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Slide 1: Trichuris trichuraPruitt & Jane J. Stein B.E Enterobius vermicularis Dr Kamran Afzal Classified Microbiologist
Slide 2: Taxonomic Classification of Helminths Sub kingdom Metazoa Phylum Class Genus – examples Nematodes Round worms; appear round in cross section, they have body cavities, a straight alimentary canal and an anus Platyhelminthes Flat worms; dorsoventrally flattened, no body cavity and, if present, the alimentary canal is blind ending Cestodes Adult tapeworms are found in the intestine of their host They have a head (scolex) with sucking organs, a segmented body but no alimentary canal Each body segment is hermaphrodite Taenia (tapeworm) Trematodes Non-segmented, usually leafshaped, with two suckers but no distinct head They have an alimentary canal and are usually hermaphrodite and leaf shaped Schistosomes are the exception. They are thread-like, and have separate sexes Fasciolopsis (liver fluke) Schistosoma (not leaf shaped!)
Slide 3: Taxonomic Classification of Helminths Sub kingdom Metazoa Phylum Class Genus – examples Ascaris (roundworm) Trichuris (whipworm) Ancylostoma (hookworm) Nematodes Round worms; appear round in cross section, they have body cavities, a straight alimentary canal and an anus Necator (hookworm) Enterobius (pinworm or threadworm) Strongyloides Platyhelminthes Flat worms; dorsoventrally flattened, no body cavity and, if present, the alimentary canal is blind ending Cestodes Adult tapeworms are found in the intestine of their host They have a head (scolex) with sucking organs, a segmented body but no alimentary canal Each body segment is hermaphrodite Taenia (tapeworm) Trematodes Non-segmented, usually leafshaped, with two suckers but no distinct head They have an alimentary canal and are usually hermaphrodite and leaf shaped Schistosomes are the exception. They are thread-like, and have separate sexes Fasciolopsis (liver fluke) Schistosoma (not leaf shaped!)
Slide 4: Characteristics of Nematodes  Cylindrical and unsegmented  Dioecious (male and female)  Complete digestive tract (mouth / esophagus / intestine / anus)  Adults: sexually reproductive life cycle stage  Larvae: developmental or asexually reproductive life cycle stage  Eggs: protective stage of zygote &/or embryo  Oviparous: production of eggs, discharged from uterus of female  Viviparous: production of embryos/L1 larvae, no rigid encapsulation of embryo
Slide 5: Intestinal Parasites : Mode of infection Ingestion of cysts, oocysts or ova Cryptosporidium Giardia Amoebiasis Toxoplasmosis Visceral larva migrans Ascaris Trichuris Enterobius Entry of larvae or oncospheres Site of adult stage or disease Intestine Trichinella Ingested Hookworm Strongyloides through skin Disseminated Intestine
Slide 6: Intestinal Parasites : Symptoms Symptoms Abdominal pain and distension Giardia Cryptosporidium Amoebiasis Diarrhoea +/- malabsorption Ascaris, hookworm, taenia Giardia Cryptosporidium Diarrhoea with blood loss Strongyloides Amoebiasis Trichuris Tenesmus, prolapsed rectum Hookworm Trichuris Parasite
Slide 7: Case History - 1  8-yr-old schoolgirl visiting Pakistan from Malaysia  1 week history of epigastric pain, flatulence, anorexia, bloody diarrhea  No eosinophilia noted  Clinical diagnosis of amoebic dysentery made
Slide 8:  However, microscopy of stool prep…
Slide 9: Trichuris trichura The ‘Whip-worm’ B.E Pruitt & Jane J. Stein
Slide 10: Morphology - of Adult worms 50 mm long with a slender anterior and a thicker posterior end The male is smaller and has a coiled posterior end
Slide 11: Morphology - of Eggs  Eggs in stool  Size: 50-54 µm by 22-23 µm,  Shape is a typical barrel  Color is yellow-brown • Unstained two polar plugs  Shell quite thick  Contains unembryonated egg
Slide 12: Life cycle
Slide 13: Life cycle
Slide 14: Pathogenesis  Humans sole host  Transmission • Fecal-oral via embryonated ova  Frequently coexists with ascaris  Reservoir • Mainly human, others possible but host specificity not well documented  Pathogenic potential • Low to moderate, dependent on worm numbers and location in LI
Slide 15:  Entirely intraluminal life cycle—eggs are ingested  Eggs hatch in intestines, larvae attach, and develop into adults  Female lays 3,000-5,000 eggs daily  Worms can pierce capillaries, cause localized hemorrhage, and allow bacteria to leave intestine
Slide 16: Clinical Features  Frequently asymptomatic  Clinical signs/symptoms - Adult worm (Pathogenic stage) • Dependent on no. of worms; None to digestive disturbances, bloody (frank)/ mucoid diarrhea, abdominal pain and distention, rectal prolapse, anemia and weakness  Severe infections • Tenesmus and rectal prolapse in children • Can be fatal in children • Rarely, elephantiasis in adults
Slide 17: •Trichuris trichiura in the large intestine •Many worms are present, each with its anterior end embedded in the intestinal mucosa, resulting in the erythema
Slide 18: Lab Diagnosis  Stool • Direct examination (Iodine stain) • Eggs • Rarely adult worms  Blood • Eosinophilia  Histopathology of the intestinal mucosa  PCR
Slide 19: Imaging  X-Rays Abdomen • Plain • With contrast / dye  CT Scan
Slide 20: Treatment and Prevention  Albendazole 400 mg once  Mebendazole 100 mg BD for 3 days (600 mg, repeated after 2 weeks)  Pay attention to personal hygiene and eating habits
Slide 21: Case History - 2  11-year-old female  Doing poorly in school  Not sleeping well  Anorectic  Complains of itching in rectal region throughout the day
Slide 22:  A Scotch-tape test reveals…
Slide 23: Enterobius vermicularis The ‘Pin-worm’ B.E Pruitt & Jane J. Stein
Slide 24: Helminthic Diseases of the Digestive System
Slide 25: Epidemiology  Enterobiasis most common worm disease of children in temperate zones  Pre-school and elementary school children affected most often  Consmopolitan, 30%~50% of the children population is infested  Most common where people live under crowded conditions (orphanages / large families / kindergartens / primary school)
Slide 26: Morphology of Adult  Adult • Female: White 8~13 mm in size Fusiform body with a long, thin, sharply tapering tail Alae (cuticular extension of head) Prominent bulb – Rhabditiform esophagus The greater part of the body is occupied by the uterus filled with eggs • Male: Like female, but about 1/3 to 1/2 size of female The tail is curved, it is rarely seen
Slide 28: Morphology of Eggs  Egg • Oval, clear and colorless • 50 to 60 µm in length, thick shell • Flattened on one side • Contains a larva
Slide 29: Enterobius vermicularis (Pinworm)
Slide 30: Transmission  Definitive host • Human  Transmitted by • Ingesting Enterobius eggs
Slide 31: Pathogenesis  Infective stage • Infective eggs  Eggs are picked up from surroundings and swallowed • Being sticky, adhere to door handles (especially toilet doors), bedclothes and mug handles etc  After hatching in the small intestine, they develop into adults  The location of adult • Cecum and colon  Anal itching occurs when mature females emerge from intestine to release eggs • Life span of female adult is 1-2 months  Right after mating, the male dies • Therefore, the male worms are rarely seen  Self-inoculation is common
Slide 32: Life Cycle
Slide 33: Life Cycle
Slide 34: Clinical Features  Mostly asymptomatic  Nocturnal anal pruritis is cardinal feature due to migration and laying of eggs  Perianal pruritus may lead to excoriations and bacterial superinfection  Occasionally, invasion of the female genital tract with vulvovaginitis and pelvic or peritoneal granulomas can occur  Other symptoms : anorexia, irritability, and abdominal pain  May have insomnia, possible emotional symptoms
Slide 35: Types of infection  Infection from environment  Auto-infection • Female crawls out of anus and release eggs on the perianal region • Patient feels anal pruritus • Scratching leads to contamination of hands and nails • Re-infection is by hand-mouth transmission  Retro-infection • Some eggs hatch on the perianal skin and become larvae • They will crawl back into the anus and mature into adults
Slide 36: Laboratory Diagnosis  Direct fecal smear • Microscopic identification of eggs collected from the perianal area is the method of choice by • Scotch tape technique • Cellophane tape impression • This must be done in the morning, before defecation and washing  Alternatively, anal swabs can also be used  Brine-floatation method  Detection of adult on anal skin at night, when the child is sleeping  Larval cultivation
Slide 37: Treatment  Since the life span of the pinworm is less than two months, the major problem is re-infection  Repeat the treatment after 2 weeks  Repeated re-treatment may be necessary for a radical cure  Albendazole is the drug of choice  Mebendazole and Pyrantel pamoate are the alternative drugs
Slide 38: Prevention  Treat and re-treat the patients and carriers  Laundering of bedding  Individual health • Observation and correction of personal hygienic and eating habits  Public health  Health education