Parasitology Flashcards
Lectures: -Week 3, day 2, lecture 1: Introduction to parasitological infections Week 3, day 2, lecture 2: Malaria as an example of protozoic infections
What is symbiosis?
Close and often long-term interaction between different biological species
Which kinds of symbiosis are there?
- Commensalism
- Mutualism
- Parasitism
What is commensalism?
Relation between two organisms where one organism benefits but the other is unaffected
What is mutualism?
Relation between two organisms in which both organisms benefit from the relationship
What is parasitism?
Relation between two organisms in which one organism (the parasite) benefits at expense of the host
Which two classes of parasites can be identified, based on where on the body they reside?
- Ectoparasites = outside of the body
- Endoparasites = inside of the body
What is the most prevalent group of ectoparasites? Which subdivisions does it have?
Arhtropods = insects + arachnids
Which groups of endoparasites can be identified? (2)
- Parasitic worms = helminths
- Parasitic protozoa = unicellular organisms
In which way do parasites differ from bacteria in a host-microbe point of view?
Parasites are eukaryotic -> immune system has more trouble recognizing them
Which two kinds of helminths are there?
- Nematoda = roundworms
- Platyhelminths = flatworms
Which two kinds of platyhelminths are there?
- Trematodes = flukes
- Cestodes = tapeworms
Roundworms and flatworms are quite far removed (phylogenetically). What does this mean?
We need different drugs to treat them
What is the life cycle of Ascaris lumbricoides? (6)
- Eggs from the faeces of an infected person develop in the environment
- Oral intake of the eggs
- Hatching of the egg in the intestine; larva penetrates the mucosa and travels into the bloodstream
- Larvae leave the bloodstream in the lungs, migrate upwards en get coughed up
- Larvae are once again ingested and maturate in the intestine
- Sexual reproduction in the intestine leads to formation of new eggs
Why are Ascaris lumbricoides eggs found in the faeces not infective?
They need to develop for 1-2 weeks in the environment first to allow the larva to develop
How does the Ascaris lumbricoides egg survive the harsh environment of the stomach?
The egg has a tough shell
What is Fasciola hepatica?
Liver fluke; platyhelmith that lives in the bile ducts
What is the life cycle of Fasciola hepatica? (5)
- Eggs are excreted through the faeces
- Eggs hatch once they come into contact with fresh water -> miracidium releases
- Miracidium infects fresh water snails, where they develop further into cercariae
- Cercariae attach to water plants; these get eten by cattle
- Once ingested, the flukes travel to the bile ducts, where they reproduce sexually and produce eggs
Why do parasites require a large genome?
They often have many stages in their life, encountering different environments and having different needs
What is the most prominent group of tapeworms?
Taenia spp.
What is the head structure of a member of the Taenia spp. called?
Scolex
What is an important characteristic of tapeworms?
They are segmented
What is a direct developmental life cycle?
Parasite only has 1 host species
What is an indirect developmental life cycle?
Parasite has multiple host species within its host cycle
What is the difference between nematodes and platyhelmints when it comes to their sexes?
Nematodes have male and female worms, whereas platyhelminths are hermaphrodites
What are the groups of protozoic endoparasites? (3)
- Apicomplexa
- Flagellates and amoeba
- Ciliates
What are examples of protozoic endoparasites belonging to apicomplexa? (3)
- Plasmodium spp.
- Cryptosporidium
- Toxoplasma
What are examples of protozoic endoparasites belonging to the flagellates and amoeba? (4)
- Entamoeba
- Giardia
- Trypanosoma
- Leishmania
