Nematodes Flashcards
Roundworms
Nematodes
T/F: Not all nematodes are parasitic
True
General characteristics of nematodes
- nonsegmentes
Cylindrical - tapered at both ends
- complete digestive tract
- separate sexes
- females are usually larger
- males are usually curved at the posterior and have special copulatory organs
T/F: Nematodes does not form through replicating or repeating segments
True. They are NONSEGMENTAL
Nematodes reproduce through…
Sexual reproduction after copulation between male and female adults
Special copulatory organs are present on __________ to _________________________
Nematodes; to hold on to female during copulation
Giant intestinal round worm
Ascaris lumbricoides
Most common intestinal nematode worldwide
Ascaris lumbricoides
A. Lumbricoides is transmitted in…
Soil
A. Lumbricoides is a (obligate, opportunistic) parasite
Obligate
Adult Ascaris lumbricoides is found in…
Small intestine
A. Lumbricoides is acquired through the…
Ingestion of contaminated food with soil that contains EMBRYONATED EGGS.
T/F: Heart-Lung migration occurs in A. Lumbricoides
TRUE
Adult Nematode that appears like spaghetti
Ascaris lumbricoides
Differentiate unfertilized and fertilized A. Lumbricoides egg
Unfertilized: larger and longer
Fertilized: round/oval, has a thick shell w/ finely granular embryo
Outermost shell of A. Lumbricoides ova is called…
Mamillary coat/layer
T/F: Fully embryonated egg of A. Lumbricoides is diagnostic in stool
FALSE. It takes several weeks for the ova to become fully embryonated
Most severe forms of ascaris infections is due to…
Ectopic migration of adults
Definitive diagnosis of A. Lumbricoides
Unembryonated Eggs in stool
Similar specie of A. Lumbricoides but hosts are pigs
Ascaris suum
Whipworm
Trichuris trichuira
T/F: Ascaris can have a co-infection with Trichuris
TRUE
T. Trichuira is a (obligate, facultative, accidental, permanent, temporary, spurious)
Obligate
Adult Trichuris trichuira is found in…
Large intestine
T. Trichuira is acquired though..
Ingestion of contaminated food of embryonated ova
T/F: Similarly to A. Lumbricoides, T. Trichuira has a heart-lung migration
FALSE. No heart-lung migration for T. Trichuira
Adult male T. Trichuira has a posterior end…
Coiled >360 degrees
Football/barrel shaped w/ bipolar plugs ova
T. Trichuira
T/F: Shells of T. Trichuira is thinner than A. Lumbricoides
True
Petechial hemorrhages in the instestines is caused by which nematode?
T. Trichuira
Rectal prolapse is seen in Chronic and heavy infection of …
T. Trichuira
T. Trichuira definitive diagnosis
Ova in stool
Two most important/common intestinal h ookworms
Necator americanus
Ancylostoma duodenale
Hookworms:
Infective Stage:
MOI:
Adult Habitat:
Diagnostic Stage:
Filariform larva
Skin penetration/ingestion
Small Intestine
Ova in stool
Hookworms (obligate, accidental, permanent, temporary)
Obligate
T/F: Eggs of Hookworms are non-infectious
TRUE
Hookworm maturity stages
Adult hookworm copulate - ova - passed on feces - not disposed - soil - larva - rhabditiform larva - filariform larva
Parasitic stage of hookworms
Filariform larva
2 modes of infection of hookworms
Skin penetration
Ingestion
Hookworms: Heart lung migration (YES, NO)
YES
Which hookworm can only be acquired of infection through ingestion?
Ancylostoma
*Necator americanus can only be through skin penetration
T/F: Transmammary and transplacental is also a mode of infection for Necator americanus
False. It is by Ancylostoma duodenale
Adult male hookworm is distinguished by female through…
Posterior structure - COPULATORY BURSA (fan-like structure w/ ribs to hold during copulation)
Compare the buccal cavity of necator and ancylostoma
Necator: semilunar cutting disks
Ancylostoma duodenale: 2 pairs of teeth
Ancylostoma caninum: 3 pairs of teeth
The teeth or cutting disks of necator and ancylosoma is used for…
Attachment and NOT for chewing food
Describe ova of hookworms
Ovid in shape
Slightly elongated
Very thin shell/membrane
W/ embyro
Rhabditiform larvae is only visible in stool if..
Px is constipated
Delayed processing of specimen
T/F: Filariform is more seen in stool tan rhabditiform
Both are rarely/almost impossible to find in stool
Hookworms clinical manifestations
Ground itch/dew itch
Bronchitis/pneumonitis
Cutaneous larva migrans/creeping eruptions
Threadworm
Strongyloides sterocoralis
Strongyloides sterocoralis is (obligate, facultative, temporary, permanent) parasite
Facultative
Parthenogenesis occurs in (hookworm, roundworm, threadworm)
Threadworm
T/F: Strongyloides has no male adults, only female
TRUE
Rhabditiform larva is the most commonly found in stools of Px infected with…
Strongyloides sterocoralis
S. Sterocoralis is acquired through…
Skin penetration or ingestion
T/F: Heart-lung migration in S. Sterocoralis
TRUE
Summary of life cycle of S. Sterocoralis
Rhabditiform - stool - fialriform - infect - heart lung migration - adult
Adult S. Sterocoralis found in…
Intestine
Buccal cavity of adult S. Sterocoralis is _____________ than hookworm
Shorter
A unique characteristic of filariform larva of s. Sterocoralis is…
Notched tail
Pruritic skin papules
Larva currens (serpentine lesions)
Lobar pneumonia
Cochin China Diarrhea
Clinical manifestations of…
Strongyloides sterocoralis
Harada-Mori, Bearmann funnel used as a culture technique in…
S. Sterocoralis
Allow larva to hatch from eggs
Increases the sensitivity of test
Strongyloides sterocorali:
Infective Stage -
MOI -
Adult habitat -
Diagnostic stage
Filariform larva
Skin penetration, autoinfection, transplacental,transmammary
Small intestine
Rhabditiform larva
Parasite of monkeys
Strongyloides fulleborni
Strongyloides spp that causes swamp itch, and infects nutria and racoon
S. Myopotami, s. Procyonis
Pinworm or seatworm
Enterobius vermicularis
Causative agent of oxyuriasis/enetrobiasis
E. Vermicularis
Nematode where female migrate to perianal region and deposit eggs on perianal region or die on the sit.
Enterobius vermicularis
Eggs of E. Vermicularis are infective w/n…
6hrs
Female vs male adult E. Vermicularis
Female: larger than male, sharply pointed tail, posterior end
Male: shorter and stout, pointed posterior
D-shaped ova (ovoid but flat on one side)
E. Vermicularis
Most effective and recommended method of diagnosis of E. Vermicularis ova or adult male
Cellophane tape swab
Scotch tape swab
Pinworm paddle
E. Vermicularis
T/F: Ova are rarely deposited on inside the intestine on E. Vermicularis infection
TRUE.
Deposit eggs on perianal region
Enterobius vermicularis
Infective stage:
MOI:
Adult habitat:
Diagnosis stage:
Embryonated ova, larvae (retroinfection)
Ingestion/Inhalation
Large intestine
Ova (usually); adult (occasionally)
Pudoc Worm
Capillaria philippinensis
Number of hosts required to complete life cycle of C. Philippinensis
2
Hosts of C. Philippinensis
Definitive:
Intermediate:
Fish-eating birds
Fish
Unique reproduction occus where 1st time to be gravid produce larva; egg hatches w/n the uterus and release larvae occurs in…
C. Philippinensis
Larviparous -
Oviparous -
Release larva
Release eggs
Adult female morphology of C. Philippinesis is similar to…
Trichuris trichuira
Posterior end is thicker than anterior end
Male does NOT have 360 coil
LONG SHEATHED SPICULE - main diff between the two
Flat polar plugs appear in T. Trichuira and…
C. Philippinensis
Peanut shaped (striated shell)
Ova of C. Philippinensis
Borborygmus, internal autoinfection are few clinical manifestations of…
C. Philippinnensis
Antigen detection on stool samples for C. Philippinensis
Coproantigen Detection
Capillaria philippinensis:
Infective stage -
MOI -
Adult habitat -
Diagnosis -
Larva
Ingestion of raw/insufficiently cooked fish
Small intestines
Ova in stool
Zoonotic parasite, parasite of herbivores where humans are accidental host and is closely related to hookworms.
Trichostrongylys orientalis
T/F: T.orientalis has heart-lung migration
TRUE
T/F: T. Orientalis’ ova is tapered in one end
True
T. Orientalis clinical manifestations
Significant blood loss
Emaciation
Trichostrongylus orientalis
Infected stage -
MOI -
Adult habitat -
Diagnostic stage -
Filariform
Ingestion
Small intestine
Ova in stool
Intestinal parasites of marine mammals
Anisakid worms
Intermediate host of Anisakid worms
Crustaceans (shrimp, cray fish, crab)
Stage 3 larva will only develop in…
Suitable host (large fish or squid)
Summary of life cycle of Anisakid worms:
Eggs on feces - embryonization - release Stage 2 larva - eaten by crustaceans - eaten by paratenic host - eaten by larger fish/squid = stage 3 larva - adult in intestines
T/F: Humans are definitive host of Anisakid worms
False. Only accidental if ate raw/insufficiently cooked fish -> perforate/embed GI tract (either die or removed surgically)
Definitive diagnosis of anisakid infections (aniisakiasis.anisakidosis)
Actual demonstration of worms from gastroscopy, vomit
**Inject dte to stain GI tract = visualize
Differentiate structures of Anisakid worms
Anisakis -
Pseudoterannova
Contracaecum
Simplest
Extensions of intestines that more anteriorly
Ventricular appendix
Ansiakid Worms
Infective stage:
MOI:
Adult Habitat:
Diagnostic stage:
Stage 3 larva
Ingestion (raw/insufficiently cooked)
Intestinal wall/stomach
Stage 3 larva
Most common blood and tissue nematode that is associated w/ human infection
Trichinella spiralis
Most common meat associated w/ T. Spiralis
Pork
Stage of parasitic maturity that causes clinical manifestations in T. Spiralis infection
Larval stage
T. Spiralis infection where larva deposited by adults in…
Mucosa of intestines
Larva finds blood vessel - striated muscle - coil up - secrete substance = create cyst wall —> ingested by another host - intestine = adult
Male and female adult T. Spiralis can be differentiated through..
Presence of cloaca (male) - 2 large appendages, 2 pairs of papilla
Male and female adult T. Spiralis can be differentiated through..
Presence of cloaca (male) - 2 large appendages, 2 pairs of papilla
Beck’s Xenodiagnosis used for identification of..
Trichinella spiralis infection on meat samples (not ideal for human tissue)
Trichinella Spiralis
Infected stage:
MOI:
Adult habitat:
Diagnostic stage:
Encysted larva
Ingestion of raw/insufficiently cooked meat (pork)
Intestines
Encysted larva (biopsy), serologic test
Previously named as Angiostrongylus cantonensis
Parastongylus cantonensis
Rat lungworm
Parastongylus cantonensis
Copulate and produce eggs in lungs
Parastrongylus cantonensis
May end up in mucuc secretions
Intermediate hosts of P. Cantonensis
Snails, slugs
T/F: In human infection of P. Cantonensis, severe form of infection because larva cannot migrate from CNS/brain to the lungs to mature. Unlike in Rats.
TRUE
Adult female: Barber’s pole appearance
P. Cantonensis
Uterus wrap around the length of GI tract
Counterpart of copulatory bursa of hookworms in P. Cantonensis
Cordal bursa
Eosinophilic meningoencephalitis caused by…
Parastrongylus cantonensis
To diagnose P. Cantonensis, criteria to diagnose include:
History of exposure
Spinal fluid eosinophilia (>10%)
Mildly ELEV CFS protein
Larvae/Young adult in CSF
CT Scan
Serologic test
Parastongylus cantonensis
Infective stage -
MOI -
Adult habitat -
Diagnostic stage -
3rd stage larva
Ingestion
Brain (natural host rats: lungs)
Larva/young adults
Parastrongylys costaricensis principally found in…
Costa Rica
Human infections associated w/…
Ingestion of slugs and raw vegetables
P. Costaricensis found in…
Mesenteric veins
Larvae of P. Costaricensis can cause…
Granuloma formation