Question

c. Necator americanus d. Taenia saginata 23. Which of the following best describes Trichinella spirallis? a. It has arthropod as an intermediate host b. It is host specific. c. Human infection is by ingestion of infected, undercooked or uncooked meat. d. Human infection is by direct penetration of the skin by parasite larvae. 24. All trematodes are monoecious and have snail as an intermediate host. a. True b. False 25. Sparganosis is a disease associated with Echinococcus granulosus. a. True b. False Provide the following information for each of the parasites (a -1): VI. 1. Name of disease (scientific name and/or local name) caused by the parasite. 2. Name the intermediate host (if none, enter "not applicable or n/a") 3. What is the parasite stage that is infective to human? 4. Mode of human infection. BE SPECIFIC (e.g. inhalation; ingestion.; direct penetration: injection during blood meal) 5. Site where adults/parasites are found in human (e.g. in the blood stream, inside white blood cells etc) 6. Method of diagnosis (e.g. biopsy/blood smear for ..; observation of feces for 7. Group the parasite belongs to. a. Echinococcus granulosus 1. 2. 3. 4. 5. 6.

Answer 1

27. The right answer is option c - human infection is by ingestion of infected, undercooked or uncooked meat.

Explanation :

• Trichinella spiralis does not use an arthropod as an intermediate host. It uses humans as intermediate host as its larvae can live in the muscles of humans. So option a is wrong.

• Trichinella spiralis is not host specific. Host specificity means the capability of the pathogens of living solely in one species of host. But in case of Trichinella spiralis, it can live in multiple species like humans, pigs, rodents etc. So option b is wrong.

• Option d is wrong as human infection occurs by ingestion of undercooked or uncooked or infected meat. This meat has the encysted larva and once its inside humans, the larvae are released from the cysts and invade the small bowel mucosa. Here they develop into adult worms. After around a week, the females release larvae. The larvae then enter the gut wall, get carried by the blood stream and finally reach the striated muscle where they get encysted. Encystment is completed within 4 to 5 weeks and the encysted larvae may remain viable for several years.