Parasitology Practice Questions for ASCP
These Parasitology Practice Questions for ASCP cover a wide range of topics, from protozoa and helminths to diagnostic techniques and specimen handling. Each question is carefully crafted to mimic the format of the ASCP exam while offering clear explanations to support your learning. Whether you’re reviewing for the first time or refining your understanding before test day, this resource will help you apply your knowledge with accuracy and confidence. Let’s begin your parasitology review journey now!
Parasitology Practice Questions – Easy (1–30)
1. As you examine a stool sample, which parasite is most likely to present with a four-nucleated cyst?
A. Giardia lamblia
B. Entamoeba histolytica
C. Balantidium coli
D. Cryptosporidium parvum
Answer: B. Entamoeba histolytica
✔️ Explanation: Entamoeba histolytica cysts usually contain up to four nuclei, aiding diagnosis.
2. When a patient presents with foul-smelling, greasy diarrhea, which flagellate is commonly involved?
A. Trichomonas vaginalis
B. Giardia lamblia
C. Dientamoeba fragilis
D. Trypanosoma cruzi
Answer: B. Giardia lamblia
✔️ Explanation: Giardia lamblia causes malabsorptive diarrhea and is commonly transmitted via contaminated water.
3. While viewing motile trophozoites in a vaginal wet mount, which organism is most likely identified?
A. Giardia lamblia
B. Trichomonas vaginalis
C. Blastocystis hominis
D. Naegleria fowleri
Answer: B. Trichomonas vaginalis
✔️ Explanation: Trichomonas vaginalis is visible as a motile trophozoite with jerky movement in vaginal secretions.
4. When collecting stool for O&P (ova and parasite) examination, how many samples are recommended over several days?
A. 1
B. 2
C. 3
D. 4
Answer: C. 3
✔️ Explanation: Three samples collected on separate days increase diagnostic yield for parasites.
5. During the diagnosis of malaria, which stage of Plasmodium is found in red blood cells?
A. Sporozoite
B. Merozoite
C. Trophozoite
D. Oocyst
Answer: C. Trophozoite
✔️ Explanation: The trophozoite ring form is typically seen inside RBCs during malaria diagnosis.
6. If a patient travels to Africa and develops cyclic fever, which parasite should be suspected?
A. Trypanosoma cruzi
B. Entamoeba histolytica
C. Plasmodium falciparum
D. Trichuris trichiura
Answer: C. Plasmodium falciparum
✔️ Explanation: P. falciparum is common in Africa and causes severe malaria with cyclic fever.
7. When stool shows eggs with a prominent operculum, what is the most likely parasite?
A. Ascaris lumbricoides
B. Trichuris trichiura
C. Fasciola hepatica
D. Taenia solium
Answer: C. Fasciola hepatica
✔️ Explanation: Fasciola hepatica eggs are large with an operculum (lid-like structure).
8. As part of its life cycle, which helminth migrates through the lungs before reaching the intestines?
A. Enterobius vermicularis
B. Trichinella spiralis
C. Ascaris lumbricoides
D. Hymenolepis nana
Answer: C. Ascaris lumbricoides
✔️ Explanation: Ascaris larvae migrate via the lungs before maturing in the intestines.
9. When a child presents with perianal itching at night, which test confirms the diagnosis?
A. Direct fecal smear
B. Duodenal aspirate
C. Cellophane tape test
D. Blood smear
Answer: C. Cellophane tape test
✔️ Explanation: The cellophane tape test is best for detecting Enterobius (pinworm) eggs.
10. Which parasite typically causes autoinfection, especially in immunocompromised patients?
A. Strongyloides stercoralis
B. Schistosoma haematobium
C. Trichuris trichiura
D. Taenia saginata
Answer: A. Strongyloides stercoralis
✔️ Explanation: Strongyloides can autoinfect the host, leading to hyperinfection syndrome.
11. As you examine a thick blood smear, which parasite should you suspect if crescent-shaped gametocytes are seen?
A. Plasmodium ovale
B. Plasmodium malariae
C. Plasmodium vivax
D. Plasmodium falciparum
Answer: D. Plasmodium falciparum
✔️ Explanation: P. falciparum has distinctive crescent-shaped gametocytes.
12. When a parasite has both a scolex and proglottids, what general class does it belong to?
A. Nematodes
B. Cestodes
C. Trematodes
D. Protozoa
Answer: B. Cestodes
✔️ Explanation: Cestodes (tapeworms) have a scolex (head) and body segments (proglottids).
13. If a stool sample reveals a football-shaped egg with bipolar plugs, what is the likely parasite?
A. Ascaris lumbricoides
B. Trichuris trichiura
C. Hookworm
D. Strongyloides
Answer: B. Trichuris trichiura
✔️ Explanation: Trichuris eggs have distinctive barrel shape and polar plugs.
14. What is the primary diagnostic stage of Giardia lamblia in formed stools?
A. Trophozoite
B. Cyst
C. Egg
D. Sporozoite
Answer: B. Cyst
✔️ Explanation: Cysts are the infective and diagnostic stage found in formed stool.
15. Which nematode produces larvae that hatch in the intestine and may penetrate tissue?
A. Hookworm
B. Strongyloides stercoralis
C. Enterobius vermicularis
D. Ascaris lumbricoides
Answer: B. Strongyloides stercoralis
✔️ Explanation: Strongyloides larvae can penetrate the intestinal mucosa, causing autoinfection.
16. When collecting a sample for suspected Cryptosporidium, which stain is most appropriate?
A. Iron hematoxylin
B. Trichrome
C. Modified acid-fast
D. Giemsa
Answer: C. Modified acid-fast
✔️ Explanation: Cryptosporidium oocysts are acid-fast positive, best seen with modified acid-fast stain.
17. Which cestode is transmitted through undercooked pork and can cause neurocysticercosis?
A. Diphyllobothrium latum
B. Taenia solium
C. Taenia saginata
D. Echinococcus granulosus
Answer: B. Taenia solium
✔️ Explanation: T. solium can cause larval cysts in the brain, leading to seizures.
18. Which helminth causes anemia through blood loss in the intestines?
A. Enterobius vermicularis
B. Hookworm
C. Trichinella spiralis
D. Ascaris lumbricoides
Answer: B. Hookworm
✔️ Explanation: Hookworms attach to the intestinal wall and consume blood.
19. When a stool sample reveals a large ciliated trophozoite, which parasite is likely present?
A. Giardia lamblia
B. Balantidium coli
C. Entamoeba coli
D. Blastocystis hominis
Answer: B. Balantidium coli
✔️ Explanation: Balantidium coli is the only ciliated protozoan that infects humans.
20. When humans ingest infective eggs, which parasite causes hydatid cysts in the liver or lungs?
A. Taenia saginata
B. Echinococcus granulosus
C. Trichinella spiralis
D. Fasciola hepatica
Answer: B. Echinococcus granulosus
✔️ Explanation: Echinococcus causes hydatid disease via larval cysts.
21. Which trematode is acquired through the ingestion of raw or undercooked fish?
A. Fasciola hepatica
B. Schistosoma haematobium
C. Clonorchis sinensis
D. Paragonimus westermani
Answer: C. Clonorchis sinensis
✔️ Explanation: Clonorchis (Chinese liver fluke) is acquired via fish and causes biliary disease.
22. When urine microscopy reveals eggs with a terminal spine, which parasite is indicated?
A. Schistosoma haematobium
B. Schistosoma mansoni
C. Clonorchis sinensis
D. Fasciola hepatica
Answer: A. Schistosoma haematobium
✔️ Explanation: S. haematobium is the only one found in urine and has terminal-spined eggs.
23. Which blood parasite causes “sleeping sickness” and is spread by the tsetse fly?
A. Leishmania donovani
B. Trypanosoma brucei
C. Plasmodium falciparum
D. Trypanosoma cruzi
Answer: B. Trypanosoma brucei
✔️ Explanation: T. brucei is responsible for African trypanosomiasis.
24. Which parasite causes cutaneous larva migrans in people walking barefoot?
A. Hookworm (animal)
B. Ascaris
C. Strongyloides
D. Enterobius
Answer: A. Hookworm (animal)
✔️ Explanation: Animal hookworm larvae penetrate the skin, causing serpiginous tracks.
25. Which protozoan causes a “flask-shaped” ulcer in the colon?
A. Giardia lamblia
B. Entamoeba histolytica
C. Balantidium coli
D. Dientamoeba fragilis
Answer: B. Entamoeba histolytica
✔️ Explanation: E. histolytica invades tissue and causes flask-shaped ulcers in the colon.
26. Which tapeworm is associated with megaloblastic anemia due to vitamin B12 deficiency?
A. Taenia solium
B. Diphyllobothrium latum
C. Hymenolepis nana
D. Echinococcus granulosus
Answer: B. Diphyllobothrium latum
✔️ Explanation: Diphyllobothrium competes for B12 and causes anemia.
27. Which parasitic infection is commonly diagnosed by muscle biopsy?
A. Strongyloides
B. Trichinella spiralis
C. Taenia solium
D. Schistosoma japonicum
Answer: B. Trichinella spiralis
✔️ Explanation: Trichinella encysts in muscle tissue; biopsy is diagnostic.
28. Which parasite causes diarrhea in AIDS patients and appears as acid-fast oocysts?
A. Cryptosporidium parvum
B. Cyclospora cayetanensis
C. Isospora belli
D. Entamoeba coli
Answer: A. Cryptosporidium parvum
✔️ Explanation: Cryptosporidium commonly affects immunocompromised individuals.
29. Which intestinal protozoa has a nucleus with a small central karyosome and peripheral chromatin?
A. Entamoeba coli ✅
B. Giardia lamblia
C. Trichomonas vaginalis
D. Balantidium coli
Answer: A. Entamoeba coli
✔️ Explanation: Entamoeba coli shows these classic nuclear features in cysts
30. Which parasite causes visceral larva migrans in humans?
A. Toxocara canis
B. Taenia solium
C. Trypanosoma cruzi
D. Trichuris trichiura
Answer: A. Toxocara canis
✔️ Explanation: Toxocara larvae migrate through organs, especially in children.
Medium Questions (31–70)
31. As you analyze a Giemsa-stained blood smear, which intracellular parasite appears as amastigotes in macrophages?
A. Plasmodium malariae
B. Trypanosoma cruzi
C. Leishmania donovani
D. Babesia microti
Answer: C. Leishmania donovani
✔️ Explanation: Leishmania amastigotes are typically found in macrophages and resemble small oval bodies with a kinetoplast.
32. When evaluating stool samples, which protozoan shows a “falling leaf” motility pattern under the microscope?
A. Giardia lamblia
B. Balantidium coli
C. Entamoeba histolytica
D. Dientamoeba fragilis
Answer: A. Giardia lamblia
✔️ Explanation: Giardia lamblia trophozoites display a characteristic falling leaf motility due to their flagella.
33. During a parasitic infection, which immune cell type is most elevated in helminthic infestations?
A. Neutrophils
B. Basophils
C. Eosinophils
D. Monocytes
Answer: C. Eosinophils
✔️ Explanation: Eosinophils respond prominently to parasitic helminth infections, aiding in defense.
34. Which intestinal parasite may be mistaken for Entamoeba histolytica but is non-pathogenic?
A. Endolimax nana
B. Dientamoeba fragilis
C. Entamoeba coli
D. Chilomastix mesnili
Answer: C. Entamoeba coli
✔️ Explanation: Entamoeba coli has similar morphology to E. histolytica but is non-pathogenic and shows more than four nuclei in cysts.
35. When analyzing a thick blood smear, which parasite often appears as ring forms and may be confused with Plasmodium falciparum?
A. Trypanosoma cruzi
B. Babesia microti
C. Leishmania donovani
D. Toxoplasma gondii
Answer: B. Babesia microti
✔️ Explanation: Babesia microti produces intraerythrocytic ring forms and sometimes tetrads (Maltese cross), mimicking malaria.
36. Which parasite is diagnosed using the knott’s concentration method in blood?
A. Toxoplasma gondii
B. Loa loa
C. Plasmodium vivax
D. Leishmania tropica
Answer: B. Loa loa
✔️ Explanation: The Knott’s technique concentrates microfilariae like Loa loa from blood for microscopic examination.
37. Which protozoan can cause severe congenital infection if a pregnant woman becomes infected?
A. Trypanosoma brucei
B. Giardia lamblia
C. Toxoplasma gondii
D. Entamoeba histolytica
Answer: C. Toxoplasma gondii
✔️ Explanation: Toxoplasma gondii can cross the placenta and lead to miscarriage, chorioretinitis, or hydrocephalus.
38. If you find barrel-shaped eggs with bipolar plugs in stool, which parasite should be suspected?
A. Hookworm
B. Trichuris trichiura
C. Strongyloides stercoralis
D. Hymenolepis nana
Answer: B. Trichuris trichiura
✔️ Explanation: These characteristic eggs belong to Trichuris trichiura (whipworm).
39. Which intestinal protozoan lacks a cyst stage and is transmitted via direct contact or fecal-oral route?
A. Dientamoeba fragilis
B. Giardia lamblia
C. Endolimax nana
D. Blastocystis hominis
Answer: A. Dientamoeba fragilis
✔️ Explanation: Dientamoeba fragilis is often passed without a cyst stage, directly as trophozoites.
40. When stool reveals trophozoites with “eye spots” and a sucking disk, what is the diagnosis?
A. Entamoeba coli
B. Giardia lamblia
C. Balantidium coli
D. Trichomonas hominis
Answer: B. Giardia lamblia
✔️ Explanation: Giardia has two nuclei that resemble eyes and an adhesive disk used for attachment. “Old man’s spectacles” looking nuclei.
41. Which test is most appropriate for detecting Schistosoma haematobium?
A. Urinalysis with egg detection
B. Stool microscopy
C. Peripheral blood smear
D. Serology
Answer: A. Urinalysis with egg detection
✔️ Explanation: Schistosoma haematobium lays eggs in the bladder wall; detection is best via urine microscopy.
42. Which parasite causes subcutaneous swelling and is visible moving across the eye?
A. Wuchereria bancrofti
B. Onchocerca volvulus
C. Loa loa
D. Dracunculus medinensis
Answer: C. Loa loa
✔️ Explanation: Loa loa, the African eye worm, causes migratory swelling (Calabar swelling).
43. As you investigate eosinophilia and muscle pain, which helminth should be suspected from eating raw pork?
A. Taenia saginata
B. Trichinella spiralis
C. Strongyloides stercoralis
D. Hymenolepis nana
Answer: B. Trichinella spiralis
✔️ Explanation: Trichinella larvae encyst in muscles, causing myositis and eosinophilia.
44. Which intestinal protozoan is commonly found in immunocompetent individuals without causing symptoms?
A. Blastocystis hominis
B. Entamoeba histolytica
C. Giardia lamblia
D. Cryptosporidium parvum
Answer: A. Blastocystis hominis
✔️ Explanation: Blastocystis is frequently present in stool of healthy individuals and is controversial in its pathogenicity.
45. If a patient from South America has chagoma and cardiac symptoms, which parasite is likely involved?
A. Leishmania donovani
B. Trypanosoma cruzi
C. Toxoplasma gondii
D. Entamoeba histolytica
Answer: B. Trypanosoma cruzi
✔️ Explanation: T. cruzi, spread by the reduviid bug, causes Chagas disease and affects the heart.
46. Which fluke’s life cycle involves humans as accidental hosts who ingest metacercaria from vegetation?
A. Paragonimus westermani
B. Fasciola hepatica
C. Clonorchis sinensis
D. Schistosoma mansoni
Answer: B. Fasciola hepatica
✔️ Explanation: Humans acquire Fasciola by consuming water plants like watercress.
47. Which parasite causes “swimmer’s itch” due to cercarial skin penetration?
A. Clonorchis sinensis
B. Schistosoma mansoni
C. Diphyllobothrium latum
D. Hymenolepis diminuta
Answer: B. Schistosoma mansoni
✔️ Explanation: Cercariae of Schistosoma can penetrate the skin, causing dermatitis
48. Which parasite is known for its unique pyriform shape and rosette-like arrangement in the intestinal mucosa?
A. Giardia lamblia
B. Trichuris trichiura
C. Isospora belli
D. Blastocystis hominis
Answer: D. Blastocystis hominis
✔️ Explanation: Blastocystis can exhibit rosette forms in stool samples.
49. Which roundworm causes rectal prolapse in heavy pediatric infections?
A. Ascaris lumbricoides
B. Trichuris trichiura
C. Enterobius vermicularis
D. Ancylostoma duodenale
Answer: B. Trichuris trichiura
✔️ Explanation: Whipworm infections in children can cause straining and rectal prolapse
50. Which microfilarial parasite is transmitted by the blackfly and causes river blindness?
A. Wuchereria bancrofti
B. Onchocerca volvulus
C. Loa loa
D. Trichinella spiralis
Answer: B. Onchocerca volvulus
✔️ Explanation: Onchocerca invades the eye, leading to irreversible blindness.
51. When diagnosing a patient with persistent diarrhea, which protozoan should be suspected if modified acid-fast stain reveals oocysts?
A. Cryptosporidium parvum
B. Giardia lamblia
C. Cyclospora cayetanensis
D. Entamoeba histolytica
Answer: A. Cryptosporidium parvum
✔️ Explanation: Cryptosporidium oocysts are acid-fast and cause watery diarrhea, especially in immunocompromised patients.
52. Which coccidian parasite, often linked with imported berries, causes cyclical diarrhea and autofluorescent oocysts?
A. Cyclospora cayetanensis
B. Toxoplasma gondii
C. Isospora belli
D. Blastocystis hominis
Answer: A. Cyclospora cayetanensis
✔️ Explanation: Cyclospora causes traveler’s diarrhea and produces autofluorescent oocysts visible under UV light.
53. While reviewing a blood smear, you observe extracellular flagellates with an undulating membrane. What is the likely parasite?
A. Babesia microti
B. Plasmodium vivax
C. Trypanosoma brucei
D. Toxoplasma gondii
Answer: C. Trypanosoma brucei
✔️ Explanation: Trypanosoma brucei is a bloodborne flagellate seen as trypomastigotes in African sleeping sickness.
54. Which intestinal protozoan is uniquely diagnosed using adhesive cellophane tape preparation?
A. Trichuris trichiura
B. Giardia lamblia
C. Enterobius vermicularis
D. Strongyloides stercoralis
Answer: C. Enterobius vermicularis
✔️ Explanation: Enterobius (pinworm) eggs are best detected via the scotch tape test from the perianal region.
55. In cases of heavy Schistosoma mansoni infections, what complication may arise from chronic egg deposition?
A. Pulmonary edema
B. Hepatosplenomegaly with portal hypertension
C. Cholangitis
D. Retinal detachment
Answer: B. Hepatosplenomegaly with portal hypertension
✔️ Explanation: Chronic S. mansoni infection leads to liver fibrosis and portal hypertension due to immune response to deposited eggs.
56. As you examine stool samples, which parasite presents with operculated eggs containing a visible knob at one end?
A. Fasciolopsis buski
B. Clonorchis sinensis
C. Taenia solium
D. Trichuris trichiura
Answer: B. Clonorchis sinensis
✔️ Explanation: Clonorchis eggs are small, operculated, and have a distinctive shoulder or knob opposite the operculum.
57. If a patient reports proglottids passed in stool and lives in a region where pork is a staple, which parasite is likely involved?
A. Taenia saginata
B. Hymenolepis nana
C. Taenia solium
D. Diphyllobothrium latum
Answer: C. Taenia solium
✔️ Explanation: Taenia solium (pork tapeworm) releases proglottids in feces and is acquired from undercooked pork.
58. In which parasitic infection is auto-reinfection a common phenomenon, especially in immunocompromised patients?
A. Giardia lamblia
B. Strongyloides stercoralis
C. Ancylostoma duodenale
D. Trichuris trichiura
Answer: B. Strongyloides stercoralis
✔️ Explanation: Strongyloides can complete its life cycle within the host, causing internal reinfection and dissemination.
59. What structure is essential for Giardia lamblia’s attachment to the host’s intestinal mucosa?
A. Kinetoplast
B. Axostyle
C. Sucker disk
D. Cilia
Answer: C. Sucker disk
✔️ Explanation: The ventral adhesive disk of Giardia helps it stick to intestinal epithelial cells.
60. Which trematode infection is most likely when a patient presents with hematuria and resides in an endemic region in Africa?
A. Fasciola hepatica
B. Schistosoma haematobium
C. Clonorchis sinensis
D. Paragonimus westermani
Answer: B. Schistosoma haematobium
✔️ Explanation: S. haematobium causes urinary tract infections, including hematuria, in endemic African regions.
61. In the life cycle of Ascaris lumbricoides, where do the larvae migrate before returning to the intestines?
A. Skin
B. Brain
C. Lungs
D. Kidneys
Answer: C. Lungs
✔️ Explanation: After ingestion, larvae migrate to the lungs, ascend the trachea, and are swallowed again to complete maturation in the intestines.
62. Which parasite causes lymphedema and elephantiasis as a chronic complication?
A. Strongyloides stercoralis
B. Trichinella spiralis
C. Wuchereria bancrofti
D. Onchocerca volvulus
Answer: C. Wuchereria bancrofti
✔️ Explanation: Wuchereria bancrofti damages lymphatic vessels, leading to elephantiasis of limbs and genitals.
63. A patient has diarrhea after visiting a daycare center. Which protozoan is likely the cause of this outbreak?
A. Cryptosporidium parvum
B. Giardia Lamblia
C. Entamoeba histolytica
D. Balantidium coli
Answer: B. Giardia Lamblia
✔️ Explanation: Giardia lamblia is the most frequently implicated protozoan in outbreaks of diarrheal illness linked to daycare centers while Cryptosporidium parvum (Choice A) can also cause daycare-related outbreaks, Giardia remains more common in such environments.
64. Which diagnostic test can detect Giardia lamblia antigen directly from stool samples?
A. Trichrome stain
B. ELISA
C. Acid-fast stain
D. Cellophane tape prep
Answer: B. ELISA
✔️ Explanation: Enzyme-linked immunosorbent assays (ELISA) can rapidly detect Giardia antigen in fecal specimens.
65. Which of the following helminths does not commonly cause autoinfection in humans?
A. Strongyloides stercoralis
B. Hymenolepis nana
C. Enterobius vermicularis
D. Taenia saginata
Answer: D. Taenia saginata
✔️ Explanation: Unlike others, Taenia saginata (beef tapeworm) requires ingestion of infected meat and does not autoinfect.
66. A stool sample reveals ciliated trophozoites. What parasite are you most likely observing?
A. Giardia lamblia
B. Balantidium coli
C. Entamoeba coli
D. Trichomonas hominis
Answer: B. Balantidium coli
✔️ Explanation: Balantidium coli is the only ciliated protozoan infecting humans.
67. Which parasite’s eggs are ingested by beetles or fleas before transmission to humans?
A. Taenia solium
B. Hymenolepis diminuta
C. Ascaris lumbricoides
D. Trichuris trichiura
Answer: B. Hymenolepis diminuta
✔️ Explanation: Hymenolepis diminuta uses arthropods as intermediate hosts.
68. What parasite can cause both intestinal and hepatic abscesses, particularly in developing countries?
A. Giardia lamblia
B. Entamoeba histolytica
C. Cryptosporidium parvum
D. Isospora belli
Answer: B. Entamoeba histolytica
✔️ Explanation: Entamoeba histolytica invades the intestinal mucosa and can spread to the liver causing abscesses
69. Which protozoan appears as a large, ovoid trophozoite with a prominent macronucleus?
A. Giardia lamblia
B. Balantidium coli
C. Blastocystis hominis
D. Entamoeba hartmanni
Answer: B. Balantidium coli
✔️ Explanation: Balantidium coli has a distinct kidney-shaped macronucleus.
70. When evaluating liver fluke infections, which diagnostic technique is most useful?
A. Sputum microscopy
B. Peripheral blood smear
C. Stool examination for eggs
D. Serology
Answer: C. Stool examination for eggs
✔️ Explanation: Liver fluke eggs like those of Clonorchis or Fasciola are identified in stool samples. These parasites lay eggs that are passed in the feces, making them detectable through microscopic analysis of stool samples.
