Causes of infectious disease Flashcards
What is an infectious disease?
A condition that adversely affects the normal functioning of an organism or parts of an organism
Difference between infectious and non infectious disease?
- Infectious diseases are caused by pathogens and can be transmitted from one organism to another
- non infectious that are not caused by pathogens and are not contagious
What are pathogens?
Any organism that is capable of causing disease in its host
What are the types of pathogens?
Bacteria, viruses, fungi, protozoans, prions
What is virulence?
the degree of pathogenicity or the degree of which a pathogen can cause disease in its host
What is the difference between sign vs symptom?
- Sign= objectively measurable factors such as increased body temperature, rash, hypertension
- symptom: factors reported by a patient such as pain, fatique, nausea
What is pathogenicity?
The ability of a pathogen to cause disease in a host.
What is bacteria
Unicellular, prokaryotic organisms which do not contain membrane bound organelles
How do bacteria cause disease?
producing toxins or chemicals that harm the host’s bodies or by direclting invading host tissues and causing damage
How is bacterial diseases treated?
Chemical treatment with antibiotics, surgical removal of dead issue, wound cleansing
What is fungi
- Eukaryotic organisms with a cell wall comprised of chitlin
- can be unicellular or multicellar
- not capable of producing own nutrients- heterotrophic
- most fungi live on dead plant and animal material- role as decomposer
What is an example of a unicellular fungi and a multicellular fungi
yeasts- unicellular
moulds- multicellular
What is protozoa
- unicellular eukaryotic organisms
- no cell wall
- binary fission
- Live in the human gastrointestinal tract and pools and sewages
Common diseases caused by protozoa
- malaria
- amoebic dysentery
Macroorganisms (macroparasites)
- multicellular eukaryotic organisms
- visible to naked eye
- classifed into two groups; endoparasites and ectoparasites
- some cause disease directly
- others act as vectors
List from the smallest to largest pathogens
Prions, viruses, bacteria, protozoa, fungi macroparasites
List some examples of diseases caused by bacteria
- Tuberculosis
- Pneumonia
- tetanus
- dysentery
Common diseases caused by fungi
- Thrush
- Ringworm
Examples of macroparasites
Endoparasites: tapeworms
Ectoparasites: ticks, fleas,mites
What is a virus
- A microscopic pathogen that consist of RNA or DNA that is enclosed by a protective protein coat
What is a capsid
The protective protein coat that surrounds the genetic material of a virus.
Antivirals
Medications or substances used for the treatment of viral infections by inhibiting the replication of viruses
Retroviruses
Viruses that contain RNA as their genetic material
What are the living Characteristics of Viruses
Viruses possess genetic material (DNA or RNA) that allows them to pass on genetic information
Non-living Characteristics of Viruses
iruses are not composed of cells and can be crystallized. They rely on a host cell for reproduction and metabolism.
Size of Viruses
Viruses are smaller than 500 nm in size, making them visible only under an electron microscope.
What is the infectious part of a virus?
the genetic material (DNA or RNA) enclosed within the capsid.
It carries the genetic info for the virus to replicate and infect host cells.
What are the steps for virus replication?
- The virus attaches to the surface of a host cell.
- The virus enters the host cell and releases its genetic material. (nucleic acids)
- The viral genetic material takes control of the host cell’s machinery and begins to replicate viral genetic materia
- New viruses are synthesised from proteins
- The host cell is destroyed or ruptured to release the newly formed virisues
- Newly released virions infect other host cells and process repeats
What are diseases caused by viruses
- measles
- influenza
- AIDs (HIV)
- herpes
- chicken pox
What are pathogenic prions
- smallest type of pathogen
- Abnormal type of protein that can cause disease in mammals
- contains no genetic material
Which body systems are mostly affected by pathogenic prions?
The nervous system, including the brain, nerves, and spinal cord.
How do pathogenic prions cause disease?
When an abnormal prion comes into contact with a normal prion, it can trigger it to fold abnormally and clump in the brain
What happens to brain tissue affected by pathogenic prions?
Brain tissue becomes filled with holes, giving it a sponge-like appearance.
How are diseases caused by pathogenic prions referred to?
They are called transmissible spongiform encephalopathies.
Where are normal prions found in organisms?
Brain and spinal cord
Examples of diseases caused by prions
- mad cow disease
- CJD
What are some ways in which pathogenic prions can be transmitted?
- Ingesting tissue containing prions,
- using contaminated surgical equipment
- inheriting a mutated gene for infected prions
- receiving contaminated growth hormone injections
- infected corneal implants from donors.
