CESTODES

GEN. CHARACTERISTICS1. MORPHOLOGY

A. head and scolex- For attachment to

intestinal mucosa B. neck

- Region of growthC. proglottids or segments

- No alimentary and vascular system

- Have nervous system- In gravid segments:

male and female organs seen(hermaphroditic)

- Series of segments = STROBILA

- Eggs are non-operculated EXCEPT for Diphyllobothrium latum

• 2. LIFE CYCLE– Requires 1 intermediate host EXCEPT for

Diphyllobothrium latum (2 I.H) and Hymenolepis nana (no I.H)

3. TRANSMISSIONAlways accomplished by the oral routeUsually only 1 worm per person infected

ORDER PSEUDOPHYLLIDEA• Diphyllobothrium latum

– Broad or fish tapeworm– Disease: fish tapeworm infection– Largest tapeworm in man (3-10

meters)– Habitat: intestinal mucosa (ileum)– Morphology:

• Bothria or sucking groove• Spatulate scolex

• LIFE CYCLE

• CLINICAL MANIFESTATIONS:– Epigastic pain, abdominal cramps, vomiting,

weight loss, anemiaDIAGNOSIS:

Stool exam – recovery of proglottid or eggTREATMENT:

NiclosamidePREVENTION:Thorough cooking of freshwater fish

ORDER CYCLOPHYLLIDEAN• 1. Dipyllidium caninum

dog tapewormDISEASE: dipylidiasis or dog tapeworm infectionCLINICAL MANIFESTATIONS:- Indigestion, loss of appetite

- Passage of progllotids in feces

• LIFE CYCLE

• DIAGNOSIS: stool exam• TREATMENT: -Niclosamide -Quinacrine PREVENTION: Insecticide dusting of dogs

• 2. Hymenolepis nana• -dwarf tapeworm• Smallest tapeworm (25-40

mm)• No I.H• TRANSMISSION:

– Ingestion of contaminated food and drinks

– Internal obstruction

LIFE CYCLE

• CLINICAL MANIFESTATIONS:• Periodic diarrhea• DIAGNOSIS:• - stool exam• TREATMENT:• Niclosamide• PREVENTION:• -personal hygiene

3. Taenia saginata• Beef tapeworm• Scolex has 4 suckers• Size: 4-6 meters long,

12 mm wide• Man is the only definite

host• Habitat: small intestine

(duodenojejunal area)

• LIFE CYCLE

• CLINICAL MANIFESTATIONS:• - Relatively benign compared to T.solium• - Epigastric pain, diarrhea, nausea,

irritability, weight loss• DIAGNOSIS:• - stool exam• TREATMENT: - Niclosamide, ParomomycinPREVENTION:• - thorough cooking of beef

Taenia solium• Pork tapeworm• Smaller than beef

tapeworm• Has circular row

of hooks(rostellum)

• Man- only definitive host

• Habitat: small intestine (jejunum)

• LIFE CYCLE

• CLINICAL MANIFESTATION:– Cysticercosis - larval migration to organs - brain: epilepsy, disordered behavior - eyes : failing vision: blindness- Upon death of parasite: fever, muscle pain,

eosinophilia- Intestinal obstructionDIAGNOSIS:

- Stool exam- Biopsy

• TREATMENT: – Niclosamide– Praziquantel– Mebendazole

PREVENTION:- thorough cooking of pork- personal hygiene

- general sanitary measures

TREMATODES (FLUKES)

GEN. CHARACTERISTICS• 1. All trematodes are dorsoventrally

flattened EXCEPT Schistosomes (cylindrical)

• 2. have 2 suckers– Oral and ventral suckers– For attachmentLIFE CYCLEa. Egg

-all TREMATODES lay an operculated ova except for Schistosomes(non-operculated)

• b. larva– Miracidium sporocyst redia cercaria

metacercaria

• C. adult• 4. Definitive host: man

– Harbors the adult worm– Infective stage: metacercaria except

Schistosoma(cercaria)

• 5. I. Host– Harbors the larval worm– All trematodes require 2 I.H except

Schistosomes(1)– 1st I.H: ALWAYS a snail

• Infective stage: miracidium• 2nd I.H.• Infective stage: metacercaria• Aquatic vegetation: Fasciola hepatica, Fasciolopsis

buski• Freshwater fish: Clonorchis sinensis• Clams or crabs: Paragonimus westermani

• 6. Manner of Transmission– Ingestion of metacercaria– Skin penetration of fork-tailed cercaria

LIVER FLUKES• 1. Fasciola hepatica

– Sheep liver fluke– Habitat: liver– Transmission: ingestion of

contaminated aquatic vegetation

– Clinical Manifestations:Colic, obstructive jaundice,

cough, vomitting

Life cycle

• DIAGNOSIS:– Stool exam– Bachman intradermal test– Complement fixation testTREATMENT:

Bithionol (drug of choice)Emetine hydrochloride

PraziquantelPREVENTION:

-Molluscides - Sanitary protection of waterbeds

2. Chlonorchis sinensis(Opistorchis sinensis)

• Chinese liver fluke• Size: 16x4 mm• Habitat: liver• Transmission: ingestion of raw or

inadequately cooked freshwater fish• Clinical Manifestations:

– Mild– Progressive – irregular appetite, fullness of

abdomen, diarrhea, edema, hepatomegaly– Severe – cirrhosis, portal hypertension

Immersion of vegetables in boiling water or thorough washing

- Avoid water chestnut in infected waters

LUNG FLUKE: Paragonimus westermani

• Oriental lung fluke• Habitat: lung• Disease:

Paragonimiasis• Transmission: eating

freshwater crabs

LIFE CYCLE:

• CLINICAL MANIFESTATION:– Productive cough occasionally blood-streaked

(hemoptysis)– Chest pain,night sweats, abdominal pain,

diarrhea, epilepsyDIAGNOSIS:

- Chest X-ray- Sputum exam- stool exam

TREATMENT: - Praziquantel