+rapid death
- affects very young children+teens
- symptoms: blotchy red/purple rash that doesn’t disappear
- antibiotics will cure the disease if given early
- vaccines protect against some forms of it
How are animal diseases transmitted?
direct transmission
- direct contact eg skin to skin, sharing bodily fluids
- inoculation eg animal bite, sharing needles, break in skin, puncture wound
- ingestion eg from hands to mouth, contaminated food/drink
indirect transmission
- fomites=inanimate objects that transfer pathogens
- droplet infection (inhalation)=droplets of saliva+mucus expelled when you cough sneeze, cough, etc=contain pathogens can be passed to those close to you
- vectors=transmit pathogens from one host to another eg mosquitoes
- spores=small reproductive structures released into environment via wind/water=reach food source ie host=start growing
Factors affecting transmission in animal diseases
- high population densities+poor housing=close proximity=high infection rate
- poor nutrition=lead to compromised immune system=easier to get a disease
- poor disposal of waste
- weather+climate=vary the incidence+location of disease
- social factors eg migration due to war=people transfer disase from infected area to a new area=up sprea of disease
How are plant diseases transmitted?
direct
- direct contact=healthy plant contacts diseased plant
indirect
- spores=small reproductive structures released into environment via wind/water=reach food source ie host=start growing
- soil contamination
- vectors=wind, water etc
Factors affecting transmission in plants
