PARA LEC: NEMATODES PART 1

• Clinical Parasitology Lecture MLS40 9 - LEC is about Testinal Nematodes.
• Roundworms are a type of Nematoda, also known as Phylum Nematoda.
• Flatworms can be either Flat and Segmented, as in Phylum Cestoda (tapeworms), or Flat and Unsegmented, as in Phylum Trematoda (flukes).
• Nematodes can be either Obligate or Facultative parasites.
• Most organs of parasitic worms are greatly reduced but the reproductive system is well developed.
• Albendazole is an alternative drug for the treatment of Capillaria philippinensis infection.
• Mebendazole is the drug of choice for the treatment of Capillaria philippinensis infection.
• Microscopic examination of stool sample (Direct Fecal Smear) is used for the diagnosis of Capillaria philippinensis infection, revealing the diagnostic stage as an unembryonated ovum.
• Weight loss, Blood-streaked stool, Anemia are symptoms of Capillaria philippinensis infection.
• Capillaria philippinensis is a parasitic worm that infects humans by eating raw fresh water fish.
• Nematodes have a complete digestive tract and separate sexes (male and female).
• Trematodes and Cestodes are hermaphrodites or monoecious.
• Nematodes have elongated, unsegmented, and cylindrical bodies, are bilaterally symmetrical, have a tapered posterior end and a rounded anterior end, except for Trichuris trichiura and Capillaria philippinensis.
• Fertile eggs of Ascaris lumbricoides measure 40 - 70 μm by 35 - 50 μm.
• Trichuris trichiura, Enterobius vermicularis are found in the large intestine (Colon).
• Embryonation of ova in soil lasts for 3 weeks and can survive in the soil for 2 years.
• Ascaris lumbricoides has an outer coarsely mammillated albuminous covering which may be lost in some eggs.
• Capillaria philippinensis, Hookworms, Ascaris lumbricoides, Trichinella spiralis, Strongyloides stercoralis are found in the small intestine (Small Chats).
• The hepato-tracheal migration phase of the parasite is about 14 days.
• The lifespan of an adult worm is 1 year.
• The adult worms of Ascaris lumbricoides are creamy-white to pinkish yellow when freshly expelled.
• A female adult worm can lay 200,000 eggs per day.
• Nematodes are protected by a cuticle from gastric acid and digestive enzyme, which is produced by the hypodermis/epidermis.
• Nematodes have separate sexes but some are parthenogenetic.
• Males are generally smaller than females.
• Roundworms, or Nematodes, have a general feature where both sexes are rounded anterior end and tapering or blunted end, males are curved posteriorly while females have flat posteriorly.
• Roundworms have longitudinal muscles that perform probing and penetrating motion.
• Trichuris trichiura has no lung migration in its life cycle, with the adult worm being flesh colored or pinkish, slender, and with an anterior two-thirds that is attenuated and thin, contrasting to the remaining posterior one-third which is fleshy and robust.
• Pathogenesis of Trichuris trichiura involves petechial hemorrhages worsening amoebic dysentery, intestinal bleeding (enterorrhagia), abdominal pain, nausea, and vomiting.
• Female Ascaris lumbricoides is tapered at both ends and large, measuring 20 to 35 cm long and up to 45 cm.
• Ascaris lumbricoides causes Loeffler’s syndrome, a disease in which eosinophils accumulate in the lung in response to parasitic infection.
• Male Ascaris lumbricoides is smaller and slender, curves posteriorly, and is equipped with a copulatory spicule.
• Diagnosis of Ascaris lumbricoides is done through microscopic examination of stool sample (Direct Fecal Smear), with albendazole, mebendazole, and pyrantel pamoate being the drugs used for treatment.
• Pathogenesis of Ascaris lumbricoides involves the reaction of the tissues to the migrating larvae (lungs), the effect of the parasite on the intestine, and the possibility of its extraintestinal migration.
• Prevention of Ascaris lumbricoides involves proper human waste disposal, hygiene education, washing of vegetables, and regular deworming.
• The head of Ascaris lumbricoides is provided with three lips and a small triangular buccal cavity.
• Roundworms do not have a true body cavity, instead they have a pseudocoelom, a fluid-filled space within the bodies of roundworm, not covered by membrane.
• The nematode nervous system is characterized by an circumoral brain or nerve ganglion (nerve ring) around the area of the pharynx and four peripheral nerves that run along the body: one ventral nerve or cord, one dorsal nerve or cord, two lateral nerves or cords.
• Amphids are cuticular depressions present on the lips surrounding the mouth in the nematodes.
• Under Roundworms: Phylum Nematoda