Lecture 56 - 3rd Asessment - Cestodes

CESTODES GENERAL: Adults: Intestine; Larvae: tissues of vertebrates. proglottids, hermaphroditic, genital opening, flattened dorso-ventrally,

scolex-suckers/hooks.

PHYSIOLOGY: Adults in lumen - anaerobic metabolism. Nourishment from semi-digested food, distal portion for attachment). from intestinal contents.

Segments-

Glycogen from dextrose.

tegument with microtriches (proximal-

Proteins from ntestinal mucosa,

carbohydrates

Starvation reduces parasites.

Larvae-nourishment from host tissue.

Reproductive organs highly developed.

LIFE CYCLE: Intermediate host (exception?). PATHOGENICITY: Adults: Minimal,

Larvae solid or vesicular.

no definite systemic effects (toxic?),

D. latum.

Vit. B12 deficiency.

a. Attachment of scoleces-avenue of bacterial invasion. b. Strobila-temporary intestinal obstruction. c. Vague GIT and nervous symptoms. d. Lowered vitality and anemia eg. D. latum. Larvae: Serious disease-Cysticerci in brain (tumour?) Pressure symptoms; shock, dissemination. SYMPTOMS: Due to toxic products of worm, mechanical irritation, deprive host of food (proteins,Vitamins etc.). RESISTANCE / IMMUNITY: Larvae provoke immunological response. Physiochemical environment for susceptibility. important for hatching ova, oncosphere.

eg.

proteolytic enzymes bile to activate

“Crowding effect”. Larvae: No striking cellular response. complete,

Barrier between larvae and tissue not

host proteins in cyst fluid and leakage of antigen. Complement consumed-evade immune response? DIAGNOSIS: Scolex,

proglottids, ova. Larvae: serology, tests interpretation.

ADULT CESTODES Species: Taenia solium,

Taenia saginata

T. SOLIUM GEOG. DISTRIBUTION: MORPHOLOGY: Scolex,

Gravid proglottid, Ova (thin hyaline membrane)

LIFE CYCLE: Ova from uterus-on soil,

hogs ingest,

emergent oncosphere into

intestinal wall, mesenteric venules, all over body, Cysticerci: Ingested,

filter out between muscles-60 to 70 days.

upper jejunum, head evaginates.

Proglottids: 5-12 w. PATHOGENESIS: None. vague, anorexia? eosinophilia ?, scolex perforates wall ? DIAGNOSIS:

Ova (species diagnosis ?), proglottids/scolex (after treatment?)

TREATMENT: Beware of rupture of segment.

T. SAGINATA MORPHOLOGY: Scolex,

proglottid,

size 25 m.

IMPORTANCE: 40 to 60 million infected. PATHOGENESIS: Larger size, appendix,

nutritional loss, intestinal blockage,

systemic intoxication (absorbed byproducts),

diarrhoea.

discomfort,

embrassment. DIAGNOSIS: Ova (species diagnosis),

sellotape swab, gravid proglottid/scolex.

TREATMENT: Praziquantel-single dose.

HYMENOLEPIS NANA GEOG. DISTRIBUTION: Kuwait, HABITAT:

HABITAT: Small intestine.

MORPHOLOGY: Size: 1-4 cm; ova; Scolex: 4 suckers/hooks.

LIFE CYCLE: Ova ingested, hexacanth embryo burrows into ant part of SI, 4 days to cysticercoid (solid), villus ruptures, larva in intestine, adults, ova passed out. PATHOGENICITY: Enteritis,

vague abdominal symptoms.

TREATMENT: Niclosamide: 5 days; PREVENTION: Hygiene,

Autoinfection.

Praziquantel: single dose.

treatment,

environmental sanitation,

safeguarding food from rodent faecal contamination.

H. DIMINUTA GEOG. DISTRIBUTION: Adults larger;

Scolex rostellum with no hooks.

LIFE CYCLE: Rat and mouse fleas intermediate host.

Cerocysts (cysticercoid).

Infected by food or hands with insects. DIAGNOSIS: Size,

Ova with no polar filaments.

DIPHYLLOBOTHRIUM LATUM GEOG. DISTRIBUTION: Temperate lake areas. MORPHOLOGY: Ova with operculum; Scolex: suctorial grooves; Proglottid shape / structure. LIFE CYCLE: Ova, from operculum,

ciliated embryophore hatches as coracidium,

cyclops (develops into procercoid), plerocercoid,

ingested by fresh-water fish,develops into

eaten,

larva attaches to intestine,

develops into adults.

PATHOLOGY: Minor clinical symptoms: Pernicious hyperchromic anemia due to vit B12 deficiency-attached in jejunum, DIAGNOSIS: Ova operculate, TREATMENT: Niclosamide

competes with host. proglottids rare.