Intestinal flukes

Trematodes

Complex life cycle

intermediate hosts (mollusks)

Definitive hosts-mammals, humans and animals

morphological forms

adult worm- in definitive host

eggs- laid by adults gain access into water

larval stage- develops in water and enters to proper intermediate host for further development

Monoecious except schistosomes

Oviparous and lay eggs that are operculated (except schistosomes

Fasciolopsis buski

largest and most common intestinal fluke infecting humans

Found attached to mucosa of duodenum and jejunum of humans and pigs.

Morphology

ovoid and pinkish in colour when alive

two suckers (oral and ventral

most distinctive features- pair of highly- branched testes occupying posterior 2/3 of body •

Life span of 6 months

Fasciolopsiasis

Damage to intestinal mucosa by adults

Inflammation, ulceration and mucous secretion at site of intestine attachment

Severe infections with secretion of mucosa leading to partial obstruction of intestinal tract

Malabsorption leading to protein loss, impaired vitamin B12 absorption

Absorption of metabolites of fluke leading to toxaemia

Prophylactic measures

Avoidance of eating aquatic vegetations without proper cleaning

Proper sanitation and disposal of faeces

Echinostomes

Echinostoma malayanum

Characterized by

presence of spines on their cuticle

a circumoral disc at the anterior end that is surrounded by spinose processes

infected by ingesting metacercariae in the tissues of edible snails

Adult worms located in the small intestine where they attach to the mucous membrane by the anterior end

life cycle

Fascilopsis buski

  1. infections occurs as ingestion of metacercaria with raw freshaquatic vegetation
  1. excystation of metacercariae occurs in duodenum , attach to the wall of small intestine and develop into adult
  1. adult worms release unembryonated eggs which are passed in feces
  1. eggs develop into larvae (miracidium) in water and enter snail
  1. miracidium develops through stages of sporocyst and develop into cercariae
  1. cercariae escape from snail in water and encyst on aquatic plants and become metacercariae