NEMATODES Abdominal Pain, Vomiting, Growth Stunting
Free living, invertebrate Intestinal Obstruction that may lead to
Millimeter-meter in size Intestinal Perforation
Phylum Aschelminthes Erratic Worms may wander into other parts
Round or cylindrical in shape of the body
Presence of pseudocoel with chitinous like Larval stage:
cuticle o may cause Eosinophilic Pneumonitis
Male- curved pposterior end with copulatory (Loeffler’s
spicules; smaller than the female Syndrome), Eosinophilia
No circulatory sytem o Presence of Charcot Leyden
Dioecoius Crystals
Stage – adult-larva(l1-l4)-egg/ovum(one Diagnosis:
female can produce 200000 eggs/day) o DFS, Kato-Katz, Concentration
Definitive host: human Techniques
o Rhabditiform larva-excreted o Examination of Sputum (Larval
o Filariform larva- infective Stages)
Intermediate host: antropods o Macroscopic ID of adult on stool or
Treatment (oral) through mouth or nose
o Albendazole(400mg/day) Treatment: Mebendazole or Albendazole
o Mebendazole (100mg twice daily for
3 days)
Digestive system: Enterobius vermicularis (pinworm)
Mouth, buccal cavity(hooks, teeth or cutting Highly communicable Seat,society worm
plates, esophagus(muscular), intenstines, causing door yard infection
rectum, anus Cosmopolitan(more common among
Reproductive system: females)
Male: spicules, copulatory bursa Most common in US
Female: uterus; vagina No free living stage
Maybe oviparous, larviparous or viviparous Perianal skin: where gravid female migrates
Chemoreceptors: Amphids and Phasmids to deposit embryonated eggs
Phasmid worm Egg- Lipoidal membrane surrounded by
Aphasmid worm thich transparent hyaline albuminous shell
o Trichuris, Trichinella, Capillaria Greater prevalence in temperatue climates
and in children
Female(0.8-1.3cm)- spindle shaped
Ascaris lumbricoides body(filled with eggs in uterus) with a long
Giant intenstinal roundworm thin sharply tail, cervical/cephalic alae at
Most common in the world(2nd in US) head
Rural>urban, children>adults FINAL HOST: HUMANS
Female(20-35cm)-vulvar waist; INFECTIVE STAGE: Embryonated Egg(D
Male(12-30cm): coiled end shaped) after 4-6hrs
Habitat: lumen of small intenstine Habitat: : Large Intestine
FINAL HOST: Man MOT: Oral, Air-borne, Retroinfection,
Infective Stage: EMBRYONATED EGG(highly Autoinfection
resistant) Pathology:
o Unfertilized- narrower, elongated Enterobiasis
with thinner shells filled with Patients experience Nocturnal Pruritus Ani,
globular protoplasm Insomnia,
Undergoes Heart Lung Migration Secondary Bacterial Infection, Loss of
MOT: Ingestion of Embryonated Eggs Appetite,
Abdominal Pain, Vulvovaginitis may also
PATHOLOGY attributed to:
o Host Immune Response occur
Familial Disease, Spreads Easily, Everyone in
o Effects of Larval Migration
the Family
o Mechanical Effect of Adult Worms
Must Be Treated
o Nutritional Deficiencies
Treatment: Mebendazole, Albendazole,
Luminal Parasite Pyrantel
Patients may suffer no signs or symptoms Pamoate
Diagnosis: Pathology:
Scotch Tape Swab; Swellengrebel; Graham’s Adults attach to the lining of the colon (PIN
technique; Petrolatum FASHION
MANNER)
Usually asymptomatic, but infections can
Trichuris trichuria (whipworm) cause:
egg only free living state o Diarrhea, Blood in Stool, IDA, Rectal
o must stay on soil for 10 days- Prolapse,
3weeks for development of Weight Loss
pathogenesis
Treatment: Albendazole (Drug of Choice),
o glycogen containing lypoidal
Mebendazole
membrane surrounded with
albuminoid membrane with mucus
Diagnosis:
plug
DFS, Kato-Katz, Concentration Techniques
no intermediate host
commonly seen with Ascaris(similar mode of o Recovery and identification of eggs in
infection), 3rd most common on US feces
STH
Female(35-50mm): anterior 2/3 is
threadlike expanding to broader posterior Hookworms
Male: similar to female but exhibiting a Kingdom: Animalia
strong curvature of tall Phylum: Nematoda
Eggs – Barrel Shaped/Lemon Shaped/Foot Class: secerentea
Ball Shaped, Order: Strongiloidae
Japanese Lanternz
Family: Ancylostomatidiae
Genus: Ancylostoma/Necator
Species: A. duodenale/N. americanus
No intermediate host
N. americanus A. duodenale
Common Name New world hookworm Old world hookworm
American hookworm Asia Hookworm
Habitat Upper level of the small intestines small intestines
Buccal cavity Dorsal and ventral cutting plates 2 ventral plates and two large teeth(6
teeth)
Buccal capsule set 2 crescent-shaped cutting plates on with symmetric pair of sharp teeth on
ventral side ventral slide
ingests 30 ul blood/day ingests 260 ul blood/day
Curvature S shaped C shaped
Life span 4-20 yrs 5-7 yrs
size of female 9-11 mm 10-13mm
size of male 7-9mm 8-11mm
Position of vulva mid body 1/3 from posterior
egg production 9000/day 25000/day
egg survival 3-5 yrs 1 yr
penetration Yes Yes
through skin
Longevity 15 years 5 years
Anterior end: Buccal capsule Posterior end: copulatory bursa
o A. duodenale: pinkish/creamy Identification of Species: Dental
gray(living worms), umbrella or bell Pattern/Buccal Cavity
shaped bursa Eggs are indistinguishable
o N. americanus: grayish yellow at times
with reddish undertone, fan-like bursa, Pathology
bipartite dorsal ray and spicule is Cutaneous Phase: Ground Itch (Allergic
barbed Reaction)
A. duodenale: secretes neutrophil inhibition Pulmonary Phase: Wakana’s Disease
factor (Pneumonitis)
N. americanus: acetyl Intestinal Phase: Blood Loss (IDA),
cholinesterase(inhabits gut peristalsis) Abdominal
Eggs: ovoid, thin colorless, 4-8 cells in feces Pain, Diarrhea, Eosinophilia
o Hatches after 24-48 hrs to be a Treatment: Albendazole, Mebendazole,
rhabditiform larvae and after 5-8 days, Pyrantel Pamoate
will form filariform larvae(infective o Not given to pregnant women
stage) Diagnosis:
Skin- lungs-trachea-esophagus-stomach- Microscopy-direct wet mount
intenstine Concentration-formalin ether, salt
FINAL HOST: Man floatation and kato katz method
Infective Stage: Filariform (L3) Stage Culture: Harada Mori
A. braziliense A. caninum
Common cat hookworm; creeping eruption hookwom dog hookworm
name
habitat duodenum duodenum
male size 7.75-8.85 x 0.35 mm 10 mm x 0.4 mm
female size 9-10.5 mm x 0.375 mm 14mm x 0.6 mm
Buccal pair of small very insconspicuous median teeth and a pair wide to accommodate
capsule of larger outer teeth aside form 2 pairs of ventral teeth the 3 pairs of ventral
teeth
Habitat: Small Intestine Technique (filter paper)
MOT: Skin Penetration Recovery of eggs in feces
Undergoes heart Lung Migration Imaging method: x-ray
Strongyloides stercoralis Parasitic or free living Male: 0.7mm,
Thread Worm rhabditiform esophagus, posteriot and
Smallest Nematode of Man curved ventrally with spicules
Soil Transmitted Helminth Parasitic Female: 2.2 mm in length,
Facultative Parasite cylindrical esophagus (1/3 body length)
Definitive host: Human, dogs, cats
Habitat: Small Intestine(duodenum and Posterior and straight:
jejunum) Free living female: 1mm in length,
Infective Stage: Filariform Larva(3rd rhabditiform esophagus, posterior and
larval stage) straight
Diagnostic stage: First stage Egg(laid in mucosa): 55x30um, oval clear,
larvae(Rhabditiform)4weeks on thin shelled similar to hookworm but
infection in feces smaller
MOT: Larval Penetration
Heart Lung Migration Diagnosis:
Forms: Parasitic, Free-living Recovery and identification of larvae and egg
Eggs are rarely seen in feces or duodenal drainage
Parasitic Males have not yet identified Direct stool smear(larvae)
Parasitic Females: Parthenogenetic Cultivation of stool (Damp charcoal or Hara-
Morphology: mon mediums)
Examination of duodenal or jejunal biopsy
obtained by endoscopy(adult worms) in
mucosa
Eosinophilia-present in uncomplicated
strongyloidiasis but lost in hyperinfection
ELISA for IgG anti-strongyloides antibodies-
for population screening in endemic areas
