Protozoa & Helminths Flashcards
What is the difference between parasites and other pathogens?
Define parasitism, commensalism, and mutualism.
- Commensalism; a symbiotic relationship in which one species benefits but the other gains no advantage/disadvantage(e.g. S. aureus on human skin).
- Mutualism; a symbiotic relationship in which both species benefit(e.g. cows and rumen bacteria)
- Parasitism; a symbiotic relationship in which one species (parasite) lives at the expense of the other (host).
Outline and draw the general Protozoa life cycle.
There are 2 keys stage of any protozoan life cycle:
- Trophozoites; these are the active cells that metabolize and multiple via binary vision like bacteria(some might have complex life cycle that include re-production sexually).
- Cysts; if cells are found in an adverse condition/environment they will form cysts which are typically dormant cells with a thick cell wall for protection.
Trophozoites typically inhabit the small intestine but if they get passed to large intestines they form cysts that if excreted can last in the environment for months. If re-ingested by another organism the cells will activate again via excystation.
Describe significant examples of protozoan parasites.
Discuss/explain malaria life cycle in detail with the aid of illustrations.
Outline a types of superficial mycoses and an opportunistic infection.
Superical mcyoses are fungal infections of the hair, skin, nails…
(E.g. Candida albicans[oral thrush] and trichopython[athletes foot])
Opportunistic infections occur after an initial infection or in individuals with a weakened immune system(e.g. Cryptococcus neoformans; spores enter lungs, infect macrophage, spread to CNS)
Differentiate between a direct and indirect life cycle. Give examples of which parasites go through each.
Direct; find a host, multiple (eggs/cysts), pass on to infect other hosts. (E.g. entamoeba histolytica)
Indirect; here 2 different species are required to complete the life cycle. (e.g. Plasmodium usually sexually reproduce in a non-human definitive host, and asexual reproduction occurs in the human intermediate host)
Describe/outline what parasite(s) causes malaria.
Plasmodium falciparum (deadliest)
P. Vivax (most common)
P. Malariae
Etc…
How does p. Fal remodel the hosts cell?
P. fal remodels cells via secreting several types of proteins:
- Parasite GII Chaperonin; other porteins bind with this enabling movment thro cytoplasm
- Erythrocyte membrane protein(create the spikes on the outside); these proteins are used to avoid the spleens immune detection of infected cells, via…(NOTES AND VOD)
Outline malaria treatments and vaccines.
- Quinine; inhibits hemzoin formation(parasite breakdown Hb as a portein source but cant use heme in anyway - iron is ver reactive in the form and is toxic however they avoid this typically by turning it into hamzoin but with this drug this formation is inhibited and thus will be toxic to the cell/parasite) - note that malaria is developing resistance to this for an unknown reason.
- Free heme and hemin poison parasite through oxidative stress.
- Primaquine; kills dormant hypnozoite inside hepatocytes via interference with ETC(ROS)
- Artemisinin; specially for P. fal - mode of action unsure.
Vaccines against malaria include:
- Vaccine was endorsed by WHO in 2021, wasn’t very effective against malaria(86% adults; 50% children).
- Vaccine was recombinant protein-based and produced antibodies against p. fal sporozoites CSP.
Discuss/explain Giardia Intestinalis, in terms of structure/motility, route of infection, life cycle, and disease caused.
Giardia(flagellates)isa tiny parasite (germ) that causes the diarrheal diseasegiardiasis. Giardia is found on surfaces or in soil, food, or water that has been contaminated with feces from infected people or animals. (CAUSES GIARDIASIS)
LIFE CYCLE DRAW
Outline the symptoms, diagnosis and treatments of Giardia intestinalis. Also briefly state any pathologies in human hosts as a result of infection.
- Symptoms; severe diarrhoea, stomach cramps, impairment.
- Diagnosis; the presence of trophozoites in stool. (Cysts are activated from stomach acid and bile, trophozoites emerge and attach to small intestine epithelium)
- Treatments; Metronidazole 250mg 3 times a day for 7 days. (People typically get over this smoothly, except immunocompromised)
Pathology - Some studies have notes that giardia causes death or apoptosis of the gut eoptehlium and serection of electrilytes (water follows causing diarrhoea)
Discuss/explain Entamoeba histolytica, in terms of structure/motility, route of infection, life cycle, and disease caused.
Entamoeba histolytica(pseudopodia) isa protozoan that causes intestinal amebiasis as well as extra-intestinal manifestations. 90% of cases are asymptotic with 10% experiencing diarrhea and abdominal pain.
- Infects via the fecal/oral route, can be a result of poor sanitation or contaminated consumables (cases cluster in developing countries).
DRAW LIFE CYCLE
Outline the symptoms, diagnosis and treatments of E. Histolytica. Also briefly state any pathologies in human hosts as a result of infection.
- Diagnosis may be carried out via microscopic examination of the stool or serology(Enzyme immunoassay to detect antibodies/antigens).
- Treatments include Metronidazole via Intravenous/oral.
Pathology - brain eating?
Discuss/explain nematodes, in terms of structure/motility, route of infection, life cycle, and disease caused, chronic effects, etc…
Nematodes arethread-like roundworms that live in a wide range of environments including soil and fresh and salt water. There are species of nematodes that feed on fungi, bacteria, protozoans, other nematodes, and plants.
- Nematodes rarely cause death, however, infected children primarily suffer from significant physical and mental impairment due to malabsorption.
- Chronic effects include: diarrhoea, abdominal pain, weakness, and impaired development.
