Communicable Diseases Flashcards
Health
A state of being free from injury or disease - someone’s mental and or physical condition
Communicable Diseases
caused by pathogens which can be transmitted - can affect animals and plants, passed on within species/between species
Pathogen
A disease-causing microorganism, types of pathogen include bacteria, viruses, fungi, protist
How do pathogens make us ill?
You come into contact with/catch the disease-causing pathogen - Bacteria – divide by binary fission and can damage cells
Bacteria – can produce toxins which affect the body
Viruses – take over our body cells and reproduce, they can damage our cells
3 mechanisms of spread
air, direct contact, water
Pathogens spread via air
- cough or sneeze exhaling droplets containing the pathogen
- these droplets are inhaled by another person
- e.g. cold, flu, TB
Pathogens spread via contact
- pathogens on infected person’s skin passed on to second person’s skin; enters via cut, nose, mouth
- can be transmitted sexually or by vectors such as mosquitos
- e.g. HIV, scabies, chlamydia
Pathogens spread via water
- infected person expels pathogen by any body route into water
- untreated water is drank by second person
- e.g. cholera, salmonella
Ways to prevent the spread of disease
- better hygiene, access to clean water, disinfectants, safe sex, dressing wounds, isolation, cooking food properly and separating raw and cooked food
where to grow bacteria
In a nutrient broth or on agar which provide everything it needs to grow and reproduce (sugar, amino acids, water and a sterile environment free from contamination)
how to grow bacteria
on agar as a lawn (spread) or streaked (streak, then flame and cool loop, repeat)
Why do we sterilise agar/broth
so no other dangerous/contaminating bacteria are growing
why do we sterilise loop or spreader
to kill contaminating microorganisms
why do we have a bunsen burner and work close to it
creates an updraught helping prevent microorganisms in the air from landing on agar and contaminating, reduce chance of bacteria inhalation
lifting lid at an angle and for a minimal length of time
prevent contamination from the air
keep the lid in place with 2 pieces of tape
prevent contaminating microorganisms getting into the plate
not sealing plate all the way round
air needs to get in to prevent anaerobic pathogens from growing - dangerous
optimum temp for bacteria
37 in hospital, 25 in school as less likely to grow pathogenic bacteria
why are these techniques useless for viruses
viruses grwo in your cells and can only reproduce in living cells
why do we store agar plates upside down
prevent condensation from the lid dropping onto the agar surface
what might limit bacteria growth on an agar plate
running out of mineral ions, glucose, amino acids, space
calculating bacteria number
beginning no x 2^number of divisions
Ignaz Semmelweis
1850s Austrian doctor, discovered washing hands could prevent the spread of infection
Louis Pasteur
Showed that microorganisms caused diseases, developed vaccines e.g anthrax, rabies
Joseph Lister
Started to use antiseptic chemicals to destroy pathogens before they caused infection in operating theatres
Hygiene - reducing spread of infection
Wash hands after contact with animals/diseased people; before cooking; after toilet
Use disinfectant on surfaces
Keep raw meat away from food that is eaten uncooked
Cough/sneeze into a tissue
Isolation - reducing spread of infection
The fewer healthy people that come into contact with the infected person, the less likely it is that the pathogen will be passed on
Destroying or killing vectors - reducing spread of infection
By controlling the no of vectors, the spread of disease can be greatly reduced
Vaccination - reducing spread of infection
Small amount of a harmless form of a particular pathogen introduced to the body - if you come into contact with the live pathogen, your immune system will be prepared and you won’t become ill
Plants physical defences
Tough waxy cuticle on leaf surface; cellulose cell walls are strong; bark on trees and a layer of dead cells on stems - pathogens lost when dead cells are shed; deciduous trees lose leaves in autumn, taking any pathogens with them
Plant defence poison
Poisons deter herbivores as animals quickly learn not to eat plants that make them feel unwell e.g foxglove, yew
Plant defence thorns
Make it unpleasant/painful for herbivores to eat them e.g. brambles, cacti - thorns unlikely to deter insects
Plant defence hairy stems/leaves
Deter insects and larger animals from eating them or laying their eggs on the leaves/stems. e.g. lamb’s ears and some pelargoniums. Some plants like nettles combine hairs with poisons.
Plant defences dropping or curling when touched
Rare but effective adaption is when leaves collapse suddenly, dislodging insects and drighteneing larger animals
e.g. mimosa pudica
Plant defences mimicry
Some plants droop to mimic unhealthy plants, tricking mammals into not eating them. Some mimic butterfly eggs on their surface so real butterflies do not lay eggs on them to avoid competition
Viral diseases and how they are spread
Measles - droplet, HIV - direct sexual contact and exchange of bodily fluids, colds - droplet, Influenza - droplet, Tobacco mosaic virus - direct contact with diseased plants.
Viral diseases prevention and treatment
Vaccinations, use condoms, don’t share needles, wash hands, isolate, rest, antiretroviral drugs
Bacterial diseases and how they are spread
Salmonella - eating unhygenic or undercooked food; Gonorrhoea - direct sexual contact; Crown gall - direct contact, enters from soil
Bacterial diseases prevention and treatment
Safe food preparaton practices to avoid contamination, contraception; antibiotics to treat; burn plants
Fungal Diseases and how they are spread
Athletes foot - direct contact with infected surfaces; rose back spot - spores carried by wind
Fungal diseases prevention and treatment
Hygiene, anti fungal powder, burn plants
Protists and how they are spread
Malaria - through a verctor; mosquitoes
Protists prevention and treatment
Treat with a combo of drugs, remove standing water, sleep under insecticide treated nets
Malaria life cycle mosquitoes
female anopheles mosquito takes a blood meal from a human and injects saliva cntaining the malarial protist into their blood
Malaria life cycle human
Malaria travels to the liver and reproduces; then infects red blood cells and as it spreads it bursts the red blood cells causing the associated symptoms
Malaria life cycle transmission
Another mosquito takes a blood meal from the infected person; protist reproduces in the mosquito and ends up in its saliva
How to prevent malaria
Insecticide nets; repellant spray, drugs, no standing water
Aphids pests
Feed on sap and reproduce asexually to form large colonies. Deprives the plant of the prodcuts of photosynthesis which can weaken/damage the plant - can also act as vectors and inject disease into the tissues of the plant
Nematode worms/insect larvae pests
Live in soil and feed off roots, damaging them in the process. This can lead to mineral ion deficiencies
Nitrates needed for
Converting sugars from phtosynthesis into protein for growth
No nitrates ;(
stunted growth
Magnesium needed for
making chlorophyll
no magnesium
leaves become yellow
disease symptoms in plants
stunted growth, spots on leaves, areas of decay and rottng, growths, malformed stems, discolouration, prescence of pests
what to do with diseased plants
BURN IT
primary defences
stop the pathogen getting in
secondary defences
kill the pathogen after it gets in
How do nose and ears and mouthstop pathogens getting in
haur, mucus and wax that traps dust and microorganisms
how does skin stop pathogesn getting in
physical barrier, secretes sebum nad oils which kill pathogens, can form a scab when damaged
eyes stop pathogens
tears contain enzymes which kill them
digestive tract and skin stops pathogens
covered in good bacteria which outcompetes bad ones
Phagocytosis
some white blood cells ingest the pathogen, digest and destroy it so it cannot make
you ill.
Antibody production
some white blood cells make special proteins called antibodies. These target specific
bacteria or viruses and destroy them. You need a unique antibody for each pathogen
because they are specific.
antigen
specific protein on the surface of the pathogen, the antibody binds to the antigen in order to kill it
Antitoxin
These counteract (cancel out) the toxins
released by the pathogen
antibody production
When a pathogen enters the body for the first time white blood cells will start to
produce antibodies.
This is slow and you will feel ill because the pathogen is rapidly reproducing.
What is left in the blood is a special kind of white blood cell called a memory cell – it
is specific to that pathogen
The next time that pathogen invades the body the memory cells make sure the
correct antibody is produced – lots of it and very quickly
They kill the pathogen before you become ill – you are now immune to that pathogen
