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