Clinical Helminthology: Intestinal Nematode (Part 1)

Metazoans

They are multicellular invertebrates characterized by elongated, flat or round bodies.
They contain internal organ systems

Parthenogenetic

It can produce an offspring from the ovum without prior fertilization

Oviparous

Produces offspring by means of egg or ovum

Larviparous

produces offspring by means of larva

Hermaphroditic

possesses the reproductive organs of both sexes

unsegmented
have mouth, esophagus, anus
have separate sexes (male / Female)
some are parthenogenetic
oviparous or larviparous

Nematodes characteristics

segmented (proglutin)
have scolex, neck, proglottids hermaphroditic
oviparous or larviparous

Cestodes characteristics

unsegmented.
leaf-like or cylindrical
generally, hermaphroditic
digenetic, oviparous or larviparous

Trematodes characteristics

roundworms

Nematodes are also known as

Nematodes

They are unsegmented, elongated, cylindrical worms with bilateral symmetry

digestive tract and a muscular pharynx that is triradiate

Nematodes possess a well-developed ___

circulatory system

Nematodes do not have ____

diffusion

Nematodes distributes food and nutrients by ____

Adult males

They are generally smaller than the adult females and have a curved posterior end

Copulatory spicules
Copulatory bursa

Reproductive system of adult male nematodes

Copulatory spicules

needle-like mating structures

Copulatory bursa

used for grasping the female during mating (hand)

Amphids
Phasmids

Sensory organs of nematodes

Amphids

sensory organ at the anterior end (upper / head)

Phasmids

sensory organ at the posterior end (lower / tail)

Phasmid
Aphasmid

Calssification of phasmid

Class Secernentea

Phasmid class

Class Adenophorea

Aphasmid class

Capillaria
Ascaris
Strongyloides
Hookworms

Small intestine

Trichuris
Enterobius

Large intestines

Wuchereria (lymph nodes or vessels)
Brugia (lymph nodes or vessels)
Angiostrongylus (eyes and meninges)
Trichinella (muscle)

Extraintestinal

Ascaris
Trichuris
Enterobius

Ingestion of embryonated eggs

Hookworms
Strongyloides

Skin penetration of filariform larvae

Wuchereria
Brugia

Mosquito bite

Capillaria (fish)
Trichinella (pork)
Angiostrongylus (snails)

Ingestion of infective larvae

Enterobius
Ascaris

Inhalation

Capillaria
Enterobius
Strongyloides

Autoinfection

Hookworms
Ascaris lumbricoides
Trichuris trichiura

Unholy Three

Hookworms
Ascaris lumbricoides
Strongyloides stercoralis

Heart-Lung Migration

Retro infection

Goes back from its original plate

concomitants

Infected with one, infected with others

Ascaris lumbricoides
Trichuris trichiura
Enterobius vermicularis
Hookworm species
Strongyloides stercoralis
Capillaria philippinensis
Anisakis

Intestinal nematodes

Ascaris lumbricoides
Trichuris trichiura
Enterobius vermicularis

Oviparous and cosmopolitan nematodes

embryonated eggs

Ascaris lumbricoides Infective Stage (IS)

unembryonated eggs

Ascaris lumbricoides Diagnostic Stage (DS)

Ascaris lumbricoides

most common roundworm

Ascaris lumbricoides

largest intestinal roundworm

Ascaris lumbricoides

requires a warm humid environment to mature and become infective

Ascaris lumbricoides

can survive within dry or freezing temperatures

Egg stage and Adult stage

Ascaris lumbricoides morphology

Fertilized
Decorticated
Unfertilized

Ascaris lumbricoides egg stages

golden brown, thick-shelled and has three layers

Ascaris lumbricoides fertilized egg morphology

Inner layer
Middle layer
Outer layer

Ascaris lumbricoides fertilized egg layers

non-permeable, lipoidal vitelline

Fertilized egg inner layer

thick, transparent, glycogen

Fertilized egg middle layer

coarsely mamillated albuminous

Fertilized egg outer layer

has no outer albuminous layer

has a more prominent chitin shell

Ascaris lumbricoides decorticated egg morphology

has longer and narrower, no glycogen membrane

Ascaris lumbricoides unfertilized egg morphology

Ascaris lumbricoides: adult males

They have curved posterior end, are smaller, and are trilobate.

Ascaris lumbricoides: Adult stage

usually assume creamy white colors with a tint of pink

Ascaris lumbricoides: Adult stage

fine striations are visible on the cuticle

asymptomatic
intestinal obstruction
pot bolus-worm ball (pot belly)
Löffler's syndrome
sandbox infection
biliary ascariasis
acute appendicitis
peritonitis
pancreatitis

Ascaris lumbricoides diseases

Direct fecal smear
Sputum examination
Kato-Katz technique

Ascaris lumbricoides diagnosis

Albendazole
Mebendazole
Pyrantel pamoate

Ascaris lumbricoides treatment

embryonated eggs

Trichuris trichiura Infective Stage (IS)

unembryonated eggs

Trichuris trichiura Diagnostic Stage (DS)

Trichuris trichiura

less resistant to desiccation, heat, and cold

Ascaris lumbricoides and Hookworms

Trichuris trichiura concomitant with

fecal-oral route, direct contact to soil

Trichuris trichiura Mode of Transmission (MOT)

cecum and rest of the colon (survive up to 10 years)

Trichuris trichiura Final site

barrel-shaped
football-shaped
lemon-shaped
Japanese lantern-shaped

Trichuris trichiura egg stage

anterior end - whip itself
posterior end - whip handle
female - straight tails
males - coiled tails

Trichuris trichiura adult stage

• rectal prolapse (detached rectum)
• blood-tinged stools, and diarrhea - hypochromic anemia

Trichuris trichiura diseases

Fecal microscopy

Trichuris trichiura diagnosis

Albendazole, Mebendazole

Trichuris trichiura treatment

Enterobius vermicularis

Infective eggs may reside in dust, sandboxes, linens, and clothing.

fecal-oral, inhalation, sexual transmission

Enterobius vermicularis Mode of Transmission (MOT)

embryonated eggs

Enterobius vermicularis Infective Stage (IS)

embryonated egg
adult female worm

Enterobius vermicularis Diagnostic Stage (DS)

D-shaped
persimmon-seed like
flat-sided

Enterobius vermicularis egg stage

has cephalic alae and prominent esophageal bulb

Adult males- rarely seen (die after copulation)

Adult females- pointed tail that resembles pinhead (lay their eggs on morning)

Enterobius vermicularis adult stage

Enterobiasis- perianal pruritus and inflammation

Hemorrhagic colitis

Enterobius vermicularis diseases

Graham's Scotch Adhesive Tape Swab

Enterobius vermicularis diagnosis

Albendazole, Mebendazole

Enterobius vermicularis treament