Roundworms

Question 1

This roundworm - nematode is found worldwide, esp in kids. IT IS THE MOST COMMON HELMINTHIC INFECTION IN THE US; ingestion of eggs in fecally contaminated food -> infection; after male and female worms mate, the female briefly craws out of the anus and lays eggs in the perianal folds. It is ID’d by sticky-tape mounts of perianal region after the child wakes up; eggs should be thin-walled

Answer 1

Enterobius vermicularis - pinworm

Question 2

What disease does Enterobius vermicularis cause?

Answer 2

1. pruritis - induced by worm secretions
2. GU infections with granulomas
3. associated dientamoeba fragilis infections

Question 3

This roundworm - nematode IS THE MOST COMMON WORLDWIDE HELMINTHIC INFECTION, but confined to areas with poor sanitation; somewhat common in the southern US; ingestion of eggs in food or water contaminated with feces -> infection; the worm matures in the lung where it gets coughed up and swallowed to make it back to jejunum to mature to adulthood. ID’d by fecal smears with knobby eggs

Answer 3

Ascaris lumbricoides

Question 4

What diseases does Ascaris lumbricoides cause?

Answer 4

1. asymptomatic
2. pneumonitis
3. intestinal perforation
4. major organ damage

Question 5

This roundworm - nematode is the Ascaris of dogs and cats; found worldwide; larvae hatch in intestine, penetrate the intestinal wall, get into the blood and invade various tissues but cannot develop further bc humans are an inappropriate host.

Answer 5

Toxocaris canus/cati

Question 6

This roundworm - nematode is found worldwide but is associated with poor sanitation; ingestion of eggs from food contaminated with human feces -> infection; larvae hatch in small intestine and embed deep into the colonic mucosa. It is ID’d by fecal smears that show a few barrel-shaped egs with polar plugs

Answer 6

Trichuris trichura - whipworm

Question 7

What disease does Trichuris trichura - whipworm cause?

Answer 7

asymptomatic to bloody diarrhea, appendicitis, rectal prolapse

Question 8

This roundworm - nematode is found worldwide in tropical areas (southern US); penetration of the human skin by filariform larvae following contact of the skin with human fecally contaminated soil -> infection; larvae enter blood and go to lungs, get coughed up and swallowed to mature in the small intestine

Answer 8

necator americanus and ancylostoma duodenale (hookworms)

Question 9

What diseases do necator americans and ancylostoma duodenale cause?

Answer 9

1. pruritis at skin penetration site
2. diarrhea
3. pneumonitis
4. anemia

Question 10

This roundworm - nematode is found worldwide, esp in kids; penetration of skin by filariform larvae present on fecally-contaminated beaches -> infection; larvae stay trapped in skin.

Answer 10

anclyostoma braziliense

Question 11

What disease does anclyostoma braziliense cause?

Answer 11

cutaneous larva migrans, ground itch

Question 12

This roundworm - nematode is found worldwide; reservoir is domestic pets; infection follows skin penetration by filariform larvae -> blood -> lung -> intestine. ID’d by fecal smear with larvae.

Answer 12

Strongyloides stercoralis - threadworm

Question 13

What disease does Strongyloides stercoralis - threadworm cause?

Answer 13

1. ground itch
2. pneumonitis
3. asymptomatic to peptic ulcer-like diseae
4. disseminated disease and hyper-infection in IC

Question 14

This roundworm - nematode is found worldwide; ingestion of undercooked pork -> infection; walruses and polar bears are involved in transmission in the Arctic; larvae released from cysts in the intestine quickly develop into adults; can remain in muscle for years until they calcify. ID’d by microscopy of infected meat, marked eosinophilia

Answer 14

Trichinella Spiralis

Question 15

What disease does Trichenella Spiralis cause?

Answer 15

trichinosis - asymptomatic to lethal, depending on worm burden and wear cysts are located

Question 16

These roundworms - nematodes are found in many tropical and subtropical places; larvae in saliva of fly or mosquito enter the wound, migrate to the lymphatics and the fertilized females make microfilarial larvae for years, which remain in the circulation until they die. Disease results from inflammation. ID’d by marked eosinophilia.

Answer 16

Wuchereria bancrofti, Brugia malaya - mosquito vector
Loa loa - mango fly vector
Onchocerca volvulus - black flies or buffalo gnat vector

Question 17

What disease do W. Bancroft, B. malaya, Loa loa, and Onchocerca volvulus cause?

Answer 17

1. filariasis - vessel clogging type disease - elephatiasis (W. bancrofti/B. malaya)
2. Loiasis - worm in eye and elsewhere (Loa loa)
3. blindness - river blindness, winter bottom’s sign (O. volvulus)