Important Parasites

Entamoeba histolytica - AmoebiasisGiardia lamblia - GiardiasisCryptosporidium parvum CryptosporidiasisTaenia solium/T saginata (tape worms)Ascaris lumbricoides (round worms)Trichuris trichiura (Whip worm)Ancylostoma duodenale (Hook worm)Enterobius vermicularis (pin/thread worm)

Irregular in shape with PseudopodiaSize varies from 10-60 microns

Active and motileSpherical nucleus with central karyosome

In acute case, trophozoites are with engulfed erythrocytes

Trophozoites divide by binary fission

Trophozoite

Trichome stain - Trophozoites

Spherical , 10-20 micronsFour nucleiMass of glycogen1-4 chromidial bars

CYST

Trichome stain - cystIodine mount - Cyst

Adhesive DiskOr Suction Disc

Trophozoite Cysts Giardia intestinalisTrophozoite pear shaped with 2 nuclei , 8 flagella & a suction disk (for attachment to intestinal wall)Cyst Oval, 4 nuclei, and internal fibers

A = cyst B= trophozoite of Giardia lamblia

Cryptosporidium parvum oocysts Acid Fast staining

Tape worm Taenia saginata(5-10 meters)Adult wormEggEgg : Bile stained, 3 pairs of hooklets

Cannot differentiate eggs of Taenia solium (pork tapeworm) from Taenia saginata (Beef tapeworm)

The eggs measure 30-35 micrometers in diameter and are radially-striated. The internal oncosphere contains six refractile hooks.

Trichuris trichura adult wormsResembles whip, 2-5 cms

Whipworm Trichuris trichiura Adult wormEggEggEgg: it is barrel shaped, 50 x 20m in size. It is brownish (bile stained) and has a translucent polar plug at either ends.

Adult worm of Enterobius vermiculais

Adult worm of Enterobius vermiculais

Egg: 50 to 60 u by 25 , persimmon seed-like, colorless and transparent, thick and asymmetric shell, with larva.

Ancylostoma duodenale-Hook wormNon bile stained- ColourlessEgg with blastomeres

Ascaris lumbricoides : Round worm

Cylindrical , 15-40 cms long

Fertilized egg ((60 x 45m) : Bile stained (brownish yellow)Oval, mammiliated thick albuminous coat Unfertilized egg (80-95u): Elongated, NonfertileAscaris lumbricoides : Round worm eggs

Vibrio cholerae Gram negative, Comma shaped bacilli

Campylobacter jejuniComma, S, girdle, spiral shaped