Disease Flashcards
How do bacteria replicate?
3 ways to classify bacteria.
Staining
Shape
Clustering
2 staining outcomes.
Gram +
Gram -
4 bacteria shapes.
Cocci (spherical cells)
- diplo = pairs
- strepto = chains
- staphylo = clusters
Bacilli (rod shaped)
Spirilla (spiral shaped)
Vibrio/filamentous (like a comma)
3 types of bacterial clusters.
Diplococci (pairs)
Streptococci (chains)
Staphylococci (cluster)
How do viruses replicate?
5 steps of viral replication.
- Adsorption
- Penetration
- Replication
- Assembly
- Release
Describe the 1st stage of viral replication (adsorption).
Viral binds to the host cell.
Describe the 2nd stage of viral replication (penetration).
Virus injects its genome into host cell (DNA or RNA).
Describe the 3rd stage of viral replication (replication).
Viral genome replicates using the host’s cell machinery.
Describe the 4th stage of viral replication (assembly).
Viral components and enzymes are assembled into coats.
Genome is packaged inside.
Describe the 5th stage of viral replication (release).
Host cell lyses and many more viral particles can infect other cells within host.
Describe reverse transcriptase.
Some viral particles containing RNA use it to replicate
- RNA is converted to DNA.
- They use the host cell machinery to replicate their genome (make their protein coats and RNA genome).
What cells do viruses infect?
Any type of cell.
Define bacteriophages.
Viruses that infect bacteria.
How are viruses classified?
Their genome
Eg: double stranded DNA, single stranded DNA, single stranded RNA, etc.
Define diseases.
Any malfunctions of the body/part of the body of an organism.
Define pathogens.
Disease causing agents.
Define infectious/communicable diseases.
Diseases that:
- Can be transmitted from one organism to another.
- Are caused by pathogens.
Define non-infectious diseases.
Diseases that:
- Cannot be transmitted from one organism to another.
- Aren’t caused by pathogens
2 non-cellular pathogens.
Viruses
Prions
Describe viruses.
Contains DNA or RNA
Molecule encased in a protein (or two protein layers) that may be covered in a lipid layer.
Shape varies greatly.
Much smaller than bacteria (0.5 to 0.01 times the size).
Can only reproduce inside a living host.
Describe prions.
Small infectious proteins
Example of a prion.
vCDJ (variant Creutzfeldt-Jakob disease)
4 cellular pathogens.
Bacteria
Fungi
Protists
Minor groups of parasites
- Endoparasites
- Ectoparasites
Describe bacteria.
Microscopic
Unicellular
Prokaryotic
No membrane bound organelles and nuclei.
Cell wall made of sugars and amino acids.
Single ‘spaghetti-like’ strand of DNA
Describe fungi.
Eukaryotic
Generally multicellular
Microscopic fungi are generally larger than bacteria.
Reproduce using spores.
Cell walls made of chitin (carbohydrate).
Contain hyphae (branching threads) that form a mass called a mycelium.
Hyphae are usually divided along their lengths by walls called septa that have pores in them to allow nutrients to pass from one cell to adjacent cells
Describe protists.
Eukaryotic.
Can be unicellular or multicellular
Reproduce sexually and asexually.
Have no complex systems.
Have a variety of shapes depending on their locomotion.
Generally cannot move themselves.
Describe endoparasites.
Live inside another organism – usually intestines
Some use other animals as intermediate hosts and humans are the definitive host.
Examples of endoparasites.
Flatworms
Roundworms
Flukes
Describe ectoparasites.
Live on the surface of another organism.
Many are vectors for other diseases such as the plague (bacteria).
Examples of ectoparasites.
Fleas
Ticks
Lice
Define virulence.
The intensity of the effect of the pathogen.
Define susceptibility/resistance.
The level of response of an organism to a pathogen.
Define symptoms.
Characteristic effects of a pathogen on the body.
Signs of the disease in the host.
Define incubation period.
The time between infection and the onset of symptoms.
4 parts of a pathogenic infection.
- Infection
- Incubation
- Symptoms
- Recovery
Define endemic diseases.
Occur at a relatively constant rate within a population
Define sporadic diseases.
Uncommon
Occur irregularly
Define epidemics.
Occur when there is an increase in the number of cases of a disease within a population is above normal
Rapidly spread.
May be triggered by:
- Increased virulence
- Introduction into a novel setting
- Changes in host’s susceptibility
Define pandemics.
An epidemic
Infects large numbers of humans over multiple populations/continents/worldwide.
Rapid spread over multiple populations/continents/worldwide.
Factors involved in the spread of disease.
Climate
Population density (urbanisation)
Infrastructure
Urban areas susceptible to epidemics and pandemics
What are the hosts of Influenza (virus)?
Numerous animals
- Humans
- Mammals
- Birds
What are the signs and symptoms of Influenza (virus)?
Fever
Sore throat
Cough may persist and gradually deteriorate for several weeks
Runny nose
Headache
Muscle pains
Lethargy
What are the hosts of Ross River virus?
Humans
- Mosquito (vector)
- Animal (source such as kangaroo)
What are the signs and symptoms of Ross River virus?
Stiff painful joints
Rash
Swollen lymph nodes
Reduced mobility
What are the hosts of the Aussie bat lyssavirus?
Humans
- Bats (particularly Flying foxes) appear to be a reservoir of the virus
What are the signs and symptoms of the Aussie bat lyssavirus?
Paralysis
Convulsions
Delirium
Death
What are the hosts of the viral diseases of honey bees?
Honeybees
- Potentially mites (vector)
What are the signs and symptoms of the viral diseases of honey bees?
Collapse of hive
Significant reduction in plant pollination
Leads to honey shortage
What are the hosts of Tetanus (bacterial)?
Humans
Horses
Cattle
What are the signs and symptoms of Tetanus (bacterial)?
Muscle spasms (lockjaw)
Swallowing and breathing difficulties (possible breathing failure)
Abnormal heart rhythms leading to high or low blood pressure.
Painful fits
Heart attacks
What are the hosts of Tuberculosis (bacterial)?
Humans
Cattle
Pigs
Birds
Dogs
Cats
What are the signs and symptoms of Tuberculosis (bacterial)?
Chronic cough
Coughing blood
Lethargy
Sweating
Weight loss
What are the hosts of the Crown of Gall affecting plants (bacterial)?
Deciduous fruits
Vine (e.g. grapes)
Berry fruits
Vegetables
Ornamentals (e.g. roses)
What are the signs and symptoms of the Crown of Gall affecting plants (bacterial)?
Small, pale lumps on upper root/stem
- Develop into large asymmetrical growths
- May stunt the growth of a young plant.
May kill plants that are stressed in dry conditions
What are the hosts of Chytridiomycosis (amphibian chytrid fungus disease) (fungal)?
Amphibians
- Frogs
What are the signs and symptoms of Chytridiomycosis (amphibian chytrid fungus disease) (fungal)?
Loss in body weight
Lethargy
Skin colour changes
Shedding of skin
Convulsions
Death
What are the hosts of Malaria (Protista)?
Humans
- Mosquito (vector) (Anopheles genus)
What are the signs and symptoms of Malaria (Protista)?
Fever
Hot and cold spells
Shaking
Headaches
Muscles aches
Weakness
What are the hosts of Phytophthora dieback (Protista)?
Several native species of plants:
- Eucalyptus
- Grass tress
- Banksia
What are the signs and symptoms of Phytophthora dieback (Protista)?
Leaves may wilt then die (outer first progressing inwards towards trunk)
Roots may darken in colour
Most plants die, particularly if under water stress
The spread of a specific disease involves what interrelated factors?
Growth of the pathogen population
Density of the host population
Mode of transmission
What facilitates the transmission and spread of disease?
Regional/global movement of organisms
Describe Dengue fever
Mosquitoadaptedd to living in urban environments as it can breed in artificial water pools (water tanks and buckets).
Can spread rapidly because of the high population density in urban environments and numerous water sources
What are the vectors of Dengue fever?
Humans
- Mosquitos (vector)
What are the signs and symptoms of Dengue fever?
Fevers
Muscle aches
Headaches
Rashes
Death
How do pathogens evolve?
Evolve in a changing environment
Bacteria divide/reproduce once every 20 mins under ideal conditions
Numerous opportunities for mutations
New strains produced
Opportunities for a more virulent strain is endless
What do design interventions include?
Implementing programs
- Vaccination programs
- Quarantine measures
Management strategies used to control the spread of infectious diseases.
Quarantine
Immunisation (herd immunity)
Disruption of pathogen life cycle
Medications – antibiotics and antivirals
Physical preventative measures
Advantages of quarantine.
Prevent specific pathogens from crossing borders or entering a country
Disadvantages of quarantine.
Inadequate checks by customs can result in a disease entering a country
Borders are porous to human and other organisms’ movements.
Illegal activities
Ignorance from travellers
Advantages of immunisation (herd immunity).
If large proportion of population has immunity, the small number of population who are not immune are protected to some extent
They live in a population in which the spread of that disease will be interrupted or stopped by people who are immune
Greater proportion of people who are immune, greater protection of those within the population who are not immune
Mass vaccination creates a ‘herd immunity’ - whole population is protected
Disadvantages of immunisation (herd immunity).
Large proportion of population decide not to have the treatment for themselves (or their children) - large population is at risk.
Epidemics are much more likely.
Resistant strains are more likely to develop in these circumstances that in time can affect the vaccinated.
Advantages of the disruption of pathogen life cycle.
If disease is spread by vector, transmission can be interrupted if vector is eradicated
Disadvantages of the disruption of pathogen life cycle.
Mosquito eradication programs (e.g. malaria) will not remove the mosquito entirely.
Insects become resistant to insecticides.
Removal of suitable breeding places not possible in tropics and sub-tropics where disease is endemic.
Advantages of medications (antibiotics/antivirals).
Successful treatment for infectious disease (e.g. antibiotics) normally reduces transmission.
Early intervention (usually prior to becoming contagious) minimises spread.
Disadvantages of medications (antibiotics/antivirals).
Pathogens frequently develop a resistance to drugs.
Advantages of physical preventative measures.
Isolation necessary to reduce the spread.
Reduce exposure to public.
Special equipment used by health workers such as respirators, gloves and special clothing
Washing hands to prevent direct contact or faecal-oral routes.
Preventative measures include sterilisation of all soiled (contaminated) equipment, clothing, bedding and treatment of human wastes
Barriers such as condoms prevent the transmission of several venereal diseases (e.g. HIV)
Early diagnosis essential to containment
Disadvantages of physical preventative measures.
Communicable diseases are still transferred to health workers and those closest to patients
May occur through error or ignorance of the disease
Health workers occasionally contact disease (e.g. Ebola in west Africa) despite protective clothing and masks
Define nosocomial infections.
Infections spread by healthcare workers.
Describe the immune system.
Made up of different cells that protect our bodies from foreign organisms
Homeostatic mechanism
Protects against foreign organisms, alien chemicals, cancerous/abnormal cells
Define antigens.
Any substance capable of causing an immune response.
Define antibodies.
Specialised proteins that are produced in response to a non-self antigen.
They attach to a specific antigen (lock and key model) and destroy or inactivate the foreign antigen
4 modes of action by antibodies to inactivate antigens.
Bind to Virus Surface
Coat Bacteria
Combine with Foreign Enzymes or Bacterial Toxins
Agglutination
Describe the action of antigen binding to virus surface.
Prevent the viruses from entering cells
Describe the action of antibodies coating the bacteria.
Bacteria are more easily consumed by phagocytes (white blood cells)
Describe the action of antibodies combining with foreign enzymes or bacterial toxins.
Either one of these:
- Inhibits reactions with other cells/compounds
- Dissolves organisms
- Reacts with soluble antigens and makes them insoluble
Describe agglutination.
Causes particles (bacteria/viruses/foreign blood cells) to clump together
Steps in immune response
- Primary response-first exposure to antigen
- Large amounts of antibodies are built up to fight antigen (takes several days)
- Primary response leaves the immune system with memory cells of the specific antigen
- Secondary response-subsequent exposures result in a much faster response because of the memory cells
Define immunisation.
Programming of the immune system to allow the body to rapidly respond to infecting micro-organisms.
Results in a secondary response
Can occur naturally or artificially
Describe passive (no memory cells) immunity.
Natural
- Antibodies enter bloodstream across the placenta/in breast milk
Artificial
- Antibodies injected into bloodstream (snake antivenom)
Describe active (memory cells) immunity.
Natural
- Attack of a disease results in the ability to manufacture antibodies
Artificial
- Antigens provided by a vaccination results in the ability to manufacture antibodies
Define vaccination.
The artificial introduction of antigens of pathogenic organisms so that the person can produce a secondary response of antibodies without the person having to suffer the disease
Define antibiotics.
Chemicals able to either:
- Inhibit the growth of micro-organisms
- Kill micro-organisms
Define antiviral drugs.
Chemicals that disable viral proteins
4 types of vaccines.
Living attenuated micro-organisms (reduced virulence)
Dead micro-organisms
Toxoids (inactivated toxins)
Sub-unit (fragment of the organism)
What do living attenuated microorganisms protect against?
Measles
Mumps
Rubella
Rabies
Tuberculosis
What do dead microorganisms protect against?
Cholera
Bubonic plague
Typhoid
Whooping cough
What do toxoids protect against?
Tetanus
Diphtheria
What do sub-units protect against?
Hepatitis B
Human papilloma virus (HPV)
Define herd immunity.
When vaccinations reduce the chance of disease and increase the immunity of the population
When a particular proportion of a population is immune, susceptible individuals are also better protected.
How are diseases classified?
Environmental
Genetic
Cardiovascular
Cancer
Injuries
Blood and immune system
Infectious and parasidic
Define phages.
Viruses that infect bacteria.
Define viroids.
Plant pathogens consisting of circular RNA.
Define capsids.
Protein shells with the shape depending on the type of virus.
