infectious disease - causes of infectious disease Flashcards
prion
- non living
- defective form of protein molecule
- does not contain DNA or RNA
- mostly attacks brain or nerve cells
( mad cow disease )
virus
- non-living
- non cellular
- contains DNA, RNA and protective coat
- requires a living host cell to replicate
( aids (HIV) )
bacteria
- living
- unicellular
- prokaryotic
- cell wall surrounding cell
(tuberculosis)
protozoa
- living
- eukaryotic unicellular organisms
- usually complex life cycle
( malaria )
fungi
- living
- eukaryotic cells with cell wall
- some unicellular most are unicellular
( tinea )
macro-parasite
- living
- eukaryotic cells multicellular organism
- mostly arthropods or worms
-mm to metres, visible with naked eye
epidemic
An epidemic is defined as an outbreak of an infectious disease that spreads rapidly among individuals in a defined area or population at the same time
transmission of ebola
- Fruit bats
- population density
- population mobility in infected areas
- host exposure and susceptibility
host response to ebola
- prevents immune response
- replicates and infects cells of multiple organs leading to cell death and the releasing of cytokines (initiate immune response)
- amount of cytokines result in thinning of the blood vessel walls causing them to drop in temperature
- body goes into shock and dies
treatment of ebola
- no cure
- treatment of specific symptoms
- vaccine developed in 2016
symptoms of ebola
- fever, fatigue muscle pain, sore throat
- vomiting, diarrhoea, rash, kidney and liver failure
- internal and external bleeding
person to person contact
when an infected individual touches or exchanges body fluids with another individual or contact with oral secretions or body lesions
prevention and control of ebola
- cook meat thoroughly
- good hygiene
- contact tracing
- safe burial quarantine
droplet spread
the result of droplets spray caused by talking, coughing and sneezing
airborne transmission
the measles and cold viruses, can remain suspended in the air for many house outside of the body. They can travel long distances and infect an individual long after the original host has left the area
contaminated objects
when a surface or object containing the pathogen is touched and the pathogen is transferred to the mouth, nose, or eyes before washing the hands
food and drinking water
improper treatment, handling, or storage of food and water
animal to person contact
occurs from a scratch or bite from infected animal or from handling waste
vector bone
spread by blood sucking insects, including mosquitos, fleas and ticks
ebola incubation period
2-21 days
germ theory
Infectious diseases are caused by the presence and actions of specific pathogens within the body
PRE germ theory - miasma theory
The miasma theory suggested that diseases are produced due to unhealthy or polluted vapors rising from the ground, or from decomposed material.
koch’s postulates 1
The pathogen must be associated or responsible for all causes of the disease and only found in infected individuals
koch’s postulates 2
The pathogen must be able to be isolated from the affected host, grown in a pure culture and recorded for its characteristics.
koch’s postulates 3
When the newly cultured pathogen is inserted into a new, healthy (unaffected) host, it must result in the new healthy host in developing the same disease (e.g. same symptoms)
koch’s postulates 4
The pathogen must be able to be isolated from the newly affected host and shown to be same pathogen (e.g. same characteristics) that was isolated from the original affected host
what did Koch DEMONSTRATE
Koch predicted that specific microscopic pathogens cause specific disease
what did Koch CONFIRM
vibrio cholera was causative pathogen of cholera
pasteur’s experiments on microbial contamination proved:
Prior to Pasteur it was believed life ‘spontaneously generated’. Pasteur predicted that this was incorrect and microbes were present in the air and that food spoils when these microbes land and become active
contributions of Louis Pasteur
disproved spontaneous generation
- swan neck flask experiment
developed world’s first attenuated vaccine
- anthrax, chicken cholera and rabies
Demonstrated that fermentation was caused by living organisms
- fermentation was caused by living yeast
invented pasteurisation
- heating liquids to high temperatures to eliminate pathogens
fire blight background
plant disease of pome fruit (apples, pears) worldwide
Australia’s pome fruit industry is worth $AU475 million per year.
fire blight cause
a highly infectious disease caused by the bacterium Erwinia amylovora.
fire blight effect
Infection results in
tissue death and
bacterial ooze droplets on infected tissue
fire blight impact
fire blight was found in Melbourne’s Royal Botanic Gardens, costing the Australian pome and nursery industries an estimated $AU20 million in lost revenue.
foot and mouth disease background
a highly contagious disease of cloven-hoofed (animals with divided hooves) animals including cattle, sheep, goats, and pigs.
foot and mouth disease cause
FMD is caused by the foot and mouth disease virus (FMDV).
foot and mouth disease effect
causes fever and blisters in the mouth and hooves of cattle, sheep, goats, and pigs the disease often leaves them weakened and debilitated. As a result, herds are destroyed.
foot and mouth disease effect
causes fever and blisters in the mouth and hooves of cattle, sheep, goats, and pigs the disease often leaves them weakened and debilitated. As a result, herds are destroyed.
malaria (protozoan plasmodium)
4 types of plasmodium
single-celled organisms that cannot survive outside of their host
500K deaths annually from malaria
plasmodium adaption - prevention of immune response
In both humans and the female Anopheles mosquito, the Plasmodium spp. change through several ‘life stages’.
At each stage different antigen molecules are produced,
preventing the host from launching an effective immune response
plasmodium adaption - liver
in the human liver cells, the Plasmodium parasites kill the cell,
causing them to separate from surrounding cells.
This creates small gaps through which the parasites move to infect other liver cells.
The parasites also accumulate calcium ions from the liver cells,
which they use to block the presentation of antigens on the surface of the cell,
thus avoiding the human immune system.
plasmodium adaption - mosquito saliva
The saliva of the female Anopheles mosquito contains an anticoagulant protein (anophelin).
When the mosquito bites a human, the protein inhibits clotting.
The Plasmodium has evolved to exit the mosquito salivary gland once the anticoagulant protein has been injected.
HIV background
Human Immunodeficiency Virus (HIV) weakens the immune system and causes Acquired Immune deficiency Syndrome (AIDS).
Provided a HIV positive person has access to effective treatment, they can lead a relatively normal life.
HIV adaptations - replication rate
high replication rate and the antigen proteins on the surface of the virus mutate rapidly which avoids the immune systems 3rd line of defence.
HIV adaptations - glycans
The virus is also covered with glycans, a carbohydrate that helps to avoid detection by the immune system.
HIV adaptations - T-helper
The primary target cells of HIV are the T-helper lymphocytes which communicate between the B lymphocytes and the T-killer lymphocytes. As a result, this communication is impaired and the immune system weakened, leaving the host susceptible to other infections.
HIV adaptations - unknowing symptoms
Initial infection with HIV typically leads to a short, flu-like illness 2-6 weeks after infection. After this, further symptoms may not present for several years. As a result, the infected person can transmit the virus to many other people unknowingly.
B lymphocytes
A lymphocyte (WBC) that is produced in the bone marrow, and responsible for the production of antibodies.
T lymphocytes
A lymphocyte (WBC) that matures in the thymus and are responsible for cell mediated immunity.
treatment of ebola
- no cure
- treatment of specific symptoms
- vaccine developed in 2016
