MODULE 7. INFECTIOUS DISEASE Flashcards
what is an infectious disease
INFECTIOUS DISEASE = Disease which can be transmitted from one organism to another, and are caused by pathogens.
what is a pathogen
PATHOGEN = Any organism which is capable of causing disease
list the types of different pathogens from smallest to largest
bacteria fungi protozoa virsuses prions parasites
how is bacteria characterised
prokaryotic unicellular organisms which don’t have membrane bound organelles and are made of one cell
how can bacteria cause disease
by releasing toxins or damaging host tissues
e.g. of bacteria
tuberculosis
- caused by mycobacterium tuberculosis that enters the lungs when a person inhales infectious droplets
how is fungi characterised
- Eukaryotic, non-photosynthetic, heterotrophic organisms with a cell wall. Can be either unicellular or multicellular
how does fungi cause disease
- The damage caused by fungi mostly arises from the enzymes they produce.
e.g. fungal disease
tinea
Mode of transmission = direct contact, skin to skin contact, surfaces e.g. shower floor
- The fungi lives in the outside layer of human skin, where they produce chemicals which break down keratin
- Symptoms include itchiness, inflammation and flaky skin
how is protozoans characterised
- Unicellular microorganisms with internal membranes. Eukaryotic with a complex lifestyle.
e.g. protozoans
• E.G. MALARIA
- Caused by plasmodium
- Plasmodium floats freely in the blood of an infected person
- It feeds on haemoglobin in the red blood cells causing them to pop
- Symptoms include fever, nausea, muscle pain and headaches
how are viruses characterised
- Non-cellular entities (not living), consisting of a single type of nucleic acid (DNA or RNA) encased in a protein coat.
how does viruses cause disease
- Needs a host cell to reproduce The virus attaches to a host cell, which it then penetrates. It hijacks the hots enzymes and nutrients to make its own viral proteins and nucleic acid
- The viral materials assemble into new viruses which are released from the host cell and infects other cells
e.g. virus
influenza
covid19
how are prions characterised
- Protein that has been altered from its normal structure and can then alter other proteins to develop more prions, so that the change spread like a chain reaction.
e.g. prions
SPONGIFORM ENCEPHALOPATHY IN CATTLE (MAD COW DISEASE)
- Progressive, degenerative and fatal disease affecting the central nervous system in cattle
- The human form is called Creutzfeldt-Jakob disease (vCJD)
- Symptoms include loss of intellect and memory, changes in personality, loss of co-ordination, slurred speech, vision problems and blindness.
define outbreak
where the disease pops up temporialiy in an isolated area
define endemic level
people affected by the disease at any given time
define pandemic
an increase in the number of cases throughout a continent or across the world
what are the two levels that contribute to epidemics
pathogen level
human level
what are factors that contribute to epidemics at a pathogen level
virulence antibiotic resistance toxins genetic shift herd immunity
how does virulence contribute to epidemics @ a pathogen level
Pathogens ability to infect or damage a host
- The greater the virulence the greater effect it will have on the health of the host
- Mutations increase a pathogens virulence, allowing it to evade detection in hosts
how does antibiotic resistance contribute to epidemics @ a pathogen level
Antibiotic resistant pathogens can’t be treated and are spread more easily.
how does toxins contribute to epidemics @ a pathogen level
- Make host more susceptible to infection
- Deter other pathogens