MCQs on Helminths/Parasitic worms(Tapeworms, Roundworms, and Flukes): Medical microbiology

          MCQs on Helminths/Parasitic worms(Tapeworms, Roundworms, and Flukes)

1. A 40 year old male elementary school teacher residing in a rural area comes to a local clinic complaining of abdominal pain, diarrhea, and fatigue. He reports experiencing these symptoms for the past two weeks. He mentions that the abdominal pain is intermittent and is often accompanied by cramps. He also has noticed the presence of blood in his stool and occasional weight loss.
The man has no significant medical history or known allergies. He is not taking any medications, and has not recently traveled to other regions.
During the physical examination, the healthcare provider notes tenderness in lower abdomen of the patient and conducts a digital rectal examination, which reveals the presence of blood-tinged stool. Vital signs, including temperature, pulse, and blood pressure, are within normal limits.
Based on the symptoms, the healthcare provider orders several diagnostic tests including stool examination, microscopic examination reveals the presence of nematode eggs consistent with the parasite species.
Based on the diagnostic findings, the patient is diagnosed with a nematode (roundworm) infection. 
Which of the following anthelminthic medication is prescribed by the healthcare provider for the treatment of the infection?
a) Chloramphenicol
b) Doxycycline and rifampin
c) Ivermectin or albendazole    
d) Metronidazole

2. What is the worldwide distribution of Ascaris lumbricoides?
a) Limited to developed countries
b) Higher prevalence in the temperate regions
c) Higher prevalence in the tropical regions    
d) Confined to specific geographic areas

3. Where do the adult worms of Ascaris lumbricoides primarily reside and reproduce?
a) Stomach
b) Large intestine
c) Lungs    
d) Small intestine     

4. Which of the following is a common clinical manifestation of acute strongyloidiasis infection caused by Strongyloides stercoralis?
a) Headache
b) Joint pain
c) Pruritic papular rash  
d) Visual disturbances

5. Which of the following statements is true regarding the distribution of Trichuris trichiura (whipworm)?
a) Found only in the United States
b) Has a worldwide distribution    
c) Limited to tropical regions
d) Restricted to arid climates

6. What is the second most common helmintic infection reported in humans worldwide after Ascaris lumbricoides infection?
a) Hookworm infection 
b) Malaria
c) Scabies   
d) Tapeworm infection

7. How do infective filariform larvae of hookworms enter the human host?
a) Through ingestion of contaminated food
b) Penetrating the skin      
c) Inhalation of airborne eggs
d) Through the bite of an infected mosquito

8. What distinguishes the life cycle of Trichuris trichiura from some other intestinal nematodes?
a) It involves tissue migration phases.
b) It includes a larval phase outside the host.
c) It has no tissue migration phase.      >
d) It involves a sexual phase in humans.

9. In strongyloidiasis, what can lead to the development of a macro-papular or urticarial rash on the buttocks, perineum, and thighs?
a) Allergic reactions
b) High fever
c) Ingestion of contaminated water
d) Larval migration     

10. In disseminated strongyloidiasis, where can larvae be found in the body, apart from the intestines and lungs?
a) Central nervous system, kidneys, and liver    
b) Heart and lungs
c) Joints and bones
d) Skin and muscles

11. How long does it take for Ascaris lumbricoides eggs to become infective after being passed in the feces?
a) 1 to 2 days
b) 2 to 6 weeks     
c) 3 to 4 months
d) 1 year

12. What is the characteristic appearance of Ascaris lumbricoides eggs?
a) Flattened and transparent
b) Smooth and spherical
c) Thick, oval, and mammillated  
d) Thin and elongated   

13. What is the life cycle stage of hookworms that is typically deposited in the soil?
a) Adult worms
b) Eggs
c) Filariform larvae
d) Rhabditiform larvae     

14. How does hyperinfection in strongyloidiasis occur?
a) Contaminated swimming pools
b) Ingestion of uncooked meat
c) Penetration of the intestine by filariform larvae    
d) Through sexual transmission

15. Which of the following nematode is responsible for lymphatic filariasis, commonly known as elephantiasis?
a) Brugia malayi
b) Loa loa
c) Mansonella ozzardi
d) Wuchereria bancrofti

16. How do humans become infected with Trichuris trichiura?
a) Inhalation of airborne cysts
b) Ingestion of embryonated eggs     
c) Skin penetration by larvae
d) Through mosquito bites

17. What environmental conditions are required for the embryonation of Trichuris trichiura eggs to become infective to another host?
a) Cold and dry
b) Dark and polluted
c) Hot and arid
d) Warm and moist      

18. How is the differentiation between Ancylostoma duodenale and Necator americanus primarily determined?
a) By examining the size of the eggs
b) Based on the adult male copulatory bursa      
c) By the presence of a hook-shaped structure in the larvae
d) Through DNA analysis of the infective larvae

19. What is the characteristic symptom of onchocerciasis, caused by Onchocerca volvulus?
a) Itchy skin and potential blindness
b) Migratory skin rashes
c) Painful joint inflammation
d) Swelling of the limbs and genitals

20. Which of the following filarial nematode is known as the African eye worm?
a) Loa loa
b) Mansonella streptocerca
c) Mansonella ozzardi
d) Onchocerca volvulus

21. What is the primary mode of transmission for filarial nematodes to humans?
a) Consumption of contaminated food and water
b) Direct contact with infected individuals
c) Inhalation of airborne microfilariae
d) Mosquito bites

22. Schistosoma mansoni and Schistosoma japonicum are examples of flatworms that belong to which class?
a) Cestoda
b) Monogenea
c) Trematoda
d) Turbellaria

23. A 34 year old female chef who works at a popular restaurant visits a healthcare center with abdominal pain and discomfort, particularly in the upper abdomen. She reports frequent episodes of nausea and vomiting.
She mentions that her symptoms began a few months ago and have progressively worsened. She has noticed these ribbon-like segments in her stool intermittently. She has experienced nausea and vomiting after eating, sometimes even hours after a meal. She reports a loss of appetite and unintentional weight loss.
Upon physical examination by healthcare provider the patient has tenderness in the upper abdomen and appears pale and has lost a noticeable amount of weight. No other significant physical findings are observed.
Stool samples are collected and examined for the presence of eggs or segments of cestodes. The examination reveals the presence of cestode segments. A complete blood count (CBC) shows mild anemia.
Based on the clinical presentation and diagnostic findings the patient is diagnosed with which of the following common parisitic/tapeworm infection?
a) Giardiasis
b) Filariasis
c) Toxoplasmosis
d) Taeniasis

24. Which characteristic is common to most flatworms?
a) A coelom (body cavity)
b) Advanced respiratory system
c) Bilateral symmetry
d) Complex circulatory system

25. Which intestinal cestode is known for causing cysticercosis, a condition resulting from the larval stage of the parasite?
a) Diphyllobothrium latum
b) Hymenolepis nana
c) Taenia solium
d) Taenia saginata

26. Which of the following intestinal cestodes is primarily associated with the consumption of undercooked or raw beef?
a) Diphyllobothrium latum
b) Hymenolepis nana
c) Taenia solium
d) Taenia saginata

27. In the life cycle of most intestinal cestodes, which host serves as the definitive host, where the adult tapeworm resides?
a) Intermediate host
b) Paratenic host
c) Reservoir host
d) Vertebrate host

28. Which of the following method is a common staining method used in identifying numerous types of helminths?
a) Direct smear preparation method using saline or iodine
b) Gram staining method
c) Haematoxylin and eosin (H&E) method
d) Period acid Schiff method

1. c) Ivermectin or albendazole 
2. c) Higher prevalence in the tropical regions 
3. d) Small intestine
4. c) Pruritic papular rash. Strongyloidiasis is usually acquired when the infective larvae of Strongyloides stercoralis penetrate the skin, often when an individual comes into contact with contaminated soil. Dissemination of the worm can lead to severe and systemic symptoms including skin rashes, itching, and allergic reactions.

5. b) Has a worldwide distribution 
6. c) Hookworm infection  
7. b) Penetrating the skin  
8. c) It has no tissue migration phase. 
9. d) Larval migration 
10. a) Central nervous system, kidneys, and liver. Disseminated strongyloidiasis infection spreads to other parts of the body often seen in immunocompromised individuals. Dissemination can lead to severe and systemic symptoms, including shortness of breath and cough due to lung involvement. Skin rashes, itching, and allergic reactions, abdominal pain, diarrhea, and weight loss. Invasion of the central nervous system and the development of meningitis or encephalitis.

11. b) 2 to 6 weeks 
12. c) Thick, oval, and mammillated  
13. d) Rhabditiform larvae 
14. c) Penetration of the intestine by filariform larvae

15. d) Wuchereria bancrofti. It is a nematode responsible for lymphatic filariasis, which is commonly referred to as elephantiasis. This disease leads to the obstruction of lymphatic vessels, causing swelling of the limbs and genitals. 

16. b) Ingestion of embryonated eggs
17. d) Warm and moist 
18. b) Based on the adult male copulatory bursa 

19. a) Itchy skin and potential blindness. Onchocerciasis, caused by Onchocerca volvulus, is characterized by intense itching of the skin and potential blindness due to eye involvement. This disease is often referred to as river blindness.

20. a) Loa loa. Also known as the African eye worm, it is a filarial nematode that can migrate under the skin and cause localized swelling and discomfort, including swelling of the conjunctiva.

21. d) Mosquito bites. Filarial nematodes are primarily transmitted to humans through the bite of infected mosquitoes. The mosquito acts as a vector, transferring infective larvae into the human host during the blood-feeding process.

22. c) Trematoda. Schistosoma spp. are blood flukes belonging to the class Trematoda. They are parasitic flatworms that cause schistosomiasis, a tropical disease prevalent in regions with contaminated freshwater.

23. d) Taeniasis. It is a parasitic infection caused by tapeworms/flatworms belonging to the genus Taenia, human infection is primarily caused by two species of tapeworms: Taenia solium and Taenia saginata.

24. c) Bilateral symmetry

25. c) Taenia soliumTaenia solium or pork tapeworm is a tapeworm that infects humans particularly due to the consumtion of undercooked or raw pork, infection can occur through the ingestion of eggs shed in human feces. Infection can lead to both taeniasis (adult tapeworm infection) and cysticercosis (larval stage infection in tissues).

26. d) Taenia saginata. Taenia saginata or beef tapeworm is a tapeworm that primarily infects humans and is associated with the consumption of undercooked or raw beef. The adult tapeworm can grow to be several meters long in the human intestine.

27. d) Vertebrate host. Intestinal cestodes are a group of parasitic flatworms that inhabit the intestines of their host organisms, which can include humans and a variety of other vertebrates. The life cycle of intestinal cestodes have typically two hosts. The adult tapeworm lives in the intestines of the definitive host, where it releases eggs in its proglottids. The eggs are then excreted in the host's feces. If ingested by an appropriate intermediate host (e.g., cattle for T. saginata), the eggs develop into larvae, which can infect the definitive host when the intermediate host is consumed.

28. a) Direct smear preparation method using saline or iodine. It is a simple and rapid method,
a small amount of feces or clinical specimen is mixed with a drop of saline or iodine on a microscope slide. A coverslip is placed over the mixture, and the slide is examined under a microscope for the presence of helminth eggs, larvae, or adult forms.