Clinical Parasitology - 02 Nematodes

o CLINICAL PARASITOLOGY NEMATODES o OUTLINE • • Nematodes o General Characteristics o Chemoreceptors o Habitats o Life Cycle o Basic Developmental Cycle • Intestinal Nematodes o Ascaris lumbricoides o Trichuris trichiura o Enterobius vermiculares o Capillaria philippinensis o Laboratory Diagnosis & Treatment o Hookworms o Strongyloides stercoralis o Laboratory Diagnosis & Treatment Extraintestinal Nematodes o Introduction o Trichinella spiralis o Filarial worms o Other filarial worms Legend: → (Example) Oviviparous ▪ Lay mature or embryonated eggs → Enterobius vermicularis Viviparous/larviparous ▪ Do not lay eggs ▪ Lays larva → Trichinella spiralis CHEMORECEPTORS • • • NEMATODES INTRODUCTION & TAXONOMY Sensory organs of nematodes Classification based on location of chemoreceptors o Amphids - cephalic chemoreceptor ▪ All nematodes o Phasmids - caudal chemoreceptors (located in the posterior tail) According to the presence of phasmids o Phasmids (secernentia) - with caudal chemoreceptors ▪ All nematodes except (adenophorea) • Trichuris trichuria • Capillaria philippinensis • Trichinella spiralis o Aphasmids (adeophorea) - without caudal chemoreceptors HABITAT • • NEMATODES • • • • • • Commonly called roundworms Elongated, cylindrical, and bilaterally symmetrical Unsegmented With complete digestive system No circulatory system Dioecious, some are parthenogenic o Dioecious - 2 separate sexes; cannot be 2 sex o Parthenogenic - may or may not require male to reproduction or copulation → Strongyloides stercoralis GENERAL CHARACTERISTICS • • Male: smaller, curved posterior, with spicule (needle like structure for copulation) Female: larger, pointed posterior, no spicule o Produces eggs: o Oviparous ▪ Lay immature or non-embryonated eggs → Ascaris lumbricoides Intestinal o Small Intestine (CASH) ▪ Capillaria philippinensis ▪ Ascaris lumbricoides ▪ Strongyloides stercoralis ▪ Hookworms ▪ Trichenalla spiralis (adult) o Large Intestine (E-T) ▪ Enterobius vermicularis ▪ Trichiuris trichiura Extraintestinal o Muscle ▪ Trichinella spiralis (larva) o Lymph nodes & subcutaneous tissues ▪ Filarial worms o Eyes and meninges ▪ Angiostrongylus cantonensis ▪ Loa loa ▪ Onchocerca volvolus LIFE CYCLE • • • Egg Larva (3 stages) o L1 & L2 - Rhabditiform larva o L3 - Filariform larva Adult BASIC DEVELOPMENTAL CYCLE • • • • • • • • • • • • Molting - newly hatched larva feeds on bacteria grows until constrained by its outer skin or cuticle o Undergo 2 process o Synthesis - formation of new cuticle inside the old cuticle until it is fully enclosed with the new cuticle o Exsheathment - casting off of old cuticle Egg L1 - larva inside the egg; release when egg hatched H - hatching; releasing larva M1 - first molting L2 - second stage larva M2 - second molting L3 - infective stage to most nematodes M3 - third molting L4 - final stage larva o Not all nematode (esp. medically important nematode stops at L3) M4 - final molting (no longer larva) Adult - can be male or female OVA/EGGS • • • • • • • INTESTINAL NEMATODES • • • • • • • Ascaris lumbricoides Trichiuris trichura Enterobius vermicularis Capillaria philippinensis Necator americanus Ancylostoma duodenale Strongyloides stercoralis Adult lays 200,000 eggs/day Nematode that lays the most egss/day Become infective 2-6 wks after deposition Survive harsh environment: dry/freezing temp Size: o Length: 85-95 mcm o Width - 38-45 mcm Egg shell consist of 3 layers o Inner Vitelline Membrane ▪ Aka lipoidal/lecithin membrane o Middle Glycogen Layer o Outermost mammillation (albuminoid layer) Stages o Unfertilized ▪ No inner vitelline layer ▪ With lecithin granules (black spots) o Fertilized corticated ▪ All layers are present o Fertilized decorticated ▪ No outermost mammillation layer o Embryonated ▪ With embryo inside ▪ Presence of larva ASCARIS LUMBRICOIDES • • • • • • • Common name: giant intestinal roundworm o Largest nematode Most common intestinal nematode of man in the philippines Habitat: small intestine Definitive host: Man Diagnostic stage: ova, adult Infective stage: ova (embryonated egg) Mode of transmission: ingestion o Adult in the small intestine, will lay egg o Egg can be hatched in GI tract that will undergo maturation ADULT WORM • Anterior head: trilobate lips MALE FEMALE Size (length) up to 30 cm 22-35 cm Color creamy white with pink tint Other features curved posterior tail pointed posterior tail PATHOLOGY: ASCARIASIS • • Member or unholy 3 o 3 nematodes that extremely common for a child to be infected with simultaneously o Ascaris lumbricoides o Trichuris trichiura o Hookworms Due to larva o Ascaris pneumonitis (Loeffler’s pneumonia) ▪ Increased eosinophils ▪ Charcot Leyden crystals - eosinophil degradation product ▪ Ascaris lumbricoides is capable of intestinal to extraintestinal movement ▪ • Ingestion of egg, larva migrate to favorable conditioned environment ▪ Intestinal wall → blood vessel → liver → blood vessel → lungs, brionchiole o Visceral Larva Migrans (VLM) ▪ Type of allergic reaction due to non-human ascaris (accidental parasites) ▪ Toxocara canis - dog ascaris ▪ Toxocara cati - cat ascaris ▪ Ascaris suum - pig ascaris Due to adult o Erratic ▪ Migration to extraintestinal sites ▪ When intestine become unfavorable • Due to medication o Obstruction by bolus formation ▪ When there are numerous worms ▪ Bolus - group of worms ▪ Treatment: surgery OVA/EGGS • • • • • Adult lays 100,000 eggs/day Mucoid prominent bipolar plugs o Unique to Trichuris trichiura Shape: Japanese lantern/football/barrel/lemon-sahped Yellowish brown in color (bile) Size o L: 50-55 mcm o W: 25 mcm TRICHURIS TRICHIURA • • • • • • Common name: whip worm Final host: man Habitat: large intestine Diagnostic stage: egg o Stage that can be easily identified Infective stage: fully embryonated egg Mode of transmission: ingestion PATHOLOGY: TRICHURIASIS • • • Bloody diarrhea - due to lacerations of pin-fashion attachment causing bleeding Epigastric pain Iron deficiency anemia o Rectal prolapse ▪ Occurs among children ▪ High number of worms in the rectum leading to edema ▪ Extruding of rectum outside of anus o Hypoalbuminemia ▪ Decrease of albumin in blood ▪ Due to competition of nutrients between Trichuris and large intestine ENTEROBIUS VERMICULARIS • • • • • • • • ADULT WORM • • • Anterior: 3/5 attenuated o Used for pin-fashion attachment o May cause lacerations in the large intestine leading to bleeding causing anemia Male: curved posterior fleshy portion Female: pointed posterior fleshy portion • Other name: Oxyuris vermicularis Common name: pinworm, seatworm, society worm, threadworm (obsolete), Tiwa o Threadworm - common name for another nematode Most common nematode in man (USA) Final host: man (only host) o Occasional cases recorded in captive chimpanzees Habitat: large intestine Diagnostic stage: ova Infective stage: ova Mode of transmission o Ingestion o Inhalation o Retroinfection - newly hatched larva migrates back into the host o Autoinfection - hand-to-mouth transmission Has familial or group infection tendencies o Active transmission within household o Eggs of E. vermicularis are able to survive in weeks under conditions CAPILLARIA PHILIPPINENSIS • • • • • • • • • Discovered by Nelia Salazar at Pudoc, Ilocos Sur (1963) Common name: Pudoc worm Final host: man/other vertebrae Natural host: migratory birds (herons, egrets, bitterns) Intermediate hosts :Fresh water fishes/Brackish water fishes/ glass fishes ▪ Bagtu ▪ Bagsang ▪ Birot ▪ Ipon (Hypselotris bipartita) Habitat: small intestine Diagnostic stage: Larva or ova found in stool Infective stage: larva in fishes Mode of transmission: ingestion of raw/uncooked fish with infective larva OVA/EGGS • • • • • Adults 15,000 eggs/night o Female adult - nocturnal Incubation to become infective - 4-6 hours Oval shaped, flattened on one side o D-shaped ovum With double layer shell Size o Length: 40-60 mcm o Width: 20-35 mcm ADULT WORM • MALE FEMALE Flask-shaped/bulb-like Gravid uterus filled with esophagus eggs Curved posterior end Pointed posterioir end Has cephalic alae (lateral wing) Enterobius vermicularis adult male usually dies after copulation. Hence, rarely seen in stool or perianal region. ADULT WORM PATHOLOGY: ENTEROBIASIS • • • • Nocturnal pruritus ani o Pruritus ani - exaggerated itching o Itching at night due to laying of eggs o Female lay eggs in anal area o Results in insomnia and irritation Loss of appetite Extraintestinal Enterobiasis → Uterus → Vagina → Fallopian tube Only nematode that cannot be controlled through sanitary disposal of human feces o Due to female laying eggs in anal area o Familial transmission occurs • • • Delicate tiny worms Male: with chitinized spicule Female: usually with eggs in utero OVA/EGGS • • • • • Guitar/peanut shaped Striated shell Flattened mucoid bipolar plugs Morphologically similar to T. trichiura Some say that it is a close relative to T. trichiura Size Shell Shape Mucus plugs Capillaria philippinensis Smaller Striated Peanut/guitar flattened Trichuris trichiura Larger No striation Japanese Prominent HOOKWORMS PATHOLOGY: CAPILLARIASIS • • • Mystery Disease (Pudoc Disease) o Mystery because people in Pudoc believed that they are destined to die due to disease from mystical river God Borborygmus - gurgling sound of stomach Severe diarrhea • • • LABORATORY DIAGNOSIS • • Ascaris, trichuris, Capillaria: Stool exam o Direct Fecal Smear ▪ Most common ▪ 2 mg of stool + 1 drop 0.85% NaCl (NSS) ▪ Routine method of stool examination ▪ Stains: Lugol’s iodine, Nair’s Buffered Methylene Blue (BMB) ▪ Examined using LPO and HPO ▪ Useful in specific specie identification ▪ Reasons why ova can’t be seen • No infection • Early infection • All male worm infection o Kato-thick ▪ Qualitative Kato technique ▪ 50-60 mg of stool cellophane ▪ Cellophane is soaked in a mixture of glycerine and malachite green solution ▪ Glycerin: clearing agent ▪ Malachite green: gives pale green color o Kato-katz ▪ Also known as “cellophane-covered thick smear” ▪ Recommended method for egg counting procedure (WHO) - quantitative o Concentration techniques ▪ Sedimentation techniques • Useful for recovery of heavy egg → T. trichiura → C. philippinensis • Heavy due to mucoid plugs ▪ Floatation techniques • Useful for recovery of lighter eggs → All nematodes except T. trichiura, C. philippinensis Enterobius: cellulose tape/Scotch tape method 1. Loop tape over end of slide to exposed gummed surface 2. Touch gummed surface several times to perianal region 3. Smooth tape on slide after apply 1 drop of Toluol or Iodine in Xylol (not used anymore) • • • • • • Second most common helminth to infect man Human hookworms o Ancylostoma duodenale - Old World Hookworm o Necator americanus ▪ New World Hookworm ▪ American hookworm, American murderer Animal Hookworm o Found in animals but can infect humans o Ancylostoma caninum - dog hookworm o Ancylostoma braziliense - cat hookworm A. ceylanicum - emerging human hookworm Final host: man Habitat: small intestine Diagnostic stage: larva or ova found in tool Infective stage: 3rd stage larva (filariform) Mode of transmission: skin penetration of infective larva OVA/EGGS • • • Adult lays 10-20 thousand eggs/day Ovoidal thin shelled and colorless Same for all hookworms LARVA Rhabditiform Larva (L1 & L2) Feeding stage (open mouth) Shourt and stout Long buccal cavity Short/small genital primordium Filariform larva Non-feeding stage (closed mouth) Long and slender Sheathed, pointed tail Infective stage ADULT WORM N. americanus • Treatment: o Albendazole, Mebendazole - Anti-parasitic drugs A. duodenale Shape S-shaped C-shaped Teeth Semilunar cutting plates 2 airs of teeth Copulatory Bipartite (2 digits); Tripartite (3 digits) bursa barbed/bristle like simple, not barbed • A. caninum - 3 pairs of teeth • A. braziliensis - 2 pairs of teeth (small medial teeth) PATHOLOGY OVA/EGGS • • • Due to larva o Allergic reaction (dermatitis) - ground itch, dew itch, colic itch, water sore, Mazza Mora ▪ Due to skin penetration o Pneumonitis - WAKANA Disease ▪ Hookworms can migrate from heart to lung o Cutaneous Larval Migrans (CLM) - caused by animal hookworms (zoonotic) ▪ Aka Creeping eruptions Due to adult o Epigastric discomfort o Malnutrition, edema ▪ Hookworm compete with nutrients o Iron deficiency anemia ▪ Microcytic, hypochromic anemia (small RBC, reduced Hgb) ▪ Adult hookworm competes with the host for nutrients as the eat LARVA Rhabditiform Larva (L1-L2) Short buccal cavity Prominent genital primordium • • • • • Common name - threadworm Rare Human-infecting Strongyloides spp. o S. fullerborni subsp fullerborni - primate parasite ▪ Causes life-threatening condition called “Swollen Belly Syndrome” o S. fullerborni subsp kellyi Final host - man Habitat o Free-living state - soil (indirect/heterogenic form) o Parasitic state - small intestine (direct/homogenic form) Diagnostic stage - Rhabditiform larva Infective stage - Filariform larva Mode of transmission o Skin penetration of infective larva o Autoinfection - intrinsic autoinfection ▪ When larva develop inside human host ▪ Rhabditiform to filariform ▪ Filariform - penetrate intestinal wall to lymphatic to bloodstream to initiate new life cycle o Hyperinfection ▪ exaggeration in the life cycle leading to excessive worm burden ▪ Occur in immunocompromised patients Filariform (L3) Notched tail Unsheathed PATHOLOGY: STRONGYLOIDIASIS • STRONGYLOIDES STERCORALIS • • Adult are parthenogenic o Clear thin shell o Chinese lantern appearance o Indistinguishable with hookworm ova • Due to larva o Allergic reaction - at the site of penetration (larva currens) o Pneumonitis - presenting Loeffler’s pneumonia Due to adult o Cochin-china Diarrhea, Vietnamese diarrhea ▪ Intermittent diarrhea (on & off) ▪ Disease was first recorded among French soldiers with diarrhea from Indo-china region (Cochin-china, Vietnam) LABORATORY DIAGNOSIS • Hookworms and Strongyloides o Diagnostic stage: Rhabditiform larva o Direct fecal smear o Concentration techniques ▪ Sedimentation technique ▪ Floatation technique o Harada Mori Stool Culture ▪ Recovery of nematode larva ▪ 48-72 hrs - Rhabditiform larva ▪ Up to 7 days - Filariform larva ▪ Always wear PPE (gloves) ▪ Conical tube & filter paper ▪ Conical tube has water - to prevent dehydration • Strongyloides only o Beale’s string test ▪ Duodenal aspiration technique ▪ Look for larva Rhabditiform Larva Hookworms S. Stercoralis Buccal Cavity Long Short Gential Primordium Small Promonent Filariform Larva Tail Pointed Notched Sheath Seathed unsheathed o S. Stercoralis - short & sexy • Treatment o Hookworms ▪ Mebendazole ▪ Pyrantel pamoate o Strongyloides ▪ Ivermectin ▪ Albendazole EXTRAINTESTINAL NEMATODES INTRODUCTION • • • • • • • Extraintestinal Nematode o Nematodes that habitats in muscles, eyes, meninges, subcutaneous tissues, or lymphatics Trichinella spiralis Filarial worms Dirofilaria immitis Dracunculus medinensis Angiostrongylus cantonensis Anisakis ADULT • • • LARVA • • TRICHINELLA SPIRALIS • • • • • • • Common Name: muscle worm, trichina worm History: o Tiedemann (1822) - first who described Trichinellosis o James Paget and Richard Owen - first to demonstrate T. spiralis among cadavers o Dickson Despommier ▪ discovered that larva resides in the nurse cells of skeletal muscles ▪ called T. spiralis as largest intracellular parasite Final Host/Intermediate Host: Pigs, Rat, Man (dead-end host) Habitat: o Adult: small intestine o Larva: skeletal muscle Diagnostic Stage: Encysted larva Infective Stage: Encysted larva Mode of Transmission: Ingestion of encysted larva T. spiralis has no egg stage MALE: with conical papillae o dies after copulation FEMALE: with club-shaped uterus o Viviparous o May live up to 30 days o Can lay 1500 larva in its lifetime • Coiled larva Encysted in the nurse cell of striated muscles (skeletal) o Nurse cell ▪ provide food for the neighboring cells ▪ Only capable cell to support T. spiralis Diagnostically important PATHOLOGY: TRICHINELLOSIS • • • “Great imitator” o Due to symptoms which can mimic other diseases Due to adult: o Diarrhea and abdominal pain Due to larva: o Eosinophilia ▪ Increase in eosinophils ▪ Trichinellosis gives the highest number of eosinophils o Muscle pain at the site of encystation, edema ▪ Eyelid Edema - edema surrounding the eye LABORATORY DIAGNOSIS • • Muscle biopsy Immunotest: o Tests that involve immunologic reaction (antigen-antibody reaction) o Bentonite Flocculation Test - serologic test to detect T. spiralis antibody in patient’s serum o Intradermal Bachmann Test ▪ T. spiralis extract is injected intradermally ▪ If there is antibody in blood, it will attack T. spiralis extract causing swelling ▪ Swelling, itching redness indicates antibody against Trichinella o Beck’s Xenodiagnosis ▪ involves animals ▪ Albino rat - test animal ▪ Albino rats are fed with suspected sample ▪ Collect muscle samples from rats for muscle biopsy TREATMENT • 8 known Trichinella spp.: o T. spiralis – most common to infect man o T. brivoti – 2nd most common, widely distributed special in Asia, Europe, northern and western Africa o T. nativa – infects wild carnivores in frigid zones of Asia, north America, and north eastern Europe o T. murrelli o T. nelsoni o T. papuea o T. pseudospiralis • • Thiabendazole - anti-parasitic agent Prednisone - to alleviate inflammation FILARIAL WORMS • • • Group of nematodes that infect man in different habitats 6 known species to infect man o Categorized based on habitat Habitat: o Lymphatics • • • • • • • o Subcutaneous tissue o Body Cavity Final Host: Man Intermediate Host: Arthropod Vectors Diagnostic Stage: Microfilaria (larval stage) Infective Stage: o Intermediate Host: Microfilaria o Final Host: Filariform Larva Mode of Transmission: Vector Borne Have only one life cycle Life cycle o Vector takes blood meals o Vector injects filariform larva o When in circulation, filariform larva will mature o When adults produce microfilaria, microfilaria can migrate in bloodstream o Microfilaria, from bloodstream taken by the vector, will migrate to thoracic muscles of vector which will eventually mature • Brugia malayi o Common Name: Malayan Filarial Worm o Vector: mosquito ▪ Mansonia spp. ▪ Anopheles o Microfilaria: Sheathed, tail with 2 separate nuclei • Brugia timori o Emerging lymphatic filarial worm o Timorian filariasis o Occurs in the Indonesian archipelago o Vector: Mosquito (Anopheles spp) o Microfilaria: same with B. malayi but larger in size Pathology o Due to Microfilaria: ▪ Tropic Pulmonary Eosinophilia • Increased eosinophil count • High IgE antibody level • Occur on patients residing in endemic areas • Presented with asthmatic attacks and enlarged spleens o Due to Adult: ▪ Acute Dermatolymphanioadenitis (ADLA) • Most common manifestation of lymphatic filariasis • Localized pain • Swelling of extremities o Lymphadenitis - inflammation of lymph nodes o Cellulitis ▪ Acute Filarial Lymphangitis (AFL) • Inflammation of the lymphatic vessels that progresses distally along the lymphatic vessel producing a palpable cord • Manifested in extremities ▪ Lymphedema • Most chronic manifestation • Can lead to elephantiasis ▪ Elephantiasis • Enlargement and hardening of limbs/extremities due to tissue swelling ▪ Genito-urinary lesion Hydrocele o Most common chronic manifestation of W. bancrofti (only causes lower infection) o Inflammation/swelling of scrotum Wuchereria bancrofti Brugia malayi Bancroftian Filariasis Malayan filariasis Lower elephantiasis Upper elephantiasis • LYMPHATIC FILARIAL WORMS • • • Can cause lymphatic filariasis o One of the most debilitating diseases plaguing tropical countries Second most common cause of permanent & long-term disability (next to psychiatric illness) Wuchereria bancrofti o Common Name: Bancroft’s Filarial Worm o Most prevalent specie ▪ Most common specie in the Philippines o Most common identified specie of filarial worms that infects man o Vector: mosquito ▪ Aedes, Anopheles, Culex o Microfilaria: Sheathed, no nuclei in tail SUBCUTANEOUS TISSUE FILARIAL WORMS LABORATORY DIAGNOSIS • Loa loa o Literally means, “worm worm” o Common Name: Eye worm o Vector: Fly ▪ Chrysops spp ▪ Tabanid fly ▪ Deer fly ▪ Mango fly o Microfilaria: Sheathed, nuclei continuous up to the tip of the tail • • • Onchocerca volvulus o Common Name: Convoluted worm, blinding worm, river blindness worm, Gale filarienne o Vector: fly ▪ Simulium spp. ▪ Blackfly - flies near river areas o Microfilaria: unsheathed, nuclei absent in the tail • Pathology o Loa loa: ▪ Calabar Swelling/Fugitive swelling • Swelling of the subcutaneous tissue ▪ Seen in eyes o Onchocerca volvulus: ▪ River Blindness ▪ Leading cause of blindness in endemic areas • Africa, Central America, Northern South America ▪ Second most common cause of blindness (first is caused by bacteria-Chlamydia trachomatis) BODY CAVITY TISSUE FILARIAL WORMS • • Non-pathogenic Mansonella ozzardi o Common Name: New World Filaria o Vector: Biting midges/gnats (Culicoides spp) o Microfilaria: unsheathed, nuclei absent in the tail • Mansonella perstans o Old name: Dipetalonema perstans o Common Name: Perstans Filaria o Vector: Biting midges/gnats (Culicoides spp) o Microfilaria: unsheathed, nuclei up to the tip of the tail • For Filarial Worms Specimen: Blood, skin snips o Wet Smears - for demonstration of live microfilaria from blood samples o Giemsa-stained Blood Smears - method of choice for demonstration of filarial worm structures (microfilaria) o Lymph node biopsy - useful for lymphatic filariasis o Ultrasound - used to detect cause of hydrocele o Diethylcarbamazine provocative test ▪ Treatment of choice for filarial worms ▪ Stimulate migration of filarial worms to blood vessels for diagnostics ▪ Add 3 mg/kg body wt. of diethylcarbamazine o Immunochromatography ▪ Antigen Detection Technique • Circulating Filarial Antigen (CFA) - includes a test kit o Embedded with filarial worm antibodies o Has sample well & test pane o Sample well for blood o + filarial worms - Ab will react with filarial worm antigen; gives off 2 bars for C & T o Concentration Method ▪ Knott’s Technique • Used when there is low number of microfilaria • To isolate microfilaria • 1 ml blood + 2% formalin (or HAc) o Formalin/HAc - to hemolyze RBCs for better visualization of microfilaria • Centrifuge for sedimentation • Sediment is smeared & stained with giemsa ▪ Membrane Filtration • Uses swincy filter (filters microfilaria) Periodicity Filarial Worm Specimen Periodicity Wuchereria Blood Nocturnal bancrofti Brugia malayi Subperiodic Blood Nocturnal Loa loa Blood Diurnal Onchocerca Skin snips Nonperiodic volvulus Mansonella Blood Nonperiodic ozzardi Mansonella Blood Nonperiodic perstans o Periodicity - event when parasites are present only during a specific time period ▪ Important to maximize demonstration o Nocturnal - occur at night o Subperiodic - no clear out of occurrence time o Diurnal - occur at daytime o Skin snips should have little to no blood contamination o Midnight - best time to collect sample from W. bancrofti & B. malayi ▪ SUMMARY o o o Adult female have red and white stripes, giving a barber’s pole appearance Infective stage: Larva Mode of Transmission: ingestion of intermediate hosts with infective larva Pathology: Larva migrates to the brain and spinal cord causing eosinophilic meningoencephalitis TREATMENT • • Diethylcarbamazine Ivermectin OTHER FILARIAL WORMS • • Dracunculus medinensis o Common Name: Guinea worm, medina worm, dragon worm, fiery serpent of Israelites o Longest nematode of man ▪ Can reach length up to 1 meter o The snake in the medicine symbol o Definitive Host: man o Intermediate Host: Crustaceans ▪ Copepods, Cyclops o Habitat: adult subcutaneous tissues o Mode of Transmission: ingestion of infected copepods o Pathology: Dracunculiasis or Guinea worm disease ▪ Found in sole area of the foot o Treatment: ▪ Immersion of affected body part to water • Stimulates worm extrusion ▪ Wound is cleaned • To prevent secondary bacterial infection ▪ Worm extraction • Be careful during extraction • When D. medinensis get split, it can no longer be extracted completely ▪ Topical antibiotics - to prevent wound infection ▪ Aspirin/Ibuprofen prescription - pain reliever, anto-inflammatory drug Angiostrongylus cantonensis o New name: Parastrongylus cantonensis o Common Name: Rat lungworm o Natural/Final Host: Rats ▪ Rattus rattus var. rattus ▪ Rattus norvegicus o Intermediate Host: Mollusks (snail) ▪ Pila luzonica (kuhol) ▪ Brotia asperata (suso) o Habitat: CNS o Diagnostic Stage: Adult worm • • • Dirofilaria immitis o Common Name: Dog Heartworm o Natural Host: Dog o Pathology: produce solitary, peripheral nodules in the lungs (coin lesions) Anisakis spp. o Common Name: Herring’s worm o Common in Japan o Definitive Host: Whales/Dolphins, Man (dead-end host) o Intermediate Hosts: 3 ▪ 1st IH: Copepods ▪ 2nd IH: Small fishes ▪ 3rd IH: larger fishes (salmon) o Infective stage: Larva o Mode of Transmission: ingestion of raw fish with infective larva o Pathology: Abdominal pain and granuloma migrating larva in intestinal wall