Communicable Diseases

health

A state of physical and mental well-being

pathogen

An organism that causes disease

how do pathogens cause disease

invade body, evade immune system, multiply, produce toxins

how are pathogens spread

air, water, direct contact

air

coughing, sneezing, talking, spores on the breeze

air examples

tuberculosis (TB), influenza (flu), colds, measles

direct contact

sexually transmitted, cuts, scratches, via vectors (like insects + disease transmitting animals eg mosquitoes). common in plants where an infected plant spreads the disease to the whole batch

direct contact examples

HIV, chlamydia, hepatitis

water

fungal spores in splashing water, water contaminated with faeces or other contaminants

water examples

cholera, dysentery, salmonella

how can microorganisms be grown safely

sterilise agar/nutrient broth, sterilise inoculating loop/spreader, bunsen burner on and working nearby, lifting the lid at a 45 degree angle and for a minimal amount of time, keeping the lid in place with two small pieces of tape, not sealing the plate all the way round

purpose of sterilisation

kills all unwanted bacteria in/on the broth/agar/spreader/inoculating loop

purpose of bunsen nearby

creates an updraft that lessens the rate of any airborne bacteria entering the plate. bacteria rise with the hot air and are carried away by convection currents. also you can use the bunsen to sterilise stuff if you want

why do you lift the lid for a minimal time period at 45 degrees

at an angle it minimises the amount of bacteria getting in from above, and minimal time naturally contributes

tape for lid

prevents the lid coming off

not sealing plate all the way around

allows oxygen in but nothing else. w/out oxygen the culture you are attempting to grow will asphyxiate and die, and anaerobic bacteria that are often more harmful to humans will grow instead. disregard if you are growing anaerobic bacteria of course

temperature bacteria is normally grown at in labs and why

37 degrees C, as it is the temperature of the human body and therefore the optimal temperature for growth. growing these faster means quicker results.

Who is Semmelweis?

Person who advocated hand-washing to prevent transmission from one patient to another

how can the spread of disease be reduced

destroying vectors, isolating infected individuals, vaccination, cooking food sufficiently, using clean water, keeping raw and cooked food separate, covering open wounds, cover mouth when you sneeze/cough, wash hands well, use disinfectants, keep crop machinery clean (plants)

HIV/AIDS facts

transmitted through physical contact - most often sexually but can be from mother to baby and from infected blood. prevented by condom use and not sharing needles.

HIV itself cannot be cured but it can be slowed with antiretroviral drugs.

HIV itself is not a problem, but it causes AIDS that weakens the immune system making other illnesses more common and severe.

measles facts

transmitted through air - droplets containing the virus are transmitted by the infected and when inhaled it spreads.

can be prevented through a vaccine, and infected people isolating.

there is no cure but paracetamol/ibuprofen can ease symptoms, and in most cases it is not fatal.

presents through cold-like symptoms, but more severe, as well as a red rash. it can lead to blindness.

salmonella facts

transmitted through water or eating uncooked/contaminated food, primarily chicken but things like eggs and flour can cause it too

prevented by vaccinating poultry, keeping cooked and raw food separate, cooking food well, keeping surfaces sterile and washing hands after handling raw food

no cure, though antibiotics can be prescribed. symptoms generally only last a few days

causes food poisoning, vomiting, cramps and diahorrea.

gonhorroea facts

transmitted through sexual contact

barrier methods of contraception prevent spread

can be treated with antibiotics like penicillin but resistant strains are increasing and some people have allergies

early on it shows as yellow discharge and pain on urination, but later symptoms include pelvic pain, infertility and potential blindness in babies born to infected mothers

Colds and flu are caused by

viruses

colds/flu facts (unsure if this is needed)

transmitted through air - droplets containing the virus are transmitted by the infected and when inhaled it spreads.

flu can be prevented through a vaccine, though strains are beginning to resist this, and infected people isolating helps both. colds are a blanket term for too many different illnesses for vaccines to be considered viable.

there is no cure but paracetamol/ibuprofen and lots of rest can ease symptoms, and in most cases it is not fatal (especially in colds).

sneezing, bunged up nose and coughing are all common cold symptoms. flu also comes with aching joints + muscles.

athlete's foot

Fungus infection usually in the skin of the toes and soles

athlete's foot facts (again, unsure if this is needed)

transmitted through direct contact with infected surfaces (as it is a fungus it doesn't need a host in the same way), often including pools or changing rooms.

prevented through good hygiene and not sharing footwear with infected people

treated with anti-fungal powder

causes an itchy rash around toes (around toenails, between toes)

malaria lifecycle

infected female anopheles mosquito takes a blood meal from a human, and the protist in its saliva enters the human's bloodstream. It travels to the liver and reproduces, and later travels to red blood cells. as it spreads, it bursts the red blood cells and causes the associated symptoms (recurrent periods of fever and shaking - presumably due to asphyxiation, as the oxygen-transporting red blood cells are destroyed). if another (female anopheles) mosquito feeds on an infected human, the protist will enter the mosquito, reproduce and end up in its saliva.

plant pathogen symptoms

stunted growth, discoloured spots on leaves, areas of decay or rot, growths, malformed stem and/or leaves, general discolouration, presence of visible pests

mineral ion deficiency

caused naturally by a lack of mineral ions, either due to root damage (eg by nematode worms / larvae) or poor soil quality. lack of nitrates causes stunted growth as these are required for amino acid and protein production. lack of magnesium causes leaf discolouration and slows the rate of growth - this is known as chlorosis, and it is due to the fact magnesium is required for chlorophyll production and therefore photosynthesis

antigen

unique proteins on cell surfaces that allow for it to be identified. antibodies recognise pathogens by their unfamiliar antigens

antitoxins

antitoxin molecules attach to toxins, rendering them neutralised. toxins are generally produced by pathogens and antitoxins by white blood cells

how do plants defend themselves from pathogens

strong cellulose cell walls keep out most pathogens

infected leaves are shed

bark is made up of near impenetrable layers of dead cells, similar to human skin

resin acts as a way to heal over wounds like human blood clotting

waxy cuticles on leaves keep out waterborne pathogens, as the wax repels water

plant herbivory defence list

poisons, thorns, hair on stem/leaves, drooping/curling when touched, mimicry

plant herbivory defence - poisons

herbivores/omnivores quickly learn not to eat deadly/sickness inducing plants. as well as this, if it causes death in organisms that attempt to eat it, the nutrients from the body will return to the soil and benefit the plant. examples include foxgloves, nightshade and yew

plant herbivory defence - thorns

thorns make consummation difficult and/or painful, especially for larger herbivores/omnivores. however this does not impact insects. birds and smaller creatures are often able to enter, and they can spread seeds. examples include brambles, gorse and cacti

plant herbivory defence - hair on stem/leaves

hair on stems/leaves deters herbivory as well as egg laying. many combine the hairs with poisons, including nettles and gympie gympie. other examples include lambs ears and some pelargoniums.

plant herbivory defence - drooping/curling when touched

drooping/curling when touched is rarer, however it can scare smaller animals and it dislodges insects. however, it expends significant energy to do so. examples include mimosa pudica

plant herbivory defence - mimicry

mimicry can involve many things including drooping to appear unhealthy, mimicking butterfly eggs on leaves to dissuade butterflies laying there or mimicking poisonous plants. examples include passiflora (butterfly eggs) or common lungwort (mimics bird droppings)

white blood cells

main secondary defence

three main types - memory, phagocytes and lymphocytes.

white blood cells - phagocytes

phagocytes are the traditional, they engulf and digest bacteria. they are highly mobile and can change their shape.

lymphocytes produce antibodies and antitoxins. antibodies kill pathogens by attaching to foreign antigens, and labelling them as a target.

white blood cells - lymphocytes

lymphocytes produce antibodies and antitoxins. antibodies kill pathogens by attaching to foreign antigens, and labelling them as a target.

white blood cells - memory cells

memory cells function as the body's reminder of how to deal with pathogens in future - upon encountering a pathogen, memory cells are produced. if the same pathogen is encountered again later, the body responds quicker and with a greater immune response. sufficient memory cells class you as immune to a pathogen

pests that damage plants examples

aphids, nematode worms/larvae, general vectors

aphids

tiny green bugs that feed on the sugar-rich sap in the phloem through their probosci. reproduces asexually, forms huge colonies, deprives plants of the products of photosynthesis, weakening it. can be treated through insecticides, though these are harmful for the environment as well as helpful insects. ladybird prey, so this is a better solution.

nematode worms

lives in the soil, feeds on the roots. causes mineral ion deficiency (symptoms next card). more difficult to notice and treat as roots are under the soil

other pests as vectors

some pests are vectors for other pathogens that can damage plants, these are often similar to aphids as the pathogens can inhabit their saliva and be injected directly into the plant.

human body primary defenses

many forms:

trachea and bronchi have cilia that waft away from the lungs

the stomach has a very low pH of 2

body parts with mucous membranes and their purpose

the anus, mouth, nose, trachea and bronchi have mucous membranes that trap microorganisms. nose, trachea and bronchi also trap dust. nose also uses hair

body parts with healthy bacteria and its purpose

skin and digestive tract, outcompetes foreign/hazardous bacteria

primary defenses - skin

skin is made of a practically impenetrable thick layer of dead cells and a waxy layer that keeps pathogens out. when cut, blood clots quickly to prevent pathogen entry. the sweat and natural oils work to reduce the unwelcome bacteria numbers

primary defences around the face

eyes produce tears containing enzymes (lysosomes) that kill microorganisms

saliva cleanses mouth

ears produce wax that inhibits bacterial growth

primary defences - urethra and vagina

urine flow through urethra prevents bacterial growth and flushes it out

vagina secretes acid that inhibits pathogen growth

stomach and lung defences

trachea and bronchi have cilia that waft away from the lungs

the stomach has a very low pH of 2

crown gall facts

spreads through direct contact, the bacteria entering through wounds in roots or stems

infected plants must be destroyed, and the area grassed to kill remaining bacteria.

no cure

causes enlarged growths on stems or trunks.

tobacco mosaic virus

direct contact between diseased plants spreads it. it affects tomatoes and tobacco among others.

good hygiene in equipment, pest control and thoroughly destroying infected plants all help. resistant plants have been bred to combat it.

no cure available, infected plants must be destroyed

causes a mosaic patterning on leaves as the virus destroys cells. growth is affected as it cannot photosynthesise as much, and so crop yield is reduced

rose black spot

spores transmitted through the wind, emitted from the leaf lesions.

prevented by removing infected plants and burning the area. resistance cannot be bred due to mutations

there is no cure currently, all infected plants must be destroyed

manifests through purplish black spots/lesions on leaves, causing discolouration and the leaves to turn yellow and drop early. The plant flowers badly.

malaria facts

transmitted by infected mosquitoes biting humans

prevented by controlling mosquitoes - mosquito nets, insecticides, removing standing water, antimalarial drugs for travellers

treatment is a combination of antimalarial drugs that work best when used quickly, but the protist is becoming more resistant

causes recurrent episodes of fever and shaking, can lead to death