11 Disease Flashcards
what is the definition of health?
being free from disease
having physical, social and mental wellbeing
having good nutrition
being suitably housed
what is the definition of disease?
a malfunction of the body and/or mind that adversely affects the health of an individual and leads to impairment of normal functioning
what is a communicable disease?
a disease or infection capable of being transmitted or communicated to another living organism
what is required for a disease to be communicated successfully?
the pathogen must:
- enter the host (i.e. pass the first line of defence)
- colonise affected tissue
- leading to development of symptoms
what is virulence?
a measure of the ability of a pathogen to cause disease
how do bacteria cause harm? give an example
production of toxin –> symptoms
e.g. streptococcus produces a pyrogenic toxin, causing a rash and high temperatures
how do viruses cause harm?
enter host cell and inhibit normal DNA/RNA/protein synthesis
then use these mechanisms to produce new viral particles
once sufficient have been formed, the cell ruptures and the virus spreads
how do fungi cause harm?
secretion of enzymes that causes an allergic reaction and allows the spread of pathogens through tissues
what is the difference between a pathogen and a parasite?
a pathogen always causes disease, whereas a parasite doesn’t always
a parasite gains energy from the host, whereas a pathogen does not
how does TB cause disease?
inhibits the action of lysosomes in phagocytic leucocytes
what happens during the 1° infection of TB?
bacteria multiply inside lung tissue and destroy it
a healthy immune system should be able to deal with it
what happens during the 2° infection of TB?
phagocytic cells accumulate round infected cells, causing a tubercule (granuloma)
lung tissue is damaged and sputum becomes blood-stained
can spread to immune system, bones, gut and kidneys
how is TB communicated?
inhalation of inhaled droplets (T)
long term contact (T)
contaminated meat/unpasteurised milk (B)
how is TB diagnosed?
microscopical analysis of sputum and chest xrays
how can TB be prevented?
reduce over-crowding
improve ventilation
testing of cattle
pasteurising milk
improve general health
give four symptoms of TB
fever
night sweats
coughing up blood
tiredness
what is latent TB?
no symptoms ∴ treatment not required but must be monitored
how is TB treated?
isolation during infectious period
intensive care and antibiotics
how are antibiotics used to treat TB?
2 antibiotics daily for 6 months
2 antibiotics daily for 2 months
n.b. if infection spreads outside lungs, used for 12 months
what are the consequences of developing MDR-TB or XDR-TB?
require 18 months’ treatment with up to 4 antibiotics and a treatment team
what is a retrovirus?
a virus that contains RNA and reverse transcriptase
which types of cell does HIV infect?
T helper cells, macrophages and brain cells
how does HIV cause disease?
reverse transcriptase creates a DNA copy of viral genome
becomes part of the cell (a provirus)
provirus activates viral DNA –> synthesis of viral RNA and viral proteins
T helper cell ruptures to prevent immune system resistance
how is HIV transmitted?
direct contact of contaminated body fluids, e.g.:
- blood
- semen
- mother’s milk/across placenta
