Parasitology Flashcards
What is a parasite?
An organism that is dependant on a host of all stages of its life cycle. It benefits off the host, while the host loses out.
Ecto-parasite
A parasite that lives on the outside of the host (e.g. tick, lice)
Endo-parasite
Parasite that lives inside the host - in the body/blood (e.g. tapeworm)
Erratic or Aberrant parasite
Parasite which wanders from its usual site of infection
Free-living parasite
Parasite capable of living in the environment leading a non-parasitic life
Definitive host
Holds the adult, mature stage of the parasite where sexual reproduction takes place
Intermediate host
Harbours some developmental stages of the parasite before transferring it to another host - holds asexual stages
Parenthetic host
Harbours a parasite at a non-developmental stage
Reservoir host
A vertebrae in which a parasite occurs naturally, but doesn’t cause disease in the host - also called a carrier
Protozoa
Structure and reproductive cycle
Unicellular
Cytoplasm consists of outer layer (ectoplasm) that functions in protection, locomotion, excretion and respiration. Inner layer is granular endoplasm.
Asexual reproduction: division of all internal structures, then whole parasite divided
Sexual reproduction: conjugation (temporary union of two individuals) where interchange of nuclear material takes place, then two individuals separate. Gametes unite permanently, resulting in a zygote.
Protozoa life cycle
Trophozoite is the active, feeding, multiplying stage. Some form dormant cysts which can survive harsh conditions (temp, chemicals)
Protozoa that completely lacks organelles
Ciliophoran
What are helminths?
Multicellular worm parasites
Cestodes
Tapeworms
Head with 4 suckers and a double ring of hooks (restellum) for attachment
Absorb nutrients through the body as they don’t have a proper respiratory or digestive system
Nematodes
Roundworms
2mm to 1m long. Females are larger than males.
Trematodes
Flatworms/flukes
2 suckers for food and attachment. Incomplete digestive system.
Where are plasmodium, Leishmania, and Trypansoma found?
Inside erythrocytes, sores inside neutrophils, blood plasma
Malaria
Pathogen, symptoms transmission, prevention, treatment
Pathogen: Plasmodium spp.
Transmission: vector - Anopheles mosquito
Symptoms: fever, headache, nausea, SEVERE ANEMIA
Prevention: hygiene, control of water/food, insect repellant, proper waste disposal
Treatment: chemotherapy or anti-parasites
Malaria life cycle
Mosquito injects sporozoites into human bloodstream which travel to liver and infect liver cells.
Over 1 week, sporozoites divide and produce thousands of merozoites per liver cell.
Merozoites leave the liver and invade RBCs. Some form gametocytes which circulate.
Mosquito bites infected human, ingesting gametocytes, which develop into gametes and then oocytes. These oocytes rupture after a week releasing sporozoites. Process repeats.
