Parasitology Test 3 Flashcards
Describe Phylum Platyhelminthes
- all members are bilaterally symmetrical
- triploblastic
- have an incomplete or no gut
- acoelomate
- cephalized
What does it mean to be acoelomate?
Space between bodywall and internal organs is filled with connective tissue and muscle fibers called parenchyma
What are 4 diagnostic features of trematodes?
- presence of ecto and endoparasite forms, with incomplete gut
- have complex heteroxenous life cycles involving at least one intermediate host, a gastropod (snail)
- body wall covered with thick cuticle
- Has 2 suckers usually one by mouth and ventral surface
___is the outermost covering of the trematode’s body, it is a tough, resistant structure
Tegument
What does syncytial mean?
multinucleated, without cell boundaries between nuclei; used to describe the tegument of trematodes
Function of glycocalyx?
- attachment to host
- protection from antibodies and digestive enzymes
- uptake and storage of vital molecules from the enviornment
_____is the region of the trematode that contains nuclei, cell organells like the ER, golgi body, mitochondria, and is responsible for the teguments maintenance
Proximal cytoplasm
What are the functions of the Tegument?
- protection
- nutrient absorption
- synthesis and secretion of various nutrients
- excretion and osmoregulation
- sensory role
Name the 2 suckers of a Trematode
- anterior oral sucker surrounding the mouth
- Acetabulum on ventral surface
Trematodes are___one individual holds both the male and female reproductive organs
Monoecious/hermaphroditic
The male organs of a trematode tend to mature first and produce sperm that are stored until needed, this is called___
protandry or androgyny
In a few trematode species, the ovary matures first, this is called___
protogyny or gyandry
What is the pathway of sperm in sperm in trematoes reproductive system?
Testis (paired except Schistosoma) -> Vas efferens -> Vas deferens -> Cirrus sac (with seminal vesicle and prostate gland) -> cirrus (male copulatory organ)
The muscular distal portion of the uterus of a trematode is called___
Metraterm, helps propel the eggs out of the uterus. Also serves in copulation
Trematode eggs typically have on one end, a lid like structure called the___ which aids the miracidium to hatch
Operculum or cap
___is a common parasite of sheep and cattle kept on damp pastures worldwide, but it is occasionally found in humans, it is the best studied trematode because of its large size (30x13mm)
Fasciola
What are the 8 genera of visceral flukes?
- Fasciola
- Clonorchis
- Opisthorchic
- Fasciolopsis
- Heterophyes
- Metagonimus
- Echinostoma
- Paragonimus
What 3 visceral flukes are found in the liver?
- Fasciola
- Clonorchis
- Opisthorchis
What 4 visceral flukes live within the small intestine?
- Fasciolopsis
- Heterophyes
- Metagonimus
- Echinostoma
What visceral fluke is found in the lungs?
Paragonimus
Where do adult fasciola reside?
Gall Bladder and Bile ducts in liver
What are 7 major characteristics of Fasciola hepatica?
- leaf shaped
- cone shaped projection at anterior end called CEPHALIC cone
- Oral sucker located at end of cephalic cone
- Oral and ventral suckers are almost of equal size
- Short, convoluted uterus is situated anteriorly
- Viteline follicles extensive, fills most of body posteriorly
- highly branched testes and cecum
What are the 8 general steps in lifecycle of Fasciola hepatic?
- Unembryonated eggs passed into feces
- Embryonated eggs go into water
- Miracidium hatch, penetrate snail
- Within snail, miracidium metamorphoses into sporocyst -> rediae -> cercariae
- Free swimming cercariae encyst on water plants
- Metacercariae on water plants are ingested by humans, sheep, or cattle
- Encyst in duodenum
- Adults reside in hepatic biliary ducts
What are symptoms of Fascioliasis in humans?
- head/back ache
- nausea
- vomiting
- fever
- abdominal pain (resulting from destruction of liver tissue and internal hemorrhage)
- Adult flues may block the bile duct causing obstructive jaundice
What is the treatment for Fasciola hepatica?
-Administration orally of bithionol & praziquantel for 2 wks
What is control and prevention measurements of Fasciola hepatica
- Sheep and cattle feces should not be allowed near aquatic regions
- Monitor snail populationn
What is Clonorchis sinensis also known as?
-Chinese/oriental liver fluke (Japan, China, Korea, Vietnam) infects 20 million
What are the reservoir host of Clonorchis sinensis in Far East?
- cats
- dog
- tigers
- foxes
- mink
What is the 1st and 2nd intermediate host of Clonorchis sinensis?
1st intermediate host: snail
2nd intermediate host: freshwater fishes
What is the lifecycle of Clonorchis sinensis?
- Emrbyonated eggs passed in feces
- Eggs are ingested by snail become Miracidia->sporocysts->rediae-> cercariae
- Free swimming cercariae encyst in the skin or flesh of fresh water fish
- Metacercariae in flesh or skin of fresh water are ingested by human host
- Excyst in duodenum
- Adults in biliary ducts
What is the definitive host of Clonorchis sinensis?
Humans and other vertebrates
How do humans become infected by Clonorchis sinensis?
Eating undercooked contaminated fish (including steamed or smoked fish)
What are symptoms of infection by Clonorchis sinensis?
- erodes bile duct, amount of damage is linked to density of worms in bile duct.
- If repetitive infection occurs, can lead to cancer of bile ducts
What is the treatment for Clonorchis sinensis?
Praziquantel taken 2 days orally
What are preventative and control measures of Clonorchis sinensis?
- Treatment of feces before using as a fertilizer
- Complete protection is achieved by cooking fish
____is the largest trematode
Fasciolopsis buski
What are 4 differences between Fasciolopsis buski and Fasciola hepatica?
In F. buski: (1) the caeca lack side branches
(2) the ventral sucker is much larger than the oral sucker
(3) no cephalic cone
(4) adults live in the small intestine and not in the liver
How do humans become infected with Fasciolopsis buski?
Infection is acquired by ingestion of metacercaria encysted on fresh-water plants (bamboo shoots, water chestnuts) which are eaten raw
What is the life cycle of Fasciolopsis buski? 8 steps
- Unembryonated eggs passed in feces
- Embryonated eggs in water
- Miracidia hatch, penetrate snail (sporocysts->Rediae->Cercariae)
- Free-swimming cercariae
- Metacercariae on plants ingested by humans and pigs causing infection
- Excyst in duodenum
- Adults in small intestine
What are symptoms of infection by Fasciolopsis buski?
- infection is light and asymptomatic.
- With many worms, there is nausea, diarrhea and severe intestinal pains
- Worms cause damage to the mucosa via inflammation, ulceration, and abscesses at the site of attachment with their large ventral sucker
What are prevention and control measurements for Fasciolopsis buski?
- Wash vegetables and carefully peel them, boil them
- Treat human feces before using it as fertilizer in ponds
- keep the pig poop away from ponds
- Dont feed pigs freshwater plants before they dry
What are morphological characteristics of Echinostoma revolutum?
-circumoral collar of peg-like spines
Fun Fact: size, number, and arrangement of these collar spines serve as important taxonomic tools for identification
What is the most common Trematode of warm-blooded vertebrates?
Echinostoma revolutum
What is the 2nd intermediate host of Echinostoma revolutum?
any bird or mammal that eats snails
What are 5 differences between Trematodes and Cestodes?
- Cestodes have a flat tape-like or ribbon like body
- Cestodes body is made up of hermaphroditic segments called PROGLOTTIDS, the whole chain is called a strobila
- They lack mouth and digestivee tract
- They are exclusively endoparisitic in vertebrates gut
- Their larvae infect both vertebrates and invertebrates
Cestodes with many proglottids are called ___
polyzoic (true tapeworms)
Cestodes with 1 set of reproductive organs are called
Monozoic (rare)
Cestodes consist of 3 body regions ___,___,and___
Scolex, Neck, and Strobila
___and____are the two types of suckers present on scolices of human tapeworms
Acetabulate and Bothraite
Describe acetabulate types of suckers of tapeworms
- cup shaped
- 4 muscular suction cups sunk into the equatorial surface of the scolex
- hooks that help anchor to host gut wall called ARMED
_____is the small rounded projection bearing hooks on apex of scolex of tapeworm
Rostellum
Describe bothraite type of suckers on scolex of tapeworm
- characterized by presence of 2 (rarely 4 to 6) longitudinally arranged shallow grooves
- weak suction power called bothria
On the tapeworm, from what zone are new segments or PROGLOTTIDS differentiated?
-Neck
____constitute a chain of proglottids and is unique among metazoans
Strobila
Strobila are grouped into 3 regions based on progessive maturity of proglottids reproductive system
- immature
- mature
- gravid
Gravid proglottids are filled with____
eggs or shelled embryos
When gravvid proglottids reach end of strobila they either:
- Detach and pass out of host intact with feces known as___
- Disintegrate in route, releasing the eggs and again discharged to exterior in feces, known as____
This process is known as ___
- Apolytic
- Anapolytic
Process known as apolysis
Being that Cestodes (tapeworms) lack any digestive tract, how do they absorb nutrients?
-Through external covering (tegument)
-
The tegument of cestodes is covered by minute projections called___project outward
microtriches
What is the function of microthrix of tapeworms?
- Agitate wall of intestine, increase accesibility to nutrients
- Apical tip helps provide resistance to peristaltic movement of intestine
Tegument of Cestodes has 2 cytoplasmic regions___and___
Distal and proximal
What are functions of distal cytoplasm of cestodes?
- contain abundant vesicles and electron dense bodies
- numerous mitochondria
What are functions of proximal cytoplasm of cestodes?
-contain all the major cell organelles
Egg morphology is important for identifying cestode species. The embryonic membranes serve as protective coverings of the embryo, which is called an ________
oncosphere
_____are morphologically & developmentally similar to trematode eggs.
Pseudophyllidean eggs
-They have a thick, quinone-tanned shell, with a lid-like operculum
Numerous vitelline cells provide nourishment for the zygote.
Zygote develops into an oncosphere- it’s covered by a ciliated embryophore that helps in swimming upon hatching.
This phase is referred to as coracidium.
What is an example of a tapeworm that has pseudophyllidean eggs?
Diphyllobothrium latum
____eggs have a thin shell and a nonciliated embryophore, but a thick outer envelope
Very few vitelline cells are associated with the zygote
Dipylidium eggs
What are examples of cestode genera that have dipylidium eggs?
Dipylidium and Hymenolepis
_____eggs have no shell or outer envelope and have very little vitelline cells
-The thick, nonciliated embryophore makes up the outermost covering.
Taeniidae
What two cestode genera have Taeniidae eggs?
Echinococcus and Taenia
