Module 7: Infectious Disease Flashcards
What is a disease?
Any process or condition that adversely affects the normal functioning of a living thing
What is an infectious disease?
Any disease caused by another organism or an infective agent known as pathogens
What are pathogens?
Any agent which causes disease in an organism
What distinguishes a prion?
Non living, defective form of protein molecules which do not contain genetic material
What are examples of diseases caused by prions?
Mad cow disease, Creutzfeldt - Jacob disease
What distinguishes a virus?
Non living, non cellular that requires a living host to replicate and contains genetic material
What are examples of diseases caused by viruses?
Hepatitis B, Aids, Smallpox
What distinguishes a bacteria?
Living, unicellular, prokaryotic cell which has a cell wall
What are examples of diseases caused by bacteria?
Tuberculosis, Anthrox
What distinguishes a protozoa?
Living, unicellular eukaryotic cell
What are examples of diseases caused by protozoa?
Malaria, Giardiasis
What distinguishes a fungi?
Living, eukaryotic unicellular or multicellular organism with cell walls
What are examples of diseases caused by fungi?
Tinea, Thrush
What distinguishes a macro parasite?
Living, eukaryotic multicellular organism visible to the naked eye
What are ectoparasites?
External parasites
What are endoparasites?
Internal parasites
What are examples of macro parasites?
Tapeworm, paralysis tick
How do bacteria reporduce?
Via an asexual process known as binary fission
What is binary fission?
A single cell dividing into two identical cells
What are the four most common shapes of bacteria?
Coccus, spirillum, bacillus and vibrio
What do coccus bacteria look like?
Spherical
What do spirillum bacteria look like?
Spiral
What do bacillus bacteria look like?
Rod shaped
What do vibrio bacteria look like?
Common shaped (ununiform tear drops)
How do bacteria cause disease?
By producing toxins and chemicals harmful to the host
How can transmission of disease occur?
Directly, indirectly or through a vector
What is an endospore?
A tough waterproof external layer on some bacteria
Why are endospores problematic?
They can lay dormant for years and can resist heat, chemicals and desiccation
What does saprophytic in context with fungi mean?
That they live on dead plant and animal material
What is mould composed of?
They are composed of hyphae, which spreads to form mycelium
What is mycelium?
The main fungal body
What is hyphae?
Microscopic tublur filaments
How can fungi reproduce?
Asexually by budding or sexually
What is a fungal cutaneous infection?
Infection of the outer skin layer
What is a fungal subcutaneous infection?
Infection beneath the skin surface
What is a fungal systemic infection?
Infection affecting internal organs
How can fungi by transmitted?
Directly or indirectly
How can protozoa be transmitted?
Directly, indirectly and by vectors
How do protozoa reproduce?
By binary fission
What are the four main classifications of Protozoa?
- Flagellates
- Ciliates
- Amoebae
- Sporozoa
What are flagellates?
Protozoa which have a whip like tail known as flagellum
What are ciliates?
Protozoa which have many hair like projections known as cilia
What are amoebaes?
Protozoa which use projections of cytoplasm to move around
What are sporozoa?
Protozoa which can not move and reproduce by releasing spores
What are some examples of endoparasites?
Flatworms, tapeworms and roundworms
What are some examples of ectoparasites?
Leeches, ticks and flees
What are helminths?
A parasitic worm
What are worms generally treated with?
Anthelmintics
How do helminths reproduce?
By releasing eggs
What are athropods?
Are invertebrates that have an exoskeleton and segmented body
What are some examples of anthropods?
Fleas, ticks, lice, mites, mosquitoes
What is a capsid?
It is a protective coat that encloses the genetic material in a virus
What can be found on the protein coat of virsus?
Chemicals which helps attachment to cells
What are prions?
Abnormal proteins causing degenerative diseases
How do prions cause disease?
By inducing abnormal folding patterns in normal proteins
Why are diseases caused by prions called spongiform?
They leave the brain filled with tiny holes like a sponge
How are prions transmitted?
By ingesting infected tissue, inheritance and it can be spontaneous
What are the three stages of chain of infection?
A host susceptible to disease
A disease causing pathogen
A mode of transmission
What is direct contact?
Transmission through physical contact between host and organisms
What is horizontal transmission?
Spread in the same generation
What is vertical transmission?
Spread from parents to offspring
What are some examples of direct contact?
Kissing, touching and biting
What is indirect contact?
Transmission when there is no direct contact between host and organisms
What is a formite?
An object or material that carries pathogens
What are some examples of indirect contact?
Coughing, sneezing, touching infected surfaces, contaminated food or water
What is vector transmission?
Transmisson through arthropods
What are some examples of vectors?
Mosquitos, sandflies, ticks
What are clusters of fungi and bacteria known as?
Colonies
What are the two conditions required for bacterial and fungal culture?
Nutrient agar and 30*C
What do bacterial colonies look like?
Tend to be smooth, glossy and coloured
What do fungal colonies look like?
Tend to be fury and large
How did people think disease was caused in the past?
BY spontaneous generation
Who developed the agar plate technique?
Koch
What did Koch do extensive studies on?
Anthrax
What did koch conclude?
That disease is caused by micro-organisms
What are the four criteria for Koch’s postulates?
- The same pathogen must be present in every diseased host
- Pathogen must be isolated and then cultured
- When sample is exposed to a host they must develop the same symptoms
- Pathogen must be isolated from second host and must be same as first
What did Louis Pasteur discover whilst researching fermentation?
Different organisms were responsible for fermentation and souring of alcohol
What is pasteurisation?
The process of heating a liquid to destroy pathogens
Who proposed germ theory?
Louis Pasteur
What experiment did Louis Pasteur do to prove germ theory?
The swan neck experiment
What vaccine did Louis Pasteur develop?
Vaccine against rabies
Why is Australia’s agriculture relatively free from many infectious diseases?
Because of the isolated nature of Australia
What is Panama Disease caused by?
A fungus
What are the signs of Panama Disease?
Yellowing and wilting of leaves and splitting of stems
How is Panama Disease spread?
From root to root contact and contaminated soil
What is footrot in sheep caused by?
A bacteria
What are the signs of footrot in sheep?
Abscesses between toes, lameness and weight loss
How is footrot in sheep spread?
Foot to foot via pasture or mud
What are the main factors increasing the risk of disease?
Increased mobility of human population
Climate change
Antimicrobial resistance
Loss of genetic diversity
Where can fungi enter plants?
Via the stomata or other openings
How does fungi impact plants?
Destroys conducting tissues preventing the absorption of nutrients
How do insects impact plants?
They can cause direct physical damage
Where can bacteria which effect plants be found?
Soil, weeds and seeds
What are the four steps for an organism to cause disease?
- Enter the host
- Multiply in host tissue
- Resist or not stimulate host defence
- Damage the host
What does a prion do to facilitate movement through the body?
May piggyback other proteins
How does a protozoa enter host cells?
Microtubule protrusion
How do protozoa protect themselves?
They form a vacuolar membrane providing protection from lysosome
How do viruses adhere to host cells?
Viral surface proteins adhere to host cell surface receptors
How does a virus enter the cell?
Receptor mediated endocytosis
What adaptations help bacteria with adhesion?
By pili and fimbriae
How do bacteria invade the body?
Enzymes break down cell contents
Toxins are secreted to damage host cells
What adaptations do bacteria have to protect itself?
Capsules resist phagocytosis
What adaptations do ticks have for invasion?
Specialised mouthparts which can be inserted in skin
Molecules are secreted in saliva to prevent clotting/inflammation
What adaptations does fungus have for invasion?
Thermotolerance
Enzymes secreted to damage cells and provide nutrients for fungus
What are adaptation of pathogens which are airborne?
Able to remain suspended in air for long periods
Resist drying out
Cause sneezing and coughing
What are adaptation of pathogens which are waterborne?
Able to colonise in water
Many can not be destroyed from boiling water
What are adaptations of vector borne pathogens?
Vector is not affected by pathogens
Are in digestive track/saliva for transmission
Life cycle of pathogen is synched with feeding of vector
What are adaptations of faeco-oral pathogens?
Pathogens very stable in all environments
Causes vomiting/diarrhoea increasing transmission
What are adaptations of soil-borne pathogens?
Form endospores to resist desiccation
Stable in a range of environments
What are adaptations of blood-borne pathogens?
Takes advantage of unique features of red blood cells
What are the two major types of passive defences for plants?
Physical and chemical barriers
What physical barriers do plants have?
Thick cuticle, cell walls and small stomata
Bark
Vertical hanging leaves reducing the risk of water pooling
What do chemical barriers do in plants?
Chemical compounds reduce fungal and bacterial growth
Enzymes break down pathogen-derived toxins
What are the three major stages of active defence in plants?
Recognition, rapid response and delayed response
What is pathogen recognition in plants?
Can recognise pathogens by certain physical and chemical signals
When does rapid response happen in plants?
In minutes to hours
What can happen during the rapid response in plants?
Release of hydrogen peroxide directly killing microbes
Reinforcements of cell wall
Cell death isolating the pathogen
When does delayed response happen in plants?
In days
What happens during the delayed response in plants?
Repairing wounds in bark
What is innate immunity?
Immunity present at birth that is none specific and includes the first and second line of defence
What is the first line of defence in animals?
Physical and chemical barriers
When does the second line of defence occur?
When the first line of defence in broken
What is the second line of defence in animals?
Cellular response such as inflammation
What is the third line of defence in animals?
Adaptive immunity which is acquired and is a specified response
What is an antigen?
A molecule which is recognised as foreign triggering a response
What does the lymphatic system consist of?
Lymph, lymph nodes and lymph vessels
What does the lymphatic system do?
Forms a drainage system for all parts of the body
What do the lymph nodes do?
FiIlter out microbes, cellular debris and cancer cells
What do macrophage do?
Phagocytosis of pathogens
What do dendrite cells do?
Trigger adaptive immune response
What do neutrophil do?
Are the most common white blood cell at the site of trauma/infection
What does the microbiome do?
Inhibits the growth and multiplication of pathogens
What can occur when microbiome is compromised?
Pathogen growth may not be controlled and disease can occur such as thrush
What can impact the microbiome?
Antibiotics
What are the three parts of skin?
epidermis, dermis and hypodermis
What is the three step process that occurs when skin is broken?
- Inflammation
- Proliferation –> new cells generated
- Maturation –> cells mature creating a new barrier
What is the mucous membrane?
Epithelial tissue which forms a barrier from pathogens
What does the mucous membrane secret?
Mucus, lysozyme and immunoglobins
What does mucus do?
Protects the lining of the body by trapping foreign substances
What are sphincters?
Circular muscles that ensures one way flow through constriction and relaxation
How is a granuloma created?
Cells die to create a wall that prevents the infection from spreading
What happens to granuloma once formed?
They are destroyed by macrophages
When does vomiting occur?
Presence of pathogens in the stomach
What does diarrhoea do?
Quickly expels organisms from the intestine
What is inflammation?
A chemical response that helps repair wounds and pathogen destruction
What are some signs of inflammation?
Pain, heat, redness, swelling
What type of response is inflammation?
Non-specific defence mechanism
What is phagocytosis?
The process of phagocytes engulfing foreign particles
What happens to particles inside phagocytes?
They are destroyed by enzymes
Where do neutrophils originate from?
Bone marrow
What do neutrophils do?
Are the first to move to the site of infection and fight acute infections
Where are monocytes?
Circulating in the blood
What do monocytes transform into?
Macrophages and dendrite cells
What do macrophages and dendrite cells do?
Fight chronic infections and act as a bridge between innate and adaptive immune systems
What is a fever?
The bodies response to pathogens by increasing body temp
What is the purpose of fevers?
To limit the growth of pathogens and enhance white blood cell activity
Why can fevers be bad?
In temperature is too high in the brain it can lead to seizures
What are cytokins?
Chemical messengers which promote development and differentiation of T and B cells
What is an example of cytokins?
Interleukin
What is the humoral response effective against?
Pathogens in body fluids
What is the cell mediated response effective against?
Intracellular pathogens
What is responsible for the adaptive immune response?
T and B cells
What are the T and B cells responsible for?
The adaptive immune response
What do B cells become?
Plasma cells which produce antibodies
What do T cells become?
Cytotoxic T cells which destroy infected body cells
What is mainly responsible for the humoral response?
B cells
Where are B cells stored?
Lymph nodes
What activate B cells?
Helper T cells which release cytokines
What happens when a B cell is activated?
- B cell multiplies
- B cells differentiates into plasma cells and memory cells
What is the cell mediated response?
When T-cells target and destroy an entire infected host cell
What are the four types of T cells?
Helper T cells, cytotoxic T cells, memory T cells and suppressor T cells
What do helper T cells do?
Release chemical that activate cloning of cytotoxic T cells and B cells
What do cytotoxic T cells do?
Move to the site of infection and release chemicals that destroy infected cells
What do memory T cells do?
Remain in the body to respond to future infections
What do suppressor t cells do?
Suppress the immune response when the infection has been defeated
What are major local factors?
Sanitation, overcrowding, poor communication, animal husbandry and culture
What are global factors?
Increased movement of people globally and rise in antibiotic resistance
What are societal factors?
Anti vaccination campaigns
Lack of education
Poverty
Immigration
Rise of international travel
What is included in personal hygiene?
Keeping our body and any openings clean
What is included in community hygiene?
Sewage and garbage disposal, sterilisation of medical equipment and reduction of overcrowding
What does DAWR stand for?
Department of Agriculture and Water Resources
What is DAWR responsible for?
Keeping Australia relatively disease free
What does vaccination involve?
The introduction of the vaccine to the body
What is immunisation?
The process in which the body reacts to a pathogen
What does an immune response produce?
Memory cells
What is active acquired immunity?
When the immune response occurs and memory cells are created
What are the three things that vaccines can contain?
Pathogens that are living but attenuated or dead and toxoids
What are booster injections used for?
To increase memory cells
What is passive acquired immunity?
Introduction of antibodies which have been produced by another organism to prevent disease from developing
How long will passive acquired immunity last for?
A couple of months
What does RICE stand for in the public health campaign approach?
Resolution of WHO to find solution
Information in form of scientific studies
Coordination on all scales
Education of human population
What are pestacides?
Chemicals used to kill pests on plants
What are the three types of pesticides?
Insecticides - insects
Fungicides - fungus
Herbicides - weeds
Why is the use of pesticides discouraged?
As organisms can build resistance and they have great harm on the environment
What are alternatives to pestacides?
Natural pesticides and companion plants
What does genetic engineering involve?
Altering of the genetic composition of an organism
Why is genetic engineering used against infectious diseases?
As it makes it possible to make organisms resistant to diseases
What are the four main classifications of antimicrobials?
Antibiotics - Bacteria
Antivirals - Viruses
Antifungals - Fungi
Antiprotozoals - Protozoa
What is an example of an antibiotic?
Penicillins
What is an example of an antiviral?
Tamiflu
What is an example of an antifungal?
Fluconazole
What is an example of an antiprotozoals?
Doxycycline
What does an antiviral do?
Does not kill a virus but inhibits development in cells
What does an antibiotic do?
Kills or slows down the growth of bacteria
What is incidence?
The number of new cases occurring during a specific time
How is incidence calculated?
Number of new cases during time/size of population x 100
What is prevalence?
The proportion of the population that have the disease
How is prevalence calculated?
All new + previous cases during time period/population during time period x 100
What is smokebush?
It is a plant that indigenous people have used for healing
Why have scientists taken interest in smokebush?
It’s properties have the potential to treat HIV
How does direct contact influence the spread of the disease?
Limits spread as it is limited to the transmission through touching or droplets in a one meter range
How does indirect contact influence the spread of the disease?
Results in disease spreading rapidly over large distances
How does vector transmission influence the spread of the disease?
Spreads disease according to the mobility and lifecycle of the vector, can spread pathogens across borders
What is a retrospective cohort study?
It uses preexisting secondary research data to examine the relationship between an exposure and an outcome
What is a prospective cohort study?
Follows a group of individuals over time
What is endemic?
Disease regularly occurring within an area or community
How were antibiotics used historically?
Historically, antibiotics have been very successful in the treatment of bacterial infections. During World
War II, many soldiers’ lives were saved due to the use of antibiotics to treat wounds
What does increased blood flow to infected areas result in?
They bring phagocytes to the site to
carry out phagocytosis, destroying the pathogen
What chemicals cause inflammation?
Histamines and prostaglandins
What does phytophthora cinnamomi cause?
Lesions in the plant which look rotten
What was one historical strategy of controlling the spread of disease and how effective was it?
In the 18th century they started isolating people who were unwell and quarantine of exposed people this was very effective
What type of protein is formed in response to a pathogen?
Antibody
What is the independent variable?
The one that is manipulated or changed
What is the dependent variable?
The variable that changes as a result of the independent variable manipulation
How do you remember the difference between dependent and independent variables?
The dependent variable ‘depends’ on the independent variable
What does heterotrophic mean?
An organism that cannot produce its own food
