Infectious disease Epidemics Flashcards
how do you define infection
Infection is the infiltration of body tissue by micro- organisms (or microbes) that may cause disease, followed by the multiplication of these micro-organisms
How do you define microorganism
A micro-organism that can cause disease is called a pathogen
How do you define contagious
- derived from the word contact and describes infections that are transmissible person to person and thus this can also be termed communicable
Whats another word for contagious
- Communicable
virtually all viral diseases are
virtually all viral diseases are caused by viruses that are communicable
How can you prevent trachoma
clean water and sanitation
What is the commonest cause of blindness
Trachoma
name the types of pathogens
- viruses
- bacteria
- fungi, protozoa, worms
What are the two types of pathogens
- opportunistic pathogens
- obligate pathogens
What is an opportunistic pathogen
Micro-organisms found in healthy host animals that may cause disease in certain circumstances, they take advantage of an “opportunity” not normally available
give examples of opportunistic pathogens
Commensals (staphylococcus, streptococcus)
describe opportunistic pathogens
- Cannot infect healthy people (nor do they need to)
- do so only when illness or injury introduces them to normally sterile parts of the body
- do not make infected people infectious to other healthy people
- do not cause epidemics
describe obligate pathogens
- have no reservoir
- must cause disease to be transmitted from one host to another
- organisms with no environmental reservoir
- do infect healthy people - they need to for their own survival
- make infected people infectious to others - need to for their survival
- introduced into a susceptible population and will spread from person to person and cause an epidemic
Name the animal sources of human pathogens
- measles
- smallpox
- coronavirus
- influenza
- tuberculosis
- herpes
- hepaitits B
- HIV
- ebola
- measles = dogs, cattle
- smallpox = cattle (cowpox)
- coronavirus = cattle, poultry
- influenza = chickens, swine
- tuberculosis = cattle (bovine TB)
- herpes = Monkeys
- hepaitits B = monkeys
- HIV = chimpanzees
- ebola = fruit bats
name some human pathogens that have derived from other human pathogens
- syphilis from bejel
- leprosy from TB
What has caused the pathogens to spread around the world
- human migration carried the organisms around the world
for organisms to survive in the short term what must it do
- cause mild symptoms that will propagate the organism to other humans
- not to kill humans or make them very ill
Why is it in the interests of the human to develop the symptoms (coughing & sneezing or diarrhoea?)
- To dump live organisms from the body (help out the immune system)
describe examples of conditions that spread by respiratory means
- Measles
- TB
- Influenza
What casues respriatory illnesses to spread
- sneezing
- coughing
- over-crowding
