Submitted by: Submitted by rhoanjayvee
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Date Submitted: 09/30/2012 07:47 AM
Rhoanjayvee BS-Bio 4 September 24, 2012
Parasitology Lab Exercise:
INTESTINAL NEMATODES
Objective:
To examine the morphology of the eggs, larva, and adult forms, and to study the life history, taxonomy, pathology, and epidemiology of some of the commonest intestinal nematodes infecting man
Discussion:
Nematodes are commonly known as roundworms. As their name implies, they have unsegmented cylindrical bodies, which are tapered are both ends and covered with cuticle. Unlike the platyhelminthes which have (or sometimes lack) incomplete digestive system, the roundworms are equipped with complete oral-to-anal alimentary canal. Sexes are separate, with females generally larger than males. Nematodes are medically important parasites of the intestines, skin, lymphatics, and other tissues. In the laboratory, we studied eight representative nematodes that parasitize human intestines. Although considered a muscular parasite, Trichinella spiralis is nevertheless included as it has an important albeit transitionary stage in the intestines. These eight roundworm species are taxonomically ranked as following:
TAXA LABORATORY SPECIMEN
Phylum Nematoda
Class Aphasmida
Family Trichinellidae Trichinella spiralis
Family Trichocephalidae Trichuris trichiura
Capillaria philippinensis
Class Phasmida
Family Strongyloididae Strongyloides stercoralis
Necator americanus
Ancylostoma duodenale
Family Oxyuridae Enterobius vermicularis
Family Ascaridae Ascaris lumbricoides
Trichuris trichiura
The whipworm is distributed worldwide, especially in area with poor sanitation and hygiene. Adults of both sexes are characterized by a slender anterior section and thickened posterior and resembling a whip. Male posterior end is tightly coiled. Female size ranges 3-5 cm while male is <4cm. The infective stage is embryonated egg (by ingestion). The eggs are eliminated with...