1. No category

Trematodes (Flukes)
Parasitology III.
Judit Szabó
Fasciola hepatica
Schistosoma
Paragonimus westermani
2013.
General details
hermaphroditic (except: schistosoma)
sexual cycle in humans, asexual cycle in
freshwater snails
Stages:
egg
miracidium
sporocyst
redia
cercaria
mature worm
Life cycle of
Fasciola hepatica
Fasciola hepatica
(liver fluke)
Liver infection in sheep cattle, ( Latin America, Africa, China,
Europe)
transmission: by eating raw sheep liver or aquatic vegetation
Symptoms
most infections are asymptomatic
liver pain
fever
hepatomegaly
obstructive jaundice
eosinophilia
Diagnosis and treatment
Diagnosis:
identification of eggs in the feces
Treatment:
praziquantel,
bithional
Schistosomiasis
Schistosoma (blood flukes)
S. haematobium (bladder veins)
S. mansoni (inferior mesent. venules)
S. japonicum (superior mesent. veins)
Geographical distribution of
S. mansoni
bilharsiasis
transmission:
larvae penetrate into skin
in Africa, Asia, Latin America
150 million infected people
separated sexes (male and female)
Geographical distribution
S. haematobium
Geographical distribution
S. japonicum
Life cycle of Schistosoma
Symptoms of acute stage
usually asymptomatic
dermatitis (Katayama-fever): itching
2-3 weeks later fever, chills, diarrhea,
lymphadenopathy, hepatosplenomegaly,
eosinophilia
Symptoms of chronic stage
S. haematobium egg
•gastrointestinal hemorrhage,
hepatosplenomegaly
•portal hypertension
(liver functions remain normal)
•fibrosis or bladder carcinoma,
hematuria
large,
terminal spine
the mortality rate is high
S. mansoni egg
large,
lateral spine
S. japonicum egg
small, lateral
spine
Diagnosis and treatment
Paragonimus westermani
(lung fluke)
Diagnosis: finding of eggs in feces or urine
paragonimiasis
transmission: eating raw or undercooked crab
meat
Treatment: praziquantel
Geographical distribution of
paragonimiasis
Symptoms
chronic cough
bloody sputum
dyspnea, cyanosis
pleuritic chest pain
bacterial pneumonia
eosinophilia
Life cycle of Paragonimus
Diagnosis and treatment
Diagnosis:
finding of eggs
in sputum or feces
Treatment:
praziquantel
General details
Roundworms
Enterobius vermicularis
Ascaris lumbricoides
Trichuris trichiura
Toxocara
Ancylostoma duodenale
Necator americanus
Strongyloides stercoralis
Trichinella spiralis
Filarial worms
separated sexes (male and female)
the male usually shorter
the male has a typically coiled tail
complete digestive tract (mouth,
anus)
cylindrical body
cuticule (resistant coating)
Embrional development of eggs
Geohelminth worms
ovipar: the egg immature (eg. Ascaris
lumbricoides)
ovovivipar: the egg is mature
(eg. Enterobius vermicularis)
vivipar: no egg, the female deposits
larvae
(eg. Trichinella spiralis, filarial worms)
Geohelminth: maturation of the egg in
the soils
Ascaris lumbricoides
Trichuris trichiura
Toxocara canis és Toxocara cati
Ancylostoma duodenale
Necator americanus
Strongyloides stercoralis
Enterobius vermicularis
(pinworm)
•
•
•
enterobiasis
500 million infected people
egg survives at room temperature
for 1-2 weeks
Source of infection:
ingestion of eggs
•
•
children most commonly affected
ab ano ad os autoreinfection
2-10 mm
Life cycle of enterobius
Symptoms
Diagnosis and treatment
can be symptomless
perianal itching
enuresis nocturna (neurosis)
secondary bacterial infection (due to
scratching)
complication: appendicitis
Trichuris trichiura (whip worm)
Diagnosis:
perianal Scotch tape (not feces!)
demonstration of the eggs
Treatment:
mebendazole
Life cycle of Trichuris
trichiuriasis
500 million people are
affected
geohelminth (5-6 weeks)
transmission:
ingestion of eggs with
contaminated water or
vegetables
Symptoms
usually asymptomatic
abdominal pain
diarrhea
rectal prolapse
loss of weight
eosinophilia
3-5 cm
Diagnosis and treatment
Diagnosis:
demonstration of eggs
in the stool
Treatment:
mebendazole
Ascaris lumbricoides
Life cycle of Ascaris
geohelminth (10-14 days)
transmission:
ingestion of eggs with
contaminated food or
water
15-25 cm
Symptoms
pneumonia
(Loeffler-pneumonia): fever, cough, bloody
sputum, eosinophilia
abdominal pain, diarrhea, loss of weight,
malnutrition
complication:
obstruction, perforation, peritonitis
Diagnosis and treatment
Diagnosis:
demonstration
of eggs
in the stool
Treatment:
thiabendazole (larva)
mebendazole (mature worm)