PHYLUM PLATYHELMINTHES

CLASS CESTODEA/CESTODA

• Intestinal parasites of humans and other vertebrates.

Form and Functions

1. Body consist of an anterior attachment organ:a. SCOLEX- Head at the anterior end , equipped with hold fast organ to maintain the position of the parasite in the gut of the host.TYPES:ACETABULUM- cup shaped, circular or oval in outline and with heavy muscular wall; normally 4 per scolex.

SCOLEX TYPES

BOTHRIDIA- Muscular , projecting sharply from scolex with leaf-like margins. (in Group of 4)

BOTHRIA- Consist of shallow pits or longer grooves. (usually 2 up to 6)

Form and Functions

b. PROGLOTTIDSc. NECK- Between scolex and proglottid; contains germinal cells that are responsible for budding of new proglottids. d. STROBILA- Consist of a linear series of sets or reproductive organs of both sexes; each set is known as the GENITALIUM

GENITALIUM

a. APOLYSIS-When mature proglottids detaches and passed intact out the host.

b. PSEUDOAPOLYSIS/ ANOPOLYSIS- Eggs released through gravid segment through uterine pore; segment detaches only when senile or exhausted.

c. HYPERPOLYSIS- Segments shed while immature and lead independent existence.

Form and Functions

2. Lacks digestive tracts; absorbs all required substance via their tegument with microtriches.3. Nervous system is primarily confined in the scolex, composed of complex set of ganglia with connecting commisures.4. Monoecious, usually protandric, some are gynandric.

ORDER PSEUDOPHYLLIDEA

• Have scolex with dorsal and ventral longitudinal grooves: BOTHRIA

• Life cycle involve:First Intermediate Host- CrustaceansSecond Intermediate Host- Fish

Family Diphyllobothrium latum

- Broad fish Tapeworm- Common in fish eating carnivores particularly

in Northern Europe- Lack host specificity; Occours in many canines

and felines, mustelids, pinnipeds, bears and humans.

Mustelids

MORPHOLOGY• Can reach to a length of 10 meters and can

shed in the region of one million eggs per day• Anapolytic which means they shed their spent

proglottids.• Scolex is finger-shaped with bothria on the

dorsal and ventral surfaces.• Proglottids are wider than they are long in

numerous testis and vittellaria.• With bilobed ovary

PATHOGENESIS

• Assmptomatic or have poorly defined symptoms

• Non-specific abdominal symptoms:- Vague abdominal discomfort- Diarrhea- Weakness- Nausea- Pernicious Anemia

DIAGNOSTICS- Fecalysis – Demo of characteristic egg in the

stoolTREATMENT- Niclosamide;Inhibition of an inorganic

phosphate ATP exchange reaction associated with worms metabolism.

- Praziquantel- Aspidium Oleoresin

SPARGANOSIS• Has been reported to occur in many countries

but it is most common in eastern Asia. • Human become Intermediate HostINFECTION OCCURS IN SEVERAL WAYS:- Drinking water infected with copepods- Eating raw undercooked second Intermediate

host.- Parasite can penetrate the skin (Broken skin)- Direct contact with Infected vertebrates

SPARGANUM LARVA

• Wrinkled, whitish ribbon-shaped organism, a few mm and up to several cm long.

• Cxommon site is subcutaneous tissue and fascia of;

Abdominal WallThoracic WallLower LimbsNeck & Scrotum

Symptoms

• Cerebral Sparganosis: Headache, generalized seizure, Hemiparesis, Dysarthria, Tonic/Clonic seizure, Hemianopsia, Focal Seizure, Mental retardation.

• Subcutaneous Sparganosis: Palpable mass that is migrating or fixed, Indolent, redness, Itchy; can be complicated by abscess formation and cutaneous hemorrhage.

TREATMENT

• Surgical removal• Praziquantel

ORDER CYCLOPHYLLIDEA

• With single, compact vitelline gland• Scolex with 4 suckers• Rostellum armed with hooks• Tapeworm of birds and mammals

Family Taeniidae

• Where the largest cyclophyllideans are• Mammals serve as intermediate host• Rostellum is armed and non retractable;

numerous testes; bilobed mass ovary near the posterior end .

Taeniarrhyncus saginatus

• “Beef tapeworm”• Most common taeniid in humansMORPHOLOGYLack rostellum or any scolex armature10-15 feet (can reach 75 ft.) as many as 2000

proglottid each wormWith four powerful suckers, followed by long

slender neck.

CYTICERCUS/ BLADDER WORM

• White, pearly; 10 mm in diameter with single invaginated scolex causes Cysticercosis Bovis

• Cysticercus can survive for several years in the animal.

• Human become infected by ingesting raw or undercooked infected meat.

• In human intestine, the cysticercus develops over 2 months into adult tapeworm and can survive more than 30 years.

PATHOLOGY

• Adult worms in humans cause no serious symptoms

Vague abdominal discomfortHunger painsChronic indigestion/ dispepsiaLoss of appetiteVerminous intoxication

Dizziness, Headache, Abdominal pain, Nausea

Diagnosis

• Fecalysis– Egg identification and examination of the scolex or

gravid proglottid.

Tainea solium

• “Pork Tapeworm”• Most potentially dangerous to humans,

possibly of self infection with cysticerci.Morphology:Adult with non retractable scolex with 2 circles

of 22-23 hooksScolex is spheroid and smallerStrobila: 6 to 10 ft. cans reach as long as 30 ft.

CYSTICERCOSIS

• Infection occurs when the tapeworm larvae enter the body and form cysticerci:

a) Ingestion of food, water contaminated with pork tapeworm egg, or putting contaminated fingers to mouth .

b) Person who has a tapeworm infection can reinfect themselves; gravid proglottid may migrate from lower intestines to stomach or doudenum.

Once inside the stomach , the tapeworm egg hatches , penetrates the intestine, travels trough blood stream and may develop into cysticerci in the subcutaneous tissue, muscles, brain, eyes, heart, liver, lungs.

TYPES

• SUBCUTANEOUS CYST– Easily palpated, lipomas

• Management (surgical removal)

• OCULAR CYSTICERCOSIS– May cause irreparable damage to retina, iris uvea or

choroid.– Visual difficulties that fluctuate with eye position– Decrease in visual acuity– Retinal detachment, edema, hemorrhage, or vasculitis

SUBCUTANEOUS CYST

OCULAR CYSTICERCOSIS

• NEUROCYSTICERCOSIS (NCC)– Symptoms are vague, rarely diagnose except in autopsy– Clinical manifestations are:

• Seizures (80%)• Headache (40%)• Visual changes (20%)• Confusion (15%)• Ataxia (5%), (Psychosis 5%)• S/S of Hydrocephalus• Decrease GCS• Increase ICP

• MUSCLES– Majority are asymptomatic– May give rise to MYOSITIS with accompanying

fever and eosinophilia– PSEUDOHYPERTROPHY- Rare because of

autoimmune response• Process- Swelling then leading to atrophy then become

fibrotic.

• DIAGNOSIS– Imaging study: CT scan, MRI– Serum analysis- Presence of cysticercosis antibody• False positive in some places that are endemic

– CSF analysis

TREATMENT

• Plaziquantel• Albendazole• Prednisone- to supress excessive immune response• Hydrocephalus- VP shuntCONTROLSanitation- Universal precautionCooking pork meat properlyProper storage of meat

Echinococcus multilocularis

• Boreal in distribution: In Europe, Asia, North America.

• ADULT- Parasites of foxes (Felines, Coyotes and Canines may also serve as definitive host)

• HYDATID CYST: In small rodents also wolves, lemmings and mice.

• Characteristics:– 1.2-1.3 mm long– 15-30 testes located posterior to cirrus pouch– Hydatid larvae: with thin outer wall that grows and

infiltrates processes into sorrounding host tissue: ALVEOLAR or MULTILOCULAR HYDATID

– In humans, pieces of the cyst sometimes breaks off and metastasize to other parts of the body.

– Dogs are the most common source of infections to humans.

E. vogeli

• Parasites of canids in Central and South America

• Rarely cause hydatidosis in humans; but dogs are the source of human infection.

• Polycystic (alveolar) in humans but produce relatively large, fluid filled vesicles with numerous protoscolices

• Natural intermediate host: Rodent (Paca)

GENUS ECHINOCOCCUS

• Pathogenesis: Hydatidosis– Depend on type and extent of pathology– Hydatid effects may not be apparent for many yrs.

(up to 20 yrs.)– As size of hydatid increases it crowds adjacent

host tissues and interferes with their normal developmental functions

• In Bone Marrow– Growth restricted to internal space resulting to

chronic internal pressure necrosis of bone; bone becomes thin and fragile leading to spontaneous fracture.

• In Unrestricted Areas:– May become enormous, accumulate a large

amount of fluid (HYDATID FLUID) may rupture, cause sudden death.

• Anaphylactic shock:– Protienaceous hydatid fluid induces adverse host

reaction.• Pulmonary Cysts:– When ruptures in bronchioles severe allergic

reaction symptoms and coughing with production of blood flecked fluid.

• Diagnosis– Routine medical x-ray, UTZ– Surgical exploration and aspiration for possible

hydatid sand– Serological test: ELISA, IHA, EIA, IFA

• Treatment– Surgery– Albendazole

Family Hymenolepidea

• Small number of testes (1-4)• Unilateral genital pores• Large external seminal vesicle

Vamperolepsis nana

• Dwarf tapeworm • Probably the most abundant tapeworm in the world

commonly found in young children• Infection rates vary widely with less than 1% of the

North American population being infected, while other Hot spots specially developing countries estimated that over 90% of the population are infected.

• Produces only mild symptoms of intestinal discomfort.

• Morphology:1. Adult: Approximate length 35mm. The

tapeworms body (strobilla) consist of proglottids in various stages of development• The scolex has four suckers and an armed retractable

rostellum with only one row of hooks (about 20-30 hooks)

• Neck long and slender , proglottids are wider than long• Genital pores, unilateral, each mature segment with 3

testes

2. Egg: 40-70 um in diameter; with presence of polar filaments in t6he area between the outside shell and the internal larva.

3. Oncosphere: Covered with thin, outer hyaline membrane and an inner thick membrane with polar thickenings with several

filament.

• PATHOLOGY– Little pathology associated with this parasite unless it

trough autoinfection.• Symptoms:

– Abdominal Pain– Diarrhea – Headache and dizziness– Anorexia– Various non specific symptoms

– TREATMENT• Niclosinamide• Praziquantel