5 - Nematodes

• Ascaris lumbricoides

• Ancylostoma duodenale

• Necator americanus

• Trichuris trichiura

• Enterobius vermicularis

• Strongyloides stercoralis

• Wuchereria bancrofti

seven examples of nematodes

intestinal nematode

what type of nematode is Ascaris lumbricoides?

Ascaris lumbricoides

also called giant roundworm

Ascaris lumbricoides

most common and largest nematode

Ascaris lumbricoides

Soil transmitted helminth

• small intestine

• soil

habitat of Ascaris lumbricoides

oval shaped with a thick chitin shell

characteristics of the egg of an Ascaris lumbricoide

• white

• elongated

• cylindrical

• lateral lines on each side

characteristics of the adult worm of an Ascaris lumbricoides

• ingestion of food or water contaminated with fecal material that contains ascaris embryonated egg (with larvae)

• survives gastric acidity

• reaches the duodenum

• excystation

• penetrate the intestinal wall

• reaches the blood circulation

• liver via portal circulation

• right side of the heart

• pulmonary vessels

• lung tissues, grow and develop there causes immune response there eventually

• cough out and swallowed again

• develop into adult worms in the small intestine

• adult worms will continue to reproduce and lay eggs, and these eggs/adult worms are seen in stool

life cycle of Ascaris lumbricoides

egg (embryonated)

infective stage of Ascaris lumbricoides

• egg (unembryonated-fertilized or unfertilized, embryonated, decorticated)

• adult worm

diagnostic stage of Ascaris lumbricoides

man

definitive host of Ascaris lumbricoides

none

intermediate host of Ascaris lumbricoides

fecal oral

mode of transmission of Ascaris lumbricoides

fertilized Ascaris lumbricoides egg

specific type of egg, and nematode

unfertilized Ascaris lumbricoides egg

specific type of egg, and nematode

Ascaris lumbricoides

what nematode?

ascariasis

disease caused by Ascaris lumbricoides

Loeffler’s Syndrome

what syndrome is caused by the lung phase of Ascaris lumbricoides?

larval migration

when does the major damage of ascariasis occur?

• acute intestinal obstruction

• malabsorption → malnutrition

what is caused by the intestinal phase of Ascaris lumbricoides?

wandering worm

what worm of Ascaris lumbricoides causes pancreatitis and appendicitis?

• direct fecal smear (egg)

• Kato-Katz technique

• direct visualization of adult worm

diagnosis of Ascaris lumbricoides

intestinal nematode

what type of nematode is Ancylostoma duodenale and Necator americanus?

• Ancylostoma duodenale

• Necator americanus

soil-transmitted, blood-sucking helminth

• small intestine

• soil

habitat of Ancylostoma duodenale and Necator americanus

hookworm

what type of worm is Ancylostoma duodenale and Necator americanus

thin wall and colorless with at least 4-8 blastomeres

characteristics of the eggs of Ancylostoma duodenale and Necator americanus

• small

• cylindrical

• characterisitc mouths

characteristics of the adult worms of Ancylostoma duodenale and Necator americanus

Necator americanus

new world hookworm

Necator americanus

the american murderer

cutting plates

characteristic mouth of Necator americanus

Ancylostoma duodenale

old world hookworm

2 pairs of ventral teeth

characteristic mouth of Ancylostoma duodenale

Ancylostoma duodenale and Necator americanus

what egg

Ancylostoma duodenale and Necator americanus

what worm

Ancylostoma duodenale

what worm

Necator americanus

what worm

• filariform larva found in soil penetrates thru the skin (percutaneous)

• blood venous system

• right side heart

• pulmonary vessels

• coughed out and swallowed again

• matures in the small intestine

• adult worm at mucosa of small intestine attached by means of their teeth, and feed on lymph and plasma

• as the adult worm grows, they also reproduce eggs which are eventually passed in feces and deposited in soil

• larva rapidly develops in eggs and hatches thereafter

• larva lives in the soil (rhabditiform larva)

• matures to filariform larva

life cycle of Ancylostoma duodenale and Necator americanus

• filarial form (ppt)

• filariform larva (google)

infective stage of Ancylostoma duodenale and Necator americanus

man

definitive host of Ancylostoma duodenale and Necator americanus

none

intermediate host of Ancylostoma duodenale and Necator americanus

larval skin penetration

mode of transmission of Ancylostoma duodenale and Necator americanus

• small intestine

• soil

habitat of Ancylostoma duodenale and Necator americanus

hookworm infection

disease caused by Ancylostoma duodenale and Necator americanus

blood loss at attachment site

major damage of hookworm infection is due to what?

hookwrom infection

major damage if this disease is due to blood loss at attachment site

ascariasis

major damage of this disease occurs during larval migration

• ground itch

• cutaneous larva migrans

diseases caused by the cutaneous phase of Ancylostoma duodenale and Necator americanus

Loeffler’s Syndrome

diseases caused by the lung phase of Ancylostoma duodenale and Necator americanus

• anemia

• malnutrition

• destroy villi

diseases caused by the intestinal phase of Ancylostoma duodenale and Necator americanus

• direct fecal smear (egg)

• Kato-Katz technique

diagnosis of Ancylostoma duodenale and Necator americanus

intestinal nematode

what type of nematode is Trichuris trichiura?

whipworm

what type of worm is Trichuris trichiura?

Trichuris trichiura

soil transmitted helminth

• large intestine

• soil

habitat of Trichuris trichiura

barrel shaped with bipolar mucus plugs

egg of Trichuris trichiura

japanese lantern appearance

appearance of the egg of Trichuris trichiura

• anterior 2/3 is attenuated

• posterior 1/3 is stout

adult worm of Trichuris trichiura

• ingestion of food or water contaminated with fecal material containing trichuris embryonated egg

• in the small intestine, one of the bipolar end will open

• larva leaves the egg

• larva enters the mucosal crypts in the small intestine

• transform to adult worm

• adult worm attaches to cecum

• increase their number in the large intestine

• egg passed out in the feces and reaches the soil

life cycle of Trichuris trichiura

embryonated egg

infective stage of Trichuris trichiura

unembryonated egg

diagnostic stage of Trichuris trichiura

man

definitive host of Trichuris trichiura

none

intermediate host of Trichuris trichiura

fecal-oral route

mode of transmission of Trichuris trichiura

whipworm infection

disease caused of Trichuris trichiura

• diarrhea

• increased peristalsis → rectal prolapse

what is whipworm infection?

Trichuris trichiura

what nematode is this?

• direct fecal smear (egg)

• Kato-Katz technique

diagnosis of Trichuris trichiura

intestinal nematode

what type of nematode is Enterobius vermicularis?

pinworm

what type of worm is Enterobius vermicularis?

Enterobius vermicularis

soil trasmitted helminth

• large intestine

• soil

habitat of Enterobius vermicularis

embryonated egg; Trichuris trichiura

type of egg, and what nematode

unembryonated egg; Trichuris trichiura

type of egg, and what nematode

Enterobius vermicularis

egg of what nematode?

d-shaped ovum with thin colorless cell wall

egg of Enterobius vermicularis

round body with lateral wings or cephalic alae

adult worm of Enterobius vermicularis

cephalic alae

lateral wings

• ingestion of food or water contaminated with fecal material containing embryonated egg or inhalation of embryonated egg

• larvae hatches in small intestine

• adult worm develops

• moves to perianal skin to lay eggs at night

• female fies after oviposition

• eggs laid on perianal area matures within 6 hours

• contaminates feces or the hand when scratched

life cycle of Enterobius vermicularis

embryonated egg

infective stage of Enterobius vermicularis

eggs on perianal folds

diagnostic stage of Enterobius vermicularis

man

definitive host of Enterobius vermicularis

none

intermediate host of Enterobius vermicularis

• fecal-oral route

• inhalation of eggs

mode of transmission of Enterobius vermicularis

enterobiasis

disease caused by Enterobius vermicularis

pruritus ani

symptom of enterobiaisis

autoinfection

what is the risk of enterobiasis?

cellulose tape preparation / scotch tape test (eggs)

diagnosis of Enterobius vermicularis

threadworm

what type of worm is Strongyloides stercoralis?

Enterobius vermicularis

what nematode is this?

Strongyloides stercoralis

what nematode is this?

facultative parasite

what type of parasite is Strongyloides stercoralis based on its dependency on a host?

• parasitic form

• free-living form

what are the two forms of Strongyloides stercoralis

• adult - male and female

• filariform larvae (infective and non-feeding stage)

• rhabditiform larvae (feeding stage)

stages of Strongyloides stercoralis

parasitic female - longer and larger than free-living form and their vulva is longer in their bodies

parasitic male - only free-living form

difference between parasitic female and parasitic male of the Strongyloides stercoralis

ovum

thin shelled partially embryonated

filariform larvae

larva that is slender, longer, and can swim in water

rhabditiform larvae

larva that is stout and shorter

• filariform larvae

• percutaneous penetration

• blood

• lymph

• small intestine

• larva develop into female adult worm

• females produce and lay eggs

• larva turns into rhabditiform larva

• passed out in stools

• filariform larva

life cycle of parasitic Strongyloides stercoralis