Infectious Diseases Flashcards
What are pathogens and examples
Theres six of them
A disease causing agent
1. prions
2. bacteria
3. protists
4. virus
5. parasites
6. fungi
What is the host
The infected organism
What are features of non-infectious diseases?
They are not caused by pathogens and not communicable. They can be caused by factors from the environment and genetic diseases (mutations).
What are features of infectious diseases?
Caused by pathogens and individuals vary in susceptibility to the pathogen. Depends on factors like age, state of health.
Symptoms in infectious diseases
Symptoms are affects of pathogen on host. Usually they don’t appear immediately but there is an incubation period. Pathogens may need time to reach target tissues or need to reproduce to cause disease
Define viruses
Non-cellular agent composed of a protein coat and nucleic acid (RNA or DNA) Infect organisms by injecting nucleic acid into host cell. Multiple copies of the viral protein coat and nucleic acid are made and assemble into new viruses. Each virus is specific to host cells - only recognises binds to specific receptors
Viruses rely on host cells for reprod. Cannot grow outside livecells
Cold/Wet conditions may lower resistence to the virus
Define protists
Unicellular eukaryotic organisms that reproduce a/sexually. In malaria, there is reproduction/infection of the red blood cells
Malaria and dysentary caused by protists by transmitting to host by mosquitos and pathogenic protists transmitted in contaminated water
Define bacteria
Some species have an outer protective capsule + whiplike flagellum for movement. They have endospores which help them withstand unfavourable condtions and helps dispersal to new hosts. Some reproduce by binary fission (spilt into two) and are asexual so they can reprod fast
Very small with a cell wall outside cell mem.
Define fungi
They secrete enzymes into host, digest externally and absorb nutrients through cell wall. The prod. and release of large quantities of fungi spores transmit fungal pathogens to new hosts
Eukaryotes that reproduce by spores
Like bacteria not all fungi cause disease. Commonly fungi irritates skins e.g. rash, itchy skin
Define parasites
Organismas that love on the host for all/part of its life causing harm and gaining nutrition from host. Intermediate hosts are organisms in which parasites undergo small portion of the lifecycle - do not reach sexual maturity. Commonly in pigs, fish or cattle and humans can get infected by eating the improperly cooked meat. Humans are definitive hosts because the adult phase of parasites produce gametes
E.g. Endoparasites tapeworms consume nutrients and reproduce and release eggs into the faeces and live on the inside of host . Ectoparasites are parasites that live on the surface
Define Prions
Small infectious proteins causing degeneration of nervous system then death. They do not have genetic info and are smaller than viruses. They are very resistant to high temps and is transmitted by entering the body in infected food, most commonly brain tissue from infected animals
Affects humans and mammals (cattle,cats,sheep)
Prion proteins normally exist in the body with important roles in memory, learning and passing signals from cell to cell.
What are adherence factors?
Adhesins which help bacteria bind to surface of host cell.
What are invasion factors?
And the factors too
Define Virulence
The measure of pathogenicity of an organism (the intensity of the patho. effect)
Virulence factors are characteristics that help establishment/maintenence of disease. e.g. ability to stick, invade, produce toxins or avoid immune system
What are capsules?
