The NematodesThe Nematodes

Ascaris lumbricoidesAscaris lumbricoidesCommon name: Giant intestinal round wormCommon name: Giant intestinal round worm

Disease: Human ascariasisDisease: Human ascariasis

MorphologyMorphology

It is the largest and the most common It is the largest and the most common nematode in man.nematode in man.

15-30 cm by 3 mm (male).15-30 cm by 3 mm (male). 20-45 cm by 5 mm (female).20-45 cm by 5 mm (female). Creamy white or pinkish worm.Creamy white or pinkish worm. Cylindrical, elongated, tapering gradually at Cylindrical, elongated, tapering gradually at

the anterior end.the anterior end.

Ascaris lumbricoides adult male and female © Ascaris lumbricoides adult male and female © Dr Peter Dr Peter DarbenDarben, , Queensland University of Technology clinical parasitology Queensland University of Technology clinical parasitology

collection. Used with permissioncollection. Used with permission

Diagnostic FeaturesDiagnostic Features

Smooth finely striated cuticle with faint Smooth finely striated cuticle with faint longitudinal white lateral lines. Which is longitudinal white lateral lines. Which is seen as a whitish streak along the entire seen as a whitish streak along the entire length of the body.length of the body.

Terminal mouth with trilobate lips and a Terminal mouth with trilobate lips and a small triangular buccal cavitysmall triangular buccal cavity

An adult Ascaris worm. Diagnostic characteristics: tapered ends; length 15-35 cm (the An adult Ascaris worm. Diagnostic characteristics: tapered ends; length 15-35 cm (the females tend to be the larger ones). This worm is a female, as evidenced by the size and females tend to be the larger ones). This worm is a female, as evidenced by the size and

genital girdle (the dark circular groove at bottom area of image). Worm passed by a female genital girdle (the dark circular groove at bottom area of image). Worm passed by a female

child in Florida. CDC  child in Florida. CDC  DPDxDPDx Parasite Image Library Parasite Image Library

The male has a ventrally curved papillated The male has a ventrally curved papillated posterior extremity with 2 copulatory posterior extremity with 2 copulatory spicules.spicules.

The female has paired reproductive organs The female has paired reproductive organs on the posterior 2/3.on the posterior 2/3.

And in the anterior and middle third is a And in the anterior and middle third is a depression wherein a vagina is located.depression wherein a vagina is located.

OvaOva There are two types of ova:There are two types of ova: Fertilized: broadly ovoid, golden brown in Fertilized: broadly ovoid, golden brown in

color.color.– A. vitelline membrane: an inner non-A. vitelline membrane: an inner non-

permeable, lipoidal layer.permeable, lipoidal layer.– B. glycogen membrane: thick, transparent B. glycogen membrane: thick, transparent

middle layer.middle layer.– C. Albuminous/ mammillary coat: outermost C. Albuminous/ mammillary coat: outermost

layer.layer.

A fertilized Ascaris egg, still at the unicellular stage, as they are when passed in stool. A fertilized Ascaris egg, still at the unicellular stage, as they are when passed in stool. Eggs are normally at this stage when passed in the stool (Complete development of the Eggs are normally at this stage when passed in the stool (Complete development of the

larva requires 18 days under favorable conditions).larva requires 18 days under favorable conditions).

Eggs, unfertilized (left) and fertilized (right). Patient seen in Haiti. CDC Eggs, unfertilized (left) and fertilized (right). Patient seen in Haiti. CDC DPDxDPDx

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Unfertilized: generally larger and longer, Unfertilized: generally larger and longer, elongated or sometimes irregular in shape.elongated or sometimes irregular in shape.

With 2 layers, relatively thinner glycogen With 2 layers, relatively thinner glycogen membrane and irregular coating of membrane and irregular coating of albuminous layer.albuminous layer.

The vitilline layer is absent.The vitilline layer is absent. If mammilary coat is absent it is called If mammilary coat is absent it is called

decorticated.decorticated.

Larva hatching from an egg. CDC Larva hatching from an egg. CDC DPDxDPDx

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Life cycleLife cycle

Fertilized ovaFertilized ovasoil 2 weekssoil 2 weeksembryonation embryonation ingestedingestedcirculationcirculationheart heart and lungsand lungsesophagusesophagus>SI>SI

Pathology Pathology

A. Larval Migration to lungs can produce:A. Larval Migration to lungs can produce:– Pneumonitis resembling asthmatic attack Pneumonitis resembling asthmatic attack

accompanied by marked eosinophilia (ascaris accompanied by marked eosinophilia (ascaris pneumonitis of loeffler’s syndrome).pneumonitis of loeffler’s syndrome).

Clinical manifestations:Clinical manifestations:

Asthmatic type of respiration, cough, urticaria, Asthmatic type of respiration, cough, urticaria, rash,edema of the lips and eosinophilia.rash,edema of the lips and eosinophilia.

Ascaris lumbricoides larva in section of lung (H&E)  © Ascaris lumbricoides larva in section of lung (H&E)  © Dr Peter Dr Peter DarbenDarben, , Queensland University of Technology clinical parasitology collection. Used with Queensland University of Technology clinical parasitology collection. Used with

permissionpermission

B. Pathology due to Adult Worm.B. Pathology due to Adult Worm. Abdominal pain, diarrhea, nausea, loss of Abdominal pain, diarrhea, nausea, loss of

appetite.appetite. Serious and sometimes fatal effects due to Serious and sometimes fatal effects due to

erratic migration of adult worms. They erratic migration of adult worms. They maybe regurgitated and vomited and may maybe regurgitated and vomited and may escape through the nostrils. escape through the nostrils.

Ascaris may pass the larynx and may lead Ascaris may pass the larynx and may lead to suffocation.to suffocation.

Or they may reach the lungs and produce Or they may reach the lungs and produce pulmonary gangrene or may pass the pulmonary gangrene or may pass the uestachian tube and provoke otitis media.uestachian tube and provoke otitis media.

They may invade the bile duct, gall bladder, They may invade the bile duct, gall bladder, liver and appendix.liver and appendix.

Diagnosis Diagnosis

Diagnosis is made by finding the eggs in the Diagnosis is made by finding the eggs in the feces, fertilized or unfertilized by performing feces, fertilized or unfertilized by performing DFS, kato-thick, kato-katz or concentration DFS, kato-thick, kato-katz or concentration technique.technique.

Stool examination may give negative Stool examination may give negative findings in the following conditions:findings in the following conditions:– When the patient is actually free from Ascaris When the patient is actually free from Ascaris

infection.infection.– Worms are still immature in the lumen.Worms are still immature in the lumen.– During larval migrationDuring larval migration– When only male worms are present in the When only male worms are present in the

intestine.intestine.

Treatment Treatment

Piperazine citrate, pyrantel pamoate, Piperazine citrate, pyrantel pamoate, mebendazole, albendazole, levimazole.mebendazole, albendazole, levimazole.

Piperazina and pyrantel pamoate are used Piperazina and pyrantel pamoate are used these days because these drugs have a these days because these drugs have a neuromuscular blocking effect on the neuromuscular blocking effect on the parasite causing paralysis.parasite causing paralysis.

Toxocara canis and Toxocara cattiToxocara canis and Toxocara catti Common name: Dog ascaris and Cat Common name: Dog ascaris and Cat

ascarisascaris Disease: toxocariasis/visceral larval migransDisease: toxocariasis/visceral larval migrans

Life cycleLife cycle

Pathology Pathology

Larval migrans can produce hemorrhage, Larval migrans can produce hemorrhage, necrosis and granuloma of the site.necrosis and granuloma of the site.

Eosinophilia, liver damage, pulmonary Eosinophilia, liver damage, pulmonary inflammation, and ocular problems has been inflammation, and ocular problems has been observed.observed.

Among children anemia with high WBC Among children anemia with high WBC count.count.

Diagnosis Diagnosis

Diagnosis is usually stablsihed on clinical Diagnosis is usually stablsihed on clinical grounds.grounds.

Examination of egg in the stool of the patient Examination of egg in the stool of the patient is not useful because the egg laying adults is not useful because the egg laying adults are not present.are not present.

However, examination of fecal material from However, examination of fecal material from infected pets often supports the diagnosis.infected pets often supports the diagnosis.

Treatment Treatment

Because the clinical course of VLM is so Because the clinical course of VLM is so variable, it is very difficult to evaluate variable, it is very difficult to evaluate efficacy of any treatment. Since the infection efficacy of any treatment. Since the infection is self limited. Only severe cases needs to is self limited. Only severe cases needs to be treated. Thiabendazole appears to be treated. Thiabendazole appears to shorten the course of the disease.shorten the course of the disease.

Eggs of Toxocara canis. These eggs are passed in dog feces, especially puppies' feces. Eggs of Toxocara canis. These eggs are passed in dog feces, especially puppies' feces. Humans do not produce or excrete eggs, and therefore eggs are not a diagnostic finding in Humans do not produce or excrete eggs, and therefore eggs are not a diagnostic finding in human toxocariasis! The egg to the left is fertilized but not yet embryonated,  while the egg human toxocariasis! The egg to the left is fertilized but not yet embryonated,  while the egg to the right contains a well developed larva. The latter egg would be infective if ingested by to the right contains a well developed larva. The latter egg would be infective if ingested by

a human (frequently, a child).  CDC a human (frequently, a child).  CDC DPDxDPDx Parasite Parasite

Toxocara canis (Dog Roundworm) egg, embryonated   © Toxocara canis (Dog Roundworm) egg, embryonated   © Dr Peter Dr Peter DarbenDarben, , Queensland University of Technology clinical parasitology collection. Used with Queensland University of Technology clinical parasitology collection. Used with

permissionpermission

Trichuris trichiuraTrichuris trichiura Common name: whipwormCommon name: whipworm

Disease: trichuriasis Disease: trichuriasis

Morphology Morphology Adult Adult They attach to the cell wall of the cecum.They attach to the cell wall of the cecum. Colored or pinkish, the anterior end is Colored or pinkish, the anterior end is

attenuated, whip-like, while the posterior attenuated, whip-like, while the posterior end is more robust.end is more robust.

3.5-5 cm ( female) straight post. End3.5-5 cm ( female) straight post. End 3-4.5 cm ( male) coiled 3603-4.5 cm ( male) coiled 36000 with a with a

sheathed single spicule.sheathed single spicule.

Trichuris trichiura adult male and female © Trichuris trichiura adult male and female © Dr Peter Dr Peter DarbenDarben, Queensland , Queensland

University of Technology clinical parasitology collection. Used with permissionUniversity of Technology clinical parasitology collection. Used with permission

Ova Ova

barrel shaped/lemon shaped/football shaped barrel shaped/lemon shaped/football shaped or Japanese lantern shape.or Japanese lantern shape.

With a prominent bipolar plugs on both With a prominent bipolar plugs on both ends.ends.

The shell is thick and composed of three The shell is thick and composed of three layers. With a yellowish outer and a layers. With a yellowish outer and a transparent inner layer.transparent inner layer.

Egg of Trichuris trichuria as seen on wet mount. The diagnostic characteristics are: a Egg of Trichuris trichuria as seen on wet mount. The diagnostic characteristics are: a typical barrel shape two polar plugs, that are unstained size: 50-54 µm by 22-23 µm. The typical barrel shape two polar plugs, that are unstained size: 50-54 µm by 22-23 µm. The external layer of the shell of the egg is yellow-brown (in contrast to the clear polar plugs). external layer of the shell of the egg is yellow-brown (in contrast to the clear polar plugs).

The egg is unembryonated, as eggs are when passed with the stool. CDC The egg is unembryonated, as eggs are when passed with the stool. CDC DPDxDPDx

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Life cycleLife cycle

EggsEggssoil 3 weekssoil 3 weeksembryonationembryonationingestedingestedlarvaelarvaececumcecum

Hookworms Hookworms

A. Necator americanusA. Necator americanus Common name: new world hookworm, american Common name: new world hookworm, american

hookwormhookworm Disease: necatoriasis, uncinariasis, tropical anemia, Disease: necatoriasis, uncinariasis, tropical anemia,

“laziness”“laziness”

B. Ancylostoma duodenaleB. Ancylostoma duodenale Common name: old world hookwormCommon name: old world hookworm

Disease: ancylostomiasis, miner’s anemiaDisease: ancylostomiasis, miner’s anemia

C. Ancylostoma brazilienseC. Ancylostoma braziliense Common name: cat hookwormCommon name: cat hookworm

Disease: cutaneous larva migrans, creeping eruptionDisease: cutaneous larva migrans, creeping eruption

D. Ancylostoma caninumD. Ancylostoma caninum Common name: dog hookwormCommon name: dog hookworm

Disease: cutaneous larva migrans, creeping eruptionDisease: cutaneous larva migrans, creeping eruption

Necator americanusNecator americanus is small and has a is small and has a tendency to go against the general body tendency to go against the general body curvature, hence a hook is formed (S curvature, hence a hook is formed (S shaped)shaped)

The buccal capsule is provided with a semi-The buccal capsule is provided with a semi-lunar cutting plates.lunar cutting plates.

They are also provided with long cephalic They are also provided with long cephalic or amphidial gland that secretes a potent or amphidial gland that secretes a potent anticoagulant and promotes the flow of anticoagulant and promotes the flow of blood.blood.

The bursa copulatrix is longer than broad The bursa copulatrix is longer than broad with a bidigitate or a bipartite dorsal ray with a bidigitate or a bipartite dorsal ray with long slender copulatory spicules that with long slender copulatory spicules that are fused at the tip to form a delicate barb.are fused at the tip to form a delicate barb.

Morphology Morphology

Ancylostoma duodenaleAncylostoma duodenale: contour tends to : contour tends to follow the general body curvature of the follow the general body curvature of the body hence looks like letter C.body hence looks like letter C.

Large buccal capsule, equipped with two Large buccal capsule, equipped with two pairs of ventral teeth.pairs of ventral teeth.

The male worms have a fan like organelle at The male worms have a fan like organelle at the posterior portion known as copulatory the posterior portion known as copulatory bursa/bursa copulatrix which is short and bursa/bursa copulatrix which is short and broad with tripartite or tridigitate dorsal ray broad with tripartite or tridigitate dorsal ray with a pair of simple, long, bristle like with a pair of simple, long, bristle like copulatory spicule, plain and free at the tip.copulatory spicule, plain and free at the tip.

Ancylostoma braziliense one of the smaller Ancylostoma braziliense one of the smaller species of hookworm with a pair of large species of hookworm with a pair of large teeth and a pair of inconspicuous median teeth and a pair of inconspicuous median teeth in buccal capsule.teeth in buccal capsule.

The bursa copulatrix is almost as broad as The bursa copulatrix is almost as broad as long and is supported by short lateral rays.long and is supported by short lateral rays.

Ancylostoma caninum is common parasite Ancylostoma caninum is common parasite of dogs. They have a wide buccal capsule of dogs. They have a wide buccal capsule bearing three pairs of ventral teeth. The bearing three pairs of ventral teeth. The cephalic or amphidial gland of the worm cephalic or amphidial gland of the worm secretes anticoagulant that delays secretes anticoagulant that delays coagulation of blood. Long moderately coagulation of blood. Long moderately slender rays supports the male bursa.slender rays supports the male bursa.

Life cycleLife cycle

EggsEggssoilsoillarva hatcheslarva hatchesrhabditiform(with open mouth/feeding rhabditiform(with open mouth/feeding stage)stage)filariform(longer, with close mouth, non-feeding stage and with filariform(longer, with close mouth, non-feeding stage and with protective sheath)protective sheath)skinskincirculationcirculationheart and lungheart and lungesophagusesophagusSISI

OvaOva

Hookworm egg provided with a very thin egg Hookworm egg provided with a very thin egg shell ( with germ cell in the process of shell ( with germ cell in the process of segementation 2-8 cell stages)segementation 2-8 cell stages)

Hookworm eggs examined on wet mount (eggs of Ancylostoma duodenale and Hookworm eggs examined on wet mount (eggs of Ancylostoma duodenale and

Necator americanus cannot be distinguished morphologically).Necator americanus cannot be distinguished morphologically).

Hookworm filariform larvae  © Hookworm filariform larvae  © Dr Peter Dr Peter DarbenDarben, Queensland University of , Queensland University of

Technology clinical parasitology collection. Used with permissionTechnology clinical parasitology collection. Used with permission

Necator americanus adult male, posterior end  © Necator americanus adult male, posterior end  © Dr Peter Dr Peter DarbenDarben, Queensland University of Technology clinical , Queensland University of Technology clinical

parasitology collection. Used with permissionparasitology collection. Used with permission

Dental PatternDental Pattern

N.AN.A 00 A.BA.B 11 A.CA.C 33 A.DA.D 22

N.americanus A. duodenaleN.americanus A. duodenale Dorsal RayDorsal Ray bidigitate bidigitate tridigitate tridigitate (bipartite) (tripartite)(bipartite) (tripartite) CopulatoryCopulatory ends with ends with simple, bristle like, simple, bristle like,

spicules spicules a barb a barb plain and free at the tip plain and free at the tip

A.braziliense A. caninumA.braziliense A. caninum CopulatoryCopulatory broad as long long moderately slender rays broad as long long moderately slender rays

spicules spicules

Pathology Pathology

Ground itch/ dew itchGround itch/ dew itch

percutaneous entry of the infective filariform percutaneous entry of the infective filariform larvae often characterized by itching larvae often characterized by itching sensation or dermatitis. It is often severe sensation or dermatitis. It is often severe and also known as ground itch or dew itch.and also known as ground itch or dew itch.

Pulmonary lesion/wakana diseasePulmonary lesion/wakana disease

is caused by passive pulmonary migration is caused by passive pulmonary migration of larval stages of hookworm. Symptoms of larval stages of hookworm. Symptoms may be similar to ascaris pneumonitis.may be similar to ascaris pneumonitis.

Creeping eruption/ cutaneous larva migransCreeping eruption/ cutaneous larva migrans

the infective laval stage can enter human the infective laval stage can enter human skin but cannot pass below stratum skin but cannot pass below stratum germinativum producing serpiginous tunnel germinativum producing serpiginous tunnel in this stratum. Common among larvae that in this stratum. Common among larvae that do not normally infect human such as do not normally infect human such as A.braziliense and A.caninum.A.braziliense and A.caninum.

Hookworm anemiaHookworm anemia adult worm suck the host’s blood and adult worm suck the host’s blood and

mucosal substances. mucosal substances. Microcytic hyopochromic anemiaMicrocytic hyopochromic anemia May cause hemorrhage to intestinal wormMay cause hemorrhage to intestinal worm

HypoalbuminemiaHypoalbuminemia due to combined loss of blood, lymph and due to combined loss of blood, lymph and

protein.protein.