Medical ParasitologyMedical ParasitologyLab8, Lab8, part 2part 2

Prepared byPrepared by::

NASR A. SinjilawiNASR A. Sinjilawi

NematodesNematodes

Ascaris lumbricoides.Ascaris lumbricoides. Hookworms:Hookworms:

A- A- Ancylostoma duodenale.Ancylostoma duodenale.

B- B- Necator americanusNecator americanus.. Strongyloides stercoralisStrongyloides stercoralis

Ascaris lumbricoidesAscaris lumbricoides Common nameCommon name: Roundworm.: Roundworm. Habitat:Habitat: Small intestine. Small intestine. Definitive host:Definitive host: Human. Human. Route of infection:Route of infection:Hands carry infective ova Hands carry infective ova

fromfrom soil contaminated with human excreta, soil contaminated with human excreta, vegetables, dust, …etc.vegetables, dust, …etc.

No Intermediate host.No Intermediate host. Infective stage:Infective stage: Eggs. Eggs. Diagnostic stage:Diagnostic stage: Eggs in Stool. Eggs in Stool. Disease:Disease: Ascariasis. Ascariasis.

Ascaris lumbricoides Ascaris lumbricoides life cycle1life cycle1

Ascaris lumbricoides Ascaris lumbricoides life cycle2life cycle2

Ascaris lumbricoides Ascaris lumbricoides life cycle3life cycle3

Ascaris lumbricoidesAscaris lumbricoides

Male: 150-200 x 2-4 mmMale: 150-200 x 2-4 mm

Curved tail. Shorter than female.Curved tail. Shorter than female. Female: 200-350 x 4-6 mm.Female: 200-350 x 4-6 mm. Habitat: Small intestine.Habitat: Small intestine. Head of adult to show arrangement of Head of adult to show arrangement of

the three lips.( SEM;above.LM; C.S. the three lips.( SEM;above.LM; C.S. below.)below.)

Ascaris lumbricoidesAscaris lumbricoides Eggs Eggs

Above-central: Thick mammillated albuminous Above-central: Thick mammillated albuminous material, thick chitin shell, embryo inside.material, thick chitin shell, embryo inside.

Above-right: Decorticated egg; only thick chitin Above-right: Decorticated egg; only thick chitin shell. Unembryonated.shell. Unembryonated.

Above-left: Unfertilized egg; unequally distributed Above-left: Unfertilized egg; unequally distributed mammillated albuminous layer,Unembryonated.mammillated albuminous layer,Unembryonated.

Normal: Corticated,Unembryonated.Normal: Corticated,Unembryonated.

C.S. in Female of C.S. in Female of A. LumbricoidesA. Lumbricoides

Cu: Cuticle of skin.Cu: Cuticle of skin. Lc: Dorsal nerve cord.Lc: Dorsal nerve cord. Ms: Muscular layer.Ms: Muscular layer. Od: Oviduct of ovary.Od: Oviduct of ovary. Uterus filled with Uterus filled with

eggs.eggs.

Ancylostoma duodenaleAncylostoma duodenale Common nameCommon name: Old world hookworm.: Old world hookworm. Habitat:Habitat: Small intestine. Small intestine. Definitive host:Definitive host: Human. Human. Route of infection: Route of infection: Filariform larvae penetrate the skin Filariform larvae penetrate the skin

of human.of human. No Intermediate host.No Intermediate host. Infective stage:Infective stage: Third stage larvae ( filariform). Third stage larvae ( filariform). Diagnostic stage:Diagnostic stage: Eggs in Stool. Eggs in Stool. Disease:Disease: Hookworm infection, Ancylostomiasis. Hookworm infection, Ancylostomiasis. Geographic Distribution: Southern Europe, North parts Geographic Distribution: Southern Europe, North parts

of Africa, China, India, and Japan. of Africa, China, India, and Japan.

Ancylostoma duodenale Ancylostoma duodenale life cyclelife cycle

Hookworm life cycleHookworm life cycle

Ancylostoma duodenaleAncylostoma duodenale

Above-right: Egg; 60 x 40 um, thin-smooth-hyaline Above-right: Egg; 60 x 40 um, thin-smooth-hyaline shell, 4-8 cell cleavage (Unembryonated).shell, 4-8 cell cleavage (Unembryonated).

Above-central: Ancylostoma feeding,C.S. in small Above-central: Ancylostoma feeding,C.S. in small intestine.intestine.

Above-left: SEM shows Ancylostoma head; Buccal Above-left: SEM shows Ancylostoma head; Buccal capsule with 2 pairs of teeth.capsule with 2 pairs of teeth.

Necator americanusNecator americanus Common nameCommon name: New world hookworm.: New world hookworm. Habitat:Habitat: Small intestine. Small intestine. Definitive host:Definitive host: Human. Human. Route of infection: Route of infection: Filariform larvae penetrate the Filariform larvae penetrate the

skin of human.skin of human. No Intermediate host.No Intermediate host. Infective stage:Infective stage: Third stage larvae ( filariform). Third stage larvae ( filariform). Diagnostic stage:Diagnostic stage: Eggs in Stool. Eggs in Stool. Disease:Disease: Hookworm infection, Ancylostomiasis. Hookworm infection, Ancylostomiasis. Geographic Distribution: Western hemisphere, Geographic Distribution: Western hemisphere,

central and south Africa, south Asia, south pacific, central and south Africa, south Asia, south pacific, and India.and India.

Necator americanusNecator americanus

Above : Buccal capsule with Above : Buccal capsule with one pair of cutting plate.one pair of cutting plate.

Below: Egg (70 x 38 um) Below: Egg (70 x 38 um) similar to similar to A. duodenale; A. duodenale; Thin hyaline egg shell, 4-8 Thin hyaline egg shell, 4-8 cell cleavage cell cleavage (Unembryonated).(Unembryonated).

Life cycle similar toLife cycle similar to

A. duodenaleA. duodenale

Hookworm EggsHookworm Eggs

Necator americanus Necator americanus life cyclelife cycle

Hookworm Rhabditiform larvaHookworm Rhabditiform larva

Immature: 270 x 15 Immature: 270 x 15 um, Mature: 540 x 700 um, Mature: 540 x 700 um.um.

Long buccal cavityLong buccal cavity small genital small genital

primordium.primordium.

Hookworm Filariform larvaeHookworm Filariform larvae

700 um700 um Long buccal cavity.Long buccal cavity. Small genital Small genital

primordium.primordium. Long esophagus.Long esophagus. Pointed tail ( below)Pointed tail ( below)

Infective stageInfective stage

Strongyloides stercoralisStrongyloides stercoralis Common nameCommon name: Thread worm: Thread worm Habitat:Habitat: Small intestine. Small intestine. Definitive host:Definitive host: Human. Human. Route of infection: Route of infection: Filariform larvae penetrate the Filariform larvae penetrate the

skin of human.skin of human. No Intermediate host.No Intermediate host. Infective stage:Infective stage: Third stage larvae ( filariform). Third stage larvae ( filariform). Diagnostic stage:Diagnostic stage: First stage larvae(Rhabditiform) First stage larvae(Rhabditiform)

in feces.in feces. Disease:Disease: Strongyloidiasis. Strongyloidiasis.

Strongyloides stercoralis Strongyloides stercoralis life life cycle1cycle1

Strongyloides stercoralis Strongyloides stercoralis life cycle2life cycle2

Strongyloides stercoralis Strongyloides stercoralis Rhabditiform larvaeRhabditiform larvae

220 x 15 um.220 x 15 um. Short buccal cavity.Short buccal cavity. Prominent genital primordiumProminent genital primordium

( black arrow).( black arrow).

Diagnostic stageDiagnostic stage

Strongyloides stercoralis Strongyloides stercoralis Filariform larvaeFilariform larvaeposterior partposterior part

Filariform larva with Filariform larva with notched tail.notched tail.

|Infective stage|Infective stage 600 x 20 um.600 x 20 um.

Comparison between hookworm and Comparison between hookworm and Strongyloides stercoralisStrongyloides stercoralis

HookwormHookworm Strongyloides Strongyloides stercoralisstercoralis

Rhabditiform Rhabditiform larvaelarvae

Long buccal Long buccal cavity, small cavity, small

genital genital primordiumprimordium

Short buccal Short buccal cavity, prominent cavity, prominent

genital genital primordiumprimordium

Filariform LarvaeFilariform Larvae Pointed tail, Short Pointed tail, Short esophagusesophagus

Notched tailNotched tail,,

Long esophagusLong esophagus

EggEgg Thin shell,4-8 cell Thin shell,4-8 cell cleavagecleavage

Thin shell,4-8 cell Thin shell,4-8 cell cleavagecleavage

Comparison between hookworm and Comparison between hookworm and Strongyloides stercoralisStrongyloides stercoralis