Enteric Nematodes of Human Prepared by professor Fedonyuk L.Ya.

OUTLINE OF PRESENTATION PART 1: Classification

PART 2: General characteristic

PART 3: Intestinal roundworms PART 4: Tissue-intestinal roundwormsPART 5: Blood-tissue roundworms

PART 6: Summary2- morphology- life cycle- clinical symptoms- diagnosis- prevention

PhylumNemathelminthes Class Nematoda Important round worm species of human :Exclusively intestinal parasites: Enterobius vermicularis (Pinworm) Trichocephalus trichiurus (Whipworm) Tissue-intestinal parasites: Ascaris lumbricoides (Roundworm) Strongyloides stercoralis (Thread worm) Ancylostoma duodenale and Necator americanus (Hookworms) Dracunculus medinensis (Guinea worm) Trichinella spiralis (Trichina worm)

Blood and tissue parasites Wuchereria bancrofti (Filarial worms): Brugia malayi, Brugia timuri Loa-loa Onchocerca volvulus

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According to the way of development round worms are classified into geohelminthes and biohelminthes.

Geohelminthes - soil-transmitted parasitic nematodes with a life cycle that involves no intermediate hosts or vectors. They are spread by the faecal contamination of soil, foods and water (Ascaris lumbricoides Trichuris trichiura Ancylostoma duodenale and Necator americanus).

Biohelminthes - have complete life cycle within a host (Trichinella siralis, Dracunculus medinesis, Filarial worms).

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General characteristic of NematodaThey are unsegmented, pseudocoelomate worms.

Their body is covered with a noncellular, highly resistant coating called a cuticle. Underlying tissues are hypoderma and four layers of muscles.

Roundworms with a cylindrical body and a complete digestive tract including mouth and anus. Nematodes have separate sexes; the female is usually larger than the male. The male typically has a coiled tail sexual dimorphism.

The excretory system modified protonephridial type.

The nervous system consists of a nerve ring and two nervous trunks.

The circulatory and respiratory systems are absent.

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Intestinal Round Worms6

Enterobius vermicularis (Pin worm)causes ENTEROBIASIS.Distribution: worldwide (more than 400 mln ). Morphology: Adult female worms are up to 10mm in length, and male worms are up to 5 mm. Location: the lower part of small intestine, the upper part of large intestine.

Eggs are transparent and colourless, asymmetrical, with thin and smooth membrane, 40-60 m.7

Enterobius vermicularisMode of transmission: faecal-oral Infective stage: eggs. The adult pinworm lives in the large intestine approximately 30 days. After fertilization female worm migrates from the anus and releases thousands of fertilized eggs on perianal skin. Within 6 hours, eggs develop into larvae and become infectious. Reinfection can occur if they are carried to the mouth by fingers after scratching the itchy skin.

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Enterobius vermicularisClinical manifestation: Infection is frequent among children under 12 years of age.perianal itching is most common symptom; vaginal irritation caused by the female migration; the itching results in insomnia and restlessness;in some cases gastrointestinal symptoms (pain, nausea, vomiting, etc.) may develop. Laboratory diagnosis: the eggs are recovered from perianal skin by using the Scotch tape technique and can be observed microscopically;anal swabs (a paddle coated with adhesive material). seldom adult worms and eggs can be found in the stool.microscopic examination of nail beds Prevention: personal hygiene, keep sanitary condition, treatment of patients 9

E:\Pinworms found on colonoscopy.mp410

Trichuris trichiuria (Whipworm)causes Trichocephaliasis (whipworm infection). Distribution: worldwide, especially in the tropics. It is estimated that 800 million people are infected worldwide.Morphology: Adult female worms are up to 5,5 cm in length, and male are up to 4 cm. The anterior end of the body is hair-like. The eggs are brown, barrel-shaped with a plug at each end, 20-50 m in size.Egg of T. trichiura in an unstained wet mount11

Trichuris trichiuria Mode of transmission: fecal-oral Infective stage: eggs (after 20-25 days). Location: the large intestine, especially caecum and appendix.Pathogenesis and clinical manifestation: Adult worms burrow their hair-like anterior ends into the intestinal mucosa. They feed on blood. Diarrhea, abdominal pain, nausea, acute appendicitis, anaemia. Most infections are asymptomatic.

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Trichuris trichiuria

Laboratory diagnosis: microscopic examination of faeces (finding the typical eggs), blood test, serological test.

Prevention: washing hands before meals; proper washing of vegetables eaten raw; treatment of patients; proper disposal of faeces; health education.

Cross-section of an adult female T. trichiura stained with H&E, showing numerous eggs. 100xClose-up of an egg in Figure A taken at 1000x magnification.AB13

1. Which of the following refers to Enterobiasis laboratory diagnosis?A. Immunological testB. Faeces ovoscopyC. Microscopy of perianal scrapesD. Blood examinationE. Muscle biopsy

Trial test

2. Lemon-shaped eggs 50x30 mm in size with plugs on both poles were revealed in human faeces. Clinical manifestations include appendix inflammation. The possible agent is.A. Cat flukeB. Ascaris lumbricoidesC. Pin wormD. Whip wormE. Echinococcus granulosus

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Tissue-intestinal Parasites15

Ascaris lumbricoidescauses : Ascariasis Distribution: worldwide.more than1.4 billion peopleare infected with Ascaris lumbricoides, representing about25 %of the world population (WHO).16

Ascaris lumbricoidesMorphology: Adult worms are creamy or pinkish, spindle-shaped, covered by striated cuticle. Adult male about 20 cm in length, posterior end is curved ventrally; Adult female about 25-40 cm in length, posterior end is straight.

Eggs are brown, oval, covered by membranes. An external membrane is tuberous (40 to 70 m by 35 to 50 m)17

Ascaris lumbricoides Life Cycle18

Ascaris lumbricoides Clinical manifestation: - In pulmonary stage: larvae may lead to brief period of cough, wheezing, dyspnoea and substernal discomfort, eosinophilia. Also it can cause pneumonia, bronchial asthma. - In intestinal stage: adults cause weakness, weight loss, anorexia, intermittent loose stool and intestinal obstruction, penetration of the intestinal wall, occlusion of the bile duct, the pancreatic duct or the appendix, toxic effects (nausea, vomiting). Most infections are asymptomatic.Laboratory diagnosis: ovoscopy larvoscopy in sputumimmunological (serological) testsPrevention: washing hands before meals; proper washing of vegetables eaten raw; treatment of patients; proper disposal of faeces; health education.19

Strongyloides stercoralis Causes : StrongyloidiasisDistribution:

Morphology: The parasitic female is larger (2.2 mm x 45 m) than the free-living worm (1 mm x 40 m).The eggs are 55 m by 30 m in size.

estimated at 50 to 100 million cases worldwide, is an infection of the tropical and subtropical areas with poor sanitation.Threadworm infection, also known as Cochin-China diarrhea20

Strongyloides stercoralis Life cycle includes free living and parasitic cycles21

Strongyloides stercoralis Clinical manifestation: - Light infections: asyptomatic.- Skin penetration: itching and red blotches.- During migration : In lungs - bronchial verminous pneumonia, acute pulmonary eosinophilia (Loeffler's syndrome). In the duodenum - burning mid-epigastric pain, tenderness, nausea and vomiting. Diarrhea and constipation may alternate, malabsorption.

Laboratory diagnosis: Larvoscopy in faeces - the presence of free rhabditiform larvae in the faeces is diagnostic. Culture of stool for 24 hours will produce filariform larvae. Immunological (serological) tests.Prevention: proper disposal of faeces; personal hygiene; using of footwear in endemic areas22

Ancylostoma duodenale and Necator americanus (Hookworms)causes ANCYLOSTOMIASIS (hookworm infection) Epidemiology: Hookworms parasitize more than 900 mln people worldwide and cause daily blood loss of 7 mln liters.A.Duodenale is the dominant species in the Mediterranean region and northern Asia.N. americanus is most common in America, central and southern Africa, southern Asia, Indonesia, Australia and Pacific Islands. 23

HookwormsMorphology: 1) Adult worms about 1 cm in length; 2) Eggs are translucent, oval with blunt poles, 40-60 m in size; 3) the rhabditiform larva is about 0.25-0.5 m, pointed tail end; 4) the filariform larva is about 0.6-0.7 m, sharply pointed tail.

Necator americanusAncylostomaduodenale Buccal capsule of Ancylostomides24

HookwormsHost: humanWay of transmission: percutaneous by filariform larva . alimentary (with vegetables, fruits, water); Infective stage: filariform larva

Clinical manifestation: 1) invasion stage (the larvae penetrate the skin): dermatitis and itching (ground itch); 2) migration stage: pneumonia with eosinophilia; 3) intestinal stage: anemia, diarrhea, abdominal pain, nausea.

Laboratory diagnosis: eggs and larvae in the stool; blood in the faeces is frequent finding.Prevention: disposing of sewage properly and wearing shoes.

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Larva migransToxocara canis and T. cattiAncylostoma braziliensis26

main clinical symptomsVisceral larva migransToxocara canislarvae invade multiple tissues: liver, heart, lungs, brain, musclefeveranorexiaweight losscoughwheezing rasheshepatosplenomegalyhypereosinophilia Larva migrans Cutaneous larva migransAncylostoma braziliensismigrating larvae cause intense pruritic serpiginous track in the upper dermis. subacute retinitis Longitudinal section of a Toxocara larva in liver tissue stained with H&E. AA27

Trichinella spiralisCauses TRICHINOSISDistribution worldwide, especially in eastern Europe and west Africa. Morphology: 1) The adult female worms are 3 0.6 mm; the adult male worms are 1.5 0.04 mm; 2) the encysted larvae (1 mm) is enclosed in a fibrous cyst wall.Location : small intestine (adult worms) and striated muscles (larvae-can survive 25 years).Any mammal (rat, bear, fox) can be infected, but pigs are the most important reservoirs of human disease.28

Infective stage for humans: larva. Mode of transmission: alimentary (eating raw or undercooked meat, usually pork, containing larvae encysted in the muscle). 29

Trichinella spiralis Clinical manifestation:initially diarrhea, abdominal pain followed by 1-2 weeks later by fever, muscle pain; periorbital edema, and eosinophilia. death, which is rare, is usually due to congestive heart failure or respiratory paralysis. Laboratory diagnosis: muscle biopsy reveals larvae within striated muscle;serologic test (become positive 3 weeks after infection). Prevention: by properly cooking pork and by feeding pigs only cooked garbage; pork inspection in slaughter houses using a trichinoscope.30

1. A natural reservoir of Trichina worm is.A. CattleB. FishC. PigsD. BirdsE. Crabs

Trial test

2. A patient complains of weakness, dizziness, headache, severe itching of the skin, especially of the legs. The patients feces contain visible small reddish worms about 1 cm in length. Blood test reveal anemia. What kind of helmithosis can be suspected?A. AscariasisB. TrichocephaliasisC. EnterobiasisD. TrichinellosisE. Ancylostomiasis

313. What route do filariform larvae take inside humans? A. Skin Bloodstream Small intestine B. Skin Bloodsream Lungs Throat Stomach Small intestineC. Skin Bloodsream Lungs Throat Small intestineD. Skin Small intestine BloodstreamE. Bloodsream Lungs Throat Stomach

Dracunculus medinensis Guinea worm cause DRACUNCULIASISEpidemiology: is estimated to infect about 50 million people in North, West and Central Africa, southwestern Asia, the West Indies and northeastern South AmericaMorphology: The adult female worm measures 50-120 cm by 1 mm and the male is half that size.

Dracunculus medinensis worm wound around matchstick. This helminth isgradually withdrawn from the body by winding the stick

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Dracunculus medinensisHosts: D.H.- human; I.H.- cyclopMode of transmission: alimentary way (with contaminated water); Infective stage: filariform larva. Location: in subcutaneous tissues.

Clinical manifestation and pathology: 1) releasing juveniles just under skin; 2) causes inflammation which results in blister; 3) blister breaks and part of worm sticks out; 4) area of a blister is very hot; 5) contamination of the blister produces abscesses, extensive ulceration and necrosis. Diagnosis: Diagnosis is made from the local blister, worm or larvae.Prevention: to avoid drinking of contaminated water.

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Blood and tissue- Parasites34

Wuchereria bancrofti Brugia malayi Brugia timuriOnchocerca volvulusLoa loa (eye worm)

BLOOD AND TISSUE HELMINTHS35

Lymphatic filariasis (elephantiasis ) - transmitted by mosquitoes, is a leading cause of permanent and long-term disabilityEpidemiology: It is estimated that 120 million people in the world have lymphatic filariasis. Geographically: Tropical & Sub-tropical countries80 countries known to be endemicDemographically: All ages & Genders - more men than women.Common in unplanned settlements with poor sanitation.

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Host: human Vectors: mosquitoesMode of transmission: By the bite of an infective mosquito with microfilaria

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MosquitoFilaria sp. transmittedAnophelesWuchereria bancrofti, Brugia malayi, B. timoriAedesWuchereria bancrofti, Brugia malayiCulexWuchereria bancroftiMansoniaBrugia malayi

Symptoms caused by filarial worms ACUTE ILLNESSof lymphatic filariasisFeverChillsPain and rednessSkin damageSwelling of affected limbLymphadenopathy38

CHRONIC DISEASEElephantiasisHydrocoeleOthers penis, vulva, breast, scrotum, jawsInternal organs e.g. Kidneys

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Onchocerca volvulus (blinding filariasis)Geographically: is prevalent throughout eastern, central and western Africa. In America, it is found in Guatemala, Mexico, Colombia and Venezuela. Morphology: Adult female measures 50 cm by 300 m, male worms are much smaller. Infective larvae of O. volvulus are 500 m by 25 m.

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Host: human Vector: black flyMode of transmission: By the bite of an infective fly with microfilaria

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Symptoms caused by Onchocerca volvulus

Nodular and erythematous lesions in the skin and subcutaneous tissue During the incubation period of 10 to 12 months, there is eosinophiliaTrapping of microfilaria in the cornea, choroid, iris and anterior chambers Photophobia, lacrimation, blindness42

Diagnosis Diagnosis is based on symptoms, history of exposure to black flies and presence of microfilaria in nodules

Onchocerca volvulus adults in section of tumourHistopathology of Onchocerca volvulus nodule43

Loa loa - Eye wormGeographically: Loasis is limited to the areas of African equatorial rain forest Morphology: female organisms are 60 mm by 500 m; males are 35mm by 300 m in size. the circulating microfilaria are 300 m by 7 m; the infective larvae in the fly are 200 m by 30 m.Host: human Vector: deer flyMode of transmission: By the bite of an infective deer fly with microfilaria

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Life cycle45

Clinical symptomsOften asymptomaticLymphedemaEpisodic andioedema (Calabar swelling)Pain, redness and itching around swellingSubconjuctival migration of an adult worm to the eyes EosinophiliaChronic abscesses (dead worms)Granulomatous reaction and fibrosisLoa loa in subconjunctival tissues. 46

SummaryOrganismTransmissionSymptomsDiagnosisTreatmentAscaris lumbricoides Oro-fecalAbdominal pain, weight loss, distended abdomenStool: corticoid oval egg (40-70x35-50 m)MebendazoleTrichinella spiralisPoorly cooked porkDepends on worm location and burden: gastroenteritis; edema, muscle pain, spasm; eosinophilia, tachycardia, fever, chill headache, vertigo, delirium, coma, etc.Medical history, eosinophilia, muscle biopsy, serologycorticosteroid and MebendazoleTrichuris trichiura Oro-fecalAbdominal pain, bloody diarrhea, prolapsed rectumStool: lemon-shaped egg (50-55 x 20-25m)MebendazoleEnterobius vermicularis Oro-fecalPeri-anal pruritus, rare abdominal pain, nausea vomitingStool: embryonated eggs (60x27 m), flat on one sidePyrental pamoate or MebendazoleStrongyloides stercoralis Soil-skin, autoinfectionItching at infection site, rash due to larval migration, verminous pneumonia, mid-epigastric pain, nausea, vomiting, bloody dysentery, weight loss and anemiaStool: rhabditiform larvae (250x 20-25m)Ivermectin or ThiabendazoleNecator americanes; Ancylostoma duodenale(Hookworms)Oro-fecal (egg); skin penetration (larvae)Maculopapular erythema (ground itch), broncho-pneumonitis, epigastric pain, GI hemorrhage, anemia, edemaStool: oval segmented eggs (60 x 30 20-25m)MebendazoleDracunculus medinensisOral: cyclops in waterBlistering skin, irritation, inflammationPhysical examinationMebendazoleWuchereria bancrofti; W. brugia malayi(elephantiasis)Mosquito biteRecurrent fever, lymph-adenitis, splenomegaly, lymphedema, elephantiasisMedical history, physical examination, microfilaria in blood (night sample)Mebendazole; Diethyl-carbamazineOnchocerca volvulusBlack fly biteNodular and erythematous dermal lesions, eosinophilia, urticaria, blindnessMedical history, physical examination, microfilaria in nodular aspirateMebendazole; Diethyl-carbamazineLoa loaDeer flyAs in onchocerciasisAs in onchocerciasisAs above

References1. Lazarev K.L Medical biology: textbook 2nd ed. Simferopol: IAD CSMU, 2003. 592p.2. M. Grytsiuk, V .Pishak Fundamentals of medical parasitology, Chernivtsi, 2010. 194p.3. Zaporzhan V.M. Medical bioogy Odessa, 2006. 350p.4. Jayaram Paniker C.K. A textbook of medical parasitology 5th ed. New Delhi, 2004. 221p.5. Chaterjee K.D. Parasitology and helmintology -12th ed. Calcutta,1990. 238p.6. Caramello P. Atlas of medical Parasitology. Totino, 2000 (www).7. Ichpujani R.L., Rajesh Bhatia Medical parasitology New Delhi, 2003. 309p

FOOD FOR THOUGHT"Disease is the warning, and therefore the friend - not the enemy - of mankind" Dr. George S. Weger

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