Cestodes.pdf

CLINICAL PARASITOLOGY BACHELOR OF SCIENCE IN MEDICAL LABORATORY SCIENCE BLOCK 2F 2nd Semester BSML-2211 | Mrs. Marilou O. Honculada, RMT, MA, MSMLS MIDTERMS: CEST...

CLINICAL PARASITOLOGY BACHELOR OF SCIENCE IN MEDICAL LABORATORY SCIENCE BLOCK 2F 2nd Semester BSML-2211 | Mrs. Marilou O. Honculada, RMT, MA, MSMLS MIDTERMS: CESTODES General Characteristics Majority are long, segmented and would resemble like tapes (tapeworms) Dorso-ventrally flattened Size varies from a few mm to several meters Adult worms are found in the intestinal canal of man and animals There are 3 regions in an adult worm: o Head: Scolex – provided with suckers and sometimes with hooks that serves as organs of attachment. o Neck: chest behind the scolex, region of growth o Body/Trunk: Strobila ▪ Consist of a series of segment called proglottids Sexes are not separate called Monoecious Body cavity is absent Alimentary canal is entirely absent Excretory and nervous systems are present Reproductive system is present and complete in each segment o According to maturity of reproductive organs, three types of segments of the strobila can be recognized from the front backwards ▪ Male and female organs are not differentiated: Immature Segment ▪ Male and female organs have become differentiated: Mature Segment ▪ Uteri are filled with eggs: Gravid Segment THERESE JOY IBAÑEZ 1 Classification of Cestodes Infecting Man (Order) Eggs Operculated; Not gives rise to Operculated; ciliated larvae do not give 1. Pseudophyllidean Cestodes rise to ciliated Possess false or slit-like grooves called larvae bothria Adult worms in Intestine Pseudophyllidea Characteristics Diphyllobothrium latum: Fish/ broad o Large worms consisting of a long chain of tapeworm segment Larval stages: Plerocercoid in Man o “Head” has two slit-like sucking grooves Infective Stage: Plerocercoid that can be called bothria instead of suckers ingested by humans o Uterine glands are widely scattered in the 2. Cyclophyllidean Cestodes parenchyma and is composed of many Possess cup-like and round suckers called acini acetabula o Genital pores are on the ventral surface Adult worms in the intestine of the segment and are not marginal Taenia saginata o Uterus opens to the exterior through Taenia solium which eggs come out Hymenolepis nana o Eggs are operculated and can develop Hymenolepis diminuta only in water; immature when oviposited Diphylidium caninum (prevalent and oncosphere gives rise to ciliated among dog) embryo According to Habitat Pseudophyllidea Cestodes Cyclophyllidean Cestodes Diphyllobothrium latum o Possess cup-like and round suckers called acetabula Common name: o Larval stages in man o Fish Tapeworm Hydatid cyst of Echinococcus o Broad Tapeworm granulosus and Echinococcus Morphology multilocularis o Adult worm is yellowish grey in color Cysticercus cellulosa of Taenia solium o Dark central marking in the strobila is due Coenurus cerebralis of Multiceps to the egg-filled uterus multiceps o Measures 3 to 10 meters in length Coenurus glomeratus of Multiceps o Life-span is for a period of 5 to 15 years glomeratus o Scolex is spoon-shaped or spatulate Cysticercus bovis of Taenia bovis (from o Scolex bears 2 slit-like grooves called infected cows, camels, or buffalos) bothria (1 on the dorsal surface and 1 Pseudophyllidean Cyclophyllidean on the ventral Head/Scolex Bears 2 slit-like Bears 4 cup- surface) grooves like suckers Uterus No branching Branching o Scolex has no Convoluted May or may rostellum and no uterine tubes not be present hooklets assume the o Neck is thin and form of rosettes unsegmented and is Uterine Pore Present Absent much longer than the head Common Ventral; in the Lateral Genital Pore midline THERESE JOY IBAÑEZ 2 o A mature segment is Ova filled with male and o Passed out in the host’s feces in large female reproductive numbers organs o Oval o Terminal segments o Bile stained (Yellowish Brown) shrink and becomes o Contains abundant granules and empty as eggs are unsegmented ovum constantly o Inconspicuous (not so evident) discharges operculum (passed for exit of the o Dried up segments developing embryo) at one end and a break off from the small knob at the other end body in chains and are passed out in the o Does not float in saturated solutions of host’s feces common salt o Uterus at the center of the segment o A single egg gives rise to a single larva appears in the form of a rosette o Contains mature embryo inside Larva o Passed first in water and then in the respective intermediate hosts o 3 stages First Stage Larva (Ingested by copepods) ▪ Coracidium (free-swimming) ▪ Ciliated oncosphere that develops from egg in water Second Stage Larva ▪ Procercoid ▪ Spindle-like solid body with cephalic invagination ▪ Found inside the cyclops (the first intermediate host) Third Stage Larva ▪ Plerocercoid (Sparganum) ▪ Head is invaginated in the neck ▪ Found in the fresh water fish, the second intermediate host (Perch, Trout, Salmon, Pike) THERESE JOY IBAÑEZ 3  o Final Host Has a similarity with Enterobius vermicularis Man, dog, cat Free gravid proglottid crawls out of the anal Small Intestines orifice and oviposits on the perianal skin o 1st Intermediate Host Cyclops or Diaptomus o 2nd Intermediate Host Fresh water fish, pike, trout, salmon, perch o Mode of Infection Ingestion of imperfectly cooked infected fish or roe containing Plerocercoid larvae Ova Infection o Liberated by rupture of ripe proglottids o Diphyllobothriasis o No uterine opening o G.I disturbances and anemia o Spherical o Causes megaloblastic anemia since o Thin, outer transparent shell Vitamin B12 is absorbed by worm o Inner embryophore is brown, thich walled o SPAGANOSIS: disease caused by drinking and radially striated water containing infected copepods o Has an oncosphere with 3 pairs of Diagnostic hooklets (inside the eggshell) o Microscopic examination of feces for the o Does not float in saturated salt solutions characteristics operculated eggs (DFS, o Eggs are resistant and remain viable for 8 Kato Technique) weeks o Infective only to cattle Cyclophyllidea Cestodes Larva o Final Host: Man Taenia Saginata o Intermediate Host: Cattle, cow, buffalo o Mode of Infection: eating beef Beef Tapeworm containing Cysticercus bovis Unarmed tapeworm of man: without hooks Adult Worm Adult worms are white and semi-transparent o Irritated by alcohol Measures about 4 to 10 meters or sometimes Pathogenesis up to 25 meters o Taeniasis Live up to 10 years or more o Passage of proglottids in stool 1,000 to 4,000 o Mild irritation at site of attachment proglottids o Epigastric pain Common genital pore is o Hunger pangs marginally situated o Weakness Vagina is provided with o Weight loss a sphincter muscle o Loss of appetite Gravid proglottid o Pruritis ani consists of a uterus and o Obstruction in intestine but also in bile and a central longitudinal stem with 15-20 lateral pancreatic ducts and appendix because branches proglottids are actively motile Highly branched proglottids Diagnosis Gravid proglottid contains 97,000 to 124,000 o Identifying characteristic eggs (resembles ova kiwi slice), proglottids or scolex Gravid segments are expelled singly and o Usual specimen is gravid proglottids force their way through the anal sphincter (lateral branches 15-30) THERESE JOY IBAÑEZ 4  o Concentration techniques for eggs (eggs Adult worms rarely passed out in stool) measure 2-4 o Perianal swabs meters Treatment Adult worms live o Praziquantel up to 25 years o 5-10 mg/kg single dose 800-1000 Criteria for Cure proglottids o Recovery of the scolex Common genital o Negative stool examination 3 months pore is marginal after treatment and thick lipped Vaginal opening is Taenia Solium not guarded by a muscular sphincter Pork tapeworm Gravid segments Armed tapeworm: with hooks are expelled Taeniasis is common among those eating passively in chains raw or insufficiently cooked “measly pork” of 5-6 at a time and (infected meat) not singly. Uncommon among non-pork eaters Gravid proglottids Man: Definitive Host/Intermediate Host contains Scolex is globular in outline with 4 circular approximately 30,000 to 50,000 eggs suckers Ova Scolex has a rostellum o Same as those of Taenia saginata armed with a double o Infective to man as well as pigs row of alternating o Thick brown striated embryophore large and small surrounding a hexacanth embryo hooklets (Acetabula) Larva Rostellar hooklets are o Final Host: Man shaped like daggers o Intermediate Host: Pig or Arabian poniards o Mode of Infection: Eating measly pork containing Cysticercus Cellulosae o Diagnosis: Stool examination for proglottids/eggs Pathogenesis o Mild, non-specific abdominal complaints o Proglottids are not as motile as T. saginata so organ obstruction is less likely Cysticercosis o Multiple o Develop in any organ or tissue o Neurocysticercosis (most serious zoonotic disease) o Chorioretinitis o Vasculitis Diagnosis o Intestinal Identifying the characteristic proglottids, eggs or scolex THERESE JOY IBAÑEZ 5  o Cysticercosis Echinococcus Granulosus Computed Axial Tomography Magnetic Resonance Imaging Taenia echinococcus Treatment Dog Tapeworm o Praziquantel: 5-10 mg/kg single dose for Hydatid Worm children and adults Man harbors the cyst and not the adult o Niclosamide: not available locally worms which however is found in the intestine Criteria for Cure of dogs and canines o Recovery of scolex Adult worms are small (3-6 mm in length) o Negative stool exam 3 months after It is composed of a treatment o Scolex o Neck o Strobila 3 segments o Immature o Mature o Gravid Scolex bears 4 suckers and a protrusible rostellum with 2 circular rows of hooks Ova o Ovoid in shape o Resemble Taenia ova o Hexacanth embryo with 3 pairs of hooks Infective to: o Man o Cattle o Sheep and other herbivorous animals COMPARISON BETWEEN T. SAGINATA AND T. SOLIUM Taenia Taenia Solium Saginata Length 4-10 meters 2-4 meters Head or Scolex Large, Armed; with quadrate, no rostellum; with rostellum and hooklets hooks Number of 1,000 to 4,000 Below 1000 Proglottids Expulsion Expelled singly Expelled and may be passively in forced through chains of 5 or 6 the anal sphincter Uterus Highly Lateral branched with branches 5-10 Definitive Host 15-30 lateral on each side, o Dog branches on thin, dendritic o Wolf each side; thin; and vaginal o Fox dichotomous sphincter in absent o Jackal Testes 300-400 follicles 150-200 follicles Intermediate Host o Sheep o Pig THERESE JOY IBAÑEZ 6  o Cattle Diagnosis o Horse o Radiographic findings o Goat o Serological tests Pathogenesis o Differential leukocyte count o Echinococcosis Treatment Pathology is caused by the o Surgical resection: not 100% effective developing larval cyst in the o Solicidal agent intermediate host Hibitane Most common site of involvement is 95% ethanol the liver Hypertonic 30% Normal Saline Solution Echinococcus granulosus cyst: o PAIR technique for inoperable cyst Unilocular hydatid cyst Puncture, Aspiration, Injection, Echinococcus multicularis: alveolar Reaspiration Intervention Albendazole cyst Some may be asymptomatic for years Hymenolepis Species Rupture of cyst in the lungs may present coughing accompanied by Genus is derived from the membranous allergic reactions character of the egg shell “hymen” 3 testes is each mature segment Uterus is sac-like and transverse Eggs possess two membranes’ outer membrane is thin and transparent Larval stage is called cysticercoid Small bladder containing the invaginated head proximally and a solid, elongated portion as a caudal appendage There are 2 species: o Hymenolepis nana o Hymenolepis diminuta Hyemenolepis Nana Dwarf tapeworm Smallest tapeworm infecting man Found worldwide Mainly among children Only human tapeworm that can complete its life cycle in a single host Man can harbor both the adult and larval stages of the parasite Adult Found in the ileum Delicate strobila 25-45 mm Worms may be present in large number from 1,000 to 8,000 Short life span, about 2 weeks Up to 200 proglottids Transverse uterus THERESE JOY IBAÑEZ 7  3 testes Pathogenesis Scolex o Symptoms are produced due to patient’s o Subglobular immunological response to the parasite o 4 suckers o Asymptomatic for light worm burden o Provided with a short retractile rostellum o Headache armed with a single row of 20-30 hooklets o Dizziness o Rostellar hooklets are shaped like tuning o Anorexia fork o Pruritus of the nose and anus Ova o Abdominal pain o Spherical or Oval o Pallor Floats in saturated solutions of o Desquamation of intestinal epithelial cell common salt or as serious as necrosis may occur o 2 Distinct membranes Regulatory immunity will eventually limit the Outer membrane is thin transparent infection and colorless Diagnosis Inner embryophore that encloses an o Demonstration of characteristic ova in oncosphere with 3 pairs of lancer the stool shaped hooklets o Proglottids are not recovered because Intermembranous space is filled with they undergo degeneration prior to yolk granules and 4-8 polar filaments passage emating from little knobs at either end Treatment of the embryophore o Praziquantel 25mg/kg single dose Drug dosage is higher than that of taeniasis because of resistant cysticercoids in intestinal tissue Hyemenolepis Diminuta Rat tapeworm Common parasite of rats and mice Accidental human infections Differs from Hymenolepis nana in morphology and life cycle because it requires an intermediate host 2 Hosts Mode of Transmission is thru o Larval stage: cysticercoid is passed in o Direct fleas Host ingests eggs that hatches in the o Adult stage: in rats and mice and duodenum accidentally in humans especially o Indirect Pathway children who accidentally ingest infected Accidental ingestion of infected fleas arthropod intermediate host like rice Larger than Hymenolepis nana and flour beetles in which cysticercoid Measures 60 cm in length larvae are released and develop into Scolex adult worms in the small intestine of o Unarmed rostellum the host o 4 suckers THERESE JOY IBAÑEZ 8  Proglottid Common among children due to o 8,000 – 1,000 ingestion of infected grain beetles, o Mature proglottids of Hymenolepis dried fruits, flour and cereals diminuta from the laboratory rat. Prevalence of H. diminuta in Philippine o The three spherical bodies are testes rats is about 8% which surround the ovaries, ootype and vitelline glands. The genital pores are on Dipylidium caninum the left margin Ova Double Pored Dog Tapeworm o Larger than H. nana Presence of bilateral genital pores in each o Outer shell is yellowish in color segment (di: 2; pylis: gate): 2 entrances o Inner embryohore has 2 knob-like Common intestinal parasite of dogs thickenings Adult o No polar filaments o 10-70 cm in length o cysticercoid of Hymenolepis diminuta. o Pale reddish o The suffix indicates it is like a cysticercus Scolex but this larva has no bladder but instead o Small and globular has a tail. o 4 deeply cupped elliptical suckers o The dark body within the spherical portion o Protrusible/retractile rostellum is the scolex. o Rostellum has 1-7 rows of rose thorn o The longer the tail, the more mature the shaped hooklets cysticercoid. Strobila o This stage is found inside an insect such as o 200 proglottids the mealworm o Narrow Mature Proglottids o 2 sets of male and female reproductive organs o Bilateral genital pores Gravid Proglottids o Have size and shape of pumpkin seeds o Filled with capsules or packets of 8-15 eggs enclosed in an embryonic membrane Pathogenesis o Hymenolepiasis o Worm burden in rodents is relatively low o In man, highest worm burden is 19 o Clinical manifestations are minimal and non-specific Treatment o Praziquantel 25mg/kg body weight single dose Epidemiology World wide THERESE JOY IBAÑEZ 9  Ova o Passed out in the feces along with the proglottids o Released by contraction of proglottids or disintegration outside the host o Spherical o Thin shelled o With a hexacanth embryo Intermediate Hosts (1st I.H) o Ctenocephalides canis: dog flea o Ctenocephalides felis: cat flea o Pulex irritans: human flea o Trichoedectes canis: dog flea 2nd I.H Dog (Cysticercoid) o Accidental host: Man Pathogenesis o Dipylidiasis o Rarely multiple o Symptoms are minimal Slight intestinal discomfort Epigastric pain Diarrhea Anal pruritus Allergic reactions Treatment o Praziquantel o 5-10 mg/kg body weight single dose Epidemiology o USA o Rhodesia o Argentina o China o Philippines THERESE JOY IBAÑEZ 10