Trematodes And Schistosomes Flashcards
1
Q
Trematodes
A
- members of platyhelminthes
- flat, fleshy, leaf shaped worms
- have two muscular suckers
- have partial alimentary tracts,
-are hermaprodites except for schistosomes.
(they have cylindric bodies and separate male and female worms exist. Shistosomes also don’t have an operculum).
- Flukes require mollusks (snails and clams) as the first intermediate host.
- Flukes have an an operculum.
2
Q
Fasciolopsis buski
A
Trematode
(giant intestinal fluke)
- largest, most prevalent, and most important intestinal fluke.
- Humans ingest vegetatin contaminated with the metacercaria (encysted larva) which develop into immature flukes in the duodenum.
- The adult fluke attaches to the mucosa of the small intestine and undergoes self-fertilization, 3 months later eggs are passed and free swimming larva (miracidium) emerges and infects snails.
- Pigs, dogs, and rabbits serve as reservoir hosts.
- Inflammation, ulceration, and hemorrhage.
- Severe infections feels like a duodenal ulcer, as well as diarrhea.
- Stools may be profuse, a malabsorption syndrome similar to giardiasis is common, and intestinal obstruction can occur.
- Eggs look like Large, golden, bile-stained eggs with an operculum on the top.
3
Q
Fasciola hepatica
A
Trematode
(sheep liver fluke)
- A parasite of herbivores (particularly sheep and cattle)
- migrate through the liver parenchyma, and enter the bile ducts to become adult worms.
- Approximately 3 to 4 months after the initial infection, the adult flukes start producing operculated eggs.
- Sheep to Snailss.
- snail as an intermediate host.
- consumption of contaminated watercress.
- tenderness, and hepatomegaly.
- Pain in the right upper quadrant, chills, fever.
- in the bile ducts cause mechanical irritation and toxic secretions leading to hepatitis, hyperplasia of the epithelium, and biliary obstruction.
- Can cause liver rot.
- eggs indistinguishable from the eggs of F. buski.
- Eggs in bile are diagnostic..
4
Q
Clonorchis sinensis
A
Trematode
(Chinese liver fluke)
-two intermediate hosts.
-snail and fish
- the eggs are eaten by the snail, where reproduction begins, fresh water fish then take up the cyst where it develop into infective metacercariae
- flukes develop first in the duodenum and then migrate to the bile ducts, in which they become adults.
- Can survive for 50 years.
- Eggs pass in feces.
- Common infections seen among Asian refugees.
- chronic infection can result in adenocarcinoma of the bile ducts..
- gallbladder may produce cholecystitis, cholelithiasis.
- Liver dysfunction.
- Repeat stool necessary.
5
Q
Paragonimus westermani
A
Trematode
(Lung fluke)
- infective stage occurs in a second intermediate host: the muscles and gills of freshwater crabs and crayfish.
- Humans ingest infected meat, larva ultimately ending up in the pleural cavity.
- Eggs appear in sputum, or in feces.
- consumption of uncooked freshwater crabs and crayfish.
- Fever, chills, inflammatory reaction in the lungs, sputum, severe chest pain, RUSTY SPUTUM, Dyspnea, chronic bronchitis,
- Fibrosis in the lung tissue
- can make it to the spinal cord.
- Sputum and feces reveals golden brown, operculated eggs.
- radiographs often show infiltrates, cysts, and pleural effusion.
6
Q
What is the most prevalent intestinal fluke
A
F. Buski
7
Q
Schistosomes
A
-Cause schistosomiasis, also known as bilharziasis or snail fever.
- Male/female.
- No operculum,
- Obligate intravascular parasite (not found in cavities, ducts, and other tissues)
- Skin penetrating free-swimming cercariae (not ingested).
- coat themselves with substances that the host recognizes as itself.
- develop in the portal vein.
- eggs elicit an intense inflammatory.
- the larvae inside the eggs produce enzymes that aid in tissue destruction.
- earliest signs and symptoms are caused by the penetration of the cercariae through the skin.
- Immediate and delayed hypersensitivity to parasite antigens result in an intensely pruritic papular skin rash.
- Katayama syndrome.
- fever, chills, cough, urticaria, arthralgias, lymphadenopathy, splenomegaly, and abdominal pain.
8
Q
S. Mansoni
A
Schistosome
- most widespread
- resides in the small branches of the inferior mesenteric vein near the lower colon
- eggs of S. mansoni are oval, possess a sharp lateral spine
- primates, marsupials, and rodents.
- disease of economic progress;.
- Needs a suitable snail host.
- Itch>rash> cough>hepatitis.
- Can be chronic or fatal.
- Chronic: hepatosplenomegaly, ascites, white pseudotubercles on liver.
- fatal schistosomiasis, fibrous tissue, reacting to the eggs in the liver, surrounds the portal vein in a thick, grossly visible layer (“clay pipestem fibrosis”)
- Anthelmintic therapy does not affect lesions caused by eggs already deposited in tissue.
9
Q
S. Japonicum
A
Schistosome
(oriental blood fluke)
- resides in branches of the superior mesenteric vein around the small intestine and in the inferior mesenteric vessels
- eggs are smaller, are almost spheric, and possess a tiny spine.
- are carried to more sites in the body (liver, lungs, brain).
- frequently involves cerebral structures. lethargy, speech impairment, visual defects, and seizures.
- Needs a suitable snail host.
- Found in stool.
- At risk occupation: workers in rice paddies/ irrigation projects.
10
Q
S. Haematobium
A
Schistosome
- develops in the liver and migrates to the vesical, prostatic, and uterine plexuses of the venous circulation,.
- Large eggs with a sharp terminal spine.
- in the uterine and prostatic tissues.
- can break free and are found in urine.
- Reservoir hosts include monkeys, baboons, and chimpanzees.
- Leading cause of cancer of the bladder in Egypt.
- hematuria, dysuria, and urinary frequency.
- Attacks bladder and lungs. dyspnea, cough, and hemoptysis.
- large, terminally spined eggs.
11
Q
Cercarial dermatitis
A
Schistosome
(“swimmer’s itch”).
- cannot develop into adult worms.
- hosts are birds and other shore-feeding animals from freshwater lakes.
- intense pruritus and urticaria.
- lead to secondary bacterial infection from scratching.
