Helminthic Infections

Question 1

Major component of inflammatory response to helminths?

Answer 1

• Eosinophils (contain basic toxic proteins)

Question 2

Cylindrical organisms with tubular digestive tracts?

Answer 2

• Roundworms (nematodes)

Question 3

Dorsoventrally flattened organsims with digestive tracts that end in blind loops?

Answer 3

• Flatworms (trematodes)

Question 4

Segmented organisms with separate head and body parts lacking a digestive tract and absorb nutrients through outer walls?

Answer 4

• Tapeworms (cestodes)

Question 5

Inflammatory parasitic infection of lymph vessels cause by roundworms Wuchereria bancrofti and Brugia malayi?

Answer 5

• Lymphatic filariasis

Question 6

Lymphatic Filariasis

Answer 6

• adult worms inhabit lymphatics in inguinal, epitrochlear, and axillary LNs, testis, epididymis
• if obstruction, severe lymphedema
• mosquito bites transmit infectious larvae that mature in LNs
• most severe form = elephantiasis
• worms are surrounded by inflammatory mediators

Question 7

Chronic Inflammation of skin, eyes and lymph caused by filarial nematode O. volvulus?

Answer 7

• Onchocerciasis - river blindness!

Question 8

Oncocerciasis

Answer 8

• transmitted by bites of blackflies
• adult worms live as coiled tangled masses in deep fasciae and subcutaneous tissue and release millions of microfilariae which migrate
• when migrate to all regions of the eye = blindness
• microfilarie die and produce vigorous inflammatory response
• can become encapsulated by fibrous scar and form nodules

Question 9

Infection by filarial nematode Loa loa

Answer 9

• Loiasis, African eyeworm

Question 10

Loiasis

Answer 10

• infection transmitted by mango flies
• adult worms can migrate in skin and cross beneath conjunctiva
• static worms surrounded by inflammatory cells

Question 11

Most common helminthic infection of humans, large roundworm and usually asymptomatic?

Answer 11

• Ascariasis, A. lumbricoides

Question 12

Ascariasis

Answer 12

• adult worms live in small intestine, penetrate bowel wall and reach lungs though venous circulation
• after leaving pulmonary capillaries, enter alveoli to glottis and are swallowed to again reach small bowel
• heavy infections can cause vomiting, malnutrition, and sometimes intestinal obstruction

Question 13

Trichuris trichiura

Answer 13

• Trichuriasis, intestinal nematode (whipworm)

- adult worms live in feces and upper colon and bury their anterior portion into the superficial mucosa

Question 14

Hookworms

Answer 14

• Necator americanus and Ancylostoma duodenale
• intestinal nematodes, infect human small bowel
• cause blood loss and anemia
• most important cause of chronic anemia worldwide

Question 15

Strongyloidiasis

Answer 15

• small intestinal infection with nematode S. stercoralis (threadworm)
• in immunocompromised, can progress to lethal disseminated disease
• adult females bury in crypts of duodenum or jejunum, lay eggs that hatch quickly and release rhabditiform larvae
• may reproduce in human hosts by autoinfection

Question 16

Pinworm

Answer 16

• Enterobiasis vermicularis, intestinal nematode
• perianal itching
• adult resides in cecum but migrates to perianal skin to deposit eggs

Question 17

Myositis associated with eating pork?

Answer 17

Trichinosis, from roundworm Trichinella spiralis

Question 18

Trichinosis

Answer 18

• inadequately cooked meat with encysted T. spiralis larvae
• larvae burrow into intestinal mucosa and develop into adult worms then enter circulation
• can only survive in striated skeletal muscle and elicits an intense inflammatory infiltrate
• in severe infections, eosinophilia can be extreme

Question 19

Infection of deep organs by visceral larva migrans, transmitted by cats and dogs?

Answer 19

Toxocariasis

Question 20

Toxocariasis

Answer 20

• infection of deep organs by helminthic larvae

- larvae invade intestinal wall, are carried to liver, and die in tissues to form small granulomas

Question 21

Cutaneous larva migrans

Answer 21

• larval nematodes migrating through skin and causing pruritis and serpiginous urticarial trails

Question 22

Dracunculiasis

Answer 22

• guinea worm, features long adult worms beneath skin
• transmitted in drinking water
• reddish papule with anterior end of female worm underneath, which can burst forward and spew larvae in water

Question 23

Schistosomiasis

Answer 23

• most important human helminthic disease (greater morbidity and mortality)
• damage to the liver, intestine, or urinary bladder
• alternate between asexual reproduction in snail and sexual reproduction in vertebrate host
• S. mansoni and S. japonicum deposit eggs in intestinal venules
• S. haematobium lays eggs in urinary bladder
• cicumscribed granuloma or cellular infiltrate of eosinophils and neutrophils around an egg
• progresses from granulomas to fibrosis

Question 24

Inhabits branches of IMV (affects distal colon, liver)

Answer 24

S. mansoni

Question 25

Inhabits veins of rectum, bladder, pelvic organs

Answer 25

S. haematobium

Question 26

Inhabits branches of SMV (affects small bowel, ascending colon, liver)

Answer 26

S. japonicum

Question 27

Infection of the hepatic biliary system by Chinese liver fluke

Answer 27

• Clonorchiasis (Clonorchis sinensis)

Question 28

Clonorchiasis

Answer 28

• sometimes associated with bile duct stones, cholangitis, and bile duct cancer

Question 29

Paragonimiasis

Answer 29

• pulmonary infection by oriental lung fluke

- peripheral eosinophilia common

Question 30

Biliary disease acquired from sheep?

Answer 30

Fascioliasis (sheep liver fluke F. hepatica)

Question 31

Fascioliasis

Answer 31

• hepatic abscesses and granulomas

Question 32

Fasciolopsiasis

Answer 32

• F. buski

- attaches to duodenal or jejunal wall which may ulcerate

Question 33

Tapeworms

Answer 33

Taenia saginata (beef)
Taenia solium (pork) - cysticercosis - systemic
Diphullobothrium latum (fish)
Echinococcus granulosus (dog feces) - liver and lungs