Final Study Questions- Helminths (Ch. 23)

Which worms have a cylindrical body that is tapered at each end, a complete digestive system, some are free- living in soil and water, while others are parasites of plants or animals?

Nematodes or roundworms

Which species of Schistosoma attacks urinary bladder, and causes dysuria and hematuria, and is found in Africa, Middle East, especially Egypt?

S. haematobium

Which species of Schistosoma is found in East Asia?

S. japonicum

Which species of Schistosoma is found in Africa, Middle East, South America, and Caribbean?

S. mansoni

In which two species of Schistosoma travels to the liver and causes hepatic and intestinal symptoms such as diarrhea, abdominal pain, and hepatosplenomegaly?

S. mansoni and S. japonicum

How is Enterobius vermicularis diagnosed?

Scotch tape test- take scotch tape and pick up worms.

What can hookworm infection lead to?

Significant blood loss which can cause anemia

What are the 2 intermediate hosts involved in Lung Fluke disease?

Snail and crab or crayfish

What are the 2 intermediate hosts that are required to complete the life cycle of Clonorchis sinensis?

Snail and freshwater fish

Which 2 trematodes have snails as one of the intermediate hosts?

Clonorchis sinensis and Paragonimus westermani

What are the 3 pathogens of Schistosoma?

1. S. haematobium 2. S. mansoni 3. S. japonicum

What are the 3 human pathogens of Trematodes?

1. Schitosoma 2. Clonorchis sinensis 3. Paragonimus westermani

How are infections with Enterobius vermicularis spread?

Adule female crawls out of anus at night to deposit eggs which can be spread orally to another human.

What is the scientific name for the hookworm that causes European infections?

Ancylostoma duodenale

What is the name given to the disease that is caused by the accidental ingestion of raw of undercooked meat that contains larvae of the nematodes Anisakis simplex and Pseudoterranova decipiens?

Anisakiasis

Which disease is most frequently diagnosed when the individual feels a tingling or tickling sensation in the throat, and coughs up or manually extracts a nematode?

Anisakiasis

Which nematode parasite of humans is a large, white worm with distinctive sexes (dioecious), lives in small intestine of humans and domestic animals and prevalence may exceed 50% in moist tropical countries?

Ascaris lumbricoides

What disease does Wuchereria Bancroft cause?

Bancrofiam filariasis

In which disease endemic in warm, humid regions of the world do the adult worms live in the lymphatic system of humans, and the females produce microfilaria that travel through the bloodstream?

Bancroftian filariasis

Why is infection with helminths so difficult to spread out of endemic area?

Because life cycle is dependent on many intermediate hosts, which may be unavailable in a new country.

What is a possible long term consequence of infection with S. heamatobium?

Bladder cancer or infertility in males.

Which disease if found in southeast Asia and Indonesia, has clinical manifestations similar to Wuchereria Bancroft, but attacks the fever and lymphadenitis may be more severe, and elephantiasis is usually confined to extremities, especially legs and below knees?

Brugia species (Brugian filariasis)

How can the Guinea worm be removed?

By catching the tail of the worm and winding it up on a stick.

How can the life cycle of helminths be controlled?

By eliminating the vector or intermediate host through the use of insecticides, etc.

How do humans get infected with Clonorchis sinensis?

By ingesting undercooked fish containing larval cysts. The larvae are freed during digestion and travel to the bile ducts. The eggs are then evacuated in human feces, and hatched into larvae in water.

Which type of platyhelminth has a head or scolex with suckers or hooks for attaching to intestinal mucosa of host?

Cestodes (tapeworms)

What species of the deer fly causes Loa loa?

Chrysops species

Which trematode causes Chinese or Oriental Liver Fluke disease that is endemic in Southeast China and Asia?

Clonorchis sinensis

What is the form of the disease of tapeworms where humans are intermediate host and the larvae encyst in the muscle or brain of humans?

Cysticercosis

The life cycle of helminths may be very complex, with a succession of intermediate hosts required for various larval stages. Adults can be dioecious or monecious. What do these terms mean?

Dioecious means the adults can be either male or female. Monoecious means the adults possess both sex organs (some can fertilize themselves.

What 2 animals can be the definitive host for Cystic Hydatid disease?

Dog or coyote

What is another name for the Guinea worm?

Dracunculus

Which pathogen is found in dry areas of Africa, India, and Yemen where people get infected by drinking standing water containing a tiny water flea that is infected with the larvae of the Guinea worm? Upon ingestion, the larvae migrates to subcutaneous tissue (usually the leg) and matures.

Dracunculus or Guinea worm

Which tapeworm causes Cystic Hydatid disease?

Echinococcus granulosus

How are the eggs for S. mansoni and S. japonicum passed?

Eggs are passed in the feces.

When nematodes are parasites in humans, which two stages are infective?

Either egg or larva is the infective stage

What is the worse case scenario for people with Bancroftian filariasis?

Elephantiasis of limbs, brests, genitalia (any lymph rich area)

Which roundworm causes Enterobiasis, is a pinworm, and is the most common worm infection in the US?

Enterobius vermicularis

Which roundworm or nematode lives their entire life in the large intestine of humans and so is called a uniquely human pathogen?

Enterobius vermicularis

In the parasitic life cycle of Strongyloids stecoralis what is the sex of the worms that are found in the superficial tissues of human small intestine?

Female- apparently there are no male parasites.

What is the characteristic of a gravid proglottid?

Filled with eggs

What are Platyhelminths?

Flatworms

Which helminths have digestive, nervous, circulatory, excretory and reproductive systems? Parasitic or free-living?

Free-living

In Schistosoma when the worms travel through the human circulatory system and get lodge in various organs, what structures do they form?

Granulomas

What are eukaryotic worms called?

Helminths

In which nematodes does the adult live in the small intestines of humans, excretes eggs in feces, the eggs then hatch into larvae that can burrow into feet of humans walking barefoot?

Hookworm (Necator americanus and Ancylostoma duodenal)

What nematode causes ground itch?

Hookworm (Necator americanus and Ancylostoma duodenal)

Who gets infected with Brugian filariasis?

Humans, monkeys, and wild and domestic carnivores

Why should the cysts of Echinococcus granulosus be surgically removed from the liver or lungs of human or mammals without breaking?

If they break, they may cause anaphylactic shock.

How are the eggs for S.heamatorbium passed out?

In urine

What are nematodes?

Roundworms

Which stage of a helminth's lifecylce usually consists of an egg, cyst, or larva and is the infective stage?

Intermediate stage

How is Bancroftian filarias transmitted to humans?

It is transmitted by a mosquito bite by various species of mosquitos including day biters.

Which pathogen is prevalent in African rainforest- up to 90% of inhabitants may be affected, travels through the bloodstream, migrate as adults through subcutaneous tissue, and may actually be visible from outside the body, and may migrate in the conjuctiva and can result in blindness?

Loa loa

Which pathogen of nematodes is transmitted by infected deer fly into tissue?

Loa loa

What are the symptoms of swimmer's itch?

Local skin inflammation

In Bancroftian filariasis, what is the name given to the entity that is injected by the mosquito?

Microfilaria

Are helminths unicellular or mutlicellular eukaryotes?

Multicellular

What is the scientific name for the hookworm that causes American infections?

Necator americanus

Which trematode causes Lung Fluke disease?

Paragonimus westermani

Which disease does China as its main endemic country, but is also found throughout the world, and is obtained when humans ingest undercooked crabs containing infective larvae, which migrate through tissue and encapsulate in the lungs? Effs are coughed up in sputum, swallowed and eventually passed out in feces into fresh water?

Paragonimus westermani or Lung Fluke disease

Helminth can be characterized as parasitic and free-living. Which may be lacking such systems as digestive, nervous, circulatory, excretory and reproductive systems, and because of this depends on host for many needs?

Parasitic form

What are the series of segments in the body of a cestode or tapeworm called that contains both male and female sex organs?

Proglottids

How can Schistosoma be spread?

Spread when human feces or urine enter water supply. The eggs hatch into free-living larvae which penetrate snails and develop into next larval stage. The eggs are released from the snail and become free-swimming. When humans wade or wash in the water, the larva burrow into the skin.

Which nematode is a usual parasite because it has both free-living and parasitic life cycles?

Strongyloides stercoralis

In what nematode does autoinfection occur where under circumstances such as chronic constipation, the larvae produced by the parasitic female will remain in the intestinal tract long enough to develop into infective stages, and in doing so will penetrate the tissues of the intestinal tract and develop as if they had penetrated the skin?

Strongyloides sterocoralis

Schistosomas that infect birds and mammals can sometimes burrow into humans if larvae are present while humans are in water. What is this infection by Schistosoma called?

Swimmer's itch

What is the scientific name for a beef tapeworm?

Taenia saginata

What is the scientific name for a pork tapeworm?

Taenia solium

The name Schistosoma means "split body". Why does the term "split body" or Schistosoma refer to?

The fact that the female lives inside a groove in the male's body.

Which part of the cestode contains fertilized eggs?

The proglottid that is furthest from the scolex contains the fertilized eggs.

Why do cestodes or tapeworm "steal" food from small intestine and are unable to ingest tissue of small intestine?

They do not have a digestive system to process the tissue.

Which nematode parasite of humans can cause ocular larva mirganes (OLM), and eye disease that occurs when a microscopic worm enters the eye?

Toxocara

According to the CDC, 14% of US is infected with 2 species of Toxocara. What are they?

Toxocara canis (dog) and Toxocara cati (cat)

What is the name given to the helminths called flukes that have leaf shaped bodies, and are usually named for the organs they invade?

Trematodes

What are the 2 classes of Platyhelminths that are of importance to humans?

Trematodes (flukes) and cestodes (tapeworms)

Which nematode is acquired in humans by eating encysted larvae in undercooked pork or game animals such as bear?

Trichinella spiralis

Where are hookworms disease endemic?

Tropical and subtropical countries

What is the characteristic of mature proglottid?

Uterine branches

Heavier or repeated Toxocara infections are rare, but the can cause swelling of the body's organs or central nervous system. What is this disease called?

VLM or Visceral larva migrans

How is Trochinosis or Trichinellos is acquired?

When encysted larvae of undercooked pork or game animal such as bear is eaten, the cysts are digested in the human GI tract, the larvae matures into adults and sexually reproduce in the small intestine. The female then gives birth to live nematodes which enter the lymph and blood circulation, encyst in muscle and other tissue until eaten by new host.

How can humans become the definitive host for the beef or pork tapeworm?

When infected human feces is eaten by grazing animals, the larvae hatch and bore through the intestinal wall of animal, migrate to the muscle and encyst. Humans are then infected by eating the cysts in meat. The result is ultimately the adult tapeworm living in human's intestine.

How can humans become the intermediate hosts for the pork tapeworm?

When the pork tapeworm eggs are ingested by human instead of pigs. Larvae will hatch in small intestine and bore through intestinal wall. These will encyst in muscles or brain of human.