Chpt.4b (108-121) Parasitic Muscle Nematodes

Question 1

21. What triggers the release of Dracunculus medinensis larvae from the female worm? a) Sunlight b) Contact with water c) Host body temperature d) Presence of copepods

Answer 1

Explanation: When the female Dracunculus medinensis worm comes into contact with water it releases its larvae.

The correct answer is b) Contact with water.

Dracunculus medinensis, commonly known as the guinea worm, is a parasitic nematode. The female worm, after migrating to the skin of the host, forms a blister. When the blister comes into contact with water, it ruptures, releasing the larvae into the water. The larvae are then consumed by copepods (small crustaceans), which act as the intermediate host. The larvae develop within the copepods, and the cycle continues when a human drinks contaminated water containing these infected copepods.

Thus, the trigger for the release of Dracunculus medinensis larvae is the contact with water, which causes the female worm to release its larvae.

Question 2

22. What is the intermediate host of Dracunculus medinensis? a) Snail b) Mosquito c) Blackfly d) Copepod

Answer 2

Explanation: Dracunculus medinensis larvae are ingested by copepods where they develop into the infective stage.

Question 3

23. What is the diagnostic stage of Dracunculus medinensis infection? a) Microfilariae in the blood b) Eggs in the feces c) Female worm emerging from a skin blister d) Larvae in the copepod

Answer 3

Explanation: The hallmark sign of Dracunculus medinensis infection is the emergence of the female worm from a blister on the skin.

Question 4

24. Which method is NOT effective in controlling the spread of Dracunculus medinensis? a) Providing safe drinking water b) Filtering drinking water c) Boiling drinking water d) Treating infected individuals with antibiotics

Answer 4

Explanation: Antibiotics are not effective against parasitic worms like Dracunculus medinensis. Control measures focus on preventing contamination of water sources and reducing contact with infected water.

Question 5

25. What is the main target organ of Toxocara canis and Toxocara cati larvae in humans? a) Brain b) Heart c) Lungs d) Eyes

Answer 5

Explanation: While Toxocara larvae can migrate to various organs they frequently target the eyes leading to a condition called ocular larva migrans which can potentially cause vision loss.

Question 6

26. How do humans acquire Toxocara infection? a) Through mosquito bites b) By drinking contaminated water c) Through contact with contaminated soil d) By eating undercooked meat

Answer 6

Explanation: Humans especially children can get infected with Toxocara by accidentally ingesting soil contaminated with the parasite’s eggs.

Question 7

27. What is the morphology of adult Toxocara worms? a) Flat and segmented b) Long and thread-like c) Round and small d) Leaf-shaped

Answer 7

Explanation: Adult Toxocara worms are round and relatively small in size.

Question 8

28. What is the specific name for the migration of Toxocara larvae through various organs in humans? a) Visceral larval migrans b) Cutaneous larval migrans c) Ocular larval migrans d) Pulmonary larval migrans

Answer 8

Explanation: The condition characterized by the migration of Toxocara larvae through various internal organs is termed visceral larval migrans.

Question 9

29. How is the diagnosis of Toxocara infection typically confirmed? a) Finding eggs in the feces b) Observing larvae in the blood c) Through serological tests d) By imaging studies

Answer 9

Explanation: Serological tests that detect antibodies against Toxocara are commonly used to diagnose the infection.

Question 10

30. What is the unique characteristic of Trichinella spiralis in its life cycle? a) It requires an intermediate host b) It can reproduce in the environment c) It completes its entire life cycle in a single host d) It has a free-living larval stage

Answer 10

Explanation: Unlike many other parasitic worms Trichinella spiralis can complete its entire life cycle within a single host.

Question 11

31. What is the typical shape of the capsule housing Trichinella spiralis larvae in muscle tissue? a) Round b) Oval c) Spiral d) Pea-shaped

Answer 11

Explanation: Trichinella spiralis larvae encapsulate in a characteristic pea-shaped capsule within the striated muscle tissue of the host.

Question 12

32. Which phase of the Trichinella spiralis life cycle is responsible for the most severe pathological effects? a) Intestinal phase b) Tissue phase c) Larval phase d) Adult worm phase

Answer 12

Explanation: While the intestinal phase can cause gastrointestinal symptoms it is the tissue phase where larvae encyst in muscles that leads to the more serious manifestations of trichinosis.

Question 13

33. What is the most common source of Trichinella spiralis infection for humans? a) Beef b) Chicken c) Pork d) Fish

Answer 13

Explanation: The consumption of raw or undercooked pork is the most common way humans get infected with Trichinella spiralis.

Question 14

34. Which digestive enzyme is crucial for the release of Trichinella spiralis larvae in the host’s intestine? a) Amylase b) Lipase c) Pepsin d) Trypsin

Answer 14

Explanation: Pepsin a digestive enzyme found in the stomach breaks down the protective coating of the ingested Trichinella spiralis larvae releasing them into the intestine.

Question 15

35. What is a characteristic early symptom of trichinosis? a) Muscle pain b) Fever c) Gastroenteritis d) Periorbital edema

Answer 15

Explanation: Trichinosis typically presents with gastrointestinal symptoms like diarrhea and abdominal pain within a week of consuming infected meat.

Question 16

36. What is a definitive diagnostic procedure for trichinosis? a) Blood test b) Stool examination c) X-ray d) Muscle biopsy

Answer 16

Explanation: A muscle biopsy can be performed to directly visualize the Trichinella spiralis larvae within the muscle tissue.

Question 17

37. Which of the following is NOT a recommended treatment for trichinosis? a) Analgesics for pain relief b) Antibiotics c) Corticosteroids for inflammation d) Albendazole (anti-helminthic drug)

Answer 17

Explanation: Antibiotics are ineffective against parasitic worms like Trichinella spiralis. Treatment focuses on relieving symptoms and using anti-helminthic drugs to kill the worms.

Question 18

38. What is the most effective preventive measure against trichinosis? a) Vaccination b) Avoiding contact with pigs c) Wearing gloves when handling raw meat d) Thorough cooking of meat

Answer 18

Explanation: The most reliable way to prevent trichinosis is to ensure that meat particularly pork is cooked thoroughly to an internal temperature that kills the Trichinella spiralis larvae.

Question 19

39. What measure can prevent Dracunculus medinensis infection during outbreaks? a) Taking prophylactic medication b) Boiling or filtering potentially contaminated water c) Avoiding contact with infected individuals d) Wearing protective clothing

Answer 19

Explanation: Since the primary transmission route for Dracunculus medinensis is through contaminated water boiling or filtering water effectively eliminates the infective larvae.

Question 20

40. What public health strategy has been instrumental in the near-eradication of Dracunculus medinensis? a) Mass drug administration b) Vector control programs c) Improved access to safe drinking water d) Development of a vaccine

Answer 20

Explanation: Global efforts to provide access to safe drinking water sources have been the most significant factor in dramatically reducing the incidence of Dracunculus medinensis infection worldwide.

Question 21

41. What is the significance of Wuchereria bancrofti microfilariae aggregating in the peripheral blood during specific times? a) It increases the chances of transmission to mosquitos b) It protects the microfilariae from the host’s immune system c) It enhances the reproductive capacity of the parasite d) It facilitates the spread of the infection within the host

Answer 21

Explanation: The nocturnal periodicity of Wuchereria bancrofti microfilariae is an adaptation that coincides with the feeding time of the mosquito vectors thereby increasing the likelihood of transmission.

Question 22

42. What is the consequence of prolonged and repeated exposure to Onchocerca volvulus infection? a) Development of resistance to the parasite b) Increased severity of skin lesions c) Higher risk of developing severe eye complications including blindness d) Spontaneous resolution of the infection

Answer 22

Explanation: Repeated exposure to Onchocerca volvulus increases the cumulative load of microfilariae in the body which significantly elevates the risk of developing severe eye pathology leading to blindness in many cases.

Question 23

43. What is the impact of Wuchereria bancrofti infection on the lymphatic system? a) It strengthens the immune response b) It reduces the risk of other infections c) It causes obstruction and inflammation leading to lymphedema d) It enhances the drainage of fluids from tissues

Answer 23

Explanation: Wuchereria bancrofti infection damages the lymphatic vessels and obstructs lymph flow resulting in the accumulation of fluid in the tissues (lymphedema) which can manifest as elephantiasis.

Question 24

44. How does the life cycle of Loa loa differ from that of Onchocerca volvulus? a) Loa loa has a free-living larval stage b) Loa loa requires two intermediate hosts c) The vector for Loa loa is a deer fly while the vector for Onchocerca volvulus is a blackfly d) Loa loa does not produce microfilariae

Answer 24

Explanation: The key difference lies in their vectors and the type of fly involved in transmission. Chrysops deer flies transmit Loa loa whereas Simulium blackflies transmit Onchocerca volvulus.

Question 25

45. What factor makes young children particularly susceptible to Toxocara infection? a) Weaker immune systems b) Increased outdoor play in potentially contaminated areas c) Frequent contact with pets d) All of the above

Answer 25

Explanation: All the listed factors contribute to the vulnerability of young children to Toxocara infection.

Question 26

46. What is the purpose of the calcified Dracunculus medinensis worm observed in x-rays? a) It is a dormant stage of the parasite b) It is a protective mechanism for the worm c) It is usually the male worm that dies and calcifies after mating d) It indicates a chronic infection

Answer 26

Explanation: The calcified worm seen on x-rays is typically the male Dracunculus medinensis which dies and calcifies after mating. This calcification can be used as a diagnostic indicator.

Question 27

47. What is the main reason why mass drug administration is not a primary strategy for controlling Dracunculus medinensis? a) Lack of effective drugs against the parasite b) High cost of medications c) The long incubation period and the focal nature of outbreaks make it less efficient d) Risk of drug resistance

Answer 27

Explanation: The long incubation period (around a year) of Dracunculus medinensis and the tendency for outbreaks to be localized make mass drug administration a less effective control method.

Question 28

48. What is the impact of Trichinella spiralis larvae encysting in muscle tissue? a) It strengthens the muscle fibers b) It provides a source of nutrients for the host c) It causes inflammation muscle damage and pain d) It enhances muscle regeneration

Answer 28

Explanation: When Trichinella spiralis larvae encyst in muscle tissue they trigger an inflammatory response that damages the muscle fibers and causes pain and weakness.

Question 29

49. What makes the control of zoonotic parasitic infections like Toxocara challenging? a) Lack of awareness about the disease b) Difficulty in treating infected animals c) Widespread environmental contamination with parasite eggs d) All of the above

Answer 29

Explanation: All these factors contribute to the challenges in controlling zoonotic parasitic infections like Toxocara making it difficult to break the transmission cycle.

Question 30

50. Which of these parasites can be transmitted congenitally (from mother to fetus)? a) Onchocerca volvulus b) Loa loa c) Dracunculus medinensis d) Toxocara canis

Answer 30

Explanation: While rare Toxocara canis can be transmitted from an infected mother to her fetus during pregnancy.

Question 31

1. Where do the adult Onchocerca volvulus worms typically reside in the human body? a) Blood vessels b) Lymphatic vessels c) Intestinal wall d) Subcutaneous tissue

Answer 31

Explanation: Adult Onchocerca volvulus worms live in nodules formed in the subcutaneous tissue of the infected individual.

Question 32

2. Which of these skin conditions is associated with onchocerciasis? a) Leopard skin b) Chickenpox c) Measles d) Ringworm

Answer 32

Explanation: Onchocerciasis can cause a skin condition known as leopard skin characterized by depigmentation and a patchy appearance.

Question 33

3. What is the infective stage of Onchocerca volvulus for humans? a) Microfilariae b) Third-stage larva (L3) c) First-stage larva (L1) d) Adult worm

Answer 33

Explanation: The third-stage larva (L3) of Onchocerca volvulus is the infective stage for humans. It is transmitted through the bite of an infected blackfly.

Question 34

4. Which gender of Onchocerca volvulus worm is larger? a) Male b) Female c) They are the same size d) Size varies depending on the host

Answer 34

Explanation: The female Onchocerca volvulus worms are significantly larger than the males reaching up to 40 cm in length while the males are only up to 8 cm long.

Question 35

5. What type of climate is associated with the prevalence of Onchocerca volvulus? a) Desert b) Arctic c) Tropical d) Temperate

Answer 35

Explanation: Onchocerca volvulus is endemic in tropical regions of Africa Central and South America and Yemen.

Question 36

6. What is the primary mode of transmission for Wuchereria bancrofti? a) Contaminated food b) Skin contact c) Mosquito bite d) Waterborne

Answer 36

Explanation: Wuchereria bancrofti is transmitted to humans through the bite of infected mosquitoes primarily those of the Culex Anopheles and Mansonia species.

Question 37

7. What term describes the periodicity exhibited by Wuchereria bancrofti microfilariae in the blood? a)Diurnal b) Nocturnal c) Sporadic d) Continuous

Answer 37

Explanation: Wuchereria bancrofti microfilariae exhibit nocturnal periodicity meaning their concentration in the peripheral blood peaks during the night.

Question 38

8. What is the purpose of the sheath covering the Wuchereria bancrofti microfilariae? a) Protection from the host’s immune system b) Protection from desiccation c) Attachment to host tissues d) Facilitating movement in the bloodstream

Answer 38

Explanation: The sheath surrounding Wuchereria bancrofti microfilariae helps protect them from drying out when they are in the mosquito’s gut.

Question 39

9. What distinguishes Brugia malayi from Wuchereria bancrofti in terms of morphology? a) Presence of a sheath b) Shape of the microfilariae c) Size of the adult worms d) Location in the host

Answer 39

Explanation: Brugia malayi adult worms are slightly smaller than Wuchereria bancrofti adult worms.

Question 40

10. Which region is predominantly affected by Brugia malayi filariasis? a) Africa b) South America c) Southeast Asia d) Europe

Answer 40

Explanation: Brugia malayi is primarily found in Southeast Asian countries.

Question 41

11. Which type of mosquito serves as a vector for Brugia malayi in some areas? a) Culex b) Anopheles c) Mansonia d) Chrysops

Answer 41

Explanation: Besides Anopheles the Mansonia species of mosquito can also act as a vector for Brugia malayi.

Question 42

12. What is the specific clinical presentation of Brugia malayi elephantiasis? a) Involvement of the entire leg b) Involvement below the knee or arms c) Genital involvement d) Facial involvement

Answer 42

Explanation: Unlike Wuchereria bancrofti the elephantiasis caused by Brugia malayi typically affects only the legs below the knees or the arms.

Question 43

13. What is the infective stage of Loa loa for humans? a) Microfilariae b) First-stage larva (L1) c) Third-stage larva (L3) d) Adult worm

Answer 43

Explanation: The third-stage larva (L3) of Loa loa is the infective stage for humans which is introduced into the bloodstream through the bite of an infected deer fly.

Question 44

14. What is the preferred habitat of adult Loa loa worms in the human body? a) Blood vessels b) Lymphatic vessels c) Subcutaneous tissues d) Intestinal wall

Answer 44

Explanation: Adult Loa loa worms mainly reside in the subcutaneous tissues of the human body.

Question 45

15. What behavior of the Chrysops fly contributes to the transmission of Loa loa? a) Nocturnal feeding b) Diurnal feeding c) Breeding in stagnant water d) Feeding on animal carcasses

Answer 45

Explanation: Chrysops flies

Question 46

16. What is the typical size difference between male and female Loa loa worms? a) Males are larger b) Females are larger c) They are the same size d) Size varies depending on the host

Answer 46

Explanation: Female Loa loa worms are larger than males with females reaching up to 7 cm in length and males up to 3.5 cm.

Question 47

17. What is the recommended treatment for Loa loa infection? a) Ivermectin b) Diethylcarbamazine c) Albendazole d) Praziquantel

Answer 47

Explanation: Diethylcarbamazine (DEC) is commonly used to treat Loa loa infection.

Question 48

18. Why is surgical removal of Loa loa worms sometimes necessary? a) To relieve Calabar swellings b) To prevent damage caused by migrating worms c) To eliminate microfilariae d) To prevent transmission to others

Answer 48

Explanation: Surgical removal is often employed for Loa loa worms as they can migrate through the conjunctiva of the eye and cause discomfort and potential damage.

Question 49

19. What is the historical significance of Dracunculus medinensis? a) It was eradicated in the 20th century b) It is mentioned in the Bible c) It was discovered by Louis Pasteur d) It is a newly emerging parasite

Answer 49

Explanation: Dracunculus medinensis also known as the Guinea worm is believed to be the “fiery serpent” that plagued the Israelites in the wilderness as described in the Bible.

Question 50

20. What is the primary host of Dracunculus medinensis? a) Humans b) Dogs c) Cats d) Snails

Answer 50

Explanation: Humans are the definitive hosts for Dracunculus medinensis.

Question 51

1. What type of organism is the Simulium blackfly?

Answer 51

Answer: VectorExplanation: The Simulium blackfly is a vector responsible for transmitting Onchocerca volvulus the parasite that causes river blindness (onchocerciasis).

Question 52

2. What is the term for the accumulation of fluid in tissues caused by lymphatic blockage?

Answer 52

Answer: LymphedemaExplanation: Lymphedema is caused by the obstruction of lymphatic vessels which prevents the normal drainage of lymphatic fluid leading to tissue swelling.

Question 53

3. What is the name for the condition in which Loa loa worms migrate through the conjunctiva of the eye

Answer 53

Answer: Ocular Loa loaExplanation: This condition occurs when the Loa loa filarial worms migrate across the surface of the eye causing irritation and visual discomfort.

Question 54

4. What is the term for an organism that harbors the adult stage of a parasite?

Answer 54

Answer: Definitive hostExplanation: A definitive host is where a parasite reaches sexual maturity and reproduces.

Question 55

5. What is the name for the protective covering around Wuchereria bancrofti microfilariae?

Answer 55

Answer: SheathExplanation: The sheath is a protective layer that surrounds the microfilariae aiding in their survival within the host’s bloodstream.

Question 56

6. What is the term for the time between infection and the appearance of symptoms?

Answer 56

Answer: Incubation periodExplanation: The incubation period is the time it takes for symptoms to appear after a host has been infected by a pathogen or parasite.

Question 57

7. What is the term for the type of periodicity where microfilariae are most abundant in the blood at night?

Answer 57

Answer: Nocturnal periodicityExplanation: Nocturnal periodicity is an adaptive behavior that aligns with the feeding patterns of night-biting mosquitoes which are vectors for filarial worms.

Question 58

8. What stage of Dracunculus medinensis is ingested by the copepod?Answer: First-stage larva (L1)

Answer 58

Explanation: The first-stage larvae of Dracunculus medinensis are released into water by infected humans and are ingested by copepods where they develop into infective stages.

Question 59

9. What is the scientific term for the inflammation of the eye caused by Toxocara larvae?

Answer 59

Answer: Ocular larva migransExplanation: Ocular larva migrans occurs when Toxocara larvae migrate to the eye causing inflammation and potential vision loss.

Question 60

10. What is the general term for a parasitic disease caused by a nematode?

Answer 60

Answer: Nematode infectionExplanation: Nematode infections refer to diseases caused by roundworms which include a wide range of parasitic species affecting humans and animals.

Question 61

1. What type of organism is the Simulium blackfly?

Answer 61

Answer: VectorExplanation: The Simulium blackfly is a vector responsible for transmitting Onchocerca volvulus the parasite that causes river blindness (onchocerciasis).

Question 62

2. What is the term for the accumulation of fluid in tissues caused by lymphatic blockage?

Answer 62

Answer: LymphedemaExplanation: Lymphedema is caused by the obstruction of lymphatic vessels which prevents the normal drainage of lymphatic fluid leading to tissue swelling.

Question 63

3. What is the name for the condition in which Loa loa worms migrate through the conjunctiva of the eye

Answer 63

Answer: Ocular Loa loaExplanation: This condition occurs when the Loa loa filarial worms migrate across the surface of the eye causing irritation and visual discomfort.

Question 64

4. What is the term for an organism that harbors the adult stage of a parasite?

Answer 64

Answer: Definitive hostExplanation: A definitive host is where a parasite reaches sexual maturity and reproduces.

Question 65

5. What is the name for the protective covering around Wuchereria bancrofti microfilariae?

Answer 65

Answer: SheathExplanation: The sheath is a protective layer that surrounds the microfilariae aiding in their survival within the host’s bloodstream.

Question 66

6. What is the term for the time between infection and the appearance of symptoms?

Answer 66

Answer: Incubation periodExplanation: The incubation period is the time it takes for symptoms to appear after a host has been infected by a pathogen or parasite.

Question 67

7. What is the term for the type of periodicity where microfilariae are most abundant in the blood at night?

Answer 67

Answer: Nocturnal periodicityExplanation: Nocturnal periodicity is an adaptive behavior that aligns with the feeding patterns of night-biting mosquitoes which are vectors for filarial worms.

Question 68

8. What stage of Dracunculus medinensis is ingested by the copepod?Answer: First-stage larva (L1)

Answer 68

Explanation: The first-stage larvae of Dracunculus medinensis are released into water by infected humans and are ingested by copepods where they develop into infective stages.

Question 69

9. What is the scientific term for the inflammation of the eye caused by Toxocara larvae?

Answer 69

Answer: Ocular larva migransExplanation: Ocular larva migrans occurs when Toxocara larvae migrate to the eye causing inflammation and potential vision loss.

Question 70

10. What is the general term for a parasitic disease caused by a nematode?

Answer 70

Answer: Nematode infectionExplanation: Nematode infections refer to diseases caused by roundworms which include a wide range of parasitic species affecting humans and animals.