Infectious Disease Flashcards
Pathogen
are any organism which is capable of causing disease
Microorganism
is a microscopic organism, which may exist in its single-celled form or a colony of cells.
Macroorganism:
is an organism large enough to be seen by the normal unaided human eye
Non-cellular pathogen
Not living. This is because viruses, Viroids and prions can not replicate outside of a host cell and thus don’t meet the requirements for ‘living’.
prion
Non-cellular infectious proteins, which are abnormally folded versions of a protein needed within an organism
virus
Non-cellular entities, consisting of a single type of nucleic acid (DNA or RNA - mechanisms used to attack)
bacteria
Prokaryotic, unicellular organisms, which dont have membrane bound organelles and are each made of one cell
fungi
eukaryotic , unicellular non-photosynthetic organisms with a cell wall
protozoan
Eukaryotic unicellular organisms
macroparasite
Eukaryotic, Multicellular pathogen which can be seen with the naked eye
epidemic
The rapid spread of disease to a large number of people in a given population within a short period of time
pandemic
a widespread occurrence of an infectious disease over a whole country or the world at a particular time
MODE OF TRANSMISSION
Direct
when there is physical contact between the host and a non-infected organism
- skin to skin
- bodly fluids
MODE OF TRANSMISSION
Indirect
when the host and another organism have no direct contact with each other
- airborne
- food and drinks
Vector Transmission
occurs when a living organism carries an infectious agent on its body (mechanical) or as an infection host itself (biological), to a new host.
- insect bites
Robert Koch
Showed bacteria were the cause of the disease anthrax
Developed postulates which were four rules of procedure for showing that a particular pathogen caused a disease
Koch’s postulates
4
(1) The microorganism must be found in diseased but not healthy individuals;
(2) The microorganism must be cultured from the diseased individual
(3) Inoculation of a healthy individual with the cultured microorganism must recapitulate the disease
(4) The microorganism must be re-isolated from the inoculated, diseased individual and matched to the original microorganism.
Pasteur
Discovered microbes can cause contamination and disease
Discovered microbes were responsible for the souring of alcohol
Work led to the development of vaccinations for anthrax and rabies
Fire blight
cause, effect, impact
cause: by the bacterium Erwinia amylovora
Effect: Infection results in tissue death and bacterial ooze droplets on infected tissue
Imapct: All apple and pear growing areas in Australia are considered high risk areas for fire blight.
Foot and mouth disease
cause, effect, impact
Cause: The foot and mouth disease virus (FMDV)
Effect: fever and blisters in the mouth and hooves of cattle, sheep, goats, and pigs (and other cloven-hoofed animals).
-> severe production losses
Impact: caused more than $AUD 19 billion in export losses.
Malaria
caused by 4 protozoan parasitic species of the genus Plasmodium
500K deaths annually from malaria
Human Immunodeficiency Virus (HIV)
weakens the immune system and causes Acquired Immunodeficiency Syndrome (AIDS)
Fungal disease signs (plants)
Leaf rust (common leaf rust in corn)
Stem rust (wheat stem rust)
Sclerotinia (white mold)
Powdery mildew
Plant Adaptions
Waxy cuticle coating the leaf
Production of toxic chemicals
thick cell walls
small stomata
PHYSICAL RESPONSES TO INFECTION
Granuloma
is a wall of dead cells formed by the immune cells to separate a pathogen from body tissues
PHYSICAL RESPONSES TO INFECTION
Vomiting and diarrhoea
a reflex action coordinated by the vomiting centre (chemoreceptor trigger zone) of the brain.
PHYSICAL RESPONSES TO INFECTION
Increased Urination
help flush out pathogens
PHYSICAL RESPONSES TO INFECTION
Wound healing
When there is a breach in the body’s barriers, ther tissues are exposed to environmental pathogens and the microbiome of the skin
CHEMICAL DEFENCES AGAINST INFECTION.
Urine
Antimicrobial peptides secreted by cell lining to prevent binding of bacteria
CHEMICAL DEFENCES AGAINST INFECTION.
Sweat and sebum
Sebum - waterproof + Lubricates skin
CHEMICAL DEFENCES AGAINST INFECTION.
Saliva
flushing action against microbes + chemical activity
CHEMICAL DEFENCES AGAINST INFECTION.
Tears
wipe out bacteria
CHEMICAL DEFENCES AGAINST INFECTION.
Gastric Secretions
acid environment in the stomach - discourages growth and survival of microbes
innate immune system provides a first and second line of *defense against pathogens, through means such as
physical* barriers (eg skin)
body *fluids (eg tears, mucus)
Cellular *responses (eg phagocytosis)
biochemical responses (eg complement activation)
adaptive immune response
The cells responsible for generating the adaptive immune response are known as B and T lymphocytes
- B cells develop into plasma cells, which produce antibodies (also called immunoglobulins) against the pathogen.
- T cells transform into cytotoxic T (killer T cells) and seek out infected body cells, binding to them and destroying them aka cell-mediated response.
- secondary immune response comes about because of the existence of memory T and B cells that were produced in the first infection with the pathogen
Inflammation response (first response)
When tissues around a wound become red, hot, swollen and painful.
- > increases blood flow at injury - deliver white blood cells to the site
Fever (responce)
The increase in temperature can damage the enzymes in bacteria or the RNA in viruses
can also increase the efficiency of the body’s defence mechanisms
Phagocytosis (responce)
The process by which one cell engulf another
Interferons
A group of signaling proteins released by host cells in response to the presence of viruses.
Antibodies
Destruction of antigen
Proteins that are made in response to a specific antigen
Produced by plasma cells
The function is to bind with the antigen to form an antibody-antigen complex.
T cells
Cytotoxic cells attack body cells that are infected with pathogens
Four types of cells: helper - interact with phagocytes memory - provide long-term immunity cytotoxic (killer) - suppressor - turn off the immune
B cells
Function in controlling antibody-mediated immunity
Two types of cells:
plasma - release antibodies into the blood
memory - provide long-term immunity
