Transcript Microscopy

Intestinal Flukes
• Causal Agent:
The trematode Heterophyes heterophyes, a minute
intestinal fluke .
• Adults (measuring 1.0 to 1.7 mm by 0.3 to 0.4 mm) .
•
In addition to humans, various fish-eating mammals
(e.g., cats and dogs) and birds can be infected by
Heterophyes heterophyes .
Adult of Heterophyes heterophyes
Metacercaria
Life Cycle
Geographic Distribution:
Egypt, the Middle East, and Far East.
• Clinical Features:
• The main symptoms are diarrhea and colicky abdominal pain.
•
Migration of the eggs to the heart, resulting in potentially fatal
myocardial and valvular damage, has been reported from the
Philippines.
•
Migration to other organs (e.g., brain) has also been reported.
Laboratory Diagnosis
The diagnosis is based on the microscopic identification
of eggs in the stool.
However, the eggs are indistinguishable from those of
Metagonimus yokogawai and resemble those of
Clonorchis and Opisthorchis.
• Treatment:
Praziquantel* is the drug of choice.
Metagonimus yokogawai
• Causal Agent:
a minute intestinal fluke (and the smallest human fluke).
• Adults (measuring 1.0 mm to 2.5 mm by 0.4 mm to 0.75 mm)
.
•
Snails of the genus Semisulcospira are the most frequent
intermediate host for Metagonimus yokogawai.
•
In addition to humans, fish-eating mammals (e.g., cats and
dogs) and birds can also be infected by M. yokogawai .
Metagonimus yokogawai Adult
Egg
Life Cycle
Geographic Distribution:
Mostly the Far East, as well as Siberia, Manchuria, the
Balkan states, Israel, and Spain.
• Clinical Features:
The main symptoms are diarrhea and colicky abdominal
pain.
Migration of the eggs to extra intestinal sites (heart,
brain) can occur, with resulting symptoms.
Laboratory Diagnosis
• The diagnosis is based on the microscopic
identification of eggs in the stool.
• However, the eggs are indistinguishable from those
of Heterophyes heterophyes and resemble those of
Clonorchis and Opisthorchis.
• Specific diagnosis is based on identification of the
adult fluke evacuated after antihelminthic therapy, or
found at autopsy.
Laboratory
Diagnosis
Metagonimus yokogawai, adult fluke is resemble Heterophyes heterophyes.
An important distinctive feature is the position of the ventral sucker, which is
to the side of the midline with its axis in a diagonal line
Treatment:
Praziquantel* is the drug of choice
Fasciolopsis buski
• Causal Agent:
The trematode Fasciolopsis buski, the largest
intestinal fluke of humans.
• Adult flukes (20 to 75 mm by 8 to 20 mm) in
approximately 3 months,
• attached to the intestinal wall of the mammalian
hosts (humans and pigs) . The adults have a life
span of about one year.
Adult worm
Egg
Life Cycle
Geographic Distribution
• Asia and the Indian subcontinent, especially in areas
where humans raise pigs and consume freshwater
plants.
• Clinical Features
• Most infections are light and asymptomatic.
•
In heavier infections, symptoms include diarrhea,
abdominal pain, fever, ascites, edema and intestinal
obstruction.
Laboratory Diagnosis
• Microscopic identification
of eggs, or more rarely of
the adult flukes, in the stool
or vomitus is the basis of
specific diagnosis.
• The eggs are
indistinguishable from
those of Fasciola hepatica
Paragonimus westermani
• Causal Agent:
More than 30 species of trematodes (flukes) of the genus
Paragonimus have been reported which infect animals and
humans.
• Among the more than 10 species reported to infect humans,
the most common is P. westermani, the oriental lung fluke
• Adults (7.5 to 12 mm by 4 to 6 mm).
•
The worms can also reach other organs and tissues, such as
the brain and striated muscles, respectively.
Adult worm
Intermediate host & Metacercaria
Geographic Distribution
• While P. westermani occurs in the Far East,
other species of Paragonimus are encountered
in Asia, the Americas, and Africa.
Life Cycle:
Life Cycle:
Clinical Features
• The acute phase (invasion and migration) may be marked by
diarrhea, abdominal pain, fever, cough, urticaria,
hepatosplenomegaly, pulmonary abnormalities, and
eosinophilia.
•
During the chronic phase, pulmonary manifestations include
cough, expectoration of discolored sputum, hemoptysis, and
chest radiographic abnormalities.
•
Extrapulmonary locations of the adult worms result in more
severe manifestations, especially when the brain is involved.
Laboratory Diagnosis
• Diagnosis is based on microscopic demonstration of
eggs in stool or sputum, but these are not present until
2 to 3 months after infection.
• (Eggs are also occasionally encountered in effusion
fluid or biopsy material.)
•
Concentration techniques may be necessary in
patients with light infections.
• Biopsy may allow diagnostic confirmation and
species identification when an adult or developing
fluke is recovered.
Microscopy
Egg of Paragonimus westermani.
•
A
They are yellow-brown, ovoidal or elongate,
with a thick shell, and often asymmetrical
with one end slightly flattened.
At the large end, the operculum is clearly
visible. The opposite (abopercular) end is
thickened. The eggs of P. westermani are
excreted unembryonated.
A
Treatment:
Praziquantel* is the drug of choice to treat paragonimiasis