Parasitology (Nematodes) Flashcards
Habitat of A. lumbricoides
Small intestine
T. trichiura and E. vermicularis habitat
Large intestine
Most common helminth
E. vermicularis, A. lumbricoides, T. trichiura
egg that contains fully developed larvae in its shell
Embryonated egg
Usual diagnostic stage of E. vermicularis, A. lumbricoides, T. trichiura
eggs/ova
C. philippinensis habitat
small intestine
Infective stage of C. philippinensis
Larva
MOT of C. philippinensis
Ingestion of larva from raw fishes
Habitat of S. stercoralis, N. americanus, A. duodenale
Intestinal
Infective stage of
S. stercoralis
N. americanus
A. duodenale
Filariform larva
MOT of
S. stercoralis
N. americanus
A. duodenale
Skin penetration
Nematodes general characteristics
Separate sexes
Male - shorter with curved tail dorsally
Female: longer straight tail
elongated, cylindrical, non-segmented
With GIT - mouth, anus
aphasmids nematodes
T. spiralis, T. trichiura, C. philippinensis
Life cycle of nematodes
Egg stage:
Larva (young worm)
Adult (Male/Female)
sensory organ found in the cephalic of nematodes
chemoreceptors
MOT: Ingestion of encysted larva following consumption of inadequately cooked pork
T. spiralis
Intermediate host of D. medinensis
Copepods - freshwater fleas
D. medinensis habitat
Subcutaneous tissues
Viviparous nematode
D. medinensis
S. Stercoralis and Hookworms life cycle
Egg
Rhabditiform larva
Filariform larva
Adult
feeding stage, w/ open mouth, shorter and robust, not infective
Rhabditiform
non-feeding, w/ closed mouth, longer and slender, infective; penetrates human skin
FILARIFORM
To differentiate RHABDITIFORM
Length of buccal cavity
Size of genital primordium
To differentiate filariform larva
Length of esophagus
Tail end
Presence or absence of sheath
Rhabditiform larva of______:
225 um long and has shorter buccal cavity - half the width of the body and distinct/conspicuos genital primordium
S. stercoralis
Rhabditiform of _____:
length of 250 um with longer buccal cavity-length is equal to the width of the body; and indistinct/inconspicuos genital primordium
hookworms
Filariform larvae of ___:
have a length of 700um with shorter esophagus, straight tail end and is sheathed
hookworms
Filariform larvae of ___:
has length of 550 um with longer esophagus, bifid or notched tail end and is unsheathed
S. stercoralis
Facultative parthenogenic that can live outside man and survive without a host
S. stercoralis
Virgin birthing - capable of producing eggs without male
Parthenogenesis
Larviparous/Viviparous: no egg stage; deliver larva species:
All filarial worms
T. spiralis
D. medinensis
Oviparous: Female nematodes that can produce eggs without developed larva in its shell species:
Female: Ascaris, Trichuris, Hookworms
Ovoviparous: Female worms that can develop larva in its shell species:
Enterobius vemicularis
Strongyloides stercoralis
General characteristics of Filarial worms:
Arthropod borne
Diagnostic stage: examined in the blood
Exhibits periodicity
Sheathed/Unsheathed
Causes Filariasis
MOT: Skin inoculation
Adult microfilaria is found in
usual habitat or lymphatics
Microfilaria is seen in what specimen
blood
larvae that goes to the blood depending on its periodicity may be sheathed or unsheathed; diagnostic stage
microfilaria
Usual specimen for filarial worms
Blood
O. volvulus specimen
skin nips (biopsy)
Filaria that can be seen in Lower lymphatics
W. bancrofti
Filaria seen in Upper lymphatics
B. malayi
Filaria seen in subcutaneous tissue
Loa loa
O. volvulus
Filaria seen in body cavities
M. ozzardi
M. perstans
Filaria seen in dermis of the skin
M. streptocerca
Filaria stage that is infective to man
L3: 3rd stage larva
Filaria infective stage to vector
Microfilaria
MOT for filaria
Skin inoculation
Sheathed filarial worm
W. bancrofti
B. malayi
L. loa
Vector for W. bancrofti
Mosquitoes
(Aedes, Culex, Anopheles,
Mansonia spp)
B. malayi vector
Mansonia spp. (mosquitoes)
Loa loa vectors
Chrysops fly
Mango fly
Deerfly
Nocturnal periodic filaria
W. bancrofti
Nocturnal subperiodic filaria
B. malayi
Diurnal filaria
Loa loa
Sheathed filaria tail morphology:
Nuclei that does not extend to the tip
W. bancrofti
Sheathed filaria tail morphology:
With 2 terminal nuclei
B. malayi
Sheathed filaria tail morphology:
Nuclei extend to tip of tail
Loa loa
Unsheathed filarial worms
M. perstans
M. ozzardi
M. streptocerca
O. volvulus
Carried by midges flies (culicoides flies)
M. perstans
M. ozzardi
M. streptocerca
O. volvulus vector
Black flies
Non-periodic filarial worms
M. perstans
M. ozzardi
M. streptocerca
O. volvulus
Unsheathed filaria tail morphology:
Nuclei that do not extend to tip of tail
M. ozzardi
O. volvulus
Unsheathed filaria tail morphology:
Nuclei extend to tip of curved tail/shepherd’s crook
M. streptocerca
Accidental ingestion causes visceral larva migrans/ocular larva migrans
Toxocara canis
Toxocara cati
Causes cutaneous migrans/creeping eruption
A. caninum
A. Braziliense
Infection in man causes nodules in lungs/ coined lesions (diagnosed through x-ray)
D. immitis
Causes eosinophilic meningitis/cerebral parastrongyliasis
P. cantonensis (A. cantonensis)
Causes anisakiasis
Anisakis spp.
Infective stage of Anisakis spp
Larval form
Definitive host for P. cantonensis
Rats
Intermediate host of P. cantonensis
Snails
MOT of P. cantonensis
Ingestion after eating raw snail
MOT for D. immitis
Skin inoculation
MOT for A. caninum and A. Braziliense
Skin penetration of filariform larva
MOT for Toxocara canis and Toxocara cati
Accidental ingestion of embryonated eggs
Adult worm:
Pink or white
Superficially resembles earth worm
Mouth: 3 oval lips - trilobate lip
Ascaris lumbricoides
Fertilized egg of A. lumbricoides appearance
Thick shell
Unfertilized egg of A. lumbricoides appearance
Thin shelled
A. lumbricoides eggs without mamillation appearance
decorticated
Adult worm:
Pinkish gray
Anterior 2/3 slender
With slender head part and fleshy tail that resembles a whip
Trichuris trichiura
Egg appearance:
Barrel/ football shaped
Lantern shaped with PROTRUDED mucus plugs/polar plugs
T. trichiura
Resembles japanese lantern ova
T. trichiura
Egg appearance:
D-shaped, flat on one side; lopsided with thin shell that encloses motile larva
Enterobius vermicularis
Adult worm:
Equipped with CUTICULAR ALAR EXPANSION and well defined esophageal bulb
Enterobius vermicularis
Egg appearance:
Peanut shaped, flat polar plugs, with striated shell
Capillaria philippinensis
Adult worm:
Thin filamentous anterior and a slightly thicker posterior
C. philippinensis
Egg appearance:
alike/identical eggs
Ovoid with thin shell containing 2-8 germ cells resembling morula ball
Necator americanus
Ancylostoma duodenal
Adult worm:
with semilunar cutting plates
N. americanus
Adult worm:
2 pairs of buccal teeth
A. duodenale
Adult worm: 1 pair of buccal teeth
A. braziliense
Adult worm:
3 pairs of buccal teeth
A. caninum
Egg appearance:
Similar to those of hookworms but are usually embryonated
Stongyloides stercoralis
Adult worm:
Short buccal cavity with indistinct lips
S. stercoralis
Soil transmitted helminths
Strongyloides stercoralis
Necator americanus
Ancylostoma duodenale
Ancyclostoma caninum
Ancylostoma braziliense
Can cause Infection — PRURITIS ANI itchiness of anal region caused by female migration
E. vermicularis
Heavy infection of E. vermicularis can lead to
Rectal prolapse
Hookworm can cause what type of anemia
IRON DEFICIENCY ANEMIA - MICROCYTIC HYPOCHROMIC TYPE OF ANEMIA
Can cause Loeffler’s syndrome
A. lumbricoides
Chinese lantern ova:
S. stercoralis
Unholy three hookworms
Ascaris lumbricoides
Trichuris trichura
Hookworms: N. Americanus and A. dudenale
Causes pneumonitis due to lung migration
Ascaris lumbricoides
Strongyloides stercoralis
Human hookworms
Unsheathed filaria tail morphology:
Nuclei extend to tip of tail
M. Perstans