11/29/2015. Metazoa/helminths. Trematoda Cestoda (flukes) (tapeworms) Nemathelminthes Platyhelminthes (roundworms/ nematodes) (flatworms)

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1 Classification of Metazoa/helmins/worms Metazoa/helminths Nemalmins Platyhelmins (roundworms/ nematodes) (flatworms) Trematoda Cestoda (flukes) (tapeworms) Nematode The intestinal nematodes Ascaris lumbricoides Enterobius vermicularis Ancylostoma duodenale Trichuris trichiura General characters of Nematodes Elongate cylinder worms with body cavity & digestive tract. Sexes are separate. Male smaller than female. Free living in soil & water. The body nonsegmented, transluscent, flesh color, tapering at both end. The alimentary canal consist of oral cavity, esophagus, midgut, hindgut or rectum ending with anus. The body is covered with cuticle to resist digestive juices & enzymes of host. 1. Ascaris lumbricoides (Round worm) 1

2 Ascaris lumbricoides is largest nematode (roundworm) parasitizing human intestine. Ascaris lumbricoides is an intestinal worm found in small intestine of man. They are more common in children n in adult. Adult Male shorter with coiled posterior end with 2 minute spicules. Female longer posterior end. with straight 3 lips which carry minute teeth A pair of female male worms of A. lumbricoides. Notice coiled end of male worm. A scanning electron micrograph of Ascaris showing three prominent lips INFECTION TO MAN It occurs when man swallows infective eggs of Ascaris with contaminated food or water. Host Definitive host : Humans Intermediate Host : -none- 2

3 Egg Round or oval, brownish in color. Egg shell The egg shell is colorless, aluminous Ovum covering, when lost named decoricated Albuminous layer egg. Fertilized egg Unfertilized egg A. lumbricoides,, fertilized egg (unsegmented) soil A. lumbricoides unfertilized egg The life cycle of A. lumbricoides Migration Larvae migrate though lungs Method of infection Infective eggs are ingested Living site Adults in small intestine HOST MAN Diagnostic stage Unfertilized eggs in feces Infective stage Eggs embryonate in soil by 2-3 wks Adult worms live in lumen of small intestine. A female produce 200, eggs per day, passed with faeces. Unfertilized eggs may be ingested but are not infective. Fertile eggs embryonate become infective after 18 days to several weeks. After infective eggs are swallowed., The larvae (Rhabditiform) hatch, invade intestinal mucosa, carried via portal, n systemic circulation to lungs. 3

4 larvae mature furr in lungs (10 to 14 days), penetrate alveolar walls, ascend bronchial tree to throat, are swallowed. Upon reaching small intestine, y develop into adult worms. Between 2 3 months are required from ingestion of infective eggs to oviposition by adult female. Adult worms can live 1 to 2 years. Symptoms of Ascariasis Fever breathing difficulty Coughing pneumonia (Ascaris pneumonities; dyspnoea, asthma) Abdominal cramps (umbilicus), loss of appetite, diarrhea, bulky foul smelling stool. Intestinal obstruction due to aggregates masses of warm. Peritonitis. Malnutrition. Worm in stool Worm in vomit Children with underweight, pale, pot- bellied due to abdominal distention appendicitis or pancreatitis Diagnosis Eosinophilia. Egg in feces (which? which?) Liver abscess formation Malnutrition, vitamin A & C deficiency. Mebendazole. Treatment Pyrantel pamoate or Piperazine citrate. The drug may cause Anaphylactic shock. Cortisone. Bronchodilator. Supportive rapy Avoid contacting Prevention soil that contaminated with human feces Do not defecate outdoors may be Wash hs with soap water before hling food 4

5 2. Enterobius vermicularis (pin worm) Enterobius vermicularis egg. Flat at one side, convex at or Host Infection Humans are only host in nature No intermediate host (direct life cycle) No larval migration between organs Stage Infective eggs, larvated, immediately infective pinworm infection or enterobiasis is a human parasitic disease one of most common childhood parasitic worm infections in developed world t is caused by infestation with parasitic roundworm Enterobius vermicularis, commonly called human pinworm Infection usually occurs through ingestion of pinworm eggs, eir through contaminated hs, food, or less commonly, water. The incubation time from ingestion of eggs to first appearance of new eggs around anus is 4 to 6 weeks. Pinworms are usually considered a nuisance rar than a serious disease 5

6 Auto infection Infective Perianal Life cycle Ingestion of infective embryonated egg. Larve hatch in small intestine. Migrate into large intestine, mature into adult. After copulation, male die, gravid female migrate to anus during night to deposit eggs. Migrate to vagina of female. Mode of transmission Person to person through contaminated clos. Small no. are airborne or inhalated. Retroinfection ; hatched larvae from anal skin back to rectum. autoinfection (eir through anus-to- mouth route) Signs symptoms The main symptoms are perineal pruritus, i.e., itching in around anus. The itching occurs mainly during night, is caused by female pinworms migrating to lay eggs around anus. The itching leads to continuously scratching area around anus, which furr results in tearing of skin complications such as secondary bacterial infections, including bacterial dermatitis boil. Vulvovaginitis in females. Diagnosis Ova (which? which?) in perianal region or vagina. Adult worm in feces Eosinphilia 6

7 Treatment Pyrantel pamoate. Mebendazole. 1% white ppt ointment at bed time to relief itching. 3. Ancylostoma duodenale (Hookworm) Majority of hookworm infections in humans caused by 1) Ancylostoma duodenale 2) Necator americanus Morphology The anterior end of The body has slight bend giving hook like appearance. The male s posterior end is exped to form a copulatory bursa (2 spicules, cloaca in which rectum & genital canal open). Buccal capsule with 2 ventral curved teeth, small dorsal pair (Sucking blood) Eggs: oval in shape, shell is thin colorless. N. americanus & A. duodenale New old Ancylostoma Buccal capsule set with Buccal capsule set with two crescent-shapedshaped symmetric pair of cutting plates on ventral sharp teeth on ventral side (shearing chitinous side., smaller dorsal plates) pair dumb soil 7

8 Life cycle Eggs are passed with feces. Eggs hatch (rabditiform larva) in about 1-2 days under favorable conditions such as (damp soil),which feed upon bacteria in feces. After 5-10 days y become filariform (infective stage) When y contact with human host, larva penetrate skin are carried through veins to heart n to lungs, are swallowed. The larva reach small intestine, where y reside mature in to adults. Symptoms 1. Skin (Cutaneous or invasion phase) itching, pruritus, swelling (ground itch). 2. Lung Infection (Pulmnonary phase) pneumonia, cough, sputum (larva). 3. GIT Infection (Intestinal phase) Attach to mucosa by teeth causing tissue deterioration& intestinal bleeding, bloody stool, reddish brown). Microcytic hypochromic anemia. Hypoproteinemia. Nausea, vomiting, diarrhea, polyphagia. Diagnosis 1. anemia. 2. Esoinophilia 3. Egg in stool (which? which?). 4. Larva in sputum. 1.mebendazole. 2. pyrantel pamoate. 3. iron rapy. Treatment Trichuris trichiura 4. Trichuris trichiura (whip worm) 8

9 Morphology Its commonly called whip worm because of shape of this worm (anterior thin posterior thick). Posterior end contain spear like projection enveloped with sheath; (penetrate intestinal mucosa) Eggs: Shape: barrel shaped Size: x 25-30μm Shell: thick egg shell with 2 polar plugs Color: Yellow-brown Content: immature egg cells Life Cycle Caecum, appendix soil Life cycle Eggs pass out unembryonated (soil) Embryo develops inside egg. embroynated eggs swallowed 1st stage larvae hatch in small intestine penetrate villi Then migrate to large intestine attach to mucosa with thin anterior end (caecum, appendix). After 2-4 month females mature lay eggs. Abdominal distention over caecum resemble appendicitis. Bloody diarrhea Rectal prolapse. Symptoms Children s infection can cause rectal prolapse, The reason is rectum is damaged by worm, rectum can be pushed out from anus. 9

10 Laboratory diagnosis 1- Eggs (Which? Which?)or worm in feces. Eggs are oval, barrel shaped. 2- Eosinophilia may occur. 3- In heavy infection proctoscopy or can show worms attached to mucosa. Treatment Mebendazole is drug of choice, with albendazole as an alternative. Personal hygiene 4- Visual detection prolapsed rectum. of adult worms on 10