Types of Hosts and Parasites

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Questions and Answers

What is the infective stage of Schistosoma species?

Cysticercus

Miracidium

Cercariae (correct)

Egg

Which clinical symptom is associated with Schistosoma haematobium infection?

Abdominal pain

Frequent motion

Dyspnea

Terminal haematuria (correct)

Which method is NOT a direct diagnostic method for Schistosoma species?

Bladder biopsy

Rectal biopsy

Egg detection in stool or urine

Eosinophilia test (correct)

What is the treatment of choice for schistosomiasis?

Praziquantel Signup and view all the answers

What is the definitive host of Hymenolepis nana?

Humans Signup and view all the answers

Which of the following is a characteristic of Taenia saginata?

Definitive host is man Signup and view all the answers

What resembles the eggs concerning the size and shape of Schistosoma species?

150x60 µm, oval Signup and view all the answers

What is the size range of Hymenolepis nana eggs?

35-45 µm Signup and view all the answers

Which symptom is commonly associated with the escape of eggs in stool for Schistosoma mansoni?

Dysentery with blood and mucus Signup and view all the answers

Which of the following is NOT a clinical symptom of heavy Hymenolepis nana infection?

Vision loss Signup and view all the answers

How do humans become infected with Schistosoma species?

Penetration of cercariae through skin Signup and view all the answers

What is the treatment of choice for Hymenolepis nana infections?

Praziquantel Signup and view all the answers

What is the primary way humans can accidentally become infected with Hymenolepis nana?

Ingestion of fecally contaminated food or water Signup and view all the answers

Hymenolepis diminuta primarily infects which type of host?

Rats and mice Signup and view all the answers

What shape do Hymenolepis diminuta eggs have?

Oval Signup and view all the answers

What is an important method to prevent the spread of hymenolepiasis?

Handwashing with soap and water Signup and view all the answers

What complication can result from heavy infections of Trichuris in children?

Rectal prolapse Signup and view all the answers

What type of anemia may result from continuous blood loss due to certain infections?

Microcytic hypochromic anemia Signup and view all the answers

Which stage is the infective stage of Ancylostoma duodenale?

Third stage filariform larva Signup and view all the answers

What is the primary mode of infection for Ancylostoma duodenale?

Active skin penetration by filariform larvae Signup and view all the answers

What type of response occurs during the pulmonary stage of Ancylostomiasis?

Verminous pneumonia Signup and view all the answers

What is the size of the eggs from Ancylostoma duodenale?

60 x 40 μm Signup and view all the answers

What should be avoided to prevent Ancylostomiasis infections?

Using human feces as fertilizer Signup and view all the answers

Which treatment is NOT commonly used for Trichuris infections?

Ivermectin Signup and view all the answers

What is the primary infective stage of Echinococcus granulosus?

Egg Signup and view all the answers

Which clinical symptom is NOT associated with Hymenolepiasis diminuta during heavy infection?

Weight gain Signup and view all the answers

What type of layer does a hydatid cyst have on the outer layer?

Laminated non-cellular layer Signup and view all the answers

Which treatment option is used for managing infections caused by Echinococcus granulosus?

Surgical removal of the cyst Signup and view all the answers

What is the size range of hydatid cysts typically found in infected individuals?

1-10 cm Signup and view all the answers

What complications can arise from the spontaneous rupture of hydatid cysts?

Severe allergic reactions Signup and view all the answers

Which of the following is a common diagnostic method for hydatid disease?

Ultrasound Signup and view all the answers

What color are the eggs of Echinococcus granulosus?

Yellowish brown Signup and view all the answers

Which of the following hosts serves as the definitive host for Trichinella spiralis?

Humans, rats, and pigs Signup and view all the answers

What is the infective stage of Trichinella spiralis?

Encysted larvae Signup and view all the answers

What type of symptoms occur during the intestinal phase of trichinosis?

Anorexia, nausea, and diarrhea Signup and view all the answers

Which method is commonly used for the direct laboratory diagnosis of trichinosis?

Muscle biopsy Signup and view all the answers

What is the main clinical picture associated with Enterobius vermicularis infection?

Pruritus ani Signup and view all the answers

How does human acquisition of Enterobius vermicularis typically occur?

Self-inoculation through hand transfer of eggs Signup and view all the answers

What is an effective method for preventing trichinosis infection?

Freezing meat Signup and view all the answers

What shape are the eggs of Enterobius vermicularis?

Elongated ovoid, planoconvex Signup and view all the answers

What is the purpose of the NIH Swab Method in laboratory diagnosis?

To collect specimens from contaminated surfaces Signup and view all the answers

When should swabs for egg detection be taken to ensure accuracy?

In the morning before defecation or bathing Signup and view all the answers

Which treatment is recommended for all household members simultaneously?

Mebendazole Signup and view all the answers

Which of the following is a characteristic of the microfilaria diagnostic stage of Wuchereria bancrofti?

Has a free tail devoid of nuclei Signup and view all the answers

What is the term for the time of day when filarial microfilariae are predominantly found in the blood?

Microfilarial periodicity Signup and view all the answers

What is the main habitat for adult Wuchereria bancrofti?

Lymphatic system Signup and view all the answers

Which method is used to directly visualize adult worms in lymphatic vessels?

Ultrasonography Signup and view all the answers

Which of the following vectors is considered an intermediate host for Wuchereria bancrofti?

Culex species Signup and view all the answers

Study Notes

Types of Hosts

Definitive host: The host that harbors the adult (mature) stage of the parasite.
Intermediate host: The host that harbors the immature larval stage of the parasite.
Reservoir host: An animal that harbors the mature stage of the parasite.
Vector: An arthropod that carries the parasite from one host to another.

Types of Parasites

Ectoparasite: Inhabits the surface of the host's body without penetrating the tissues. Infection is called infestation.
Endoparasite: Lives within the host's body. Infection is called invasion.
Temporary parasite: Visits the host to take a blood meal.
Permanent parasite: Lives on or in the host throughout its life.
Facultative parasite: Lives as a parasite or as a free-living organism.
Obligatory parasite: Cannot survive without a host.
Specific parasite: Affects only one particular host.
Nonspecific parasite: Normally infects an animal host and can also infect humans without completing its life cycle.
Opportunistic parasite: Can cause disease only in immunocompromised individuals, while immunocompetent individuals remain asymptomatic.

Fasciola

Disease: Fascioliasis
Habitat: Bile ducts of the liver and gall bladder.
Definitive host: Herbivores (sheep, cattle, goats).

Egg in Stool (Diagnostic Stage)

Size: 150 x 90 μm
Shape: Ovoid
Shell: Thin, operculated
Color: Bile-stained (yellowish brown)
Content: Embryonic cells (immature)

Encysted Metacercaria (Infective Stage)

Size: 0.25 mm diameter
Shape: Spherical with a thick white cyst wall

Mode of Infection (Fasciola)

Ingesting contaminated vegetation or drinking water with metacercaria.

Clinical Picture (Fasciola)

Acute phase: Prolonged febrile illness, anorexia, and right upper quadrant abdominal pain.
Chronic phase: Biliary obstruction (biliary colic, epigastric pain), jaundice, and anemia.

Laboratory Diagnosis (Fasciola)

Stool examination: Confirming detection of parasitic eggs.
Serological tests: Antibody and antigen detection during the migratory stage and in ectopic infection.
Eosinophilia, Ultrasound, CT, and Molecular diagnosis (nested-PCR for parasitic DNA in human stool and urine samples).

Other Parasites and Information

Heterophyes heterophyes:
- Habitat: Small intestine
- Definitive host: Man and fish-eating animals (dogs, cats).
- Intermediate host: Pirenella conica snail and Boury & Bolty fish.
- Infective stage: Encysted metacercaria
- Diagnostic stage: Egg in stool.
- Size: 30 μm x 15 μm
- Shell: Thick double walled with operculum and posterior knob
- Color: Brownish yellow.
- Content: Miracidium -Mode of infection: Eating raw or undercooked fish that contains the encysted metacercaria.
Schistosomes:
- S. haematobium: Definitive host: Man, Reservoir hosts: Primates, such as rats, Intermediate host: Bulinus (Snail), Habitat: vesicles, prosatic, and uterine plexuses
- S. mansoni: Definitive host: Man, Reservoir hosts: Primates, such as rats, Intermediate host: Biomphalaria (Snail), Habitat: Branches of the inferior mesenteric vein in the lower colon.
- Eggs: Shape: Oval, Size: ranges from 150x60, 140x60 (μm), Shell: Thin (terminal or lateral), Color: Translucent or yellowish brown, Content: Miracidium, Secreted in: Urine or stool
Taenia saginata (Beef tapeworm):
- Habitat: Upper third of the small intestine.
- Definitive host: Man
- Intermediate host: Cattle
- Infective stage: Cysticercus bovis
- Diagnostic stage: Gravid segments (containing eggs).
Taenia solium (Pork tapeworm):
- Habitat: Small intestine
- Definitive host: Man
- Intermediate host: Pigs
- Infective stage: Cysticercus cellulosa
- Diagnostic stage: Eggs, Gravid segments
Hymenolepis nana (Dwarf tapeworm):
- Habitat: Small intestine
- Definitive host: Man
- Intermediate host: Man, fleas, and rats
- Infective stage: Egg and cysticercoid.
- Diagnostic stage: Eggs, Gravid segment
Echinococcus granulosus (Hydatid worm):
- Definitive host: Dogs, foxes, wolves
- Intermediate host: Man, cattle, pigs, sheep
- Infective stage: Eggs
- Diagnostic stage: Hydatid cyst
Ascaris lumbricoides:
- Habitat: Small intestine
- Definitive host: Man
- Intermediate host: None
- Infective stage: Eggs containing second-stage rhabditiform larvae
Trichuris trichiura (Whipworm):
- Habitat: Large intestine (mainly caecum)
- Definitive host: Humans
- Intermediate host: None
- Infective stage: Eggs containing first-stage larvae
Ancylostoma duodenale:
- Habitat: Small intestines (mostly jejunum)
- Definitive host: Man
- Intermediate host: None
- Infective stage: Third-stage filariform larvae
- Diagnostic stage: Immature eggs
Trichinella spiralis:
- Habitat: Small intestine
- Definitive host: Man, rats, and pigs
- Intermediate host: Man/rats/pigs
- Infective stage: Adults, larvae, and muscle encysted larvae
- Diagnostic stage: Adults, larvae, and muscle encysted larvae (sometimes eggs)
Enterobius vermicularis (Pinworm):
- Habitat: Large intestine
- Definitive host: Man
- Intermediate host: None
- Infective stage: Eggs

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Description

Explore the various types of hosts and parasites in this quiz. Understand the differences between definitive, intermediate, reservoir hosts, and learn about ectoparasites, endoparasites, and more. Test your knowledge on how these organisms interact with one another.