TREMATODES -2-
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Transcript of TREMATODES -2-
TREMATODESTREMATODES-2--2-
Fasciola hepaticaFasciola hepatica
Dicrocoelium dendriticumDicrocoelium dendriticum
Clonorchis sppClonorchis sppParagonimus spp
Doç.Dr.Hrisi BAHARDoç.Dr.Hrisi BAHAR
Fasciola hepatica and F. gigantica are bile duct parasites of domestic ruminants.In their life cycle freshwater snails act as intermediate host Humans become accidentally infected when they eat plants to which infectious parasite stages (metacercariae) adhere
Dicrocoelium dendriticum is a bile duct parasite in sheep,cattle, and other herbivores, Its life cycle includes two intermediate hosts (terrestrial snails and ants). Humans become infected accidentally when they ingest ants containing infective metacercariae of the lancet liver fluke.
Fasciola hepaticaF. hepatica is a flattened,leaf-shaped parasite
about 2–5 cm long and at most1 cm wide.
Dicrocoelium dendriticum
The lancet liver fluke (0.5–1.0 ! 0.2 cm)
Fasciola hepatica egg Dicrocoelium dendriticum egg
Life cycle of Fasciola hepatica
Adult liver flukes parasitize in the bile ducts. They produce large golden brown, operculated eggs that are shed by the bile duct-intestinal tract route. Under favorable conditions, a ciliate larva, the miracidium, develops in the egg within a few weeks. The miracidia then hatch and penetrate into freshwater snails where they transform into sporocysts.
Life cycle of Fasciola hepatica
After formation of further asexual reproductivestages, tailed cercariae develop and swarm outof the snails into the open water. They soon attach to plants and encyst,
transforminto infective metacercariae, which are theningested with vegetable food of their definitivehosts. Eating watercress contaminated with
metacercariaeis one of the sources of infection for humans.
Life cycle of Fasciola hepatica
The juvenile liver flukes hatch from the cyst in thesmall intestine, penetrate the intestinal wall, andmigrate through the peritoneal cavity to the liver.After migrating through the hepatic parenchymafor about six to seven weeks, the parasites finallyreach the bile ducts, in which they developto sexual maturity.Egg excretion begins two to three months
Life cycle of Life cycle of Dicrocoelium dendriticum
It stands apart from most trematodes since it has a landIt stands apart from most trematodes since it has a landbased life cycle. The definitive host's feces containbased life cycle. The definitive host's feces containmiracidia which do not hatch until after they are eaten miracidia which do not hatch until after they are eaten
bybythe first intermediate host, a land snail, the first intermediate host, a land snail,
The miracidium emerges inside the intestine of the snailThe miracidium emerges inside the intestine of the snailand metamorphoses into a sporocyst and than intoand metamorphoses into a sporocyst and than intocercaria.cercaria.
The second intermediate host is the common brown ant,The second intermediate host is the common brown ant,There cercaria turns to metacercaria. There cercaria turns to metacercaria. Upon ingestion by the definitive host, the metacercariaUpon ingestion by the definitive host, the metacercariaarrive in the duodenum and migrate up the common arrive in the duodenum and migrate up the common
bilebileduct to the liver. The adult fluke matures in 6-7 weeks,duct to the liver. The adult fluke matures in 6-7 weeks,producing egg capsules about a month later. producing egg capsules about a month later.
Fasciola hepaticaEating watercress contaminated with metacercariae is one of the sources of infection
for humans.
Dicrocoelium dendriticum
Humans become infected accidentally when they ingestants containing infective metacercariae of the lancet liverfluke.
Such infections are rare and either run an asymptomaticcourse or manifest in mild abdominal and hepaticsymptoms.
• Fasiola hepatica in liverFasiola hepatica in liver
Fasiola hepatica in liver
Diagnosis of Fasciola infection . The manifestations to be expected during the migration phase of the liver fluke include mainly leukocytosis, eosinophilia, and a rise in liverspecific serum enzymes. Detection of eggs in stool or duodenalfluid is not possible until at least two to three months . Other diagnostic tools include detection of serum antibodies and of coproantigen in stool.
Diagnosis of Dicrocoelium infection. Diagnosis is basedon detection of eggs in stool (about 40 25 µm, oval, darkbrown containing a miracidium with two rounded germinalcells) Ingestion of contamined beef or mutton liver canresult in egg excretion in stool without infection.This is intestinal passage.
Treatment of Fasciola infection
The drug of choice is triclabendazole, the infection can be avoided by not eating raw watercress and other plants that may be contaminated with metacercariae.
Treatment of Dicrocoelium infection
Praziquantel has been shown to be effective
against Dicrocoelium in animals .
Clonorchis sppClonorchis spp
Liver flukes of the genera Clonorchis occur mainly in
river and lake regions of Asia and Eastern Europe.
The definitive hosts of Clonorchis species are fisheating mammals like cats,dogs, pigs, and
humans,inwhich these trematodes colonize the bile ducts.
Clonorchis sppClonorchis spp
The life cycle of these organisms involves variousspecies of aquatic snails as the first intermediatehosts and freshwaterfish species as the secondintermediate hosts.
The infective metacercariae are localized in themusculature of the fish and,when raw fish isingested, enter the intestinal tract of the definitivehost, they migrate through the common bile duct
Clonorchis spp eggClonorchis spp egg
Clonorchis sppClonorchis spp
Pathogenesis and clinical manifestationsPathogenesis and clinical manifestations..
Clonorchis infections cause proliferations of the bile duct epithelium,cystlike dilatation, inflammation,and fibrosis of the bile duct walls aswell as connective tissue proliferation in the hepatic parenchyma. A high incidence of bile duct carcinomas has been reported from areasin which C. sinensis are endemic.
Clinical symptoms of more severe infections include variable fever,hepatocholangitic symptoms with hepatomegaly, leukocytosis, upperpains, and diarrhea.
Clonorchis sppClonorchis spp
Diagnosis, therapy, and preventionDiagnosis is made by detection of eggs (26–32 lm long) in
stool or duodenal fluid
Therapy and preventionThe drug of choice is praziquantel; albendazole can also
beused. Reliable preventive measures include boiling or frying
fishto kill the metacercariae, which die at temperatures aslowas 70 C, and freezing to –10 8C for five days.
Paragonimus sp (Lung Flukes)
Lung flukes of the genus Paragonimus are endemic in
parts of Asia, Africa, and America.
Parasitize in pulmonary cysts and cause atuberculosis-like clinical picture.
Following development in two intermediatehosts(freshwater snailsband crabs or crayfish),infective stages (metacercariae) can be transmitted
tohumans by eating the crabs or crayfish uncooked. Parasite eggs are detectable in sputum or stool.
Paragonimus sp (Lung Flukes)
The sexually mature parasites live in cystlikedilatations in the lungs,usually in connectionwith the bronchial tree. The yellow-brown, operculated eggs laid bythe adultworms are shed either in sputum orstool.
Paragonimus sp.adult and Paragonimus sp.adult and eggegg• eggegg
Adult
egg
Paragonimus sp (Lung Flukes)The life cycle then continues in water,where a miracidium develops in each egg,hatches and invades an intermediatebhost.Egg-shaped cercariae with short tails developin the first intermediate host, a freshwatersnail.The cercariae encyst in the second intermediatehost like crayfish or crabs to form the infectiveMetacercariae.
Paragonimus sp
When a suitable definitive host ingests thecrustaceans uncooked, the young trematodeshatch in the small intestine,migrate through theperitoneal cavity to the diaphragm and finally
intothe lungs. The prepatent period is two to three months.Parasites that deviate from the normal migrationroute may enter other organs.
Paragonimus sp
Besides humans, crustacean eating mammals playa significant epidemiological role as reservoirhosts.
Young lung flukes can be localized in themusculature of pigs and other “transport hosts”
andbe transmitted to humans who ingest the raw
meatof these animals.
Clinical manifestations. Typical cases areclinically characterized by pulmonary symptomschronic cough, bloody expectoration, thoracic
pain.Parasites following the normal or deviant
migrationroutes can also cause abdominal,hepatic,pancreatic or CNS symptoms, or skin lesions likeswelling, nodules.
Paragonimus sp
Diagnosis, therapy, and prevention.
An etiological diagnosis is based on detection of eggs insputum or stool and of serum antibodies.
Regarding the differential diagnosis especially tuberculosis
must be kept in mind.
The drug of choice is praziquantel, but triclabendazolem can also be used .
Cooking crustaceans before eating them is a reliablepreventive measure.
Paragonimus sp