Helminths: Nematodes/Roundworms (Exam 2)

______ can occur when infective eggs hatch inside the host and develop into an adult.

Auto-reinfection

The buccal cavity is the ______ of roundorms.

oral cavity

Corticated means possessing an outer, bumpy, ______ coating.

albuminous

Diurnal means occurring during the ______.

day

Elephantiasis is the overgrowth of the _______ and ______ in limbs or genitalia.

skin, subcutaneous tissue

Elephantiasis occurs as a result of obstructed ______ in the lymphatic vessels.

circulation

Microfilaria is the ______ stage of the filarial parasites.

embryo

Microfilaria are found in the ______ of humans.

blood/tissue

Filariform larva are ...

- Infective

- Non-feeding

- Sheathed

- 3rd stage larva

Filariform larva have a long, slender ______.

esophagus

Gravid means ______.

pregnant

Periodicity refers to ______ at a regular time.

recurring

Pruritus means intense ______.

itching

Rectal prolapse is the weakening of the rectal musculature resulting in ______ of the rectum.

"falling down"

Visceral larval migrans is a disease in humans caused by the migration of the larval stage of a roundworm through the ...

Liver, lungs, eye or other organs

Cutaneous larval migrans is a disease caused by the migration of the helminth larvae traveling under the ______ of humans.

skin

Cutaneous larval migrans is referred to as _______.

"creeping eruption"

What are the stages, in order, of the nematode life cycle?

1. Un-embryonated egg

2. Embryonated egg

3. Rhabditiform larva

4. Filariform larva

5. Adult

Un-embryonated egg characteristics

- Non-infective

- Resistant to drying, extreme temperatures, and UV light

- Thick shell

Embryonated egg characteristics

- Exits into environment

- Infective

- Hatch in soil or intestinal lumen

Rhabditiform larva characteristics

- First stage larva that hatches out of the egg

- Non-infective

- Long buccal cavity

- Short genital primordium

- Mini worm

- Feeds, molts

Filariform larva characteristics

- Infective

- Non-feeding

- Have buccal cavities

- Feed on humans (penetrates hands and feet)

Adult characteristics

- Stay in the intestines

- Possible to find a remnant in stool

Female nematodes are ______ than male nematodes.

larger

Female nematodes have a ______ and release 10,000-200,000 eggs per day.

genital primordium

Male nematodes have a ______ tail.

curled

Enterobius vermicularis common name

Pinworm

Trichuris trichiura common name

Whipworm

Ascaris lumbricoides common name

Giant intestinal worm

Ancylostoma duodenale common name

Old World hookworm

Necator americanus common name

New World hookworm

Strongyloides stercoralis common name

Thread worm

Enterobius vermicularis S/Sx

Pruritus

Trichuris trichiura S/Sx

Enteritis, diarrhea, rectal prolapse

Ascaris lumbricoides S/Sx

Pneumonia, diarrhea, bowel obstruction

Necator americanus S/Sx

Larval dermatitis, pulmonary issues, microcytic and hypochromic anemia

Strongyloides stercoralis S/Sx

Larval dermatitis, pulmonary issues, abdominal pain, vomiting, diarrhea, eosinophilia

Trichinella spiralis S/Sx

Gastric distress, fever, eye edema, eosinophilia, acute muscle pain

Toxocara canis/cati S/Sx

Fatigue, weight loss, ocular problems

Stool specimens are collected for examination of ...

Eggs, larvae, adult worms are rare

Enterobius vermicularis infects humans via ingestion of ______.

eggs

Trichuris trichiura infects humans via ingestion of ______.

eggs

Ascaris lumbricoides infects humans via ingestion of ______.

eggs

Ancylostoma duodenale infects humans via penetration of the ______ via filariform larvae.

skin

Necator americanus infects humans via penetration of the ______ via filariform larvae.

skin

Strongyloides stercoralis infects humans via penetration of the ______ via filariform larvae.

skin

Trichinella spiralis infects humans via ingestion of ______ in raw/undercooked pork, bear, or walrus meat.

larvae

Toxocara canis/cati infects humans via ingestion of ______ by paratenic hosts.

eggs

Larvae may enter lymphatics and the blood stream and travel to the ______.

lungs

From the lungs, they can be coughed back up, swallowed, and returned to the ______.

intestines

Submucosa females release larvae which disseminate into the ______.

bloodstream

This larvae encyst in ______.

striated muscle

Enterobius vermicularis egg

48-60um

Flattened on one side

Enterobius vermicularis adult

7-14mm

Trichuris trichiura adult

Female: 35-50mm

Male: 30-45mm with 360 degree coil at caudal end

Trichuris trichiura ova

50-54um

Double wall

Clear mucoid polar plugs

Ascaris lumbricoides adult

Female: 20-35cm

Male: 15-31cm with curved posterior

Ascaris lumbricoides fertile egg

45-70um

Oval

Ascaris lumbricoides infertile egg

90x40um

Elongated

Rough outer shell

Ancylostoma duodenale/Necator americanus ova

Female: 9-13mm

Male: 5-11mm

Head slightly bent

A. dudenale slightly longer than N. americanus

Ancylostoma duodenale have ______ in their buccal cavity.

teeth

Necator americanus have ______ in their buccal cavity.

cutting plates

Ancylostoma duodenale/Necator americanus rhabditiform larvae

275x16um

Ancylostoma duodenale/Necator americanus filariform larvae

Strongyloides stercoralis adult

Female: 2x0.04mm

Colorless

Strongyloides stercoralis egg

54x32um

Strongyloides stercoralis rhabditiform larva

380x20um

Short buccal cavity

Prominent genital primordium

Short tail

Strongyloides stercoralis filariform larva

630x16um

Notched tail

Trichinella spiralis adult

Female: 3.5x0.06mm

Male: 1.5x0.04mm

Trichinella spiralis larvae

Coiled in muscle in lemon shape

Toxocara canis/cati larvae

Larvae in biopsy specimens

Cats and dogs

Dracunculus medinesis

Guinea worm

Wuchereria bancrofti adult

230-300um

Sheath

No terminal nuclei

Short cephalic space

Wuchereria bancrofit has ______ periodicity.

noctural

Wuchereria bancrofti causes ______.

Elephantiasis

Granulomas, chills, fever, eosinophilia

Brugia malayi adult

175-250um

Sheath

2 nuclei at tip of tail

Long cephalic space

Brugia malayi has ______ periodicity.

nocturnal

Brugia malayi S/Sx

Granulomas, chills, fever, eosinophilia

(Same as Wuchereria bancrofti)

Loa loa adult

Sheath

Nuclei extend continuously into the tail

Loa loa is known as the ______.

African eye worm

Loa loa causes ______ swellings.

Calabar

Loa loa has ______ periodicity.

diurnal (afternoon)

Onchocerca volvulus adult

No sheath

Nuclei to the tip of the tail

Onchocerca volvulus is diagnosed via examination of ______.

skin snips/biopsies

Onchocerca volvulus causes ______.

River Blindness

And subcutaneous nodules

Dirofilaria immitis

Dirofilaria immitis is a heartworm disease in ______ only.

dogs

Dirofilaria immitis causes ______.

eosinophilia (pulmonary disease)

Vector for Wuchereria bancrofit

Culex and Anopheles mosquito

Vector for Brugia malayi

Anopheles and Aedes mosquitoes

Vector for Dirofilaria immitis

Aedes, Anopheles, Culex, Mansonia mosquitoes

Vector for loa loa

Chrysops deer fly

Vector for Onchocerca volvulus

Silulium black fly