PaRaSiToLoGy Practicals 1

Nematodes - trematodes

srjp_011686

Enterobius vermicularis ova

• D-shaped

• Scratching of the perianal area leads to hand contamination with infective ova and reinfection of the host

Enterobius vermicularis - Male Enterobius vermicularis - Female

Strongly curved ventral end and conspicuous copulatory spicule

Pointed tail in females; more

frequently found in cellophane

tape preparations

Common name: PINWORM

Trichuris trichiura (fertilized ova)

• smooth shell with polar prominences, known as polar “plugs”

• “football shaped”; “chinese lantern”

• female worm shed 3,000 and 20,000 eggs per day

• requires tropical temperature for embryonation to occur

• an infective egg can survive for 1 year

Trichuris trichiura - female

Common Name: WHIP WORM

Trichuris trichiura – male worm

• characteristically coiled tail

Trichuris trichiura – cross section appendix

Trichinella spiralis ( Muscle Worm)

• Cosmopolitan in distribution

• when infective larvae in inadequately cooked pork is ingested, they reach maturity in the intestine

• larvae enters the bloodstream and are carried to the muscle tissue throughout the body

• pigs and rats are the most important reservoir hosts in nature

• Larvae are most abundant in tongue, masseter muscle, diaphragm and other active muscle tissues.

Capillaria philippinensis ova

• “peanut shaped”

• unembryonated fertile eggs

• striated shells and inconspicuous polar prominences

Capillaria philippinensis - adult worm

• Common name: “PUDOC WORM”

• Diagnostic stage: unembroyenated egg, fertilized egg and larva

Ancylostoma braziliense – female worm Ancylostoma braziliense – male worm

Ancylostoma species

The posterior end of the male has a broad transluscent

membranous caudal bursa with rib like rays and spicule which is

used for attachment to the female during copulation.

Ancylostoma caninum – adult female worm

Ancylostoma caninum – adult male worm

Ancylostoma caninum

The anterior portion of the of an adult is responsible for the

attachment which is known as the mouth part. Has 3

cutting plates.

Hookworm – adult male

Hookworm – adult female

Necator americanus – mouth part

Hookworm – rhabtidiform larvae

Hookworm – filariform larvae

Hookworm (3rd stage, filariform larva)

• much longer and more slender than the rhabtiditoid form

• short esophagus, long intestine, pointed tail

• this stage is usually found in soil or in feces cultured for 5 days or longer

Hookworm (rhabtidiform larva)

• maybe confused with strongyloides larva normally passed in feces

• has long, tubular, buccal canal and the genital primordium cannot be seen

Strongyloides stercoralis - rhabditiform

If free living female in feces, are allowed to stand at room

temperature and remain moist for 2-3 days, the rhabditoid larva may develop into free living adult

Strongyloides Stercoralis - Filariform

• 3rd stage, infective stage

• longer and slender than rhabditoid stage

• differentiated from hookworm filariform by its long esophagus, equal in length intestine, and by

its blunt, notched tail

• Parasitic females rarely are seen in feces

Strongyloides stercoralis - filariform

Ascaris lumbricoides – unfertilized ovum

Has a poorly developed irregular mammillated layer.

Ascaris lumbricoides – fertilized ovum

Presence of mammillated external layer of the thick shell; one stage cell normally found

in feces.

Ascaris lumbricoides – embryonated ovum

Ascaris lumbricoides – decorticated ovum

The outer albuminoid,

mammillated layer is absent.

Males: curved tail

Females: straight tail

Intermediate host for Schistosoma japonicum

Schistosoma japonicum ova in human intestine

Schistosoma japonicum ova in x-section appendix

Ascaris lumbricoides – embryonated ovum

Schistosoma japonicum ova in liver

Schistosoma japonicum ova in spleen

Schistosoma japonicum ova in human brain

Note: kahit ako, hindi ko makita yung ova sa mga organ. Sorry, ito lang kasi yung nakita kong pix…

Schistosoma spp: cercaria are the infective forms. After encountering the skin, the cercariae penetrate and lose the tail transforming into schistosomulae.

Known as the “forked tail cercaria”

Schistosoma japonicum – in copula

• adult schistosomes live in pairs in the portal system and in mesenteric venules

• Females are slender and longer; are held in the gynecophoric canal during copulation

• Males have a ventral infolding from the ventral sucker to the posterior end forming the gynecophoric canal

Schistosoma japonicum – adult

male

Schistosoma japonicum – adult

female

Schistosoma japonicum – ova

Schistosoma japonicum ova

• smaller than those of S. haematobium and S. mansoni

• Ovoid and has thin clear shell

• a small spine or hook on its lateral margin that may be inconspicuous or difficult to see

• contains a miracidium when passed into the feces