Parasitology Week 3 PDF

intestinal 3-4 nematodes nematodes Phylum: nemathelminthes aka round worms general characteristics Adult nematodes are elongated, cylindrical worms, primarily bilaterally symmetrical Anterior end may be equipped with hooks, teeth, plates, and papillae for purpose of abrasion, attachment and sensory...

intestinal 3-4 nematodes nematodes Phylum: nemathelminthes aka round worms general characteristics Adult nematodes are elongated, cylindrical worms, primarily bilaterally symmetrical Anterior end may be equipped with hooks, teeth, plates, and papillae for purpose of abrasion, attachment and sensory responses Supporting body well consists of an outer, hyaline, noncellular cuticle subcuticular epithelium a layer of muscle cells Alimentary tract is a simple tube extending from mouth to anus. Complete digestive tract and a muscular pharynx that is characteristically triradiate. There is no circulatory system. Mouth: Entry; Anus: Disposal Equipped with complete reproductive system Life cycle: Egg stage Larval stagE Adult stage They are provided with separate sexes (dioecious) although some may be parthenogenetic MALE small, curved posterior, with spicule FEMALE larger, pointed posterior, no spicule found EGGS OVIPAROUS OVIVIPAROUS OVOVIVIPAROUS VIVIPAROUS lay immature/unembryonated/unsegmented eggs e.g. Ascaris lay embryonated/mature eggs lay eggs in segmented stage E.G. ENTEROBIUS VERMICULARIS lay larva not eggs e.g. Trichinella spiralis CHEMORECEPTORS specialized sensory cells that allow nematodes to detect and respond to chemicals in their environment These chemicals can include food sources, mates, potential dangers, and even communication signals from other nematodes. amphids cephalic chemoreceptors PHASMIDS CAUDAL chemoreceptors APHASMIDS without caudal chemoereceptors E.G. Trichuris, Trichinella, and Capillaria CLASSIFICATION BASED ON HABITAT OF ADULT WORMS Small Intestine Large Intestine Ascaris lumbricoides Hookworms Strongyloides stercoralis Capillaria Trichinella spiralis (adult) Trichuris trichiura Enterobius vermicularis Small Intestine Large Intestine Ascaris lumbricoides Hookworms Strongyloides stercoralis Capillaria Trichinella spiralis (adult) Trichuris trichiura Enterobius vermicularis Ascaris lumbricoides Common Name: Giant Intestinal Roundworm Most common intestinal nematode of man occurs most frequently in the tropics Vector of Ascaris: Flies and Cockroaches Member of Soil Transmitted Helminths (STH): HATS Member of Unholy Three: HAT Member of parasites having Heart-Lung Migration: ASH Habitat: Small Intestine Final Host: Man Diagnostic Stage: Ova found in the stool (fertilized/unfertilized) Infective Stage: Embryonated Egg Mode of Transmission: Ingestion of embryonated eggs (fecal-oral transmission); embryonates in soil adult ascaris White, cream, or pinkish yellow when fresh Head is provided with 3 lips and a triangular buccal cavity/trilobate lips female male EGGS Become infective 2-6 weeks after deposition Survive harsh environments: dry/freezing temperatures Either fertile or infertile Lecithin granules is present in unfertilized egg Egg shell consists of 3 layers: a. Inner Vitelline/Lipoidal/Lecithin later b. Middle Glycogen layer c. Outermost Mammillation/Corticated layer heart-lung migration Resembling Loeffler’s Syndrome (eosinophilia) Ascaris pneumonitis (pneumonialike symptoms) Increased Eosinophils (+) Charcot-Leyden crystals visceral larva migrans larva will hatch but will not mature into adult worms Ascaris suum large roundworm of pigs human infection is rare eggs are morphologically identical to A. lumbricoides Toxocara cati Cat Ascaris Toxocara canis Dog Ascaris Can be ingested by man (accidental) and cause Visceral Larva Migrans/Ocular Larva Migrans Laboratory Diagnosis Stool Exam (DS: Eggs) If (-) Stool Exam: a. No infection b. Early infection (no eggs laid yet) c. All male worm infection Treatment: Albendazole Mebendazole Pyrantel Pamoate Enterobius vermicularis Common Names: Pinworm, Seatworm, Social Worm, Society Worm has familial or group tendency; active transmission within the household Habitat: Large Intestine Final Host: Man Diagnostic Stage: Embryonated Egg Infective Stage: Embryonated Egg Mode of Transmission: Inhalation, Ingestion, Autoinfection (External), Sexual Transmission has been reported The only nematode that cannot be controlled through sanitary disposal of human feces because the eggs are deposited in the perianal region instead of the intestinal lumen. Personal cleanliness and hygiene are essential. the most common helminth to infect man adult worm Small, whitish, or brownish in color anterior end with lateral wings or cephalic alae Male: dies after copulation Female: will go to the perianal region oviposit dies autoinfection Possesses a clear, pointed tall that resembles a pinhead (pinworm) eggs Elongated, flattened on one side, D-shaped; Embryonated Double layered: albuminous layer and lipoidal layer; no glycogen layer “tadpole-like embryo” life cycle Adults in colon Gravid female migrates to perianal region to deposit eggs Egg ingested, hatch in small intestine, releasing larvae and develop into adult worms Symptoms and Pathology Pruritus ani /Nocturnal Pruritus ani Hemorrhagic colitis Extraintestinal enterobiasis: vagina, uterus, fallopian tube Autoinfection: External Treatment mebendazole albendazole Trichuris trichiura Common Name: Whipworm Other species: T. suis (pig whipworm) T. vulpis (dog whipworm) Habitat: Large Intestine Final Host: Man Diagnostic Stage: Ova found in stool Infective Stage: Embryonated Egg Mode of Transmission: Ingestion of embryonated egg (fecal-oral) adult Flesh colored or pinkish gray worms, slender or attenuated in the anterior Anterior is attenuated and slender resembling a whip Anterior 3/5 portion is traversed by a narrow esophagus resembling "string of beads" eggs Barrel-shaped (football-shaped) with bipolar mucus plug Prominent hyaline polar plug Resembling Japanese Lantern life cycle Adults in the colon Undeveloped eggs in feces, embryonates in warm, moist soil Embryonated egg ingested by man Larvae hatch in small intestine, penetrate and develop in villi, return to lumen and migrate to cecum and then mature into adults. Symptoms and Pathology Diseases: Trichuriasis, Trichocephaliasis, Whipworm Infection Bloody or mucoid diarrhea Weight loss, abdominal pain Rectal Prolapse: Heavy Infection Petechia Hemorrhage: provide good site for Entamoeba histolytica Treatment mebendazole albendazole Capillaria philippinensis Discovered by Dr. Nelia P. Salazar in 1963 Common Name: Pudoc Worm/Mysery Worm Pudoc Disease/Mystery Disease (from Pudoc, ilocos Sur) Close relative of Trichuris trichiura Habitat: Small Intestine Final Host: Man True Definitive Host: Migratory birds Intermediate Host: Freshwater Fish/Brackish Water Fish Ipon (Hypselotris bipartita), Birot, Bagsang, Bagtu, Biyang Bato, Guppy Diagnostic Stage: Larva and /or ova found in stool Infective Stage: Filariform Larva Mode of Transmission: Ingestion of raw/undercooked fish/seafood bearing the infective larva adult Delicate, tiny worms Male with chitinized spicule Females usually have eggs in utero eggs With flattened bipolar mucus plugs, striated, and smaller than Trichuris egg Guitar, peanut-shaped typical egg immature eggs unembryonated eggs will go to stool will go to freshwater where the embryonation process occur eaten by fish Atypical egg segmented egg embryonated egg hatch inside the small intestine responsible for autoinfection (similar to S. stercoralis) To differentiate from Trichuris egg: 1. smaller and striated and 2. mucus plugs are not as protruded Capillaria hepatica Causes hepatic capillariasis Egg: shell of egg is striated with shallow polar prominence Adult: slender, anterior narrow and swelled posterior; rarely seen intact, dies in parenchyma Pathogenesis: Prefers to infect livers, egg deposition in liver parenchyma, larval migration in lungs, kidneys or organs Humans: accidental host Infective Stage: Embryonated Eggs (requires air and soil) Diagnostic Stage: Liver Biopsy unembryonated eggs, adults (rare) Mode of Transmission: Ingestion of embryonated eggs QUIZ 7 1 5 2 3 4 6 8 9 10