Helminths

Question 1

Nematodes

Roundworms

Answer 1

Ascaris
Pinworms
Whipworms
Hookworms

Question 2

One of the largest and most ubiquitous

Most common infection caused by soil-transmitted helminthes

1 billion infected worldwide

Answer 2

A. lumbricoides (Ascaris)

Question 3

Most common helminth infection in US

Oral-fecal transmission; eggs can be in dust/clothes

Answer 3

Enterobius vermicularis (scratchy butt)

Question 4

Similar to pinworm lifecycle except eggs require 2-3 wks in soil to become infectious

Answer 4

Trichuris trichuria

“whip” like appearance

Question 5

Most important complication is iron deficiency anemia

Walk on soil= penetration–> get to circulation and lungs –> cough and swallow –> Attach and mate in intestine

Answer 5

Anclyostoma, Necator
In tropics

Hookworms

Question 6

eggs hatch in intestinal mucosa and rhabditiform larvae are passed in feces

More in immunosuppressed i.e. AIDS patients or high dose corticosteroids

Answer 6

Strongyloides

Question 7

From ingesting eggs from feces of animals NOT from eating animal itself

Liver and lung are most common site of cysts
Like slow growing tumor

Answer 7

Echinococcus granulosus (hydatid cyst)

Cestodes (Tapeworms)

Question 8

Embryonated eggs ingested by (pig/cow)

Humans eat undercooked meat , scolex attaches to intestinal wall, produce strobila

In pork, BUT NOT BEEF, cysticercosis can develop and the human can transmit

Answer 8

Taenia species

Question 9

Taenia species

Anterior attachment organ=Scolex

____ chain of segments (proglottids)

T. saginata=beef tapeworm –requires intermediate host

T. solium=pork tapeworm

Answer 9

Strobila

Question 10

Requires 2 intermediate hosts

Answer 10

Diphyllobothrium latum
“Fish tapeworm”

Eggs passed in feces hatch into ciliated coracidium larvae–> then ingested by small crustaceans

Fish eat the infected crustaceans–> third stage larvae develops

Human eats fish; larva grow in small intestine

Question 11

Taenia species

Anterior attachment organ=_____

Strobila=chain of segments (proglottids)

T. saginata=beef tapeworm –requires intermediate host

T. solium=pork tapeworm

Answer 11

Scolex

Question 12

Diphyllobothrium latum
“Fish tapeworm”

Eggs passed in feces hatch into ciliated coracidium larvae–> then ingested by small crustaceans

Fish eat the infected crustaceans–> third stage larvae develops

Human eats fish; larva grow in ______

Answer 12

small intestine

Question 13

Taenia species

Anterior attachment organ=Scolex

Strobila=chain of segments (proglottids)

_____ =beef tapeworm –requires intermediate host

T. solium=pork tapeworm

Answer 13

T. saginata

Question 14

Mainly in kids
no intermediate host needed
Polar filaments or ova in feces

Answer 14

Hymenolepis nana

Question 15

may produce a B12 deficiency anemia indistinguishable from pernicious anemia

Answer 15

Diphyllobothrium latum

“Fish tapeworm”

Question 16

Taenia species

Anterior attachment organ=Scolex

Strobila=chain of segments (proglottids)

T. saginata=beef tapeworm –requires intermediate host

_____ =pork tapeworm

Answer 16

T. solium

Question 17

Used to be very common, but now only ~100 cases/yr, usually from undercooked pork or consumption of wild animals

Answer 17

Trichinella spiralis

Question 18

Trichinosis: larvae in _____________

Bilat periorbital edema, conjunctivits

Answer 18

heart, muscle, brain and GI tract

Immunological tests or muscle biopsy in setting of symptoms and marked eosinophilia

Question 19

Most common cause of lymphatic filariasis (usu unilateral)

Agent of elephantiasis=grotesque swollen limbs and scrotum

Answer 19

Wuchereria bancrofti (Filaria)

Transmitted by mosquitoes; humans are only reservoir

Question 20

Transmitted by black fly, simulium

causes river blindness

Answer 20

Onchocerca volvulus

–> itching in eye–> blindness

Question 21

Dermatitis (“swimmer’s itch”)
Katayama fever
Chronic fibro-obstructive sequalae

Answer 21

Schistosomes

Trematodes (Flatworms or Flukes)

Ova in urine

Question 22

S. mansoni (gut): Arabia, Africa, Caribbean, S. America

S. japonicum (gut): China, Japan, Phillipines

S. haematobium (______): Africa, Middle East

Answer 22

bladder

Question 23

Heavy infection= abd pain with bloody or mucoid diarrhea; appendicitis; prolapsed, edematous rectum

Answer 23

Whipworms

Question 24

No eosinophilia

Answer 24

Whipworms

Question 25

Pneumonitis

Sudden asthma attacks in non-asthmatics

Heavy infections of adult worms may cause intestinal obstruction

Answer 25

A. lumbricoides (Ascaris) ((Nematodes (Roundworms)))