Parasitology: Platyhelminths Flashcards
(110 cards)
1
Q
General Characteristics of Phylum Platyhelmithes
A
- flat mostly
- hermaphrodites (have both sex organs)
- definitive host diagnosis– eggs
- at least 1 intermediate host (diagnosis is difficult)
- tapeworms and flukes
2
Q
Which worms are associated with Class Cestoda?
A
Tapeworms
3
Q
Characteristics of tapeworms
A
- segmented, often long
4
Q
Where should we generally assume Cestodas are
A
in small intestine
5
Q
T/F: tapeworms have an intestine
A
false; they do not, and they absorb nutrients across the surface
6
Q
Tapeworms have at least 1 _____.
A
intermediate host
7
Q
What are the segments of the Adult Tapeworm
A
- the scolex
- the neck
- Proglottids (segments)
8
Q
What is the function of the Scolex?
A
the anterior end, has suckers and/or hooks that allow it to attach to gut wall, though they are capable of moving around
9
Q
What is the importance of the neck in tapeworms?
A
it is the region of cell division, which gives rise to proglottids (segments)
these mature as they move down the chain
10
Q
What are the Proglottids?
A
oldest segments of the tapeworm, located at the posterior end
11
Q
Each segment of a tapeworm has at least _____
A
one set of all reproductive organs of both sexes
12
Q
The segments of tapeworms are classifed as____ or _____
A
immature: fertilization cannot take place, will mature as it moves down the chain
Mature: fertilization can take place here.
13
Q
A Gravid contains what?
A
fully developed eggs
14
Q
What is a gravid?
A
a segment of Tapeworm that is full of eggs. Essentially, the uterus full of eggs. As soon as it comes out of the host, it is fully infective
15
Q
What is the general term for a larval tapeworm?
A
metascestode
16
Q
What is the general life cycle of tapeworms?
A
- Adult tapeworm lays eggs which are passed into environment.
- Infective eggs are eaten by the intermediate host.
- Metacestode/intermediate host eaten by the definitive host
17
Q
What are the definitive and intermediate hosts of the family Taeniidae
A
vertebrates
18
Q
What do the segments of Taeniidae look like?
A
square to rectangular in shape
19
Q
Which stage is most important for disease and/or ecnomic loss?
A
the larval stage
20
Q
Why don’t we see Taeniidae eggs in fecal samples
A
Because the eggs are located in the segments (gravid)
21
Q
For the Family Taeniidae, the definitive host is generally a _____
A
predatory mammal
22
Q
for the family Taeniidae, the intermediate host is generally a____
A
herbivore or carnivore
23
Q
what are the two important larval forms of Taeniidae?
A
- Cystticercus
- Hydatid
24
Q
What is cysticercus composed of?
A
- have fluid-filled bladder
- have an inverted, invaginated scolex
25
1 cysticercus will produce how many adult tapeworms in the definitive host
only 1
26
what is an infection with cysticercus called?
cysticercosis
27
What are some noteworthy taeniid species with canid or felid definitive hosts in the US.
- Taenia pisiformis
- Taenia taeniaeformis
- Taenia hydatigena
- Echinococcus mutilocularis
28
T. taeniaeformis is a common tapeworm of ____
hunting cats
29
What is the intermediate host of T. taeniaeformis? where are the larvae located?
- rodents
| - the liver
30
What is the definitive host of T. pisiformis?
canids
31
What is the intermediate host of T. pisiformis?
rabbits
32
T/F: if a cat eats a rabbit infected with T. pisiformis, it will get a tape worm.
false
33
Clinical signs of tapeworms
- pretty benign, don't cause many issues
| - no diarrhea, no weight loss
34
T/F: fecal floats are good at detecting tapeworm eggs
false
35
How do you diagnose tapeworm infections?
segment or egg detection
36
T/F: tapeworm segments can move away from where they were dropped
true, to a short distance
37
how are tapeworm eggs dispersed from the segment?
segment dissolves or dries out, and the eggs are released
38
What is the definitive host of T. hydatigena
canids
39
What is the intermediate host of T. hydatigena
wild, domestic ruminants, pigs
40
Where are the cysticerci attached to in these intermediate hosts? When would these cause concern
on the peritoneal membranes; at slaughter of food animals
41
Why does Echinococcus have a different species name than other tapeworms?
its a different kind of tapeworm in its larval stage
42
Differentiate between Echinococcus spp. and Taenia spp.
Echinococcus spp. are much tinier than Taenia spp. (3-6 mm in length
- the host will have many small tapeworms rather than a few big ones
43
What is the metacestode stage of Echinococcus spp.
the Hydatid cyst.
44
T/F: Echinococcus spp. are zoonotic
true
45
What is the importance of the hydatid cyst asexual multiplication
multiple scoleces are formed, could potentially form thousands of scoleces
46
What are the two types of hydatid cysts?
- multilocular cysts, which continue to bud off new chambers (seen in E. multilocularis)
- unilocular hydatid cysts, which grows like a balloon as more buds form within it (seen in E. granulosus and others)
47
What is the definitive host of E. multilocularis
- foxes, but sometimes dogs and other canids (and rarely a cat)
48
What are the intermediate hosts of E. multilocularis?
small rodents, humans
49
What is the larval stage of E. multilocularis?
..... multilocular hydatid cyst
50
What is the clinical importance of E. multilocularis?
- ITS ZOONOTIC (hydatidosis)
| - difficult to surgically remove because of invasive growth
51
T/F: Echinococcus multilocularis infection is easy to diagnose in dogs.
false, Hard af
52
What type of hydatid cyst do E. granluosus form?
unilocular hydatid cyst formed in intermediate hosts
53
What is the definitive host of E. granulosus? the intermediate host?
definitive: dogs
Intermediate: sheep
54
Should you expect your sheep guard dog to be infected with E. granulosus?
no, your guard dog shouldn't be eating your sheep
55
Why don't we worry about E. granulosus in US?
we don't allow for the cycle to be completed. we remove the carcasses of sheep who die. The dogs therefore can't eat them
56
What are the intermediate and definitive hosts of Taenia saginata?
definitive: humans
intermediate: bovines
57
What type of T. saginata larvae are present in the intermediate host? where in the host?
- cysticerci
| - the muscles
58
Clinical importance of T. saginata
- causes mild abdominal discomfort
- occurs worldwide (was less of a problem in US, but prevalence likely rising due to immigrants from endemic areas and contaminated cattle feed)
59
How do you diagnose T. saginata?
- slaughter inspection: check masseter, tongue, heart incised, and other muscle examination
60
How do you treat T. saginata?
- none in cattle
| - cysticerci killed by heating to 57 C or freezing to -10 C for 10 days
61
What are the definitive and intermediate hosts of Taenia solium?
Definitive: Humans
Intermediate: porcine
62
What are the concerns regarding T. solium infection in humans?
- humans can also be intermediate hosts for T. solium, The cysticerci can form anywhere in the body
- known as cysticercosis, neurocysticercosis
63
Clinical signs of cystercercosis/neurocysticercosis
- headache, confusion, seizures
| - this is the leading cause of adult onset epilepsy
64
what are the intermediate hosts of Non-taeniid tapeworms
arthropods
65
What is the metacestode stage of non-taeniid tapeworms called?
cysticercoid
66
What does a cysticercoid look like?
a small cyst with an invaginated single scolex, no fluid filled bladder
67
What are the definitive and intermediate hosts of Dipylidium caninum?
- definitive: canids and felids
| - intermediate: fleas
68
Dipylidium caninum lifecycle
- gravid segments released containing egg packets
- flea larvae ingest these egg packets, allowing cysticercoids to develop
- infection of definitive host follows ingestion of flea
69
What is the PPP of D. caninum
2 weeks
70
How do you diagnose D. caninum?
- tapeworm segments in perianal area
71
why can't you see D. caninum eggs in a fecal float
the egg packets aren't usually seen unless the segment has been broken up
72
What is the clinical importance of D. caninum infection?
infections are usually subclinical, may cause scooting
| - can be zoonotic. Children are most likely to be infected, but this is very uncommon
73
What is crucial to breaking the D. caninum cycle?
year-round flea control
74
Anoplocephala perfoliata is the most common and important non taeniid tapeworm for which species?
horses
75
Moniezia spp. infect which host?
ruminants
76
What is the intermediate host of ruminant and equine tapeworms?
pasture mites
77
When are the definitive hosts of equine and ruminant tapeworms infected?
when they inadvertently ingest mites while grazing
78
What is the clinical importance of Anoplocephala perfoliata?
- while usually asymptomatic, this common infection can occasionally cause inflammation and ulceration.
- more severe cases, it can be associated with perforation, intussusception
79
T/F: it is difficult to diagnose Anoplocephala
true
80
T/F: horses are routinely treated at least once per year because Anoplocephala is hard to diagnose
true
81
T/F: Anaplocephala attach at the anterior end of the host GI tract.
false; they attach at the ileocecal junction
82
T/F: Anaplocephala is long, and horses are generally only infected with a few adults
false; they're short and horses can be infected with many at once
83
T/f: Moniezia is a very common infection in ruminants, and is also easy to detect in fecal samples
true
84
What are the shapes of Moniezia spp. eggs in cattle and small ruminants?
- square shaped in cattle
| - more triangular in small ruminants
85
Clinical significance of Moniezia infections?
- while it appears dramatic, it does not appear to have any significant effect on production
86
T/F: avian tapeworms can be pathogenic in large numbers
true
87
where would you expect to find cyclophyllidean tapeworms in birds?
in the small intestine
88
Which worm is associated with class Trematoda
flukes
89
Two orders of flukes
- Digenea (important flukes of domestic animals and humans)
| - Monogenea (important external parasites of fish, reptiles, and invertebrates
90
Physical morphology of Order Digenea
- leaf-shaped
- unsegmented
- 1-2 suckers
91
Where are Digenea eggs passed?
in feces
92
How many intermediate hosts do Digenea flukes have?
- what is always the first intermediate host?
usually two
snails (which species of snail depends on which species of fluke)
93
Lifecycles of Trematode
- adult produces eggs
- egg hatches in water, ciliated larval stage hatches
- larvae swims to specific snail host, though some use land snails that ingest the egg
94
T/F: asexual development of Trematode occurs in the snail
true
95
What is the Trematode stage that emerges out of snails called
Cercaria
96
How do Cercaria reach their hosts?
- in water, they usually swim to it
| - on land, they get ingested by the next host
97
What are larvae called when they are consumed by or attached to the second intermediate host?
metacercaria
98
How does the metacercaria get into the definitive host
ingestion
99
Where do the adults of Fasciola hepatica and Fascioloides magna live in their definitive hosts?
- Fasciola hepatica: liver and bile ducts of ruminants, rabbits, people, dogs, etc.
- Fascioloides magna: white-tailed deeer
100
Where do cercaria of F. hepatica encyst and become metacercaria?
on vegetation or debris. and they they wait to be consumed by the definitive host
101
After ingestion, where do larval flukes migrate?
- larval flukes migrate through intestinal wall to liver
- this migration in the liver may take several weeks
- Then enters bile duct and matures
102
Clinical importance of F. hepatica in cattle
can be a chronic disease, characterized by:
- anemia, hypoproteinemia
- weight loss, decreased milk production
- immunity will gradually develop
103
Why is clinical F. hepatica more severe in small ruminants than cattle?
- acute damage from larval migration can occur
| - Black Disease (Clostridium)
104
What are the geographical US regions of clinical importance in regards to F. hepatica?
- Gulf Coast States
- Pacific northwest
- Hawaii
105
How is F. hepatica diagnosed?
- patient history and clinical signs
| - fecal exam, using the SEDIMENT procedure (not very sensitive)
106
Control of F. hepatica
good management: drain, fence out wet areas to prevent spread of larval stages and snails
107
What geographical regions is Fascioloides magna more important in?
- Midwest and Northeast US
108
T/F: F. If a sheep or goat is infected with a magna larvae, it will continue to move around until the host dies
true
109
What is the 2nd intermediate host and definitive host of Nanophyetus salmincola
- 2nd host: fish
| - DH: dogs
110
What is the importance of N. salmincola
it is a disease vector for a ricettsia organism that causes "salmon poisoning" in dogs
