Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
33 Cards in this Set
- Front
- Back
|
Into what two categories can all species in the phylum platyhelminthes (flatworms) be placed? |
Cestodes (Tapeworm) Trematodes (Fluke) |
|
|
Briefly describe the life cycle of Fasciola hepatica. |
Eggs passed out in faeces Embryo in egg (miracidium), which has cilia for swimming, eventually hatches Reproduces asexually in intermediate host - the snail Released as cercaria (tail to swim in water) Immature fluke in grass waits to be eaten by sheep - the definitive host Matures in bile ducts and produces eggs |
|
|
What is the pre patent period? |
Time before infection is established |
|
|
How long is the prepatent period of Fasciola hepatica? |
12 weeks |
|
|
What damage occurs during the acute phase of Fasciola hepatica? |
Damage to liver during migration |
|
|
What damage is seen during the chronic phase of Fasciola hepatica infection? |
Blood loss from feeding in bile ducts Calcification of bile ducts |
|
|
In what ways may a fluke avoid attack by the immune system? |
Immune evasion Immune modulation |
|
|
What are the disadvantages of treating sheep and cattle for fluke by regular worming? |
Repeated treatment required Costly Drug residue in meat and milk Effects environment Parasite resistance may occur Not always effective |
|
|
What is the name of the species that acts as an intermediate host for Fasciola hepatica? |
Galba (Lymnaea) truncatula - mud snail |
|
|
What conditions are optimal for Fasciola hepatica growth? What implications does this have for growth of this fluke?
|
15-22 degrees celsius in damp conditions Favours warm, humid conditions - seasons and location are an important factor in growth |
|
|
At what temperature does Faciola hepatica growth stop? |
Below 5 degrees celsius |
|
|
How does infection of snails most likely occur in the summer? |
Eggs hatched in early spring summer infect, may be from overwintered eggs on pasture or eggs excreted by infected animals |
|
|
What is the result of a large number of snails being infected by Fasciola hepatica in the summer? |
Metacercariae will be on pasture in autumn which is ingested late in grazing season, causing acute disease and then chronic disease through winter. |
|
|
How can a large number of snails be infected in winter, and does this occur at a high or low level? |
From eggs hatched in autumn before hibernation in winter, leading to metacercariae on pasture in spring. Occurs at a low level. |
|
|
Why are more infections occurring in summer now than before? |
More snails infected in colder months due to milder winters. |
|
|
What causes Bilharzia and what is an effect of this? |
Schistosoma - causes "swimmer's itch". |
|
|
What is the latin name for a lancet fluke? |
Dicrocoelium dendriticum |
|
|
What does the lancet fluke do to its intermediate host, the ant? |
Invades CNS, making it wait on a blade of grass to be eaten by definitive host. Even gets the ant to nest when temperature drop before return the next day. |
|
|
What are the hooks and suckers called on the cestode? |
Scolex and neck (suckers on neck) |
|
|
What are the segments of a cestode called, and what do these combine to form? |
Proglottid, forms strobila. |
|
|
What is found in a segment of a cestode? |
Male and female reproductive parts |
|
|
Generally speaking, what is the life cycle of a estode? |
Mature in definitive host gut, absorb nutrients causing little harm Immature in intermediate host, can cause very harmful cysts |
|
|
What species of tapeworm is associated with carnivores? |
Taenia |
|
|
What are the latin names for the beef tapeworm? |
Taenia saginata / Cysticercus bovis |
|
|
What is the life cycle of taenia saginata? |
Definitive host is human, secreted eggs in sewage eaten by cows, the intermediate host, which are then eaten again by humans. |
|
|
State the life cycle of Taenia solium. |
Definitive host is human, intermediate host is the pig - called Cysticercus cellulosae Can also use human as intermediate host - called Neurocysticercosis |
|
|
What is the life cycle of Taenia avis? |
Definitive host dog Intermediate host sheep (causes sheep measles) |
|
|
What is the life cycle of Echinococcus granulosus and where does it impact the intermediate host? |
Definitive host carnivore - little effect Intermediate host most mammals, including humans - causes cysts in liver and lungs |
|
|
What cysts do Echnococcus granulosus cause? |
Large cysts called hydatid cysts containing endogenous "daughter" cysts and exogenous cysts |
|
|
What are the effects of hydatid disease in humans? |
Destruction of liver and lungs (and possibly places like CNS) |
|
|
What is the life cycle of Echinococcus multilocularis? |
Definitive hosts - Fox, dog (cats) Intermediate hosts - Rodents, humans (sometimes primates) |
|
|
What is the latin name for dog tapeworm, and what is its life cycle? |
Dipylidium caninum Definitive host - dog Intermediate host - Fleas |
|
|
What is the life cycle of Anoplocephala? |
Definitive host - Horse Intermediate host - orbatid mite on pasture (cystercercoid here) |
