91 Questions
What distinguishes Schistosomes from other trematodes?
Their intestinal caeca reunite after bifurcation
How do Schistosomes infect their definitive hosts?
By penetrating the unbroken skin
Which species of Schistosome affects the urogenital system?
S.haematobium
What is the intermediate host for S.mansoni?
Biomphalaria
Which species of Schistosome affects the intestinal system?
S.japonicum
How do Schistosomes infect their intermediate hosts?
Through ingestion of contaminated water
What is the main method of transmission for Schistosoma spp.?
Contact with contaminated water
What is the infective form of Schistosoma spp. that encounters the skin?
Cercariae
What is the prepatent period for Schistosoma haematobium?
10-12 weeks
What clinical symptom is associated with egg deposition and extrusion by Schistosoma haematobium?
Painless hematuria
Which organ can be affected by tissue proliferation and repair due to Schistosoma mansoni infection?
Lungs
What is the most practical method for the diagnosis of Schistosomiasis?
Microscopic identification of eggs in stool or urine
Which species of Schistosoma may lead to obstructive uropathy due to tissue proliferation in the bladder and lower ureter?
Schistosoma haematobium
What is the characteristic clinical manifestation associated with egg deposition and extrusion by Schistosoma mansoni?
Dysentery
When should stool examination be performed for the suspected infection of S. mansoni or S. japonicum?
When infection with S. mansoni or S. japonicum is suspected
What type of biopsy may demonstrate eggs when stool or urine examinations are negative for Schistosomiasis?
Rectal biopsy
Which immunological serological test can be used for the diagnosis of Schistosoma spp.?
Antibody detection test
What is the main clinical feature of S. haematobium infection?
Painless terminal hematuria
During the migratory phase of S. haematobium infection, what symptoms might a person experience?
Rashes and itchy skin
Which organ can be affected by tissue proliferation and repair due to S. mansoni infection?
Lungs
What is the characteristic of eggs laid by female S. haematobium?
They are passed in the urine
What is the effect of the release of toxic metabolites by schistosomulae during the growth stage of S. haematobium infection?
General anaphylactic reaction
Which type of schistosomiasis primarily involves vesical, prostatic, and uterine venous plexus?
S. haematobium infection
Which species of snails are implicated as intermediate hosts for S. haematobium in India?
Ferrissia tenuis
What is a common complication associated with chronic S. mansoni infection?
Cor pulmonale and endarteritis
What is the habitat of Oncomelania species, the snail intermediate host for Schistosoma japonicum?
Rice fields
How is hepatic cirrhosis caused by Schistosoma japonicum different from true cirrhosis?
It results from fibrosed granulomas
What is the main method of transmission for Schistosoma japonicum?
Skin contact with contaminated water
Which immunological test is used to demonstrate antibodies in serum for Schistosoma japonicum?
Falcon assay screening test (FAST/ELISA)
How can infection with Schistosoma japonicum be prevented near lakes, ponds, and rice fields?
Avoiding excretion near these areas
Which organ exhibits clay pipe stem cirrhosis due to Schistosoma japonicum infection?
Liver
What is the infective form of Schistosoma spp. that encounters the skin?
Cercariae
How are Schistosoma japonicum eggs demonstrated in stool examinations?
Kato Katz Smear technique
What distinguishes hepatic fibrosis caused by S.mansoni from that caused by S.japonicum?
Increased egg load in S.japonicum fibrosis
How is the diagnosis of schistosomiasis typically confirmed?
By finding ova in feces
What is a common consequence of liver involvement in schistosomiasis?
Portal hypertension
Which species of Schistosoma causes Oriental schistosomiasis?
S. japonicum
What is a potential consequence of urinary system involvement in schistosomiasis?
Obstructive uropathy
What are the primary organs affected by S. japonicum infection?
Liver and brain
What can lead to pipe-stem fibrosis in schistosomiasis?
Vascular occlusion by ova
What is the potential consequence of brain involvement in schistosomiasis?
Seizures
Which drug is specifically mentioned as a treatment for Schistosomiasis in the text?
Albendazole
What is the main clinical feature of urinary schistosomiasis caused by S. haematobium?
Dysuria and frequency of micturition
What is the characteristic manifestation of cercarial dermatitis caused by Schistosoma species?
Papules, macules, and vesicles on the skin
What is the common name for swimmer's itch caused by penetration of the skin by cercariae?
Cercarial dermatitis
What is the characteristic pathological response to damage by eggs in tissue due to Schistosomiasis?
Hoeppli reaction
What are the initial toxic and allergic symptoms associated with urinary schistosomiasis caused by S.haematobium?
Not marked, but bladder and ureter involvement
What is the typical clinical manifestation of intestinal schistosomiasis caused by S.mansoni?
Papules, papillomata, ulceration
What is the primary difference between protozoa and helminths?
Protozoa consist of a true membrane-bound nucleus and cytoplasm, while helminths have no definite nucleus
Which type of parasite causes rupture of red blood cells, leading to a specific disease?
Plasmodium
What is the primary mechanism of disease production by parasites through mechanical injury?
Rupture of red blood cells
Which type of worms lead to iron deficiency anemia due to their blood-sucking activities?
Round worms (Nematoda)
Which class of parasites has larval stages parasitizing one or more species different from hosts of adults?
Trematoda
What is the primary method of disease production by parasites through the introduction of pathogenic microorganisms?
Urinary carrier rate of Salmonella typhi linked to urinary schistosomiasis caused by Schistosoma haematobium
Which parasite results in the deprivation of nutrients, fluids, and metabolites by competing with the host for food?
Competing for other micronutrients causing Protein energy malnutrition as in Ascaris, Strongyloides etc.
What are the larval stages of trematodes that have an enormous impact on human populations?
Miracidium, redia, cercaria, and metacercaria
Which organism is responsible for intestinal obstruction?
Ascaris lumbricoides
What is the primary effect of histolytic enzymes released by Entamoeba histolytica?
Lysis of cells
Which parasite leads to the blockage of ducts such as blood vessels or lymphatics?
Strongyloides stercoralis
What is the primary difference between Platyhelminthes and Nematoda?
Platyhelminthes are flat worms while Nematoda are round worms with multi-layered nuclei
What characteristic distinguishes Protozoa from Helminths?
Presence of a nucleus and functional organelles
What distinguishes Parasites of medical importance in terms of their kingdoms?
Eukaryote and unicellular
Which statement best describes the general characteristic of trematodes?
Presence of an incomplete alimentary canal
What is the main characteristic feature of Arthropoda among the listed parasites?
Insects, spiders, mites, ticks etc
What is the distinguishing factor between Protozoa and Helminths in terms of reproduction?
May have a sexual phase of their life cycle in another host
What is a general characteristic feature of Helminths?
Reproductive system highly developed
What distinguishes Arthropoda from other parasites?
Insects, spiders, mites, ticks etc
What is a distinguishing feature of trematodes?
Body covered with integument, also bears spines
What differentiates Protozoa from Arthropoda?
Reproduce quickly and asexually in the host
Which parasites possess flame cells and collecting tubules as part of their excretory system?
Helminths (nematodes, trematodes, cestodes/platyhelminths)
What is a distinguishing characteristic of Acanthocephala or thorny-headed worms?
Body covered with integument and bearing spines
What is the length range of the adult Fasciolopsis buski worm?
5 mm to 7.5 cm
Where are the metacercariae of Fasciolopsis buski found?
On fresh water plants
How many eggs does each adult Fasciolopsis buski worm produce per day?
8000 to 50,000 eggs
What is the most common human intestinal trematode causing infection in humans?
Fasciolopsis buski
Which host serves as the definitive host for Fasciolopsis buski?
Pigs and humans
Where is Fasciolopsis buski found within the human body?
Small intestine
What is the size range of the eggs produced by the adult Fasciolopsis buski worm?
$130-140$ µm to $80-85$ µm
Which snails act as the first intermediate hosts for Fasciolopsis buski?
$Planorbid$ snails of certain genera
What is the infective form of Fasciolopsis buski to humans and pigs?
$Metacercariae$
What was the year when Fasciolopsis buski was first described?
1843
What is the primary source of infection for Clonorchis sinensis?
Raw or partially cooked fish
Which animal is mentioned as a reservoir for Clonorchis sinensis?
Dogs
What is the most frequent complication of Clonorchis sinensis infection of long-standing duration?
Recurrent pyogenic cholangitis
How is the definitive diagnosis of Clonorchis sinensis infection typically made?
Demonstration of eggs in the faeces or duodenal contents
What is the most frequent complication of long-standing clonorchiasis infection?
Cholangiocarcinoma
What is the recommended treatment for clonorchiasis?
Praziquantel
How can clonorchiasis infection be prevented at the community level?
Avoiding consumption of raw fish
Where does the adult Paragonimus westermani worm live in the definitive host?
Close to the bronchioles in the lung
Which specimen is the preferred choice for parasitic diagnosis of Paragonimus westermani infection?
Sputum
What is the infective form of Paragonimus westermani to humans and other definitive hosts?
Metacercaria
Study Notes
Characteristics of Schistosomes
- Schistosomes are distinguished from other trematodes by their unique characteristics.
- They infect their definitive hosts through skin penetration.
Schistosoma spp. Infections
- Schistosoma haematobium affects the urogenital system.
- Schistosoma mansoni affects the intestinal system.
- Schistosoma spp. infect their intermediate hosts through cercarial penetration.
Transmission and Diagnosis
- The main method of transmission for Schistosoma spp. is through skin contact with contaminated water.
- The infective form of Schistosoma spp. that encounters the skin is cercariae.
- The prepatent period for Schistosoma haematobium is 6-8 weeks.
- Clinical symptoms associated with egg deposition and extrusion by Schistosoma haematobium include hematuria and dysuria.
- The liver can be affected by tissue proliferation and repair due to Schistosoma mansoni infection.
- The most practical method for the diagnosis of Schistosomiasis is through stool examination.
- Immunological serological tests, such as ELISA, can be used for the diagnosis of Schistosoma spp.
Clinical Manifestations
- The main clinical feature of S. haematobium infection is hematuria.
- During the migratory phase of S. haematobium infection, symptoms may include fever, cough, and malaise.
- The characteristic clinical manifestation associated with egg deposition and extrusion by S. mansoni is bloody diarrhea.
- The characteristic of eggs laid by female S. haematobium is that they are larger than those of S. mansoni.
- The release of toxic metabolites by schistosomulae during the growth stage of S. haematobium infection can cause an inflammatory response.
Intermediate Hosts and Habitat
- The intermediate host for S. mansoni is Biomphalaria snails.
- Oncomelania species are the snail intermediate hosts for Schistosoma japonicum.
- The habitat of Oncomelania species is in lakes, ponds, and rice fields.
Prevention and Treatment
- Infection with Schistosoma japonicum can be prevented near lakes, ponds, and rice fields by avoiding contact with contaminated water.
- Praziquantel is a specific treatment for Schistosomiasis.
Test your knowledge on the morphology and features that distinguish Schistosoma from other trematodes. Learn about the main species infecting humans and their distinguishing characteristics.
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