WEEK 4: PARASITES AND PARASITIC INFECTIONS Flashcards
What is a parasite?
- Organism which lives UPON or WITHIN another living organism (the host) at whose expense the parasite obtains some advantage
What are 2 advantages for a parasite?
Provision of nutrients (essential)
Protection from environment, host immune system etc.
What is one disadvantage for parasites?
Host controls and regulates parasite growth and development (host immune system)
What factors are host-parasite relationships affected by? (3)
- Social and economic
- Environmental
- Travel and human migration/population movement
What are the 6 different types of organisms that parasitic diseases can be caused by?
- Viruses
- Bacteria–> Chlaymdia trachomatis-STD and eye disease
- Fungi/Yeast and Algae –>Candida albicans
- Protozoa –> unicellular
- Helminths
- Arthropods
What are the two different types of parasites?
- Ectoparasite and endoparasite
What is an ectoparasite?
- An organism that lives on the surface of its host e.g. mosquitos tse tse flies as vectors of transmission
What is an endoparasite?
- Parasitic organism that lives within the host
What are the common features of eukaryotic cells?
- Membrane delimited nuclei
- Membrane bound organelles that perform SPECIFIC functions
- Intracytoplasmic membrane complex serves as transport system
MORE STRUCUTRALLY COMPLEX and larger thana bacterial and archaeal cells
What does a fungal yeast cell (eukaryotic) contain that a human eukaryotic cell doesn’t?
- Bud scar and storage vacuole
What does a protoozan cell (eukaryotic) contain that a human eukaryotic cell doesn’t?
- Water vacuole
Are fungi eukaryotes or prokaryotes?
- Eukaryotes
Do fungi contain cell walls?
- Yes
Do fungi have typical eukaryotic organelles?-
- Yes
Do fungi contain unicellular (for yeast) and or multicellular filaments? (If so, what are these known as?_
- YES!
- Known as hyphae or mycelia)
How many cells do the spores produced by fungi in the sexual or a sexual life cycles give rise to?
- Gives rise to MULTIPLE cells (unlike bacteria)
What role to fungi normally play?
- Play role in the decomposition of organic material
Are fungi mostly non pathogenic?A
- Yes , only 300 linked to disease
What is the most common plant pathogen (general)?
- Fungi
What are human mycoses caused by?
- TRUE fungal pathogens and opportunistic pathogens
What is the most common fungi that causes Candidias?
- Candidia albicans
Where does Candidia normally reside?
- The intestinal tract and can be found on mucous membranes and skin
What causes the symptoms of Candidia to devleop?
- Overgrowth of Candidia albicans organisms
What is a vulvovaginal yeast infection?
- Panful infalmmatory condition of the genital region that causes ulceration and whitish discharge
Where does cutaneous candidiasis occur?
- In chronically moist areas of skin and also in burn patients
Is Candida auris contagious?
- YES!
- It is spread from person-person or from fomite contamination
What is the treatment for Candidiasis?
- There is NO SATISFACTORY TREATMENT BUT
- antifungals are used for cutaneous lesions and systemic candidiasis
Are most protists unicellular or multicellular?
- Most are UNICELLULAR
Are protists prokaryotic or eukaryotic?
- Eukaryotic
Are protists polyphyletic?
- YES–> derived from more than one common ancestor
What is the distribution of protists?
- Grow in MOIST habitats
- Free living
- Chemo-organotrophic forms play role in recycling N and P
- Terrestrial and planktonic forms
- Parasitic forms in humans and dogs
Which areas of the body can protists infect?
- ALL major tissues and organs
How do extracellualr protists evade the immune system?
- Evade the recognition of their plasma membrane
- e.g. trypanosomes undergo antigenic variation of surface antigens
- Mlaria has polygenic vairation
How do intracellular protists evade the immune system?-
- They ‘hide’ inside a host cell
- e.g. Leishmania evades harmful effects of reactie O2 species in phagolysosome
What are the 4 infection routes?
- Via an intermediate host (Accidental ingestion of larvae in tissue of another host e.g. pork meat)
- Via fecal-oral route (accidental ingestion of larvae or eggs from faeces of infected host)
- Active skin penetration (larval stages invade through skin-hookworm?)
- Injection by blood-sucking insect (Larval stages develop to infectivity in insect intermediate host)
Can there be parasitic infections transmitted from mother to fetus?
- YES
What are most parasitic infections acquired through?
- Contaminated water, food or via insect vectors
Are protozoa single celled eukaryotes?
- YES
What is an example of a protozoa that is an oprotunistic pathogen?
- Cryptosporidium
What are zoonoses and some examples?
- Animal diseases transmissible to humans that can be transferred by DIRECT or INDIRECT methods
- E.g. Parasites–> Cryptosporidium, Giardia, Leishmania, Toxoplamsa, Plasmodium, Taenia solium (pork tapeworm), Rabies
What percentage of pathogens known to infect humans are zoonotic?
- 70%