9. Parasite strategies Flashcards
How do parasites usually enter our bodies?
- anus to mouth (usually via fingers)
- nose/mouth in the air
- through the skin
- sexual intercourse
- via intermediate host/vector
What are the different ways parasites can enter via intermediate hosts?
- intermediate host is eaten
- carried into the final - scratched in (ie. lice)
- injected into final host
- in the water and then penetrate the skin
What happens if we are the intermediate host?
- usually harmless if cysts are in the meat we ear
- worms colonise our gut
•its bad if we put eggs in our mouth - oncospheres develop in out muscles
Why is dog tapeworm even more dangerous?
- hydatid (big) cysts develop in the liver and other organs
* need surgery and chemotherapy
Why do insects/ticks make excellent vectors for microparasites?
- often highly mobile
- actively search for new hosts
- mouthparts adapted to penetrate the skin barrier
Sleeping sickness vector
Tsetse fly
Malaria vector
Mosquito
Leishmaniasis vector
Sand flies
Chagas’ disease vector
Assassin bug
Bubonic plague vector
Fleas
Typhus vector
lice
What the different strategies that parasites use to survive in our bodies?
- Many copies, genetically variable
- avoid recognition
- present a moving target
- hide from defenders
- attack
How do parasites avoid recognition and give example
• Schistosome (class trematoda) use camouflage
Live in the blood vessels-
• avoid attack by coating themselves with host antigen proteins
• also produce enzymes that destroy or detach complement proteins
Presenting a moving target and examples
- trypanosomes (protists - kinetoplastids)
* can make 1000 different surface antigens
Hide from defenders examples
In gut
• tape worms, hook worms
• low risk as immune system is not strong in the gut
Inside cells
• plasmodium and trichinella spiralis in muscle cells
• it then makes the cell grow and get extra blood supplies
